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DOCTORAL THESIS
INFRASTRUCTURE ANALYSIS FOR
RENEWABLE HYDROGEN PRODUCTION IN
PAKISTAN
IRFAN AHMAD GONDAL
05-UET-PhD-ME-25
Department Of Mechanical Engineering
Faculty Of Mechanical & Aeronautical Engineering
University Of Engineering & Technology
Taxila-Pakistan
June 2012
[1]
Table of Contents 1 INTRODUCTION ..................................................................................................................................... 6
1.1 General .......................................................................................................................................... 6
1.2 Objective Statement ..................................................................................................................... 9
1.3 Thesis development .................................................................................................................... 11
2 Hydrogen – Basics & Challenges ......................................................................................................... 13
2.1 Hydrogen-General ....................................................................................................................... 13
2.2 Properties-physical and chemical ............................................................................................... 13
2.2.1 Combustion properties ....................................................................................................... 13
2.3 Why Hydrogen Energy ................................................................................................................ 14
2.3.1 Organizational : ................................................................................................................... 19
2.3.2 Technical ............................................................................................................................. 19
2.3.3 Regulatory ........................................................................................................................... 20
2.3.4 Financial .............................................................................................................................. 20
2.4 Security of Energy supplies ......................................................................................................... 21
2.5 Climate Change ........................................................................................................................... 25
2.6 Atmospheric pollution ................................................................................................................ 30
2.7 Electricity Generation ................................................................................................................. 31
2.8 Conclusion ................................................................................................................................... 34
3 Hydrogen Production-Feed stocks & Processes ................................................................................. 35
3.1 Introduction ................................................................................................................................ 35
3.2 Hydrogen production from fossil fuels and biomass .................................................................. 37
3.2.1 Steam methane reforming .................................................................................................. 38
3.2.2 Partial Oxidation / Autothermal Reforming Of Methane ................................................... 39
3.3 Coal Gasification ......................................................................................................................... 40
3.4 Biomass Pyrolysis/Gasification ................................................................................................... 41
3.5 Hydrogen Production from Nuclear Heat and Alternative/Renewable Energy Sources ............ 42
3.6 Electrolysis .................................................................................................................................. 43
3.7 Sulfur-Iodine cycle ....................................................................................................................... 48
3.8 Photosynthetic / Photobiological................................................................................................ 49
3.9 Photocatalytic Water Splitting .................................................................................................... 50
[2]
3.10 International Hydrogen demonstration projects: ....................................................................... 52
3.10.1 Wind-to-hydrogen project .................................................................................................. 52
3.10.2 International projects ......................................................................................................... 54
3.11 Discussion .................................................................................................................................... 54
3.12 Conclusion ................................................................................................................................... 57
4 Renewable Resources of Pakistan-Assessing the H2 Potential ........................................................... 59
4.1 Introduction ................................................................................................................................ 59
4.2 Renewable Resource Potential ................................................................................................... 61
4.2.1 Solar Potential ..................................................................................................................... 62
4.2.2 Data Inferences: .................................................................................................................. 66
4.2.3 Wind Potential .................................................................................................................... 67
4.2.4 Major wind resource areas: ................................................................................................ 73
4.3 Renewable Hydrogen-An estimation .......................................................................................... 74
4.3.1 Calculation methodology .................................................................................................... 74
4.3.2 Solar hydrogen generation ................................................................................................. 76
4.3.3 Wind hydrogen estimation ................................................................................................. 78
4.4 Conclusion ................................................................................................................................... 79
5 Energy Infrastructure-Evolution, Evaluation & Development ............................................................ 81
5.1 Introduction ................................................................................................................................ 81
5.2 The challenging infrastructure .................................................................................................... 84
5.3 Infrastructure initiatives ............................................................................................................. 85
5.3.1 US Department of transportation ....................................................................................... 85
5.3.2 Anticipated long-term outcomes ........................................................................................ 85
5.4 Framework for Renewable Hydrogen infrastructure.................................................................. 88
5.4.1 Model Development ........................................................................................................... 88
5.4.2 Infrastructural Framework .................................................................................................. 92
5.4.3 Outward radiating distribution System: ............................................................................. 93
5.4.4 Optimization: (O3 for R3) .................................................................................................... 94
5.4.5 RESULTS ............................................................................................................................... 95
5.4.6 Future Work ........................................................................................................................ 95
5.5 DISCUSSION ................................................................................................................................. 96
6 Infrastructure Analysis ........................................................................................................................ 97
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6.1 General ........................................................................................................................................ 97
6.2 Distributed Vs Concentrated production .................................................................................... 97
6.2.1 Wide spread H2 Vs limited use ............................................................................................ 98
6.2.2 Spatial/Storage issues: ........................................................................................................ 99
6.2.3 Futuristic vision ................................................................................................................. 100
6.3 Natural gas infrastructure in Pakistan ...................................................................................... 101
6.3.1 General .............................................................................................................................. 101
6.3.2 Sui Northern Gas Pipelines Ltd (SNGPL)............................................................................ 101
6.3.3 Sui Southern Gas Company Ltd (SSGCL) ........................................................................... 104
6.4 Layout of Natural Gas Infrastructure ........................................................................................ 105
6.4.1 Compressors ..................................................................................................................... 108
6.5 Model Formulation ................................................................................................................... 109
6.5.1 Introduction ...................................................................................................................... 109
6.5.2 Model Build up .................................................................................................................. 110
6.5.3 Assumptions ...................................................................................................................... 111
6.5.4 Variables’ definition .......................................................................................................... 113
6.5.5 Constraints: ....................................................................................................................... 116
6.5.6 Database ........................................................................................................................... 118
6.5.7 Cost for elements of Hydrogen supply chain .................................................................... 119
6.5.8 Discussion .......................................................................................................................... 123
6.6 Gas pipeline Network ................................................................................................................ 127
6.6.1 Components & Terminology ............................................................................................. 127
6.6.2 H2 & Natural gas-Energetic attributes ............................................................................... 129
6.6.3 Pipeline material aspects in H2 distribution ...................................................................... 132
6.6.4 H2-Natural Gas mixtures by % volume .............................................................................. 134
6.6.5 Transition to 100% hydrogen transport in NG pipelines. ................................................. 137
6.7 Options for transmission & distribution of Hydrogen .............................................................. 138
6.7.1 Alternate energy systems ................................................................................................. 139
6.8 Conclusion ................................................................................................................................. 146
7 Summary of Conclusions & Recommendation ................................................................................. 148
7.1 Summary ................................................................................................................................... 148
7.2 Hydrogen Supply Chain-Infrastructural Analysis ...................................................................... 148
[4]
7.2.1 Renewable Resource Assessment ..................................................................................... 148
7.2.2 Integrated Renewable Hydrogen Network ....................................................................... 149
7.2.3 Gas Networks .................................................................................................................... 149
7.2.4 Biomass Based Renewable Hydrogen Model.................................................................... 149
7.2.5 Distribution and delivery................................................................................................... 150
7.2.6 Model application ............................................................................................................. 150
7.2.7 Transition to hydrogen economy ...................................................................................... 150
7.2.8 Recommendations ............................................................................................................ 151
7.3 Infrastructure Analysis & Recommendations ........................................................................... 152
7.4 Food for thought-Future research direction ............................................................................. 154
8 LIST OF APPENDICES ......................................................................................................................... 163
[5]
ABSTRACT
Energy being the life line of any flourishing economy is one of the foremost issues
faced by the developing and the developed world alike. Limited fossil fuel
reserves have constrained the energy planners to look for avenues that lead to
sustainable energy supplies. Hydrogen based on renewable resources is
purported to give a lasting solution to this problem.
The goal of this thesis is to present a representative and workable pathway to a
hydrogen economy based on renewable resources. In this regards an assessment
of wind and solar resources has been carried out. A Mixed integer non-linear
program has been developed as a tool for optimizing the hydrogen supply chain
based on biomass that can be used with a realistic Geographical Information
System. Pakistan being an agricultural economy has vast amounts of biomass
feed-stocks; however the major challenge exists in the form of its dispersed
locations. Subsequently after the processing of biomass, the produced hydrogen
has to be optimally dispensed to end users in energy consumption centers. Three
modes of hydrogen transportation have been discussed in the study namely as
gas mixtures in existing pipeline infrastructures, as methane in NG pipeline or as
methanol in liquid tank carriers.
It has been found that hydrogen can be produced from biomass at rates
competitive with steam methane reforming. The results can be refined with more
accurate and realistic statistical database of any region where the modeling tool is
employed. It has also been concluded that hydrogen can be transported as a
mixture with natural gas (without a major change over of material and hardware)
only in distribution network up to 17% by volume. Further the end-use appliances
i.e. burners etc. can tolerate up to 48% H2 mixtures with natural gas. Site specific
Multi-criteria Decision making (MCDM) techniques are recommended for
developing an integrated hydrogen supply chain for Pakistan.
[6]
CHAPTER 1 1 INTRODUCTION
1.1 General
Pakistan is facing a severe energy crisis with power shut down of up to 12 hours in
rural areas. The problem originated in 1980s and has compounded further ever
since with no end in sight. Initially it started with the lack of planning on part of
the Government with authorities like the then “Water and Power development
Authority (WAPDA)” not being alive to the looming crisis. However later as time
passed by, with the lack of political will as well, hydel power (most suitable for the
region comprising of several North-south flowing rivers) could not be developed
to cope up with the rising demand.
Gradually as world woke up to the “climate change scenario” and moved to the
“post-oil peak era” as well as “post-fossil fuel” era, Pakistan lagged even further.
As oil production crossed over the peak combined with 9/11 triggered wars and
other socio-political factors world-wide, oil prices spiraled upwards. Consequently
Pakistan is presently faced with high oil import bills, energy drought and
challenges resulting from altered weather patterns. Globally “Sustainability” is the
catch word in the emerging alternate energy systems driven by a number of
causes:
Liberation of Carbon dioxide in the atmosphere has to be reduced to an
extent as low as Twenty percent by the end of this decade, as suggested by a
number of initiatives listed in Table 1.1.
[7]
Table 1.1 World-wide GHG initiatives
Region Name Dates Coverage Nature
United Kingdom UK Emissions
Trading Scheme
2002-2006
(closed) Any sector Voluntary
United Kingdom Carbon Reduction
Commitment TBA
Non-energy intensive business and
public sector entities with
electricity consumption above a
threshold level
Mandatory
Australia
Carbon Pollution
Reduction
Scheme
2011 start
Direct emissions from large
facilities and upstream fuel.
Initially excludes agriculture and
land use
Mandatory
New South Wales
Greenhouse Gas
Abatement
Scheme
2003-present Electricity Generation Mandatory
Europe
EU Emissions
Trading Scheme
2005-
2007(Phase I)
2008-
2012(Phase II)
Energy generation, refineries,
ferrous metals, minerals, pulp,
paper and others
Mandatory
Worldwide
Kyoto Protocol
'flexible
mechanisms'
Entered into
force 2005,
first
commitment
period 2008-
2012
All sectors except international
aviation and shipping
Mandatory for
developed
countries,
voluntary for
developing
countries
Japan
Japanese
Voluntary
Emissions
Trading Scheme
2006-present Food, drink, buildings, textiles,
pulp, paper, metals, and ceramics Voluntary
Norway Emissions
Trading Scheme
2005-2007
(Phase I) 2008-
2012 (Phase II)
Large direct emitters, linkage to
EU ETS in 2008 Mandatory
New Zealand
Emissions
Trading Scheme
was 2008 start,
has been
postponed
Forestry initially, all sectors by
2013 Mandatory
Switzerland
National
Emissions
Trading System
2008-2012 Large direct emitters expected to
participate Voluntary
North East USA
Regional
Greenhouse Gas
Initiative
2009 start
Fossil fuel electricity generation
above 25 MW, burning >50%
fossil fuel
Mandatory
[8]
California
TBA under
Assembly Bill 32 2012 start TBA Mandatory
Western USA
Western Climate
Initiative TBA TBA Mandatory
United States
TBA under
Lieberman-
Warner Bill
2012 start TBA Mandatory
United States
Chicago Climate
Exchange
2005-2007
(Phase I) 2008-
2012 (Phase II)
Any sector Voluntary
Energy security issue that encompasses not only the reserves/resources but
also its economical availability and ease of transport-ability.
The beginning of the end of fossilized fuels is, and would cause a “sine-
wave” of their prices with a steep rise towards the complete exhaustion, that is
likely to be in the order of 40,65 and 150 years for petroleum, methane and coal
correspondingly.
Hydrogen has the potential to replace the fossil fuels and can be used as a new
mode of energy transfer. Interest in the hydrogen fuel has remained variable over
the years, rising and declining with the energy trends and situations. Surplus
electrical power can be stored in the form of hydrogen and has been a favorable
choice with the energy conservators and environmentalists supporting alternate
energies. Hydrogen is also compatible with coal conversion technologies as it
facilitates carbon sequestration. Similarly nuclear energy also can cleanly and
efficiently be used to generate hydrogen with the help of Very High Temperature
Reactor (VHTR)/Generation IV reactor.
[9]
Hydrogen has some very distinctive characteristics for its ability to be used as an
energy medium as well as a means of storing surplus power, in a variety of
applications:
Hydrogen is easily and efficiently convertible into other energy types in a
variety of ways by using fuel cells.
Hydrogen storage can be all forms whether gaseous, liquids or in solids.
Transportation of H2 can be effected by rail, road (trucks/tankers/cryogenic
vessels) or in pipe-line networks.
Hydrogen has the ability to be converted into electrical power as well as
heat with the help of fuel cells, and without any polluting by-products.
The above qualities/characteristics can help in early assimilation of
alternate energy resources into the current energy mix, especially wind energy
that is inherently irregular/ discontinuous in nature.
While certain organizations such as the “International Association for Hydrogen
Energy” has decades old regular publication “International Journal of Hydrogen
energy” with a presumed hypothesis of realizing the Hydrogen economy, yet
some of its staunch opponents do not find it comparable to the flexibility,
electricity has to offer.
1.2 Objective Statement
This thesis does not advocate or refute the usefulness of Hydrogen Economy nor
does it support or negate the use of Hydrogen as a fuel. It however is assumed
that considering the present consumption and thereby exhaustion of fossil fuels,
hydrogen will find a central place in a future energy supply chain. In such an event
[10]
it is imperative that hydrogen be integrated or rather facilitated to make inroads
into the society to match the today’s energy vector-electricity. This study is
focused on the transition stage, as and when hydrogen economy is realized, the
means of producing, transporting and distributing hydrogen must be devised for
ease of availability to end user.
A new fuel that has entirely different sets of physical/chemical properties requires
a compatible infrastructure that can sustain the energy demand at current level.
However the impediment in any fuel in the initiation and transition stage is the
famous “chicken & egg” problem. Till the time users of the new fuel are not
available, investors are reluctant to invest any new infrastructure, while on the
other hand users are willing to buy hydrogen-enabled applications only when a
well-established and sustaining infrastructure is available. Thus a supply &
demand chain relationship is necessary to overcome the deadlock.
Further, the end of fossil fuels and its rising prices is likely to open up avenues for
Renewable energy sources and technologies to flourish. Hydrogen and electricity
are complimentary and compatible; hence in any energy system hydrogen cannot
be treated in an isolated manner. Thus this study considers the production of
hydrogen from renewable energy sources integrating it with the existing
infrastructure.
The transition to the hydrogen economy has already been studied elsewhere
however certain inadequacies have been observed:
Emphasis is seen on producing hydrogen with no mention of its
transmission and distribution.
Hydrogen is mainly considered for transport applications while stationary
Fuel cell applications are completely over looked.
[11]
Energy demand and supply is an ever fluctuating scenario, hence while
considering the need for storage the variability in demand must be taken into
account.
Transition to the new fuel infrastructure is much important than the model
for a full-fledge Hydrogen Economy.
Chicken & Egg scenario is often ignored resulting in an assumption that FC
applications are readily and economically available while the same is likely to
remain uneconomic until widespread demand for the new fuel H2 gas is created.
An attempt has been made to address the above mentioned issues thereby
providing a means for facilitating the transition by use of existing Natural gas
pipe-line network for transporting large quantities of hydrogen as a mix with
methane. This can address the chicken & egg scenario to some extent by averting
the need for economical and widespread accessibility of FC applications. In this
study mainly renewables are suggested as means for generation of H2. An
integrated model for distribution is also developed that is based on renewable
resource availability all over the region under consideration.
1.3 Thesis development
2nd chapter describes the hydrogen properties and gives a premise for the
use of hydrogen as the replacement fuel of future. The discussion is based on
studies leading to the conclusion in the light of climate-change scenario and fuel-
security issues.
3rd chapter takes into account hydrogen production from various feed
stocks and methods. It further describes a number of international hydrogen
demonstration projects to enlighten the viability of Hydrogen Economy.
[12]
4th chapter explores the Renewable resources of Pakistan and evaluates the
complete wind and solar potential with a concluding output of hydrogen from
these resources.
Chapter 5 evaluates the energy infrastructure of Pakistan and develops an
Integrated modeling approach for the transmission of surplus energy from one
grid to another.
6th chapter describes the development of a MINLP for a biomass based
Hydrogen supply chain. Subsequently transport of hydrogen in the existing
pipeline infrastructure is handled and further suggests means for transporting
hydrogen in the form of synthetic methane/methanol. NG infrastructure of
Pakistan is described along with the energetic and material aspects of pipe line
material.
7th chapter provides a summary of all conclusions and provides thought for
future work on the subject.
[13]
CHAPTER 2 2 Hydrogen – Basics & Challenges
2.1 Hydrogen-General
Hydrogen is the first element of the periodic table with only a single proton in its
structure. It is also one of the most abundant element present not only in the
universe but on this planet as well. Hydrogen is a chemically active element
especially in presence of oxygen and carbon. Hydrogen gas in its diatomic form is
not freely available in the atmosphere but usually exists as a compound mainly as
H2O and in the form of hydrocarbons or fossil fuels. Being the smallest element it
normally exists as a gas at atmospheric conditions. Its energy value is highest
when considered in terms of weight; however it is lowest in terms of volume.
2.2 Properties-physical and chemical
Properties of H2 in comparison with other fuel gases such as natural gas and
methane are shown in Table 2.1 obtained from Baade [1] and Padro [2], along
with CO2 which is frequently obtained as a by-product.
2.2.1 Combustion properties
Combustion properties of H2 and methane are given in Table 2.2. Wobbe Index is
the most significant parameter with regards to combustion; it determines the
interchangeability amongst different gases with respect to the burners and a
means of categorizing the group to which each gas belongs [3]. It also classifies
the end use gas appliances. Mathematically Wobbe Index Ws is given by:
√ (2.1)
where
[14]
Hs Higher heating value (HHV) MJ/Nm3
d relative density
Table 2.1 Comparison of Properties[1][2]
2.3 Why Hydrogen Energy
Present day fuel or the world energy reserves mainly comprise of various
hydrocarbons that have accumulated over the years. Once expended the fossil
fuels cannot be reclaimed. Distinguishingly on the other hand the Renewable
resources are sustainable, yet short-lived in the sense that they are to be used as
[15]
generated for example wind, solar, tidal energy. Other renewables such as hydro
or biomass can be stored for a limited time.
Table 2.2 Combustion properties[4][5]
Although widely available, these resources are difficult to harness, expensively
generated and diffused in nature. Fossil fuels further carry a negative attribute of
raising the pollution level, indicated by the CO2 concentration that has risen from
280-300 ppmv to 360-380 ppmv over the last two centuries [6].
Hydrogen, being a carbon free fuel is now a symbol of pollution free fuel.
Hydrogen is looked upon as a universal vector for conveyance of renewable
resources to the end-user. Economy sustained by Hydrogen supply Chain is
commonly referred to as Hydrogen Economy illustrated in Fig 2.1.
[16]
Fig 2.1 A sustainable Hydrogen economy [7]
Though a very favorable proposition, Hydrogen economy is still farfetched
because renewable resources themselves do not complete the picture as they are
not cost competitive and difficult to harness on a scale as required by the present
day world. The nuclear power option is also undesirable owing to the radioactive
by-product it generates.
Hydrogen, although found in abundance in the universe, yet in elemental form it
is scarce. Thus external energy is required to extract it from other compounds
most commonly water or the less common and more sought after hydrocarbons.
Hence hydrogen itself is not an energy source but a vector. Various paths are
available for hydrogen production and are summarized in Fig 2.2:
[17]
Fig 2.2 Hydrogen Supply options and major uses [8].
Hydrogen being a medium for storing energy is produced from a primary resource
and can be used to convey energy to the point of utilization. Thus hydrogen has
an analogy with electricity which is also a secondary form of energy. Hydrogen
and electricity are complementary as well as inter-convertible. Hence electricity is
used to generate hydrogen by electrolysis and hydrogen can be used in fuel cells
to generate electricity, the efficiency of these electrochemical devices is however
[18]
less than an ideal 100%. Success of the proposed hydrogen economy is
unquestionably related with the development of such efficient devices.
Almost all renewable resources have an immediate conversion to electric power
where it is to be used. However for applications such as transport that run on
fuel, it entails that the renewable resources be converted into hydrogen which
can then used in fuel cell to drive an electric powered vehicle or used for
combustion in an IC engine. Such a process is highly inefficient as well as quite
uneconomic. It is preferable to use Renewable energy generated electricity
directly. Certain exceptions are always there, such as in isolated communities or
island where the renewable resources exceed the consumption. Excess electricity
can then be stored in hydrogen for use as part of the greater Hydrogen Supply
Chain or later converted to electricity on demand. Ultimately when fossil fuels are
really scarce and expensive and when renewable energy technology has become
economically competitive it may prove practical on much wider basis to convert
renewable electricity to hydrogen fuel. However that time is still far from
realization. The International Energy Agency (IEA) has forecasted that renewables
(excluding hydro and nuclear) will still account for only 10% of world energy
supply by 2030 [9]; of this more than half is expected to be derived from biomass.
The initiatives for Hydrogen economy as the fulfillment of an environmental
dream for the long term future are driven by four key motivational factors:
Secure energy provision
Global warming
Atmospheric pollution
Electrical power production
[19]
The complexity of the above mentioned drivers is interrelated and increasingly
multifaceted, however there are a number of other factors that are to be
overcome before “Hydrogen Economy” becomes a reality. These obstacles are
categorized as:
2.3.1 Organizational :
Development and implementation of a far-sighted National Energy Strategy
in the wake of a liberalized energy economy.
The near sightedness of political hierarchy and the productive sector
(Manufacturers and industrialists)
The rigidity of the current energy supply chain and the extended durations
linked to any shift over to any alternative methods of energy provision and
consumption.
The absence of any Hydrogen enabled network and the enormous
expenditure involved in establishing a new infrastructure.
The huge amount of hydrogen required to sustain the fuel supply chain
necessary at the national level on one hand ; while the lack of capacity of the
current hydrogen generators to meet this demand on the other.
The incomparable size of renewably powered generators to produce
electricity to match this scale.
The minimal requirement in the foreseeable future.
2.3.2 Technical
The technical hurdles connected with the generation, transportation and
use of this new fuel-beginning with the conventional hydrocarbons and thereafter
the employment of carbon mitigation techniques.
[20]
Use of clean energy technologies for production of economical and
environmentally friendly hydrogen.
The absence of any reliable hydrogen storage technologies especially for
fuel cell vehicles; transport being a major energy consumption sector.
The limitations of fuel cell applications for their reliance, longevity and
practical usage.
2.3.3 Regulatory
Issues related to the secure handling of hydrogen in storage, transportation
and delivery especially when the same has to have extensive use in society.
The lack of standardizations on the international level to ensure safe
dispensation of hydrogen and promoting wide spread utilization.
The importance of imparting technical knowhow to the handlers of this
new fuel and developing manpower with expertise in the subject.
2.3.4 Financial
The colossal capital required to be injected for introducing and establishing
a new energy infrastructure.
The necessity to revise down the operating cost of the new supply chain to
be at par with the conventional systems and with portable functions such as fuel
cell vehicles.
The large price gap between the FC applications and its corresponding
conventional engines.
The above mentioned impediments are real and trying and there is a strong
necessity to devise an all-inclusive strategy to address these issues in a
[21]
wholesome manner. Fossil fuels such as petroleum, diesel and natural gas are
widely available and comparatively cheaper while hydrogen fuel on the other
hand may not demonstrate itself evenly compatible in terms of its price. A
competition is probable only when the price of the traditional hydrocarbons reach
a point when they become comparable with that of hydrogen or the policies for
carbon mitigation are stringent enough to incur huge taxes.
2.4 Security of Energy supplies
By 2030 the global energy requirements are expected to reach 17,000 Million
TOE, which is a 40% rise considering the energy supplies of 2005. The sharp
increase is not only due to an exponential rise in population but it is also linked to
a general increase in the affluence. This validates a strong relation between the
increase in the Gross Domestic Product and the energy expenditure of any nation.
For the nearer future, there is not likely to be any marked difference between the
fossil fuel dominated current share of energy market in relation with that
foreseen in 2030. However it is expected that there will be an escalation in gas
shares, coal will remain relatively stable while nuclear generation would decline
as old stations are not replaced by newer ones on completion of their
commissioned life. Despite these predictions certain facts seem to point the other
way keeping in view the huge resources of coal with India and china along with
the economic boom these economies are experiencing. This is the official stance
of International Energy Agency and hence it can be deduced that Renewable
sources are to face stiff opposition in the wake of availability of cheap fossil fuels.
The introduction of hydrogen as a fuel within this time span thus also remains
questionable. Nevertheless these forecasts might prove otherwise with the turn
of the events.
[22]
Geological and petroleum experts maintain a ballpark figure in the range of 2 to 3
trillion barrels of the globe’s oil stocks. It is further considered that about half of
the same have already been consumed while ninety percent of the predictable
reserves have been revealed and under exploration. Most of the significant
reserves have already crossed the peak of the output and are on the regress, the
remaining are fast approaching the peak. Moreover the pace of discovery is far
behind the production output resulting in an unsustainable cycle.
Saudi Arabia is the only country whose reserves are easily exploitable in contrast
to ones that are inaccessible and require huge investments for any worthwhile
output.
Countries experiencing an economic boom such as Malaysia, India and China are
likely to have larger import requirements predictable with their growing GDP.
Resultant affluence would have a probable mechanization of society that in turn
multiplied with the swelling population would reveal a greater demand in the
energy pie. Consequently these circumstances would lead to escalating prices
resulting from the limited availability of oil and related petroleum products, not
withstanding a political facet emerging out of the complete scenario.
More than half the discovered and available sources of oil lie in the Arabian Gulf
region. Keeping in view the limited supplies these countries may choose to
minimize the output to enhance the life of their stocks, or to escalate the prices
for political gain
60% of the explore-able supplies are concentrated in just five Arab countries i.e.
Saudi Arab, UAE, Kuwait, Iraq and Iran. In the wake of competition these
[23]
countries may decide to restrict production for political reasons to extend the life
of reserves or to raise the prices. Even if they decide to increase the production
along with the rise in demand, this might not prove possible practically or in
terms of capital requirement. It is widely forecasted that oil prices will continue to
spiral upwards. The situation as regards natural gas is somewhat better.
Authorities believe that global reserves of natural gas have been greatly under
estimated and that, despite growing demand, there is unlikely to be any supply
limitation throughout the course of this century. In this context it is noteworthy
that total world reserves stood at 42x1012 m3 in 1970 and are now 176x1012 m3
despite 56x1012 m3 having been consumed during this period. In the longer term,
if/when natural gas supplies become depleted, the world can fall back on its
massive reserves of coal, which are sufficient to last for a century at least. This
fuel switching will be dependent upon clean coal technologies being well
advanced to produce hydrogen for use in gas turbines or fuel cells with almost no
emissions of CO2.
Renewable resources are and will continue to grow progressively and the
costs of manufacture and installation will decline through the benefit of large
scale production. Despite these developments the new energy forms will make
only a modest contribution to the global energy supplies during the next couple of
decades with marked variation from country to country. Exxon Mobil has
forecasted that the contribution of non-fossil fuels to the total world energy
supply will be less than 20% in 2020, and that wind and solar will provide only
0.3% of the total.
[24]
Fig 2.3 Contribution of non-fossil fuel to Total energy supply [10]
On the top of all the above mentioned calculated concerns is another dimension
that is political in nature. Generally the public and its political representatives are
more worried about the prevailing state of affairs. They are primarily concerned
with the imminent and foreseeable risks and hazards and hence the elected
officials are preoccupied with the challenge of upcoming elections.
Correspondingly the common man is more thoughtful of its own short term
problems such as livelihood, shelter and other domestic comforts and the risks to
humanity and planet are a far-off consideration, low in priority. The responsibility
is thus taken up with members of civic society that include engineers, planners
and environmentalists who then shoulder to create awareness about the looming
dangers of the energy scarcity and its effects on climate change. A major portion
of this task has to be taken up by educators to inculcate the growing generation
about the long term effects of energy security. Addressing this issue through
teachers has already worked appreciably well as far as the global warming and its
[25]
effects to ozone layer are concerned. Resultantly terms such as “Greenhouse gas
emissions” and “ecological footprints” are well known amongst today’s society.
2.5 Climate Change
The following are unarguable facts in the context of Climate change scenario and
its initiation:
(i) Global warming is raising the overall temperature of Earth
(ii) ever since the Industrial Revolution gained ground the amount of CO2 being
released in the atmosphere has continued to rise
(iii) these large concentrations of carbon dioxide prevent the escape of reflected
infrared radiation from the earth’s surface resulting in warming of the planet.
It is widely believed that the above three points describe the complete picture of
carbon dioxide release in the atmosphere and that hydrocarbons are the sole
accountables for the global warming. The other side of the story is however
different.
Many aspects contribute to the climate change scenario and the same are not
widely comprehended. CO2 is absorbed into the atmosphere from a number of
originators that include processes that follow a natural cycle such as the
photosynthesis taking place in biological life forms as well as in their
decomposition. Similarly sea life in the form of algal forms and land animals also
contribute to large amounts of carbon dioxide in the environment. Other
contributors include volcanic eruptions and evaporating process continuously
taking place in seas, oceans and other water bodies. Such large scale releases of
[26]
carbon through natural processes diminish what is contributed by fossil fuels and
its combustion. With such large scale releases the natural sinks to absorb and
recycle these emissions have gradually shrinked with extensive deforestation that
has been occurring with the expansion of civilization. An analytical summary from
[11][12] of the world wide increase in carbon dioxide is exhibited in Table 2.3.
Table 2.3 Worldwide Carbon Transfers
The tabulated values above indicate that Hydrocarbon based fuels are responsible
for only a portion of the gross influx i.e. 6 Giga Tonnes out of a total of
approximately 200 Giga Tonnes forming about 3.5% of the entire figure. Apart
from carbon dioxide other contributors to Greenhouse emissions include:
NOX: Oxides of nitrogen also result from the burning of fossil fuels as well
as from performing certain farming processes such as fertilization of soil and
biodegradation of biomass. Other contributors to NOX emissions include chemical
production and a variety of naturally occurring environmental and ecological
processes.
[27]
CH4 is generated from various human as well as vegetative activities such as
developing and extraction of minerals like coal, oil and natural gas. Similarly
conventional use of biomass for cooking and heating also contribute to methane
formation. Sowing of crops such as rice and cattle/livestock growth practices also
increase the methane flux. Moreover flora decomposition and metabolism
process within the huge population of insects and ruminant creatures release
considerable amount of methane. Studies have also indicated the release of
methane from surface as well as marine plantations.
Refrigerant blends and gases to include all forms of organoflourine
chemicals such as Chloroflorocarbons, Hydrofluorocarbons as well as
hydrochlorofluorocarbons have all contributed to global warming and green
house gas emissions. SF6 used in producing Aluminium and Magnesium is also a
significant contributor of harmful gases.
The radiation absorption rates of these chemicals is spread over a wide spectrum
corresponding to their existence in the environment till they are subjected to the
sun-light-triggered effects or finally taken up by surface or marine absorption.
Troposphere (the closest atmospheric space indicated in Fig 2.4) holds methane
at about 1.7 parts per million by volume which is quite small in comparison with
CO2.
Fig 2.4 Troposphere [13]
[28]
In contrast Methane’s potential to cause global warming over the course of a
century is far ahead of carbon, as much as twenty times that of the standard i.e.
one for carbon. While the lifespan of CH4 is quite short owing to its early
oxidization to CO2, however the risk it poses to environment is almost 50% less as
compared to that caused by CO2. On the other hand NOX emissions are relatively
more stable while the potential to cause global warming is more than three
hundred times that of carbon. Similarly organoflourine compounds have the
highest GWP amongst these emissions ranging from hundred to a few thousands.
Further the lifespan of these compounds also is the longest approaching upto
several centuries. PFCs and SF6 have the highest GWP lasting up to a maximum of
ten thousand years and 23,000 years respectively. However because of its
emission in relatively minute quantities the overall effect is diminished. The effect
of human activities on the environment has been found to be minimal, causing a
rise of less than a degree rise in temperature over the last century. The CO2 levels
have risen from 275ppmv form the pre-industrial age to about 375 ppmv by 2010
[14], resulting in 6.6 Giga tons of carbon, a significant rise has been noticed
around the mid of last century.
Scientists and environmentalists that the world should focus on keeping the CO2
levels at a maximum of 400 ppmv in order to avert grave dangers to the global
weather. Amongst certain serious consequences are the melting of the Arctic ice-
cap (shown in Fig 2.5), Antarctic and Greenland ice shield. Moreover larger
releases of CO2 also results as the earth heats along with CH4 releases that also
remain unabated from the seas as well as the great ice lands of the poles.
Acidifying of the water bodies also has adverse effects thereby reducing their
potential to absorb CO2. It has been found that sea levels may rise by up to 7
[29]
metres and 6 metres respectively if the Greenland and the West Antarctic ice
sheets melt down. Other weather altering factors include the concentration of
water vapours in the atmosphere, ash of combustion and SO2. The extensive
Fig 2.5 Shrinking Arctic Ice cap [15]
discussion only demonstrates the complexity of the climate change scenario and
the vast canvas it offers to various altering factors. It is thus imperative that
predictions of global warming need to be revisited to shift and preferably
accelerate the mitigation steps to restrain any further degradation of the
environment that is liable to cause irreversible damage to global well-being of the
planet and human civilization. It is deemed that unless strict policy measures are
enforced to limit the greenhouse gas emissions, the level of CO2 is predicted to
double by 2099. With the present levels of approx 350 parts per million by
volume the climatic effects are liable to make an exponential rise with any
increase in carbon concentration.
Countries with growing economies especially China and India that are not party to
the Kyoto protocol have large requirements of fossil fuels. Thus promoting
[30]
alternative fuels may trigger use of coal which has high carbon content leading to
a gross increase of carbon dioxide as much as up to 40 Giga tons within the next
two decades. Thus all carbon mitigation techniques may falter unless stringent
policy measures are adopted to curb the trend.
Solid waste management has gained wide recognition, acceptability and
implementation in the near past replacing the traditional method of discarding in
earth. Reprocessing and recycling has substituted wastefulness , however the
means for disposal of large amounts of CO2 remain a big challenge. Hydrogen as a
replacement fuel for the ultimate switch over from fossil fuels would address the
climate change scenario provided the methods for the mass production of
hydrogen is free of any liberation of carbon dioxide. If however CO2 release is
unavoidable from large-scale hydrogen generators then means must be employed
for its sequestration and subsequent disposal. Researchers are hence exploring
further avenues for efficient capturing and subsequent safe disposal of carbon
dioxide.
2.6 Atmospheric pollution
Atmospheric pollution has successfully been curbed to a certain extent over the
last half of the century. Early Legislation in the developed world has lead to an
early control of the atmospheric pollution. However growing traffic population all
over the globe has resulted in smog over large cities. Petrol emissions have been
managed through policy measures, use of catalyst devices as well as better
combustion processes. Particulate emissions originating from diesel engines are
still under research. Sulfur present in small quantities gets oxidized and reacts
with water to cause acid rain and thereby causing acidification of the water
[31]
bodies. These sulfur contents have been lowered considerably by oil companies
after strict policy measures. Vehicular traffic is not the sole polluter of
atmosphere, rather a great number of large ocean-liners as well as locomotives
also contribute to the polluted air. Similarly factories engaged in manufacture of
metals, building materials and those requiring boilers and power generators have
a much greater share. Besides legislation for limiting discharge of sulfur oxides in
the environment, catalysts or reactors are also employed at the exhaust to
neutralize the discharge to lesser harmful substances.
2.7 Electricity Generation
Electric energy is considered as one the most flexible, multi-purpose and greenest
type of power available in today’s world that has widely penetrated in our
society. Electricity was approximately 17% of the final global consumption in
2005 [9]. Its versatility is evident from the various techniques that it can be
produced as well as the supply chains i.e., alternative energy, biomass feeds as
well as hydrocarbon based fuels. The generation capacity of electricity has also
multiplied several times over the years. The fourth quarter of the last century
registered a 2.75% increase while it rose by 8.65% in just two years from 2003-
2005. Electricity use has also increased in the recent years, mostly in the
industrial sector that was recorded at 41.75%, while transportation sector used
only 1.65% depicted in the pie diagram at Fig 2.4
[32]
Fig 2.6 Electricity as Final energy consumption [9]
Efforts are under way for access to grid electricity to the masses. China has now
provided electric power to 98% of the populace, despite this a coal-fired plant
with a capacity of 30-40 GW is added each year. Expansion in India’s electricity
grid is also growing rapidly. However 25% of the world’s population mainly
dispersed in the African region is still without electric power.
Another point of concern in the developed world is the ageing of the plants setup
in 1960s which are due to be decommissioned by the end of present decade. The
power industry is also progressing towards distributed generation employing
micro turbines or engines, solar energy or wind turbines.
Localized electricity or stand-alone generation have an inherent problem of the
need for a back-up system necessary for a fluctuating electricity supply to match a
fluctuating demand. This can be
[33]
Mains electricity
Alternate local source such as diesel generating sets or
Energy storage
The prime candidates for local electricity storage are batteries and hydrogen; the
fuel cells being the main requirement in case of hydrogen, for conversion into
electricity.
A growing trend in electricity is that of distributed generation which is based on
micro turbines, solar energy (photovoltaic, solar-thermal) or wind turbines. In this
regard fuel cells supplied with hydrogen are one of the best suited systems for
distributed generation. They are noiseless, have flexibility in output and are
pollution free. Just as gas turbines and diesel generators, they can supply both
power and heat depending upon the type of fuel cell. For use in cities/population
centres fuel cells have to be supplied through a pipeline while in remote locations
hydrogen is to be produced on site.
Considerable efforts are in progress for the development of fuel cell vehicles and
various automotive companies are marketing fuel cell vehicles. However the goal
of replacing the conventional vehicle with a fuel-cell powered one is not only
ambitious but lucrative as well keeping in view the number of vehicles plying on
road as of today. It must though be kept in mind that such a transition requires a
well-established infrastructure which would evolve over the years. Moreover
hydrogen is likely to be derived from fossil fuels/hydrocarbons till wide availability
of renewable energy. Interest in hydrogen also stems from its desirable feature as
[34]
an energy vector (similar to electricity) as well as an alternate medium for storing
energy.
2.8 Conclusion
Hydrogen has the potential to address several of the imposing questions of
today’s world which has propelled the research and progress towards a hydrogen
economy. The wide availability in the form of water eliminates the worries for
security of energy supplies provided the means of extracting hydrogen in usable
form are well developed and economically feasible. Its use in fuel cells or in
combustion is free from any carbon residues or NOX emissions thereby reducing
the global warming as well as environmental pollution. Hydrogen and electricity
are complimentary; hence the widespread introduction of fuel cells in appliances
and vehicles is not impractical.
While hydrogen economy seems to answer all questions yet the smooth running
of the Hydrogen Supply Chain is the biggest challenge that is to be overcome in
the realization of this dream.
[35]
CHAPTER 3 3 Hydrogen Production-Feed stocks & Processes
3.1 Introduction
Several pathways exist for producing hydrogen which not only include a variety of
feed stocks but also how each feed stock can be treated to generate desired
quantities of hydrogen from it. The idea behind the concept of hydrogen
economy aims to address two broad issues i.e.
Presenting hydrogen as a next generation of fuel that could replace the
declining fossil fuel reserves with a presumed sustainability in terms of
unlimited supply in the form of water.
The potential to address the issue of environmental pollution as it promises
zero carbon emissions and none other harmful products.
Thus the benefits of hydrogen economy can be exploited to the fullest extent if
hydrogen production is carried out through renewable sources of energy. It has a
two-fold scenario as well, firstly the production of hydrogen from hydrocarbon
based feed stocks would again pose a query of their long-term sustainability.
Secondly if the input energy for any hydrogen production process continues to be
derived from fossil fuels, the original question remains answered. Therefore
production of hydrogen from sustainable feed-stock as well as sustainable energy
input methods can only lead to a sustainable hydrogen supply chain that can
effectively produce large quantities of hydrogen enough to match the present day
energy requirements being met by fossil fuels. This chapter briefly discusses the
conventional and renewable methods of hydrogen production.
Renewable paths of hydrogen generation are shown in Fig 3.1, originating mainly
from solar, wind and biomass, which form the discussion scope of this study.
[36]
Fig 3.1 Pathways for Renewable Hydrogen production [16]
Figure 3.2 indicates the allocation of today’s world resources being used for
producing hydrogen. It is evident that with the present reign of fossil fuels over
the energy market, the hydrocarbons lead the way in this context as well.
Resultantly Methane comprises about 47.5% while petroleum constitutes about
30.5% of current global production of hydrogen. Electrolysis being the simplest
process yet available for producing hydrogen from renewably generated
electricity forms only a small portion i.e. 4% of the entire distribution pie.
Fig 3.2 Resource Distribution in Hydrogen production[17]
[37]
Hydrogen derived from petroleum resources has been found to be consumed
within the refineries itself. For electrolysis it is worth mentioning that the
electricity used currently in the process is mainly derived from hydrocarbon based
sources of energy. Figure 3.3 indicates an energy comparison for different
hydrocarbons that indicate the amount of input energy required for producing
hydrogen from the various feed-stocks. Electrolysis based hydrogen generation
has the highest energy consumption while light hydrocarbons require the least
energy input.
Fig 3.3 Energy consumption comparison from different feed-stocks[17]
Thus for all practical purposes Hydrogen economy will have to take a jump start
based on fossil fuels subsequently to be replaced by more sustainable feed stocks.
The other different methods of hydrogen production are described below to
assess their feasibility as well as to draw a comparison for their suitability for
Hydrogen Economy.
3.2 Hydrogen production from fossil fuels and biomass
Hydrocarbons such as the fossil fuels and biomass contain hydrogen in a
compound form that can be released with an input of energy. This hydrogen is
generated as a result of liberation from the chemical bond by application of
inherent energy of the fuel to disassociate hydrogen from water/hydrocarbon.
[38]
Production of hydrogen from Fossil fuels is not only the historically tried and
tested system but is also one of the most economic as well. As fossil fuels are
hydrocarbons hence oxides of carbon are the predominant by-products when
they are treated to release stored energy. Consequently production of hydrogen
from carbonized feed stocks does not address the apprehensions which hydrogen
economy is supposed to eradicate i.e. pollution caused by greenhouse gases and
the need to minimize dependence on non-sustainable fuels. Biomass based
methods have been made part of this section since their behavior is compatible
with fossil fuels i.e. carbon present in their chemical composition. Pyrolysis and
gasification processes have also been included in this section because they are
very similar to fossil fuel reforming and gasification processes. Biomass is also a
carbon based fuel, so its treatment by any means adds to carbon dioxide releases
in the atmosphere.
3.2.1 Steam methane reforming
This reforming consists of three sub-processes that generate hydrogen. First
Natural gas or methane is heated to a high temperature to produce a mixture of
carbon monoxide and H2 gas. The mixture is then catalytically reacted to coalesce
CO and H2O to release Hydrogen gas. The product is then extracted by adsorption.
The process can be signified by the following chemical representation:
CH4 + H2O →2 H2 + CO Δ H= + 206 kJ/mol
2 CO→CO2 + C Δ H = -172 kJ/mol
CO + H2O → CO2 + H2 Δ H = - 41 kJ/mol
The first step produces a mixture of CO, CO2 and H2 along with certain other by
products. A greater amount of steam is used in the process to increase the
reaction rate as well as to avoid thermal cracking which is expected in this
Boudouard reaction [18].The increased amount of steam accelerates the second
sub-reaction which is the production of syngas to Hydrogen gas.
The last part of this reaction takes place at a comparatively lower temperature
than the initial reforming process. Pressure Swing Adsorption (PSA) is used to
purify and segregate the residuals such as CH4, CO2, CO, Nitrogen and the actual
[39]
product i.e. hydrogen gas. Another method of separating hydrogen can be carried
out by chemical absorption with the help of amine contactor and later reacting
with methane to remove oxides of carbon [19].
Industrial Hydrogen production is mostly carried out in steam methane reformers.
It is one of the most cost effective methods of producing hydrogen (if the CCS,
carbon capture and storage is excluded) due to the cheap availability of methane
gas and the simple chemical process which is highly efficient as well. Also the
infrastructure or the Natural Gas Supply Chain is well established in terms of large
pipeline networks and the technology for their extraction, transportation and
end-use is highly developed and very economical. Steam methane reformation is
well suited for mass production of hydrogen, however in any future Hydrogen
economy that may emanate from Distributed generation; this process is un-
economic for small scale generation.
It is hence considered that the SMR can only be a stepping stone for a full-fledged
Hydrogen Economy and can advance its pace during the early stages of inception.
It can be of significant use when a transition of fuel takes place, however because
of its short-lived reserves the process is to be overtaken by more sustainable and
longer lasting feed stocks, primarily Renewable resources such as wind and solar.
3.2.2 Partial Oxidation / Autothermal Reforming Of Methane
Another substitute to Steam Methane Reforming is the partial oxidation and auto
thermal reforming of CH4. Partial oxidation is a single step process, oxidizing
methane directly, however in auto thermal reforming oxidation and reforming
takes place in a single step. A mix of carbon monoxide and hydrogen results from
partial oxidation of CH4 chemically represented as:
CH4 + ½ O2 → CO + 2H2 Δ H = - 36 kJ/mol
Comparing this with the total oxidation reaction:
CH4 + 2O2 → CO2 + 2H2O Δ H = -890 kJ/mol
[40]
Total oxidation is inhibited by increased temperatures and volumetric supply of
oxygen in the desired stoichiometric proportions. In this process there is no
requirement of catalyst however its use can increase the production of hydrogen
and decrease the overall heat input. Rhodium, platinum and nickel as catalyst
have been under investigation however the rhodium based catalysts have been
demonstrated to be able to achieve over-oxidation of hydrogen with a greater
input of activation energy [20]. In partial oxidation CH4 is combusted in the
container holding the reactants, which is also an exothermic reaction it is not
possible to re-use the purge gas to enhance the efficiency [21].
Projects based on auto thermal reforming of CH4 on a mega scale are still under
investigation, however demonstration projects such as one installed in Canada by
Kellogg Brown & Root, and a syn gas plant in China are in the initial stages. [22]
3.3 Coal Gasification
The process is comparable with SMR as it also consists of three sub processes;
firstly steam at a temperature of 13000C + is treated with coal, followed by
reaction in presence of a catalyst in the second step and finally in the third step
hydrogen is purified.[23]
Coal (carbon source) + H2O → H2 + CO + impurities
CO + H2O → CO2 + H2
Coal is partially oxidized as oxygen is added in a vessel which has an air/oxygen
blower. Reactors that have nitrogen induction tend to be more expansive as well
as expensive and costs of carbon sequestration also tend to be on the higher side.
[24]
The process takes place adiabatically in presence of a catalyst namely cobalt
molybdate at a high temperature (upto 4550C). Other catalysts used in this
process include oxides of chrome and iron at pressure less than 50 bars. Pakistan
has large reserves of coal and because of its comparatively cheap availability and
proven technology which is already in place commercially; it is an economical and
viable source of energy. The only additional requirements to suit the
environmental climate are the introduction of CCS technology in existing setups.
[41]
3.4 Biomass Pyrolysis/Gasification
Biomass is another feedstock and includes crops and other agricultural product or
residue such as wood, chaff, straw, husk etc. Other forms of biomass can take the
shape of solid waste that can be combusted to produce steam which can then be
used for gasification. Gasification and pyrolysis are two such methods by which
biomass can be treated to generate hydrogen.
Biomass gasification is analogous to coal gasification as discussed in the previous
section. In another process called pyrolysis, an oil type substance is produced by
reforming biomass. These reactions are chemically represented as: [25]
Biomass + Energy →Bio-oil + Char + Gas Impurities (pyrolysis)
Bio-oil + H2O → CO + H2 (reforming)
CO + H2O → CO2 + H2 (shift reaction)
The process is low yielding because only 8.5 gms of hydrogen are extracted out of
100 gms of bio-oil. The reaction is as follows:
CH1.9O0.7 + 1.26 H2O → CO2 + 2.21 H2
Biomass gasification is relatively a new advent in the commercial arena, hence the
only plants yet available are for demonstration purposes only that are able to
generate electrical power or utilized in other chemical production. [26]
As biomass resources can be termed as renewable hence they can be significant
contributors to any future hydrogen supply chain. The only inhibiting aspect is the
low yield of hydrogen from large amounts of biomass that have to be transported
over large distances from the agricultural fields to the gasification plants. The
weight percentage of H2 in biomass is only 6.45%. While comparing the two
methods the pyrolysis option is considered more favorable than gasification
because of the ease in transportation as well as the greater energy density of bio-
oil. Carbon capture and sequestration is required in both the methods and would
entail further investments in terms of hardware and operational requirements,
thereby raising the price as well.
[42]
Carbon mitigation in biomass gasification is not considered essential by certain
experts owing to the natural cycle in which biomass decomposes after a period of
time and releases carbon dioxide in the atmosphere. It is comparable to the
plants that consume carbon dioxide during the day as part of the photosynthesis
process and release as they decompose. [25]
3.5 Hydrogen Production from Nuclear Heat and Alternative/Renewable
Energy Sources
Heat generated from nuclear resources as well as renewable energy sources can
also be used to split water for generating hydrogen. These are technically novel
methods as compared to the gasification processes discussed earlier. As the
technologies are still lacking maturity hence the hydrogen production from these
resources tend to be costlier as compared to the more easily and readily available
hydrocarbon based methods. The main advantage of these technologies is the
absence of any environmentally harmful byproducts such as the oxides of carbon
and NOX gases etc. Radiation from the sun is used for photo-biological/photo-
catalytic methods while nuclear sources provide energy for the sulfur iodine
method.
In methods that use electrolytic splitting of water the electrical power provides
the energy used in such processes. Conventionally fossil fuels are used to
generate this electrical power however renewable resources such as hydel, wind
and solar can be used to provide the electricity. Electrolytic generation of
hydrogen from water is recommended because of the absence of any carbon
thereby eliminating formation of carbon monoxide or carbon dioxide etc as by
products in the reaction.
[43]
Fig 3.4 Renewable Hydrogen
3.6 Electrolysis
In this process electrical energy is used to split water into its constituent elements
to give hydrogen and oxygen. Electrical current is passed through an alkaline
electrolyte solution which acts as the carrier for the electrons that are introduced
through the electrodes. The electrolyte is generally potassium hydroxide.
Hydrogen and oxygen is released at the cathode and anode respectively. The
reaction is chemically denoted by [27]:
Cathode: 2 H2O + 2 e- →H2 + 2 OH
Anode: 2 OH- → ½ O2 + H2O + 2 e-
H2O →H2 + ½ O2
The process is simple as hydrogen and oxygen is generated by application of
electrical current to water. Theoretically 1.22 volts are required for this
electrolytic dissociation at a temperature of 76oF, provided absorption of heat
takes place from the surroundings. The rate of reaction depends upon the voltage
[44]
supplied, thus higher voltage can increase the reaction rates. The increased
reaction rates are nevertheless associated with lower efficiency rates because of
greater loss of heat. One of the ways to address the issue is by using catalysts or
enhancing the surface area of the electrodes. Another method is to increase the
temperature and pressure, that though raises the efficiency level however it is
associated with a price tag based on the additional costs incurred on the material
that is pressure and corrosion resistant. [27]
Electrolysis takes place in an electrolyser which is mainly of 3 types:
Unipolar tank type
Potassium hydroxide forms the electrolytic solution in this type of
electrolyser. The positive and negative electrodes are arranged in an
alternating pattern in the reactant vessel. In order to check any
amalgamation of the gases and air pockets the electrodes are are kept
apart through a membrane. Uni-polar are simple in structure thereby
comparatively more cost effective in maintenance and operation.
Bipolar filter press
In this type of electrolyser the cathodes and anodes are placed in a
compact structure with each side forming the anode and cathode. The
separating membrane is also placed in this electrolyzer as well to prevent
mixing of the gases. Bipolar electrolysers have a compacted design and
suitable for taking up greater current densities and temperature. The
conduction medium in this type is also potassium hydroxide electrolyte.
[27]
Solid polymer electrolyte (SPE) or the PEM (Proton exchange membrane)
As the name suggests, the electrolyte in this type is in the form of a solid
membrane. Liquid electrolytes are required to be retained near the
electrodes and in order to enhance the surface area complicated designs
are involved. In contrast the solid electrolytes have a simple design as
compared to the unipolar/bipolar versions already discussed. The chemical
processes in the SPE are different from the aqueous electrolytes however
the overall result is identical: [28]
[45]
Cathode: 2 H+ + 2 e- → H2
Anode: H2O →½ O2 + 2 H+ + 2 e-
H2O → ½ O2 + H2
Large amounts of electricity are required to generate a good quantity of hydrogen
to sustain any future hydrogen supply chain. The renewable resources like wind
and solar although widely available are still under research for any major
economic and technically feasible output in practical terms for implementation.
Fig 3.5 Renewable Electrolytic Hydrogen
Studies are under way to develop highly efficient electrolysers that operate at
increased temperature ranges as compared to the conventional electrolysis units.
Nuclear heat is one of such option to generate higher heating temperatures.
Nuclear Hydrogen Initiative run by the US department of Energy is one such
initiative. The Idaho National Engineering and Environmental Laboratory (INEEL)
has been tasked to develop a 5MW project to demonstrate its technical feasibility
and assess its commercial utility.[29]
[46]
The electrodes in a high temperature electrolysis unit are made up of a porous
material which are kept apart by an impermeable solid electrolyte. The cells of
the electrolyser are provided with inter connected channels that allow the flow of
hydrogen and steam from one side and O2 from the other. Electricity can pass
through these interconnected channels in an axial direction. The concept is
explained in the diagram below:
Fig 3.6 High Temperature Electrolysis Conceptual Diagram[30]
Fig 3.7 Cell Stack Assembly[31]
Small scale units for demonstration purposes operate at atmospheric pressure,
however larger plants with greater output operate at high pressures. This is
[47]
important as higher pressures are required to compress hydrogen for storage
purposes and has a comparatively lower density. Thus it is less costlier to
compress the water than to compress hydrogen at the end of the cycle.
Demonstrative plants provide the heat for the process by placing the complete
plant in a heating system. Larger plants however require greater heat input which
is then supplied by nuclear sources through restorative heat exchangers. [29]
The engineering problems encountered in high-temperature electrolysers
comprise mainly of the sealant required for the cells necessary to avert losses of
the generated hydrogen product. The material of the seal should be able to
reduce the oxidizing and reducing effects of the anode and cathode respectively.
Seals made of glass ceramics and pastes are under study but are costly and their
feasibility and efficacy is yet to be tested. Also materials used in the
manufacturing of the interconnected channels are significant. The channels made
of metal are economically better, the resistance losses are reduced and have an
added advantage of sustaining higher thermal and mechanical shocks, however
temperature is a limiting factor. One of the remedial option is to employ
intermediate temperature electrolysers till suitable materials are discovered and
necessary research has been undertaken for implementation. Other avenues that
still need to be explored are the types of electrolyte and the performance of the
electrodes that can be enhanced. [29] A comparison of the efficiency analysis is
tabulated below at Table 3.1. Cost comparison as a function of capacity is given at
Appendix G.
Table 3.1 Electrolyser efficiency
Process Electrolyzer efficiency
(%)
Efficiency including
electricity (%)
H2 product (kg/hr)
Stuart: IMET 1000 73 24 5.4
Teledyne: EC 750 63 21 3.8
Proton: HOGEN 380 56 18 0.9
Norsk Hydro:
Atmospheric Type No
5040 (5150 Amp DC)
73 24 434
Avalence: Hydrofiller 175 64 21 0.45
[48]
Electrolysers for industrial production of hydrogen are commercially available and
marketed by various companies. Amongst the major ones, The Stuart, Teledyne,
and Norsk Hydro systems are based on the bipolar filter press while Avalence is a
unipolar tank type system. Proton provides the system that has a proton
exchange membrane type electrolyzer. The production ability and comparable
efficiency of each is given in Table 3.1 [28].
3.7 Sulfur-Iodine cycle
It is a three step process that uses heat to drive the thermo-chemical reaction.
Water is added to a mix of iodine and sulphur dioxide that releases oxygen and
hydrogen in the process at a temperature range of 850o-950oC [32]. The S-I cycle
is described by the reactions:
2 H2O + SO2 + I2 → H2SO4 + 2 HI (<120 ºC) Δ H = -216 kJ/mol
H2SO4 → H2O + SO2 + ½ O2 (>800 ºC) Δ H = 371 kJ/mol
2 HI → H2 + I2 (>300 ºC) Δ H = 12 kJ/mol
Net Effect: H2O → H2 + ½ O2
Thus the net result is the formation of oxygen and hydrogen by adding water and
providing heat to the reactants. No polluting byproducts are formed. The initial
step, also known as Bunsen reaction is carried out by reacting increased amounts
of iodine in melted form with a combination of I2, SO2 and water.
S-I is also in its infancy and quite a lot of effort is required before any worthwhile
economic and commercial benefits are achieved. The acids used in this cycle i.e.
sulfuric acid as well as Hydrogen Iodide are intensely corrosive in nature, and the
temperature range surpass 850oC, hence anti-corrosive and strong heat resistant
materials are required to carry out the reactions repeatedly for extended
durations. Hence material development is the fore-most challenge to scale up this
cycle for an industrial sized plant. Similarly catalysts that are able to withstand the
[49]
sulfuric acid environment for long durations also need to be developed and
evaluated. [32]
3.8 Photosynthetic / Photobiological
Photosynthetic production involves the reducing of hydrogen ions in an aqueous
solution to release hydrogen gas. Algae provides for the catalytic reaction in the
form of hydrogenase enzymes as well as a source of electrons. The normal
photosynthesis reaction draws electrons from water to generate oxygen, however
in this case this step is suppressed and electrons are used for reduction of H+
ions.
Green algae contain the hydrogenase enzymes for catalytic reduction and
generation of hydrogen gas. Controlled environment is used to propagate the
generation of hydrogenase enzymes that can then be used for production of
hydrogen. The hydrogenase enzymes are of three variants:
[NiFe]-hydrogenases
[Fe]-hydrogenases &
Those without a catalytic metal center
The second variant i.e the [Fe]-hydrogenase is hundred times as much active as
the remaining two. HYdA protein is a special type of such enzyme that has protein
content with an activity of 1000 units/mg. The genetic material for this type is
found in green algae such as Chlorococcum littorale, Chlorella fusca, S. obliquus
and Chlamydomonas rein hardtii. [33]
[50]
Fig 3.8 Non PV Solar pathways [ 34]
Economically justifying the employment of this method for hydrogen production
may not be cost effective at present when compared with other conventional
methods. Another point in consideration is the cost of additional tanks that are
required for storage during periods of low sun-light. Other suggestions for
improving the process are to determine an ideal antennae size, overall reduction
in cost of plant by reducing the materials for the reactor and formulation of
hydorgenases that have more tolerance towards oxygen to avert limiting the
hydrogen generation by the expenditure rate of oxygen. [33]
3.9 Photocatalytic Water Splitting
Photo-catalyst materials perform catalytic splitting of water by using solar
radiation energy from the sun. Catalysts comprising of nitrides of oxygen, TaON,
Ta3N5, and LaTiO2N, nickel doped indium-tantalum-oxide catalysts, and CdS/ZnS
systems are found to be effective materials. Dissociation of water takes place in
the presence of light activated catalyst and electron donor and acceptor, resulting
in generation of oxygen and hydrogen. Semiconductors can also be employed to
propagate the oxidation and reduction reactions and are able to form an electron
[51]
acceptor as well as donor. The band-gap for semi-conductors is small indicating
the small amount of energy change from the valence band to the conduction
band. The latter freely allows the carriage of electricity while in the former the
electrons are restrained to the ion lattice. Thus band-gap is also a measure of
conductivity of any material. Metals have no band-gap hence are good
conductors of electricity while insulators have a large band-gap because no free
electrons are available in the conduction band. Semi-conductors have an
intermediate band-gap and visible light can provide the band-gap energy. [35]
As light falls on the surface of a photo-catalytic semi-conductor that is dipped in
water, photons are absorbed by the material resulting in the band shift of the
electrons to the conduction band. The valence band is then left with +ve charged
holes. Hydrogen gas is then released as a result of reduction of the hydrogen ions,
provided the conduction band is at a higher level than the reduction potential of
H2. Oxygen is also released because of the low energy level of valence band than
the oxidation potential of hydrogen. The concept is shown in Fig 3.9.
Fig 3.9 Photo-catalyst concept
This method has been only demonstrated at a laboratory scale and not feasible
for commercial production of hydrogen. Water-splitting process generating
oxygen and hydrogen is environmentally safe as no harmful by products are
obtained. Further the solar energy involved is sustainable in long term. At present
the hydrogen production from this method is not large enough to be used as fuel.
[52]
Also the effectiveness and price issues are yet to be determined and its
competitiveness is to be evaluated in comparison with other methods [36].
3.10 International Hydrogen demonstration projects:
This section lists a number of Renewable energy powered projects that have been
installed worldwide for demonstration purposes. These projects are a
manifestation that the projects are not only practical but also have the
prospective feasibility to be run on commercial basis. The facilities/set ups listed
here do not constitute all that are available but only a sample size of various set-
ups with different technologies, sources and location. Most of these are based on
electrolytic generation and are located in United States, wind and solar resource
top as the main energy input medium. Similarly there is an example of one being
run with the feedstock as Biomass. Photo-chemical is being represented by a
United Kingdom facility while one basing entirely on solar energy is from Israel.
3.10.1 Wind-to-hydrogen project
This project uses the wind power and solar generated electricity to split water by
electrolysis to generate hydrogen. This project has been installed at National
Wind Technology center and jointly developed by the National Renewable Energy
Laboratory and Xcel Energy. Electronic converters developed by NREL have been
linked with the turbines and solar panels to identify the point where peak power
is achieved. Hence the maximum achievable energy is then used to perform
electrolysis of water to split it into hydrogen and oxygen. Hydrogen is then stored
in compressed form to be used on demand either in an Internal combustion
engine or used in any fuel cell application.
Two types of wind turbines have been used in this project. One is a 100kW
turbine developed by Northern Power Systems while the other is a smaller 10 kW
from Bergey, shown in Fig 3.10. Both are provided with choice to change speed
that is dependent on the blowing wind. Resultantly the electricity produced is also
varying in a nature according to the wind speed with fluctuating magnitude and
frequency. The output from Bergey turbine is converted to DC and then fed to the
[53]
electrolysis panel for producing hydrogen. The associated solar panel of 10 kW
generates a current range of 55-235V, which is considered to be on the higher
end for the electrolyser. Hence specially designed power electronics converters
based on “maximum power point tracking” is used to perform the DC-DC
conversion. Power output of the 100kW turbine is fed to another 33kW alkaline
electrolyser for generating hydrogen. [37]
Fig 3.10 Wind-to-hydrogen project [37]
NREL aims to achieve two major objectives from this project.
3.10.1.1 Reduced Cost:
Research studies carried out on the project has revealed that hydrogen
production from wind turbines through eletrolysers can be reduced by upto 7%
percent if the power electronics used in the system are suitably optimized. There
is also room for enhancing the efficiency by integrating the renewable energy
sources and the electrolysis units. This will improve the transfer of energy within
the system ultimately which would increase the overall efficiency thereby
reducing the cost of generation.
[54]
3.10.1.2 Efficiency Measurements:
It has also been discovered that electrolysis carried out in Proton Exchange
Membrane are more efficient as compared to the conventional alkaline
electrolysers. The former was rated at 56% system efficiency while the latter had
42%. It may be highlighted that the delivery of hydrogen as calculated was found
to be 20% less that specified by the producer. The system efficiency is expected to
reach 50% with full delivery rate.
3.10.2 International projects Prince Edward Island Wind-Hydrogen Village Project [38]
Wind-to-Hydrogen Feasibility Study in Pico Truncado, Argentina
http://www.scidev.net/News/index.cfm?fuseaction=readNews&itemid=897&language=1 [39]
Renewable-Powered Electrolysis in Iceland
Wind-Electrolysis Hydrogen at Mawson Research Station, Antarctica
http://www.aad.gov.au/default.asp?casid=13736 [40]
Wind-Electrolysis System at Stralsund, Germany
http://www.ieahia.org/case_studies.html [41]
Wind-Hydrogen System on Utsira Island, Norway
http://www.h2cars.biz/artman/publish/article_506.shtml [42]
Clean Urban Transportation Europe (CUTE) Project
http://europa.eu.int/comm/energy_transport/en/prog_cut_en.html#cute [43]
Integrated Wind-Solar-Hydrogen System at the Hydrogen Research Institute, Quebec
PHOEBUS PV-Hydrogen Demonstration at the Julich Research Center, Germany
Residential PV-Hydrogen System in Zollbruck, Switzerland
Hydrogen Solar Tandem Cell Demonstration, Leicestershire.
http://www.hydrogensolar.com/October5.html [44]
A more detailed account has been carried out in [45] that enumerate details of
number of projects world-wide involved in hydrogen production.
3.11 Discussion
Hydrogen Economy necessitates a sustaining infrastructure which can handle the
energy demand of all sectors with hydrogen as a fuel. The essence of hydrogen
economy is an energy system that is free of any harmful emissions hence any
suggested method for mass generation of hydrogen must be based on fossil-free
[55]
resources and hence the evident option available are the Renewable sources of
energy.
The end of the fossil fuel era leads to a transport infrastructure where vehicle
fleets run on fuel that is derived from a range of renewable sources including
biomass based bio-oil, electric powered as well as hybrid FC vehicles. Fuel cell
powered vehicles are considered as one of the most demanding in technical
terms. It may be difficult yet it is also one of the most suitable in the wake of the
Climate-change scenario, because of its capacity to reduce the dependence and
expenditure of fossil fuels, reduce the carbon content in the atmosphere and
mitigate environmental pollution.
Hydrogen itself is not a resource for energy and serves to act as a transporting
medium. In order to accrue the maximum advantage of this new fuel, it must be
drawn from sources other than those based on hydrocarbons. Thus renewable
sources are best suited for a sustainable hydrogen economy. Even today the
hydrogen generated worldwide is estimated at more than 5x107 tonnes annually.
However hydrogen is currently generated mainly from hydrocarbons that include
methane, coal, natural gas, petroleum or nuclear-powered processes. In contrast
the alternate sources of energy are most preferred because of their range of
availability, wide-accessibility, abundance and its capacity to remain sustainable.
Nevertheless the greatest hurdle in generating Renewable hydrogen is not only
the technology development but also the cost of producing hydrogen to match
that derived from the fossil fuels.
The available hydrogen production processes and methods number quite a few,
however it has been demonstrated in the preceding paras that almost all of them
require special materials, technologies and reactants to enable large scale
production output of hydrogen. Electrolysis is currently the only mature
technology, besides combustion of fossil fuels that can be entrusted and
developed for any future Hydrogen supply chain. Hydrogen production from
renewable resources is the preferred method because of its relative abundance,
wide availability and reliably sustained provision. Besides all the benefits, one of
[56]
the most significant challenges to the hydrogen economy is the need to generate
hydrogen at rates that are compatible with that of petrol, CNG and diesel in the
current scenario.
Fig 3.11 Ranges in delivered hydrogen cost estimates[46]
Keeping in view the cost of hydrogen production as graphically depicted in Fig
3.11 and the technological and economical maturity of the processes, Steam
methane reforming and coal-based processes are the most probable candidates
for the evolving Hydrogen Supply chain. Water dissociation is the most preferred
method as far as environmental pollution and climate change is concerned,
however developments are yet awaited for pollution free and sustainable
production of hydrogen gas. Miller and Penner [47] have drawn a roadmap (Fig
3.12) that may predict the transition path for hydrogen generation technologies.
Research advances can only envisage how early these stages are reached in the
road to a fully functional hydrogen economy.
[57]
Fig 3.12 Application of Hydrogen Technologies in the Future
3.12 Conclusion
A range of renewable energy resources are available that can be used to provide
the input energy for hydrogen generation from an equally good number of
technologically mature processes. These range from photolysis to electrolysis and
from thermo-chemical to bio-chemical. Of all the methods the splitting of water
through an electrolyser is the one that is free of any technological complications.
It is also one of the only methods from which mass quantities of hydrogen can be
produced without any apprehension of harmful derivatives that are normally
associated with other hydrocarbon based fuels. The biomass derivative methods
of hydrogen production are still in the developing stage, yet they are attractive as
they provide the opportunity of putting organic waste to use and producing
hydrogen from various routes. The transformation of syn gas to a fuel that can be
used in transport is one of the most economical path for the generation of
hydrogen. Thermo-chemical, photo-chemical and electrolysis constitute the paths
for solar generation of hydrogen.
As far as efficiency is concerned hydrogen production from heat derived from
solar energy can be termed as the best process in comparison with photo-
chemical conversions or the electrolysis. Other methods include the dissociation
[58]
of water molecule from photo-electrochemical and photo-biological processes.
Green algae and similar organisms such as cyano-bacteria that contain
Hydrogenase can also perform a highly efficient conversion from water to
hydrogen through sun light, without any participation of hydrocarbon based fuels.
The technologies are still in a developing mode and extensive research efforts are
required for their economic, commercial and technical implementation.
Demonstration projects as listed above need to be evaluated for extended
duration and conditions for their practical applications.
[59]
CHAPTER 4 4 Renewable Resources of Pakistan-Assessing the H2 Potential
4.1 Introduction
Energy situation of Pakistan over the last two decades can be very conveniently
termed as grim. This is plainly attributed to the population growth rate which is a
straight line with a constant rising slope that eventually translates into an equally
parallel rise in energy demand. Also with the advent of cheap Chinese technology
and a comparative affluence although not comparable with the GDP, the energy
demand slope is relatively steeper seen in Fig 4.1 and Fig 4.2.
Fig 4.1 Population Growth[48]
[60]
Fig 4.2 Energy consumption[49]
The energy problem has been further compounded by the fact that no major
Energy project has been commissioned over the last two decades. Pakistan has
tremendous potential for power generation from Renewable resources, however
lack of political will combined with vested interests of the successive governments
[61]
and above all poor foresightedness has plunged the country into annals of
darkness.
Like all other organizations, the Alternate Energy Development Board tasked with
the promotion and implementation of Renewable technologies, has failed
disappointingly to meet its self-set targets. Initial target of generating 10% power
requirement by 2015 [50] is far from meeting the reality by the due date. Despite
the bleak prospects the potential has been termed as excellent subject to
consistent policy and sincerity towards the country. This thesis primarily focuses
on solar and wind resource of Pakistan.
4.2 Renewable Resource Potential
Several studies have been concluded on the renewable resource potential of
Pakistan however in this thesis region wise assessment has been carried out. The
regions have been identified according to Longitude and Latitude as well as by the
place/region name. This identification is significant to assess administrative
convenience as well as for first-hand information on infrastructure as well as
other development data much needed for the planning of new Energy systems.
Studies such as those by M.A. Sheikh [51] have painted a broader picture of the
availability of Renewable energy resources however they lack the requisite data
pinpointing and identifying the areas as well as the potential. Other points in
consideration as regards the information on location are the accessibility and
terrain factors that are important in terms of Resource availability. Thus solar
radiation and wind availability may be excellent at mountain tops however
harvesting this potential is a major concern with energy researchers and planners.
[62]
The study carried out here is significant in this simple yet very important content
which would go a long way in determining the priority of areas:
Resource rich and accessible areas
Resource rich Populated areas but low in priority due to lack of space for
Solar/Wind power stations
Resource rich but inaccessible areas
Accessible areas with low renewable potential
Areas with low Resource potential as well as inaccessibility
Accessibility is one of the major issues in Hydrogen economy. Transportation and
distribution of hydrogen in either gaseous or liquefied form, forms one of the
daunting tasks of the future energy system. This subject is discussed in detail in
chapter 5.
4.2.1 Solar Potential
Pakistan’s geographical location lies 300 north of the equator which receives
maximum solar incident radiation. Data for solar radiation has been obtained
from NASA and presented both in the form of colour coded maps as well as in
tabulated form. NASA website indicates the data as a record of ten years over the
period 1983-1993 [52]. Month wise maps are given below:
[63]
[64]
Solar potential has been tabulated in Microsoft Excel Files region wise as per
Appendix A. Data indicate that 31% of the land has more than 6 kWh/m2/day of
solar radiation while the average annual minimum stands at 5.2 kWh/m2/day.
Solar radiation is available on average of 7-8 hours annually.
[65]
More than half of Pakistan’s 72496 kilometer surface has very good solar
insolation, and thinly populated as well. The area has water availability in
abundance (River Indus, see map at Fig 4.3), combined with high solar radiation
and relatively less cloudiness, the available area for solar generation of hydrogen
exceeds approximately 150,000 sq. km. Approximations indicate that about 2
percent of this area can hold more than hundred Solar Thermal plants of 200 MW
each. Cumulative generation approaches to around 20 GW, with considerable
projections for further expansion [53].
Fig 4.3 Indus River
Lutfi and Veziroglu [54] have proposed and analyzed a solar-hydrogen system for
Pakistan; however the present study completely translates the solar potential
available anywhere in Pakistan into hydrogen, with the help of NASA’s 10 year
solar data [52]. Insulation Data is presented as “Monthly Averaged Clear Sky
[66]
Insolation Incident on a Horizontal Surface (kWh/m2/day)”. Data has been
obtained from Atmospheric Science Data Centre of NASA Surface meteorology
and Solar Energy. The data is averaged on a 10 year record and tabulated
according to Latitude/Longitude. Areas have also been identified along with the
Insulation values.
4.2.2 Data Inferences:
Average insolation was observed to range from 5-7 kWh/m2/day, whereas about
30% area of Pakistan has insolation greater than 6 kWh/m2/day, with the
remaining ranging from 5-6 kWh/ m2/day.
Table 4.1
Max and Min values for Insolation
Min average insolation
Max average insolation
5.2275 kWh/m2/day
7.0016 kWh/m2/day
Table 4.2
Insolation Percentage Area
>6.0 kWh/m2/day
5-6 kWh/m2/day
30.69
69.31
The solar hydrogen generation prospects are very encouraging keeping in view
round-the-year availability of solar insulation. Hydrogen generation potential has
been discussed later in this chapter.
[67]
4.2.3 Wind Potential
Pakistan Metrological Department has spearheaded the Wind mapping in
Pakistan. Data for wind presented here has been obtained from satellite at a
height of 50 meters from earth’s surface and indicates good potential for wind
generation. Speeds of 5-7 m/s have been observed in Sindh and Baluchistan
provinces mainly along the coast line. Khyber Pakhtoon Khawa has also some
promising valleys with good power potential. Studies carried out have
demonstrated up to 20,000 MW [51] of wind power that can be tapped in an
economical way. The assessment exercise has been carried out with the support
of Ministry of Science and Technology. The regions of concern included coast
lines, North Pakistan and the provinces of Sindh and Baluchistan.
Internationally it is accepted that if any site has a capacity factor of 25% and
above, then that site is considered to be suitable for the installation of
economically viable commercial wind power farms. The above sites and their
surrounding areas therefore can be classified as suitable sites for installing wind
farms. The identified wind corridor in Sind covers an area of 9700 Sq. kMs. Gross
wind power potential of this area is 43,000MW but keeping in view the area
utilization constraints, etc., the exploitable electric power generation potential of
this area is estimated to be about more than 11,000 MW. [51]
Monthly wind potential is shown in the succeeding pages in the form of colour
coded maps, from January to December, and is based on 10 year data obtained
from NASA metrology for more diversified input. Tabulated data gives a further
refined picture of resource availability. Monthly and spatial data is significant not
only for identification of potential generation sites but also for the IJPGS
(Integrated Just-in-time power generation System) proposed in this thesis.
[68]
Appendix B presents the Wind Data in tabulated form in Longitude/Latitude as
well as locations [52].
Fig 4.4 Pakistan Meteorological Stations[55]
USAID and NREL (National Renewable Energy Laboratory) have also made certain
efforts in observation and recording of Metrological Data as shown in Fig 4.4.
[69]
[70]
[71]
Wind potential in Pakistan is termed as moderate [51]. Wind power potential is
being assessed in terms of class categories. Hence regions have been classified
according to the wind availability and are a common practice to allocate Class
according to the power potential of the region. The internationally recognized
wind classifications are represented in Table 4.3.
Table 4.3 Classification of wind potential
Today the regions being used for large scale wind power production employing
bigger turbines are categorized mainly as Class 5 or higher. As research in wind
turbines progresses to include lower speed for power generation, wind regions
classified as class 4 are also being contemplated. As large wind turbines
considered unsuitable for Class 1 and class 2 regions hence small wind machines
are being developed for such areas where importance of energy is more
significant.
The data is presented as “Averaged Wind Speed At 50 m Above the Surface of the
Earth for Terrain Similar to Airports in m/s”. Mapping carried out by the author,
with the help of NASA data reveals the wind class distribution and potential
availability (in MW) as per Table 4.4 below:
[72]
Table 4.4 Wind Resource and Capacity
Wind Resource Wind Class Wind Power W/m2
Wind Speed m/s
% Area Total capacity MW
1. Excellent 2. Good 3. Fair 4. Marginal
5 4 3 2
500-600 400-500 300-400 200-300
7.3-7.7 6.8-7.3 6.1-6.8 5.4-6.1
1.98 6.93 9.9
25.74
87752.5 60812 86875
225874 (theoretical calculation)
Calculations are based on fol assumptions:
Installed capacity per km 2 = 5 MW
Total land area of Pakistan = 877,525 km2
Only land area included in calculations [55]
1.2 MW Vensys 62 already installed at Jhimpir, Thatta, Sindh by Zorlu Enerji
Pakistan Limited [56] has been assumed for the calculation purposes. Detailed
specifications are given in Table 4.5 below:
Table 4.5 Vensys 62 Specifications[56][57]
POWER Rated power : Cut-in wind speed : Rated wind speed : Cut-out wind speed : Survival wind speed :
1,200 kW 3 m/s 13.5 m/s 25 m/s 59.5 m/s
ROTOR
Diameter: Swept area : Speed range:
62 m 3,019 m2 10-20 r/min
Data obtained from wind speeds provides an assessment of the hydrogen
potential from the specific regions, usually wind Class 3 or higher are generally
considered suitable for wind power generation. With the existing techniques Class
4 is assumed appropriate, however for the purpose of this study regions carrying
[73]
Class3 category have also been considered economically competitive [55].For
Area wise details of wind speed, please refer to Appendix “B”. The analysis used
updated wind resource data that were available for several locations.
4.2.4 Major wind resource areas:
4.2.4.1 Southeastern Pakistan especially
Hyderabad to Gharo region in southern Indus Valley
Coastal areas south of Karachi
Hills and ridges between Karachi and Hyderabad
4.2.4.2 Northern Indus Valley especially
Hills and ridges in northern Punjab
Ridges and wind corridors near Mardan and Islamabad
4.2.4.3 Southwestern Pakistan especially
Near Nokkundi and hills and ridges in the Chagai area
Makran area hills and ridges
4.2.4.4 Central Pakistan especially
Wind corridors and ridges near Quetta
Hills near Gendari
Elevated mountain summits and ridge crests especially in
northern Pakistan [55].
Summarising it can be added that wind potential in Pakistan is
Class 4+ (good-to-excellent for utility-scale applications)
26,400 sq km, about 3% of Pakistan’s total land area (800,000 sq km)
132,000 MW of potential installed wind capacity (assumes 5 MW/sq km)
Good potential for many wind/diesel and off-grid applications
[74]
Almost 9% of Pakistan’s land area has Class 3 or better wind resource
4.3 Renewable Hydrogen-An estimation
Renewable resource availability has been discussed in detail in preceding
paragraphs as regards the solar and wind energy is concerned. Hydrogen
economy shares the vision of sustainability along with elimination of ozone
depleting and “climate-change triggering” fossil fuels, hence any hydrogen that is
to sustain the Hydrogen economy must be produced from sustainable Renewable
resources in quantities comparable to the energy requirements of today’s energy-
intensive world.
This section describes the methodology by which an estimation of Renewable-
hydrogen (from solar/wind resources) is made for the region under study (i.e
Pakistan).
4.3.1 Calculation methodology
Renewable hydrogen potential was calculated as per Administrative divisions
(districts), province wise as given in Table 4.6 below:
Table 4.6 Provinces-Area and population [58]
Province No of Districts Population Land Area (sq km)
Punjab
Sindh
Balochistan
NWFP
Kashmir
Northern Areas
FATA
36
23
26
06
06
08
07
73621290
30439893
6563885
17735912
2972501
970347
3176331
205345
135306
347190
74521
13297
69971
27220
Average power per capita was taken as 48.4 watts based on population of
157,935,000 and total electricity consumption of 67,060,000 MWh/yr [59].
[75]
(4.1)
And
(4.2)
Solar PV system is considered to estimate power output and resulting
Hydrogen generation. Power technologies Energy Data book published by
NREL of the US Department of Energy provides an estimation of the land
requirements for photovoltaic systems of a given size after subtracting the
portion of PV that may be placed on rooftops of buildings. Thus 1000 KW of
photo-voltaics is estimated to require 6.4 acres [60]. This calculation assumes a
generating capacity of 1000 KW, where each KW requires an average of 0.004
acres per KW. For metric units 6.4 acres are equivalent of 0.0259 sq.km
resulting in following short equation:
(4.3)
Land area required for generating power for the population calculated in (4.2)
results for each district. Area of the district gives complete PV generation
capacity from its land by equation (4.3) above.
It is further assumed that max of 5 sun hours availability would be a safe
estimation to prevent any exaggerated figures
As explained earlier in chapter 2, the amount of energy required to create
hydrogen from water using electrolysis is 52.3 kWh/kg. However in terms of
electrical output 39.41 kWh are obtained from each kg of hydrogen, thus there
is considerable loss connected with this electrolytic conversion and electrical
output.
To summarize we arrive at the following assumptions for basing future
calculations:
[76]
Max of 5 sun hours daily
Energy input – 52.3kWh/kg of hydrogen
Electrical output – 39.41 kWh/kg of hydrogen
Land area – 6.4 acres per 1000kW.
Comparing the per capita energy requirement with the population as well as the
land area, we estimate the area of land required for generating equivalent
electricity from hydrogen through photovoltaic systems. Area required as a
percentage of total land, for each province is reproduced below as Table 4.7:
Table 4.7 Area required for PV generation out of total area
REGION TOTAL AREA
SQ KM
REQUIRED AREA SQ
KM
PUNJAB 2.05x105 2.21x103
SINDH 1.35x105 9.15x102
BALOCHISTAN 3.47x105 1.98x102
NWFP 2.72x104 9.55x101
KASMIR 1.32x104 8.94x101
N.A 6.99x104 2.91x101
7.98x105 3.54x103
PERCENTAGE 0.443561489
Thus 0.45% of total of total land can fulfill the electric power requirement of the
entire country. Excel sheets attached as appendix “C” translates into 3542 sq km.
The theoretical generation capacity amounts to 1.16x1011 kWh from complete
land area.
4.3.2 Solar hydrogen generation
In this section an estimate is made of hydrogen that can be produced by
electrolysis followed by an estimate of the electricity generation capacity of the
[77]
produced hydrogen. Solar hydrogen output, based on 52.3 kWh for producing 1
kg of hydrogen, for each province, in kilo tones is given in Table 4.8. Power output
from resultant hydrogen @ 39.41 kWh/kg gives the kWh potential.
Table 4.8 Solar Hydrogen potential & Equivalent Power output
PROVINCE/REGION KILOTONNES OF SOLAR
HYDROGEN
kWh potential
1. BALOCHISTAN
2. KASHMIR
3. NORTHERN
AREAS
4. NWFP & FATA
5. PUNJAB
6. SINDH
TOTAL
1281
49
258
100
758
500
2746
5.05E+10
1.93E+09
1.01E+10
3.96E+09
2.98E+10
1.96E+10
1.16E+11
These values can be used to assess the weekly/monthly or yearly potential for
each area/location. The areas rich in solar resource are identified from the values
attached (Appendix A). District wise, solar PV generation is compared with the
requirement in Table 4.7. This indicates that 0.117% of the total area that can
fulfill the entire electrical energy needs (excluding the distribution/transmission
losses etc). This is represented graphically in Fig 4.5. The multi-colored stack on
the left indicates the cumulative potential of all provinces/regions based on
electrolytic hydrogen from respective province/region. It is evident that if
transportation and delivery is not considered at this point, the smallest region i.e.
Kashmir can fulfill the complete electricity demand.
In terms of land use for solar generation of hydrogen 0.45% of the total land area
if dedicated for solar hydrogen is sufficient for fulfilling the electrical energy
requirements.
[78]
Fig 4.5 Solar Hydrogen Generation
4.3.3 Wind hydrogen estimation
Wind power potential in Pakistan is moderate; however it is also one of the most
promising renewable resources for power generation. Local researchers have
recommended wind as a long term measure for envisaged road map to hydrogen
economy. The current experience with wind technologies indicate that hydrogen
may provide a much needed solution for managing intermittent nature of wind
energy.
Estimated wind power is given in Table 4.9:
Table 4.9 Wind power estimation
REGION CAPACITY kWh REQUIRE kWh
PUNJAB 2.99x1010
8.55x107
SINDH 1.96x1010
3.53x107
BALOCH 5.05x1010
7.62x106
NWFP 3.96x1009
3.68x106
KASHMIR 1.93x1009
3.45x106
N.A 1.02x1010
1.12x106
1.16x1011
1.36x108
Utilization % 1.17x10-1
0.00E+00
2.00E+10
4.00E+10
6.00E+10
8.00E+10
1.00E+11
1.20E+11
CAPACITY KWH REQUIRE KWH
PROVINCE WISE SOLAR HYDROGEN GENERATION
N.A
KASHMIR
NWFP
BALOCH
SINDH
PUNJAB
[79]
The 2.354x105 MW assessed potential from Fair to excellent wind resources
mentioned at Table 4.4 translate into 45,017 tonnes of hydrogen, based on 52.3
kWh/kg of electrical input [61]. This when converted into electricity results into an
yearly availability of 6.475X1011
kWh (Appendix D). (Assuming 39.41 kWh from
one kg of hydrogen).The calculations are summarized in Table 4.10:
Table 4.10 Electrical potential from Wind generated Hydrogen
Hydrogen generated Electricity from assessed Wind power/year in kWh
MW potential 10 hr aval 52.3 kWh/kg Electricity generation potential Yearly potential
87752.5 877525 16778680.69 661247805.9 2.41355E+11
60812 608120 11627533.46 458241093.7 1.67258E+11
86875 868750 16610898.66 654635516.3 2.38942E+11
235439.5 45017112.81 6.47555E+11
It has been estimated that a cumulative of 2800 kilo tonnes of hydrogen can be
generated from Solar and wind powered electrolysis which theoretically can fulfill
the entire energy needs.
4.4 Conclusion
Pakistan is blessed with immense resources in Renewable energy. Solar energy is
not only available all year round but is also widely available all over Pakistan. The
insolation values amply demonstrate the feasibility of use of solar powered
appliances in all sectors of the economy irrespective of their geographical
location. Similarly wind potential termed as fair- to- moderate is an encouraging
fact keeping in view the worldwide growth in Wind energy @ 31.7% in 2009 [62].
Also organizations that are well established, funded and staffed have been in
place for more than a decade to promote and encourage while demonstrating the
feasibility of Renewable energy projects.
[80]
Policy measures and national regulations need to be formulated to realistically
aim and achieve the self-set goals. Sincere government efforts are essentially
required not only to steer in the right direction but also to monitor, supervise and
shoulder the responsibility, if at all fossil fuel bills are to be minimized and to help
alleviate damage caused by environmental degradation.
[81]
CHAPTER 5 5 Energy Infrastructure-Evolution, Evaluation & Development
5.1 Introduction
Annual Energy year book (2009) of Pakistan [59] gives a very clear picture of the
energy infrastructure that has evolved over the years. Thus as Compressed
natural gas forms the major portion of the energy pie; it is evident that the same
is not only available in considerable quantities but also leads to the conclusion
that the associated infrastructure would be well established and adequately
researched. The essential parts of any Energy supply chain would encompass the
production, its delivery to refueling stations, storage for varying durations and
delivery to the end user.
Fig 5.1 Hydrogen supply chain[63]
Apart from the supply chain certain other components such as safety codes and
standards, public acceptance and awareness along with any health issues are
some of the other factors that are to be evaluated before any infrastructure is set
in place. While discussion on all the issues are beyond the scope of this study;
however the major underscore in current study is the distribution and delivery of
Hydrogen. Glancing on two main energy indicators, we can clearly see the major
energy supply resource, as given below:
[82]
Primary energy supplies by source (Table 5.1)
Final energy consumption by source (Table 5.2)
Hence Natural Gas infrastructures are the most well-established in Pakistan’s
energy market. Natural gas is the major component of domestic, commercial,
industrial as well as transport sectors.
JBS Haldane forecasted the Hydrogen Economy during his address to a Cambridge
University society namely Heretics, in 1923. He envisioned a Hydrogen-based
energy system that would replace the fossil fuels on their exhaustion after a
predicted age of approximately four centuries. His description of the
technological transformation was more of a renewably generated energy system.
[83]
He compared the wind and sunlight with the convenience of coal and petrol. He
envisioned rows of metallic windmills that would generate electricity and the
surplus would be used for electrolytic decomposition of oxygen and hydrogen [7].
Today’s researchers find them in the same footsteps, though some of the details
of Haldane may be outdated, yet the proposed Renewable-Hydrogen production
and distribution/delivery seems to be the solution in the long term energy
scenario. Haldane’s concept of storing excess wind and solar energy remains the
cornerstone of the far yet realizable Hydrogen economy. Interest in Hydrogen
system has been rising and fading since its first concept in early 1920s. The 1960s
and 70s saw the surfacing of hydrogen energy related studies, with main
emphasis on long-term and large scale nuclear and renewable energy system.
Present interest in hydrogen has been led by political as well as industrial focus.
United states DOE has spearheaded the studies and covered a wide range of
topics that include hydrogen generation, storing options, distribution networks
and delivery systems.
Research on individual components of hydrogen infrastructure is not only well-set
but the information is widely available and reliable. This has resulted in studies to
model integrated hydrogen system in a larger scale. Several studies have been
initiated however the report published in 2004 by National Academy of science
has been the subject of varied discussions. The said report predicts a 100 percent
conversion of the transport sector to hydrogen by 2050. The queries raised and
issues identified can be broadly discussed as:
a. The development of economical fuel cell and storage systems.
b. The evolution of infrastructure that could support the hydrogen supply
chain
c. Competitive production of renewable hydrogen
d. Carbon mitigation strategies in coal-based hydrogen generation.
Several recommendations made in the above mentioned report has given
impetus for various research directions. The present study focuses on an overlap
of b & c. It proposes a framework for renewable hydrogen infrastructure, with
[84]
main emphasis on distribution of hydrogen through existing infrastructure which
is mainly based on natural gas.
5.2 The challenging infrastructure
The evolution of an infrastructure for an entirely different type of fuel is not only
complicated but also interesting. Starting from generation up till its delivery, the
large number of Hydrogen Supply chain components point to an array of potential
stake holders. Accordingly the economic and political dimensions are also multi-
lateral. The famous chicken and egg problem is almost always associated with the
evolution of hydrogen infrastructures, particularly in relation to the automobiles.
Thus hydrogen powered vehicles would only be produced once hydrogen stations
are established, and hydrogen stations would only be set up once a sufficient
number of vehicles are on the road/market.
Transition to a fully functional hydrogen energy system is dotted with a range of
interconnected and multi-faceted issues, it is hence imperative that considering
the risks associated and apprehensions of the stake holder, existing energy
support network must be incorporated in any future hydrogen infrastructure.
The development of a new energy system requires sustained government and
political support for successful implementation, mainly because of planning as a
policy matter as well as part of efforts to reduce the climate-change triggered
environmental degradation. Policy aspects affecting the hydrogen infrastructure
have been identified by Melaina [64].
Fig 5.2 Aspects of Hydrogen Infrastructure Challenge
[85]
5.3 Infrastructure initiatives
Several research as well as practical initiatives have been taken up world-wide
and are briefly discussed in this section. Transition to a full blown hydrogen
infrastructure is not only cost intensive but also not risk free considering the large
number of stake holders involved in this shift over. Moreover governmental
support is a must for regulatory as well as energy security issues.
5.3.1 US Department of transportation
DOT has envisaged Research, Development, Demonstration and Deployment
roadmap for Hydrogen vehicles and infrastructure to support a transition to a
hydrogen economy. The project has been divided into “Roads” and “Road 2”
pertains to hydrogen infrastructure. A nation’s transportation system is supported
by the infrastructure. The transport infrastructure includes road networks used by
all sorts of transport, the railway network, shipping freights as well as the gas
pipeline network’s transmission and distribution infrastructure. Further it also
includes the Air network with all the commercial and private airlines, as well as its
supporting elements such as the maintaining set-ups and refueling terminals.
Among the prime infrastructural challenges in hydrogen supply chains is the
selection of the mode of transport that is able to handle the fuel in sufficient
quantities. The other major issue is the transition of the entire conventional fuel
(CNG, petrol, diesel) dispensing facilities to one that is able to provide hydrogen in
the same quantities and with appreciable security of supplies.
Lastly the Department of transport has to warrant the ability of certain
components to effectively transit to hydrogen.
5.3.2 Anticipated long-term outcomes
The final result of Road 2 is the establishing of the infrastructural network
required by the new fuel to enable the country’s transport and power supply
system in place. As already discussed it would include the hydrogen dispensing
terminals backed by a complete supporting system; the pipeline network
emanating from the generation stations to the logistical system and from there to
the end –user at the tail of the distribution network. This also takes into account
[86]
the logistical issues pertaining to the delivery of feed stocks from the resources to
the plant and the modes of transport required for the actual fuel itself. Moreover
it aims to integrate the power output of the fuel cells into the national system
[65].
Fig 5.3 Infrastructure Development and Deployment[65]
In order that the transport system keeps functioning uninterrupted without
adversely influencing the economy, the key challenge remains that the entire
transition process and corresponding development of infrastructure takes place in
a smooth fashion which as economical as well. The new fuel also requires a new
set of rules and regulations for its efficient dispensing and upkeep of the vehicles
switched on hydrogen. The development of hydrogen supply chains presents
fresh research initiatives for the safety and loss inhibition in the entire system.
This entails establishing of new techniques and measures to develop the “finest
technologies”.
Apart from the dwindling/shrinking sources of fossil fuel, the global transport
sector is strained to alter its fuel mix ratio in order to mitigate carbon emissions
and to offset the high prices of carbon based fuels. In this regard the
electrification of vehicles or introduction of hybrid vehicles is one of the strategies
[87]
to reduce greenhouse gases and this can be addressed in two ways. Firstly
batteries of such vehicles can be charged from the grid electricity with the
assumption that it is generated from non-fossil resources (Hydel/others) while the
second option is the use of hydrogen gas in fuel cell fitted cars.
The hydrogen powered fuel-cell cars provide equal travel range in comparison
with the electric cars; however the lack of hydrogen distribution infrastructure is
the major impediment when fuel (hydrogen gas) availability is concerned. Grid
electricity is widely distributed as compared to Hydrogen filling stations.
A number of studies have discussed the distribution of hydrogen fuel. Yang and
Ogden [66] have compared the conventional delivery systems for supplying
hydrogen i.e. trucks, liquefied hydrogen carriers, and gas pipelines. It was
concluded that for low volumes of gas, distribution in gas trucks is the most
economical. If consumption is high then gas pipelines are the most efficient
modes of transport without any distance issues. Liquid distribution in trucks is
only feasible if distances are large and consumption rate is moderate at the site of
delivery.
Minz et al [67] also concluded similar results. Pigneri [68] worked on another
option, which included the provision of electricity for electrolyser at the refueling
station and drew a comparison with compressed trucks and gas pipelines. He
found that by using grid electricity in the distribution system, cost benefits were
achieved; as pipeline that had to be built would not come into use until a degree
of penetration (at least 25%) is achieved.
Researchers tend to define the hydrogen production and distribution models
according to the resource available and the networks already established which
they tend to study. Thus the assumptions are also varying in nature as per the
developer’s interest. This study has attempted to build an integrated model with
only renewable sources as the major source of power generation that can be used
in a variety of ways to produce hydrogen.
[88]
5.4 Framework for Renewable Hydrogen infrastructure
5.4.1 Model Development
Pakistan is selected as the region for the development of integrated model. The
country is divided into 101 grids as shown in Fig 5.4 to match the
longitude/latitude for simplicity.
Variables are listed below for Mathematical formulation
Renewable resources available in each grid square and resultant hydrogen
output from each method is represented as:
Rs for Solar
Rw for wind
Rb for Biomass
Fig 5.4 Pakistan grid map
Yield of hydrogen from each grid square
101
0n no HH
Transportation factor between each production plant and point of use (energy
consumption centers)
i. fT1-for pipeline
ii. fT2-for truck
iii. fT3-for trailer
[89]
A portion of the hydrogen product may be used in Fuel-cell applications directly
as Hydrogen gas (or liquefied form) and transported to Energy consumption
centers. The remaining is converted to Electricity and connected to Main Grid for
distribution [Fig 5.5].
Hydrogen output from each grid is represented by
101
1n bbnwwnssno fRfRfRH
Where
Rsn=Product of area of grid available for solar energy and average solar radiation
for the region.
Rwn= Product of area of grid available for wind energy and average wind density
for the region.
Rbn=Product of area of grid available for biomass and average extraction for the
region.
fs=Solar factor defined by the Solar technology
fw=Wind technology factor
fb=Biomass conversion factor
n=number of grids
if p=Percentage of Hydrogen used for Fuel-cell use:
101
1n bbnwwnssnf fRfRfRpH
Hydrogen for conversion into electric power
101
11
n bbnwwnssne fRfRfRpH
Hydrogen which is to be used in “fuel cells” in compressed form or liquid
hydrogen is to be transported to energy consumption centers. Various options are
available for its transportation, which include pipeline, truck and trailer.
[90]
Cost of hydrogen transportation to various cities depends not only upon distance,
but also a factor that is peculiar to each mode, defined by fT.
ffDfRfRfRpH Tbabbnwwnssnf )(
f = Terrain factor depending upon the ground conditions i.e. plain area, desert,
mountainous area etc.
This study presents hydrogen supply chain network that is based on “Renewable
Energy Database” at the back end. Solar and wind resource availability has been
assessed in detail in chapter 4.
Hydrogen Demand is determined based on population and per capita energy
requirement:
greqd PEH
Where gP = population of grid
[91]
Fig 5.5 Framework for Renewable Hydrogen Infrastructure
[92]
This also requires identification of geographically dense areas in terms of
population as well as the industrialized areas. Excess hydrogen (Hx) from each grid
can be transported to the next grid or point of demand.
d
f
xH
HH
5.4.2 Infrastructural Framework
Various elements of the framework are illustrated in Fig 5.5. Hydrogen production
from each grid, “Ho” of complete area under-study is fed into the Master Data
Analyzer (MDA). MDA in turn forms the decision support tool for the IJPGS
(Integrated Just-in-time Power Generation System).
Fig 5.6: Feedback cycle of IJPGS
The system decides the proportionate distribution of hydrogen and, that for
conversion to electricity. Electrical output is fed to the main grid and onward to
power distribution companies (indicated as IESCO, GESCO, FESCO etc). Liquefied
or compressed hydrogen is transported via trucks, trailer or pipelines depending
upon the distance, quantity and population density of the target users, as
[93]
discussed in Para 3 above. Increase in cost of transportation with distance and
mode is illustrated in the magnifier (Fig 5.5). Excess hydrogen from each grid is
notified to MDA and directed to the grid with deficiency. Feedback cycle of IJPGS
is shown in Fig 5.6.
5.4.3 Outward radiating distribution System:
In this suggested distribution system (Fig 5.8), energy consumption centers form
the (proposed) focal point for distribution of hydrogen. Import and export of
hydrogen from these “focal points” depends on excess hydrogen product
available in the adjoining grids. The scenario can be compared with a vessel with
multiple pressure sensitive valves in its perimeter. Thus if any excess hydrogen is
available in any of the adjacent grids, flow of hydrogen takes place towards that
grid. Flow is optimized at this stage as depicted by O2 in Fig 5.7.This can be
referred to as an Intelligent Just-in-time power generation (IJPGS) system.
However the intelligence has to be derived from the Master Data Analyzer (as
illustrated in Fig 5.6), which is again dependant on the “Resource Data Bank” that
has live feedback, schematically shown in Fig 5.6. Block diagram (Fig 5.8) indicates
the grids as the boundaries (although not a real life assumption) that are
connected with a flow path from grid-to-grid. Pathways are controlled and
Fig 5.7 Areas for optimization
[94]
operated by the IJPG system. Excess and deficient Hydrogen in each grid is
represented by “+” and “–” symbols respectively. Arrows are indicative of the
flow of hydrogen from an “excess holding” grid to one that is deficient.
5.4.4 Optimization: (O3 for R3)
Three stage optimization results in an optimal cost proposal for an integrated
renewable hydrogen system (thus named as O3 for R3). Fig 5.7 shows the three
points of application of optimization, described as:
a. Decision as to the proportion of Renewable resource to be converted
directly to hydrogen, and that to electricity.
Fig 5.8 Intelligent Just-in-Time Power Generation System
[95]
b. Mode of transportation-Pipeline, truck or tube-trailer (depending
upon the distance).
c. Distribution network (A, B, C or D, refer to fig 5.7) to be adopted
within the city depending upon the population density and the
dispersion of points of use.
5.4.5 RESULTS
Various pathways have been identified in different regions to initiate and
accelerate the deployment of Hydrogen Economy. Accordingly infrastructural
requirements are being worked out for ease and user-friendly supply of fuel. This
study demonstrates the integration of renewable resources in the production of
hydrogen, the management of resources through an intelligent system termed as
the Master Data Analyzer and then identifies the optimization areas. A
comprehensive database of Solar/Wind and other Renewable resources
(Biomass/Hydel/Waste etc.) is foremost for the implementation of any transition
to a fully sustainable and Renewable-based Energy System. Just-in-Time System
also has to have a live feed back of the fluctuating demand and supply scenarios
of the region under study. The application of Solar/Wind data to a specific
grid/region presents satisfactory results. The same can be extrapolated for
application to a regional or national level, and trials are required to be carried out
to assess the feasibility of the proposed systems. Delivery systems are also under
development, pipelines are considered to be the most economical way of
transporting Hydrogen over long distances in a full-fledged Hydrogen Economy.
Similarly for Low-pressure Distribution i.e. within the cities, patterns as exhibited
in Fig 5.8 are to be followed depending upon the population/user density as well
as the distances. Extensive simulations and real-life situations would lead to a
practicable method that can address the “Energy question”.
5.4.6 Future Work
Data for the renewable resources may be integrated with the Master Data
Analyzer, which has to be interpreted through special software primarily designed
for the purpose of processing the data according to pre-defined criteria.
Optimization techniques such as Lingo may be employed to determine the
[96]
economical pathway for a region, which can then be applied to the whole area or
country. Similarly the distribution networks are to be analyzed for suitability
depending upon the cities.
5.5 DISCUSSION
As the world crosses over the “Oil Peak” and enters the post-fossil era,
research work and studies are increasingly focusing on alternative means of
energy sources. While various options are available such as Nuclear, Hydro, Tidal,
Geothermal and Renewable to name a few, the single biggest challenge remains
“Sustainability”. Climate change, environmental degradation and effects on
Ecological footprints are some of the phenomena affecting the human health,
well-being and livability. Thus any study must preclude the fossil fuels in any
future Energy Systems. A number of studies have been carried out on the
evolution of the Hydrogen Supply Chain, nevertheless most, if not all, initiate with
fossilized feed stocks of Hydrocarbons. Keeping in view the effects indicated very
briefly, the study has been made which layouts the framework for development
of Hydrogen Economy.
Wind conversion technologies are not only widely researched but are also
one of the technologies most rapidly penetrating in the world energy systems
[69]. Pakistan’s wind potential is moderate however the generation capacity can
play an effective role in the power structure of Pakistan. Pakistan’s Solar
resources are excellent and the harnessing technology is also well developed, as
discussed in chapter 4. Hydrogen just like electricity is an energy vector [is a form
of energy], and can be used as fuel in internal combustion (IC) engines or
converted into electricity on demand or fed into fuel-cell applications. Proposed
framework indicates that Hydrogen can be produced all over the country, which
can either be fed to the National Grid through the Power Distribution companies
or transported as liquefied/gaseous Hydrogen in Tankers/trailers (Fig 5.5). The
mathematical model evaluates the amount of Hydrogen production capacity
available in each grid, which can either be consumed or exported depending upon
the local requirement, as elaborated in Fig 5.8. The IJPGS controls the entire
Energy system through the Master Data Analyzer as part of the feedback loop
exhibited at Fig 5.6.
[97]
CHAPTER 6 6 Infrastructure Analysis
6.1 General
The word “infrastructure” in an Energy Supply chain denotes the connecting
elements between the Energy resources where energy/fuel production takes
place and the places where it is used i.e. the end consumers. Infrastructure
includes all types of transport starting from wheeled carriages, shipping
containers, rail networks along with means for storing, distribution and the
dispensing facilities.
This chapter discusses the infrastructural requirements for the hydrogen
economy. It is considered as one of the main impediments in the transitory stages
as the cost of constructing an exclusive infrastructure network for hydrogen is
substantially high, especially in a scenario where demand for H2 is almost
nonexistent. This leads to the historical demand & supply scenario commonly
known as chicken and egg problem whereby suppliers are equally nonexistent in
the absence of any demand. In this regard various countries have laid down
ambitious hydrogen pathways to initiate transition to hydrogen economy,
however the arising technical issues in such a transition are lacking in most of
these studies. It is quite surprising since hydrogen economy cannot be realized
without a well thought out and planned resolution of these difficult queries.
There are as many solutions proposed to the barriers as there are researchers in
the evolution of hydrogen economy. However disparity of views is seen amongst
the comity of authors on the actual evaluation of the entire transitory problem.
We now address some of the most significant issues pertaining to Hydrogen
economy evolution that would allow an analysis of the infrastructural problems
especially in context of our area of study i.e. Pakistan. Infrastructure analysis is
carried under following broad categories:
6.2 Distributed Vs Concentrated production
Most of the studies carried out previously on the subject of transition have mainly
concentrated on the distributed production of hydrogen building on the
[98]
argument that it can help to overcome the infrastructural barriers. Distributed
production has been proposed to circumvent the infrastructural build up and
consequent supply/demand issue. However it must be kept in mind that
distributed or “stand alone” generators require small reformers or electrolysis for
producing hydrogen, and FC stacks in case of FCVs. In this proposal electrical
power or fossil fuels are required to run the stand alone Hydrogen generation
plants. This theory is based on the fact that government owned or public/private
concerns with large transport fleets would initiate entry of H2 into the
transportation sector. This would be followed by privately owned vehicles that
would join so the demand for hydrogen would start rising. As demand increases
the stand alone or distributed generators would be joined by pipelines and the
evolution process will continue and expand to a full-fledged H2 economy.
The main drawback of this approach is that it fails to address some of the main
issues for which hydrogen is to be used as a fuel i.e. the environmental benefits
and the use of oil/gas generated electricity for powering the stand alone
generators. Distributed generation employs small reformers/electrolysers that do
not support carbon capture and storage, hence environmental benefits are lost.
Secondly the presumptions that vehicle fleets would be the early initiators have
been proven otherwise by Sperling [70], in case of new fuels.
Moreover, private fuel cell vehicles would not enter the market thereby keeping
the chicken and egg problem unsolved. It has been found by Van Benthem [71]
that vehicle owners are reluctant to change over to a new fuel, if it is not available
at almost 25% of the existing dispensers. Further accessibility to inexpensive FCs
remains a precondition, and small reformers with stand-alone generators are
likely to make these generators costlier because of the extra cost of the
reformers. Distributed generation scenario has other lackings when the complete
system is examined.
6.2.1 Wide spread H2 Vs limited use
Studies suggesting H2 entry in the fuel market through road transport propose a
limited use to vehicle fleets, while if H2 has to encompass other sectors also, then
[99]
the domestic and industrial sectors must also be integrated from the very
beginning. Neglecting the use of hydrogen in these sectors would strongly impede
the introduction and development of FCs in the stationary applications. Moreover
if at all an infrastructure is build, it is very pertinent to consider the market forces
i.e. the choice of a fuel as well as a supplier. Every consumer exercises his right to
choose the type of fuel. These aspects are altogether being ignored, once only the
transport sector is being considered for the transition stage. Hence a significant
part of the energy market would restrict to develop.
6.2.2 Spatial/Storage issues:
Decentralized hydrogen production is based on on-site reformers and
electrolysers -which have an inherent drawback of limited production and
delivery options. Estimations in this regard do not address the issues of increase
in production with growing demand while the space/available area remain
constant. Thus for an average reformer and electrolyser the dimensional
requirements are:
Reformer 12x12x15 metre3
Electrolyser 04x06x14 metre3
In an event of increased demand, the need arises for greater production
capability as well as a need for larger storage system, which can rise exponentially
considering the demand that is to be generated with stationary applications [72].
Research work in this regard carried out by [70][73][74] tend to ignore the spatial
considerations of decentralized production. Thus for a good estimation of the
actual demand of hydrogen and its supporting infrastructure, it is imperative that
production requirements and associated delivery network be quantified. Spatial
and storage solutions are much needed since as demand curve rises, the supplies
must be increased and means must be available to address the spatial and
infrastructural problems arising thereby. Thus as already exemplified the size of
reforming plants and electrolytic generators very clearly indicate the space
infrastructural problems arising in a distributed production scenario, consequent
with a rising demand.
[100]
6.2.3 Futuristic vision
Evolution is generally a slow process and takes place gradually as milestones are
achieved. Thus decentralized production is associated with short term planning.
Hence options for generation, storage and delivery under consideration must
keep in view the optimized utility. For instance the storage option as discussed is
just a case in point which requires addressal in long term scenarios as well. Such
approaches not only enhance the costs of transition but also holdup the product
development initiatives. Resultantly the short term solutions are cost intensive
owing to low efficiencies of smaller production units. Moreover the storage
aspect is diminished because the supply calculations are based on peak demand.
The problem is mostly overlooked by proposing the linkage of fuelling stations as
demand rises leading to an extensive pipe network with further rise in demand.
This would entail more investment. Also since stationary applications are
overlooked in decentralized production focusing mainly on the transport sector,
this would imply integration of small reformers which could later be connected
with the main gas grid. Cost of such fuel cell systems would escalate along with
those of on-board reformers. Manufacturing units would then compromise on the
quality of such products which are to be replaced in the near term, when switch
over to hydrogen is completed.
Transition to a hydrogen economy has several options; however the most viable
option that addresses all technological, economic and practical issues is yet to be
pronounced. In order to realize hydrogen-powered society, the foremost thing is
the path of transition which must encompass a long term and centralized
assessment in a wholesome manner.
The preceding writing has effectively highlighted the need for developing an
integrated approach for generation and transport of hydrogen through
indigenous renewable resources. In the succeeding sections the back bone of
Pakistan’s energy supply chain i.e. Natural gas pipeline network is discussed and a
biomass-based hydrogen supply chain is developed with the help of a
mathematical model. Subsequently a novel approach for transporting hydrogen,
with the help of existing pipe-line infrastructure as well as in the form of methane
and methanol is presented.
[101]
6.3 Natural gas infrastructure in Pakistan
6.3.1 General
Major gas fields of Pakistan are indicated in Fig 6.1. The figure indicates the
largest single field at Sui in Baluchistan with estimated reserves of 340 MMCFD
justifying the development of the Gas network that originates from Sui and other
33 sources (indicated in Fig 6.1) are dove-tailed into the main Transmission
system for distribution all over the region.
Fig 6.1 Major Gas Fields
Transmission and distribution of natural gas in Pakistan is carried out by two
companies namely:
6.3.2 Sui Northern Gas Pipelines Ltd (SNGPL)
SNGPL as the name suggests responsible for provision of natural gas to 3.4 million
consumers of Northern Pakistan to include Punjab and Khyber Pakhtoon khwa.
[102]
SNGPL’s system supplies natural gas from Sui, Baluchistan all the way to
Peshawar, KPK covering a distance of 7,347 Kms in the form of Main & Loop lines,
and joining 1,624 towns and villages of the two provinces. Distribution system
comprises of 67,449 kms of pipe line. Transmission system comprises of 6-36”
diameter pipes transporting natural gas over a distance of 6260 Kms. The system
also includes compressor stations which increase the pressure to 1235 psig to
meet the demands of the industrial, commercial and domestic consumers [75].
The Gas Control Centre at Faisalabad is the main artery of the transmission
system. The whole network is controlled with the help of a 'state of the art'
SCADA system which provides data monitoring facility apart from remote control
operation during emergencies. Transmission network of SNGPL is shown in Fig
6.2. The figure is indicative of the well-established and well-penetrating network
in terms of its extensiveness and accessibility to small towns and villages.
Distribution department is responsible for the safe, reliable and efficient
distribution of natural gas through the utility pipes to customers. The total
length of SNGPL's distribution network is approximately 67,449 kilometers.
Distribution department is distributing 1680 million cubic feet per day (mmcfd)
natural gas to 3.45 million customers in 1542 towns and Villages of Pakistan.
[103]
Fig 6.2 Sui Northern Gas Pipelines Ltd Transmission Network [75]
[104]
6.3.3 Sui Southern Gas Company Ltd (SSGCL)
SSGCL is responsible for transmission of natural gas from Sui and its distribution
to 29 districts of Sindh and Baluchistan. Transmission network is spread over
3,062 Km while distribution pipelines have an overall length of 27,542 Kms.
Salients including the major gas fields in this region are also shown in Fig 6.3.
Fig 6.3 SSGCL Transmission and Distribution Infrastructure[76]
[105]
6.4 Layout of Natural Gas Infrastructure
Both the Transmission/Distribution companies i.e. Sui Northern pipelines Ltd as
well as Sui Southern Gas Company have an identical layout, however for the
purpose of this study the infrastructure layout of SNGPL is being evaluated for the
necessary analysis.
SNGPL has organized its infrastructure as per procedure in vogue worldwide i.e.:
a. Transmission Infrastructure
b. Distribution Infrastructure
Regional Establishment for Transmission/Distribution is organized in 8 regions as
per Table 6.1, all over the country including the provinces of Punjab, KPK, Federal
Capital and Azad Jammu and Kashmir
Table 6.1 Regional Establishment
Transmission Network Distribution Network
Faisalabad
Lahore
Multan
Wah
Islamabad
Lahore
Peshawar
Faisalabad
Multan
Gujranwala
Abbotabad
Bahawalpur
This network receives the gas from various gas fields (Fig.6.2) and transmits it
upcountry through pipelines. Gas received in the network system from various
gas fields is as per Table 6.2
[106]
Table 6.2 Gas Received province-wise
Province Total MMCF Avg/day
Balochistan
Punjab
Khyber PakhtoonKhwa
Sindh
143,216
50,887
123,676
355,206
392.37
139.42
338.84
973.17
Detail of the number of consumers supplied by SNGPL is tabulated below. Table
6.3 indicates that Bahawalpur and Abbottabad has the lowest number of
consumers. Domestic sector is further reduced in Abbottabad, while the
Industrial, Commercial and Bulk Supply are lower for Bahawalpur.
Table 6.3 Region-wise number of consumers
Region Industrial Commercial Domestic Bulk Supply Total
Abbottabad
Bahawalpur
Faisalabad
Gujranwala
Islamabad
Lahore
Multan
Peshawar
Total
121 1297 66763 1791 69972
40 791 95029 851 96711
471 3967 316473 5645 326556
763 7403 330562 2866 341594
338 7338 481322 19770 508770
1227 12791 721491 779 733288
118 2011 212798 2784 217711
226 5886 223185 890 230187
3304 41484 2447623 35376 2524789
Transmission system has been further sub-divided into segments and can be
categorized according to the length of the segment, pipeline diameter as well as
flow rate through the segment. Details are enumerated in Table 6.4
Analysis of the segment flows indicated in Table 6.4 shows max flow at Bhong-
AC4, however Mardan-Mingora section is the lowest flowing segment. Technical
characteristics are indicated in Table 6.5
[107]
Table 6.4 Transmission System – Segment wise Capacity & Utilization
Pipe Segment Available Capacity
(MMCFD)
Max. Flow passed
(MMCFD)
% age of Capacity
Utilization
Sui- Bhong 790 681 86
Sawan- Qadirpur 370 275 74
Qadirpur- Bhong 850 764 90
Bhong -AC4 1630 1344 82
AC4 - AV22 1590 1328 84
AV22 - Kot Addu 350 45 13
Dhodak - Kot Addu 70 32 46
AV22 - Multan 1430 1265 88
Multan - AV29 1350 1201 89
AV29 - Sahiwal - Lahore 650 549 84
AV29 - Faisalabad 990 887 90
Faisalabad -Lahore 450 336 75
Faisalabad -Galli Jagir 350 169 48
Wah - Peshawar 110 281 255
Wah - Abbottabad 94 51 54
Gurguri - Kohat 315 346 110
Daudkhel- FC1 - C6 110 136 124
Nowshehra - Mardaan 75 64 85
Mardaan - Mingora 30 16 53
Table 6.5 Technical Properties
Pipeline Characteristics
Transmission
Distribution
Diameter (inch)
8-36
4-18
Wall Thickness(inch)
0.32-0.562
0.24-0.44
Grade
Yield
UTS
Operating pressure
Type of coating
Carbon Steel
52,000 psi
68,000 psi
1440 psig
Bitumen/PE coating
[108]
6.4.1 Compressors
Turbine driven Centrifugal compressors are being used in Transmission network
for recouping the pressure drop due to frictional losses and to boost the pressure
up to the required standards. Compressors employed in SNGPL are made by M/S
Solar Turbines, a Caterpillar company. Two models in extensive use are C16 and
C33, whose performance specifications are as per Table 6.6.
Table 6.6 Compressor Characteristics
Property C 16 C 33 Efficiency % >75% isentropic >80% isentropic
Maximum Speed rpm 23,800 16,500
Maximum Flow m3/min 50 269
Maximum Head kJ/kg 215 257
Maximum Casing Pressure kPa 24,130 18,620
Maximum Torque Nm 3920 7457
There are 11 compressor stations installed in the Transmission network of Sui
Northern Gas pipelines ltd. In all 65 compressor packages have been fitted. The
average distance between two consecutive field gas compressor stations is 112-
155 kms.
The gas flows in various regional establishments of SNGPL Distribution network
are given below. Distribution capacity figures for Lahore indicate that the network
is widely dispersed and deeply penetrated to serve the larger population as
compared to Abbottabad with the lowest capacity.
[109]
Table 6.7 Distribution Network
Sr. No. REGION CAPACITY (MMCFD)
TOTAL CONTRACTED AVAILABLE
1 Bahawalpur 321 243 78
2 Multan 649 487 162
3 Faisalabad 597 433 164
4 Lahore 967 927 40
5 Gujranwala 364 301 63
6 Islamabad 408 245 163
7 Peshawar 277 191 86
8 Abbottabad 156 141 15
TOTAL 3739 2968 771
Table 6.1 to Table 6.7 gives a brief overview of the Natural gas infrastructure
within the scope of this study. The next section discusses and evaluates the
possibility of hydrogen production from biomass resources followed by
development of options for its transportation. Cropping pattern of Pakistan is
shown in Fig 6.13. Legend of the figure indicates wheat as the pre-dominant crop
cultivated throughout the country, in either Rabi or Kharif season. Chemical
characteristics and cost elements of biomass is discussed in succeeding sections.
Model developed here is based on wheat straw resources available all over the
region for the production of hydrogen.
6.5 Model Formulation
6.5.1 Introduction
Energy supply chains and modes of transport are very much interconnected with
one another. Although efficiencies have greatly increased over the last century,
however the energy demand is continuously rising because of the continuous
climb in population figures in sync with the demand. It may also be noted that the
energy supply chain is heavily reliant on the modes used for the transport of feed
stocks as well as the finished products (i.e. energy carriers such as hydrogen
and/or fuels).
[110]
Renewable sources being widely dispersed require greater dependence on the
transportation modes with significant effects on delivery infrastructure in urban
and rural regions.
This study is focused on designing a system for renewable production of hydrogen
and its delivery through the 3-modes, relevant to the scope of this thesis i.e.:
a. Hydrogen as a mixture with natural gas
b. Hydrogen after conversion into methane
c. Hydrogen as methanol
In all these cases, the cost of hydrogen are primarily based on two factors i.e. the
cost of the input raw materials and the mode/facility of production. Transport is a
major factor contributing to the cost of hydrogen fuel. Problems of establishing
production facility are also part of designing the network and associated logistical
analysis.
The decision for placement of a plant can be addressed in a variety of ways. The
cost of transportation between the production facility and the end user is one of
the significant input data to the placement model. In the present work, the
process of transporting H2 fuel through various modes is studied along with the
placement as the same are closely linked with the consumer centres.
Developing a supply chain model is in-deterministic with respect to the consumer
requirements, provision and the technique. Various techniques have been
employed to the modeling problem such as [77] [78] [79]. In the current work,
deterministic approach has been applied with minor change in the stochastic
models.
6.5.2 Model Build up
The model builds on the objective of determining the quantity of hydrogen and
size of the hydrogen generation facilities in a network that maximizes the
efficiency (in terms of the mode of transport and the paths to be adopted)
between the feed stock sources and the production facilities as well as the H2 –
path from the generation facility to the end consumer.
[111]
Four constituent parts of the model can be identified as:
a. A database containing the sources of biomass availability, its forecasted
requirement as well as the distance between the user and consumer.
b. Cost effect of each constituent part of the model.
c. An optimized model based on Mixed Integer Non Linear Programming.
d. Model conception based on the results.
6.5.3 Assumptions
a. The sources of biomass feed stocks are identified.
b. Energy consumption centres and extent of H2 fuel requirement is previously
known.
c. Likely placement of generation facilities.
d. Input material is transported through wheeled vehicle such as cart, truck or
dumper etc.
e. Mode of H2 delivery is via pipeline, liquid fuel bowzers and gas trucks.
f. The complete system is assumed at steady state with no increase in
otherwise fluctuating demand.
g. Optimization is based on the cost of generating H2 from agriculture residue.
Table 6.8 Index and Subscript Assignment
Index Description (refer page 112)
r
s
t
m
Feed stock resource
H2 generation facilities location
Energy consumption centres
Mode of H2 transport
[112]
[113]
Table 6.9 Data provision to the model
Biomass Resource
Pt
Requirement/dayt
αq
H
B_lossm
t_lossm
D_lossm
drs
dst
Biomass harvested from area ‘r’ (tons/yr)
Price of H2 at energy consumption center ‘t’ ($/kg)
Daily requirement at energy consumption centre ‘t’(kg/day)
Factor to scale the different technologies
H2 obtained from unit biomass residue (kg/ton)
Factor to account for the loss of biomass input during delivery and
stowage.
Factor to account for the loss of H2 from the terminal of mode ‘m’
Factor to account for the loss of H2 from the distribution system in
mode ‘m’
Biomass resource area ‘r’ & production facility ‘s’ distances in km
Production facility ‘s’ and energy consumption centre ‘t’ distances
in kms
6.5.4 Variables’ definition
Table 6.10
Decision variable Description
Rrs
Cs
Tms
Hmst
Hbvst
It1t2
Ibvt1t2
SCmt
Annual amount of biomass resource provided from resource ‘r’
to the production facility ‘s’ (tons/yr).
Daily production capability of hydrogen in kg from facility ‘s’.
Dispensing Capability of mode ‘m’ from facility ‘s’.
Capability of transporting hydrogen by mode ‘m’ from facility
‘s’ to energy consumption centre ‘t’ in kg/day.
Binary variable for availability of pipe-line between production
facility ‘s’ and energy consumption center ‘t’.
Pipe capacity for transporting hydrogen between energy
consumption centres t1 and t2 in kg of H2/day.
Binary variable for availability of pipe line between energy
consumption centre t1 and t2.
Capability of mode ‘m’ to supply hydrogen to energy
consumption centre ‘t’ (kg/day).
[114]
Table 6.11 Intermediate variables (cost in $/yr)
RCrs
PCs
TCms
DCmst
ICt1t2
LCmt
RCmt
Xt
Biomass resource from area ‘r’ to production facility’s’
Production cost at facility ‘s’
Cost at terminal for facility ‘s’ by delivery mode ‘m’
Cost of transportation from production plant’s’ to energy consumption
centre ‘t’ by mode ‘m’
Transport cost through pipeline between two consumption centres t1
and t2
Transport cost for local distribution within the city through ‘m’ mode
Cost of refueling at energy consumption centres ‘t’ recieving hydrogen
through mode ‘m’
Annual sale of H2 in energy consumption centre ‘t’
Objective function is designed to maximize profits and is given by:
Maximize
Z=∑ -yearly cost (6.1)
Yearly cost = ∑ ( ) +
∑ ( ) + ∑
( )
+
∑ (
) +
∑ (
) +
∑ (
) +
∑ (
) (6.2)
Yearly cost of producing hydrogen is dependant on the individual ability of the
network components along with the amount of hydrogen feed stocks that are
transported and converted to hydrogen at each of the plants and delivered to
various energy consumption centres. As already mentioned, the quantities
[115]
produced at each node and delivered there from is assumed to be constant. CF
indicates a proportion of the production capacity that is utilized.
Cost of biomass resource includes the harvesting, storing and stacking per unit
weight i.e. tons
RCrs (Rrs,drs) = (cost of harvestr + cost of stowager + cost of transport rs(drs).Rrs) (6.3)
Production cost:
It includes the cost of installing the production facility as well as the cost of
operation and other overheads. CRF stands for capital recovery factor is the
amount of interest that may be paid on yearly basis depending on the cost of
installation of production facility.
PCs(Cs) = (capital recovery factor+ overheads + maint) x capital cost.
Cαs+∑ (6.4)
At the site of production another cost added to the H2 fuel is its preparation for
onward delivery which is referred here as the terminal cost ( ). This cost
basically represents the costs of establishing and operating the terminal
machinery.
(
) ∑ ( ) ( )
+
∑ (6.5)
The cost of delivering H2 can be broken down into the costs incurred for delivery
by pipe line and secondly the costs for transportation by truck mode.
DCm=gas,liquid(
)= ( )
(#trl ( )+op pay(#trl (
)) + per kmm. dst (6.6)
Transporting through network of pipes includes the cost of running the machinery
and those involved in maintain it. Compressors used in pipe line networks are
included in the cost already calculated for the terminals.
DCstm=pipe = (Hbvst,dst) = (CRF+overhead +maint) x capital cost x Hbvst.dst (6.7)
[116]
Transportation of hydrogen gas between two energy consumtion centres is also
treated with binary variable, Ibvt1t2, it is given by:
ICt1t2 (Ibvt1t2,dt1t2) = (CRF+overhead +maint) x capital cost x Ibvt1t2.dt1t2 (6.8)
Each delivery mode has some additional charges incurred to replenish the fueling
stations
RCmt(SCm
t) = ∑ ( ) ( )
+
∑ (6.9)
6.5.5 Constraints:
For real life modeling of the scenario, certain constraints need to be applied to
the objective function. If there are no limitations in the form of constraints, the
modeling scenario would aim to generate and sale unlimited amounts of H2,
which would ultimately lead to unlimited profits.
Constraint on yield
The crop harvested for input to any production facility ‘s’ from any agricultural
field ‘r’ has to be within the harvest yield.
∑ ≤ Biomass resourcer (6.10)
The annual production capability of any facility has to be more than the
biomass resource being made available to the production plant. B_loss make up
for the loss of feed stock in transport and stowage.
∑ ≤ 365.CF.Cs (6.11)
H accounts for the amount of hydrogen that is obtained from a given quantity of
Biomass resource.
The terminals at the production facility must be able to handle the generation
capacity of the facility
∑
= Cs (6.12)
[117]
Similarly the capability of a terminal at ‘m’ should be larger as compared to
output of the hydrogen production capacity at that mode.
∑ ≤ t_lossm.Tms (6.13)
The distribution network of an energy consumption centre must be able to handle
the amount of hydrogen coming into the area ‘t’
∑
≤ (6.14)
Correspondingly, the gas network within the local energy consumption centre
must be able to handle the amount of hydrogen coming in the area ‘t’ through
the pipe supplying the area
∑ ∑
∑ ≤ (6.15)
Distribution network of an energy consumption centre should have a higher
capacity than the quantity of H2 being sold at any energy consumption centre
given by
Xt≤ ∑
(6.16)
The sale of H2 at any energy centre ’t’ cannot be greater than the requirement of
H2 at the same energy consumption centre.
Xt≤ daily demandt.365 (6.17)
Limitations in terms of constraints also apply to the production facility. The
quantity of H2 obtainable from a given biomass resource must be the same as
that obtained as output in the form of H2 from the production plant. In this
regard the presence or else in case of a pipeline is represented by the binary
variable.
∑
∑
∑
∑
(6.18)
[118]
In the energy consumption centre, the presence of a local pipeline within area ‘t’
is defined by the binary variable ‘Ibvt1t2’
∑
∑
∑
∑
∑
(6.19)
The capacities of all areas, production facility as well as transport modes are non-
zero entities.
6.5.6 Database
Throughout the course of this work, it was found that statistical base is either
non-existent or minimally addressed in most of the government departments. In
order to present a real life model as developed above – accurate data is required
for presentable results and conclusions.
However several visits to the Federal Bureau of Statistics, Statistics Division,
Government of Pakistan remained futile. Organized in three sub-setups i.e.
a. Federal Bureau of Statistics
b. Population census organization
c. Agriculture census organization
[119]
Nevertheless, no worthwhile data on land-use, quantity and type of
biomass/crops is available. Similarly no statistics are available for the energy
consumption city-wise, district –wise or any other category. Neither the vehicles
plying in any area nor the number of fuel (CNG, petrol, diesel) stations in any
given region are documented.
Similarly for any model to be developed especially when placement of production
facilities is being considered, modeling region has to be carefully mapped. Also,
the pipeline network, availability of trucks/trailers and their charges are neither
documented, nor can be quoted for any concrete research output.
Moreover energy consumption centers are to be based on urban/rural
consumption data, whereby clusters are generated to designate a sizable energy
demand center. Identification of energy consumption centres than has to define
its center for the purpose of calculating the distances.
Biomass feed-stocks from agriculture residue are an important statistical figure in
the choice of potential placement of hydrogen production facilities. This is
essential not only to minimize the transportation costs of biomass feed stocks but
also the terminal costs, thereby minimizing the overall cost and optimization of
the entire Renewable Hydrogen supply chain.
Thus the complete exercise remained academic in the absence of real life data.
Instead data available from the internet for statistically advanced countries was
used to present the viability of an otherwise practical model. For the purpose of
this study the energy requirement was calculated on the basis of per capita
energy requirement @ 48.4 KW [59]. The same has been used for assessment
earlier as well in Chapter 4.
6.5.7 Cost for elements of Hydrogen supply chain
All the components of this biomass based renewable hydrogen chain i.e. biomass
feed stocks, transportation, stowage, cost of conversion, the delivery network,
the dispenser facilities have to have a price-based function. In the complete
absence of relevant data, cost data had to be derived from external sources.
[120]
During the course of literature survey, following reports were analyzed for use of
relevant data:
a. “Gasification-based fuels and electricity production from biomass” by Eric.
D. Larson [80].
b. H2A Delivery components, published by the United States Department of
Energy, for costs pertaining to the delivery of H2 to energy consumption
centres [81].
Cost of biomass residue has been reported in various biomass studies with
different connotations. For the purpose of this study these costs have been
replicated from a study by Jenkins et al [82] titled, “Equipment Performance,
Costs, and Constraints in the Commercial Harvesting of Rice Straw for Industrial
Applications”. The study takes into account various methods for harvesting and
includes all fuel costs involved in this process. Summary is given in table below:
Table 6.12 Harvesting Methods
Methods Basic Cost ($/wet ton) Fuel charges ($/wet ton)
Rake method Swath method Bale formation Roadside Transfer Total
1.40 5.16 4.96 3.68+1.05*r 11.45+1.05*r
0.85 2.71 1.43 0.75+0.30*r 3.73+0.30*r
r denotes the radius of the agriculture resource area
The model can be evaluated with a no of problems as regards the availability of
biomass feed-stocks and the level of hydrogen demand. This results in a matrix of
case studies that can be evaluated for conclusions, as shown in Table 6.13.
Table 6.13 Matrix of feed-stocks
Hydrogen Demand
Biomass feed-stock availability
5% 10% 25% 30% 40% 50% 75% 1%
10%
25% 50%
[121]
28 different case studies have been exhibited in Table 6.13 and the same can be
enhanced for detailed evaluation.
For the purpose of evaluation the energy demand was selected corresponding to
that of Faisalabad. The city was selected owing to the extraordinary agricultural
output and consequent anticipated biomass availability in the area and its
surroundings. Faisalabad's major crops include maize, rice, sugarcane, millet,
wheat, barley, gram and fodder. Moreover improved varieties of seeds, fertilizers
and pesticides have greatly increased per-acre yield. Annual demand of hydrogen
is set at 4031072 kg/day, equivalent to 4.031 kilo tonnes that have been
generated keeping in view the energy consumption per capita and population of
the area. The data was fed into MATLAB for generating solutions. However since a
lot of data is based on assumptions, hence only results for 10% demand of
Hydrogen are presented here to demonstrate the applicability of this model.
Results are presented in Table 6.14 to Table 6.16.
Table 6.14 Production Plant and allied costs
Hydrogen demand Biomass feed aval
10% 75%
10% 50%
10% 25%
10% 5%
Hydrogen Production Facility Production rate(kg/day) Initial Investment $ Cost of Feed-stock/annum Overhead & maint costs/yr
291,979 398,809,300 62,758,688 23,289,902
193,602 286,318,511 43,897,224 16,179,316
93,000 177,517,800 20,826,513 9,852,692
19,843 56,439,176 4,541,621 3,112,960
Table 6.15 provides the costs incurred at the terminal for various modes of
Hydrogen transportation i.e. pipeline, liquid H2 carriers and compressed gas
trucks. It is evident from the figures that pipeline costs have not been indicated
because of the low demand volume and consequent low production. Similarly
costs for liquefied hydrogen terminal have also not been shown for feed-stock
availability of less than 75%.
[122]
Table 6.15
Costs incurred at Terminal of various categories
Hydrogen demand Biomass feed aval
10% 75%
10% 50%
10% 25%
10% 5%
Compressed H2
Volume handled(kg/day) Initial investment($) Overhead & maint /annum
235,756 119,341,511 14,420,761
120,681 73,479,894 8,827,365
25,195 23,501,858 2,829,901
Liquefied H2
Volume handled(kg/day) Initial investment($) Overhead & maint /annum
362,369 428,860,311 17,225,470
H2 pipeline
Volume handled(kg/day) Initial investment($) Overhead & maint /annum
The following table indicates the costs for distribution of hydrogen in the energy
consumption centres via the Gas/Liquid Hydrogen carriers and through the
hydrogen pipeline. Corresponding to Table 6.15, this table also indicates a
proposition for distribution of hydrogen through compressed hydrogen carriers at
lower availability of feed stock. At 75% availability liquid trucks are employed
while pipe-line may be non-existent owing to the lack of hydrogen demand.
Table 6.16
Costs incurred in various Distribution modes
Hydrogen demand Biomass feed aval
10% 75%
10% 50%
10% 25%
10% 5%
Compressed H2 carriers
No of carriers Initial investment($) Overhead & maint /annum
171 162,787,511 41,073,486
93 82,516,956 19,233,177
25 16,722,509 3,892,132
Liquefied H2 carriers
No of carriers Initial investment($) Overhead & maint /annum
31 16,838,786 8,653,695
H2 pipeline
Length in kms Initial investment($) Overhead & maint /annum
[123]
6.5.8 Discussion
Other costs assumed for this study derived from literature survey are given at
Appendix E. The model has been developed for optimizing the production of
hydrogen from Biomass resources. The unit cost of hydrogen for 10% demand
comes to $3.95-5.14/kg. This is comparable to the hydrogen costs presently
achievable from steam methane reforming process of natural gas. [37] has
documented delivered cost of hydrogen from SMR ranging from $ 4.5-5/kg of
hydrogen. Cost comparison of various hydrogen generation technologies is given
in Fig 6.4. However the full extent of its benefits can be assessed when it is fully
integrated with an accurate Database of Biomass feed stocks and a Geographical
Information System. Moreover as already highlighted statistics form a backbone
of any model whose conclusions are based on data. A model is only as realistic as
the statistical base provided to it. This model provides a detailed insight into the
hydrogen supply chain based on biomass and assesses the cost incurred in
production, transportation and distribution of hydrogen in the energy
consumption centers.
Fig 6.4 Comparison of delivered hydrogen estimates
[124]
The model is an important decision making tool if hydrogen economy is to be
realized through renewable energy resources. The costs incurred in biomass-
based hydrogen chain can be brought in comparison with other resources for
furthering the analysis of the energy infrastructure.
Energy Infrastructure has several components/elements that are linked together
in optimization to deliver economically suitable fuel to the consumers. The most
important components of an energy infrastructure are:
1. Production/Generation
2. Transportation
The scope of this study has been the generation of hydrogen through renewable
resources that have been assessed from Wind, solar and biomass in the preceding
chapters. The transportation of hydrogen through the following modes:
a. Compressed H2 trucks.
b. Liquefied H2 trailers.
c. Dedicated H2 pipelines.
have been evaluated in various studies. Fig 6.5 indicates the hydrogen flow
corresponding to various distances in kilometers. The table is a guideline for
transportation of hydrogen as a gas and liquid. Since dedicated hydrogen
pipelines are neither available nor the same can be built in the near future, hence
the initiation of hydrogen economy would entail transport of hydrogen as liquid
or gaseous form in trucks/trailers, excluding the option of pipe-line network.
[125]
Fig 6.5 Hydrogen delivery options Vs Hydrogen flow and distances [66]
The analysis of the various renewable resources available in Pakistan discussed in
previous sections leads to an Integrated Renewable Hydrogen model. This model
is heavily reliant on three Renewable resources i.e. solar, wind and biomass.
While solar and wind energy are essential for the generation of electricity which is
used to run the electrolyser. Electrolyser generates hydrogen and oxygen from
the electrolysis of water. The hydrogen then generated has to be transported to
the energy consumption centers. It has been demonstrated that hydrogen can
only be transported in the distribution network upto 17% by volume, without any
major changes in pipeline material and network. However for any larger amount
of hydrogen, other techniques that can be used are by converting hydrogen into
methane and injecting the same into the existing transmission/distribution
networks. Another method is to convert hydrogen into methanol and then
transport it through liquid fuel tankers to the energy consumption centres.
6.5.8.1 Geographical Information System
GIS forms one of the most significant elements of any developing energy supply
chain model. In this model the pipeline network of the natural gas distribution
companies has to be interfaced with a GIS system. Moreover, a data base of
biomass feed stock availability is also to be integrated to arrive at a decision as to
the actual potential of hydrogen from any area. Schematic diagram of the GIS
[126]
assisted and Biomass based renewable hydrogen model is given in Fig 6.6. GIS has
to identify following important information for this system:
1) Biomass Resource
a) Area of agricultural fields with geographical coordinates.
b) Type of crops.
c) Topographical information.
d) Output from the fields as per the coordinates in terms of
longitude/latitude.
2) Infrastructural information
a) Road networks – distance from fields to nearest road head.
b) Pipeline networks – gas transmission and distribution networks.
3) Geographical data
a) Terrain
b) Wind data
c) Solar data
d) Urban/rural categorization.
e) Land use – forest/river/sea/protected areas.
4) Energy requirement
a) Indigenous sources of energy
b) Population density
c) Cost of fuel
It is pertinent to mention here that the suggested GIS-based system (Fig 6.6) is
only a decision making tool, with several databases and live update of feedback. It
provides information on placement of biomass based H2 production plants, basing
on the availability of accurate information provided in the form of biomass feed-
stocks and infrastructural networks of roads and pipelines.
[127]
Fig 6.6 GIS assisted Biomass based Renewable Hydrogen System
6.6 Gas pipeline Network
In this section the possibility of transporting hydrogen in existing natural gas
infrastructures is first evaluated in the form of mixtures.
6.6.1 Components & Terminology
Pipeline infrastructure emanating from the resource field is distinguished in two
main heads:
High pressure grid-transport network.
Low pressure grid-distribution network.
[128]
High pressure lines are characterized by larger diameter and stronger piping with
compression stations after regular distance intervals. Low pressure or distribution
networks are identified by pressure reduction stations and relatively smaller
diameter piping network. The pipeline network has a twofold function. It serves
to supply energy to the consumer in the required quantity. At the same time the
pipeline also holds storage for the fuel gas in a considerable quantity depending
upon the dimensional capacity of pipeline and the demand-supply gap. When
supply surpasses the consumer demand, the excess gas is held “packed” in the
pipeline, and hence named as “line pack”.
This in turn facilitates and provides cushions to the highly indefinite demand
patterns. Line pack also allows the demand to change independently of the input
into the system. However in order to increase line pack capacity, higher pressures
are anticipated. Demand side pattern determines the flow rate of gas through the
pipeline, thus satisfactory meeting of demand implies higher flow rates. Flow rate
of a gas is expressed as [83]:
√
(6.20)
Where
Q flow rate
C constant
D pipe diameter
e pipe efficiency
f Darcy-weisbach friction factor
G gas specific gravity
L pipeline length
Pb pressure base
P1 inlet pressure
P2 outlet pressure
Ta average temperature
Tb temperature base
Za compressibility factor
[129]
This flow of gas is expressed in normal metre3/hour denoted as Nm3/h. This factor
represents mass flow instead of volumetric flow. Flow is dependant on the
roughness of the conduit as well as a factor named as Reynold’s number given by:
(6.21)
=viscosity of gas in m2/s
=speed of gas flow m/s
Definitions
The higher heating value (HHV; also known as the gross calorific value or gross
energy) of a fuel is defined as the amount of heat released by a specified quantity
(initially at 25 °C) once it is combusted and the products have returned to a
temperature of 25 °C.
The lower heating value (also known as net calorific value, net CV, or LHV) of a
fuel is defined as the amount of heat released by combusting a specified quantity
(initially at 25 °C or another reference state) and returning the temperature of the
combustion products to 150 °C.
6.6.2 H2 & Natural gas-Energetic attributes
Some relevant physical properties such as HHV (higher heating value), density and
specific gravity are summarized in Table 6.17:
Table 6.17 Comparison of physical properties
Gas HHV
MJ/Nm3
Density
Kg/m3
Specific gravity
relative to air
Hydrogen 13 0.084 0.07
Natural gas 40 0.65 0.55
Keeping in view equation 6.20 and the above value of HHV indicates that if the
same energy demand is to be satisfied, the volume of H2 to be transported is
[130]
thrice that of natural gas. However the density of natural gas is approximately
nine times that of hydrogen (9 x 0.084), hence if the hydrogen flow rate is kept
three times, the pressure drop for Natural gas and hydrogen would be the same.
It may be added here that pressure drop is one of the most significant parameter
in design of piping infrastructure.
Variables affected by flow rate include ‘Z’ and ‘f’. Investigations made in this
regard indicate that for an unchanged pipe-line and pressure drop, energy flow by
hydrogen is 98% with lean natural gas, while in comparison with rich natural gas,
it is 80%. Relative energy flows from 0-100% mixture by volume with natural gas
is shown in Fig 6.7:
Fig 6.7 Energy flow comparison-H2 Vs H2-NG mixture (constant pressure)
Line-pack is one of the significant elements afforded in any pipeline network,
which is affected mainly by rate of flow. The inverse relationship indicates a
higher line-pack with a reduced flow, while a higher flow rate implies a diminished
line-pack or storage. Line pack can be analyzed by equation 6.22 [83].
70
75
80
85
90
95
100
105
0 10 20 30 40 50 60 70 80 90 100
Re
lati
ve E
ne
rgy
flo
w V
s 1
00
% N
G
Hydrogen Addition % vol
LEAN GAS
RICH GAS
[131]
If Vstorage,n=storage volume at normal temperature and pressure (273oK and
1bar)
&Vgeom =volume of pipeline then
[
]
(6.22)
Pm =upper mean pressure
Pm’=lower mean pressure
Km =compressibility factor
Principle of line pack is shown in Fig 6.8. The space between the upper and lower
pressure profiles indicate the available line pack.
Fig 6.8 Line Pack illustration [84]
When H2 is made to flow in the present natural infrastructure, the storage of H2 in
the form of line pack lies between 65-71% that of Natural gas, assuming rate of
flow ranging from 500000 to 1500000 Nm3/h. These figures represent the line
pack in terms of volume however the significant point here is the energy carried
by any fuel which has to meet the customer demand as a first priority. Keeping
[132]
this in view, the energy content of hydrogen is approximately a quarter when
brought in comparison with Natural gas. This may hamper the security of supply
in short term. Fig 6.9 shows these values at various mixtures ranging from 0-100%
hydrogen (for lean natural gas). It is very evident from these graphs that transport
of hydrogen in the existing infrastructure is not feasible. The concept of line pack
as storage of H2 is also not suitable in this context.
Fig 6.9 Line pack relative to various H2-NG mixtures
6.6.3 Pipeline material aspects in H2 distribution
Apart from the physical/chemical properties of hydrogen that affect the pipeline
network, certain other issues are also among the considerate with hydrogen
infrastructure; these include leakages and pipe damage.
6.6.3.1 H2 Leakage
Hydrogen first in the “periodic table” by virtue of being the smallest element is
more likely to escape easily as compared to natural gas. Basing on their diffusion
coefficients hydrogen can diffuse up to four times faster than natural gas. Hence
components of any pipeline network are to be designed to prevent leakage from
valves, seals, gaskets thereby raising safety hazards.
Hydrogen leakage though high in volumetric terms, are lower in energetic losses.
Also as discussed earlier the amount of hydrogen leakage depends largely on
-2
-1
0
1
2
3
4
5
0 51
01
52
02
53
03
54
04
55
05
56
06
57
07
58
08
59
09
51
00Lin
ep
ack
(HH
V -
1E
07
J)
Hydrogen Addition % vol
500000 Nm3/h
1000000 Nm3/h
1350000 Nm3/h
1500000 Nm3/h
[133]
pipeline material. Cast iron and fibrous cement pipelines have a greater leakage
risk. Currently Polyethylene pipelines are in use in most of the distribution
networks. Leakage/diffusion of hydrogen is five times higher than natural gas;
however it is negligibly small owing to its energetic content. Research has shown
that the annual loss of hydrogen by leakage is approximately 0.0005-0.001% of
the total volume transported [85].
Further, the compressors installed along the transmission line are another point
in consideration. Compressors can be either reciprocating or centrifugal.
Reciprocating machines can be of piston type or diaphragm configuration and are
being used in hydrogen pipeline networks around the world. Air liquide, the
pioneer in hydrogen technologies is using volumetric compressors, however on
the other hand the natural gas networks are provisioned with centrifugal
machines [75]. Thus if hydrogen is to be transported in high pressure transmission
network, the volume of hydrogen to be transported in high pressure transmission
network, the volume of hydrogen to be transported has to be thrice that of
natural gas as already discussed. This results in an increase of compression
capability as much as twice that of the current capacity. From the previous
discussion it is clear that rotational velocities would have to be increased
manifold to match the rate of mass flow. Increased velocities are limited by the
material strengths of the compressors, hence it may be concluded that the
compressors installed in the existing infrastructure is insufficient to handle
hydrogen in the same quantum as of natural gas. It may also be mentioned here
that the same is not true for distribution infrastructure since compression stations
are not employed therein [86].
Another distinguishing behavior of hydrogen is exhibited when its pressure is
reduced. Natural gas when subjected to pressure reduction causes a drop in
temperature of 0.5oC with each bar, due to Joule-Thompson effect. However on
the other hand, the temperature of hydrogen rises by 0.35oC for each increase of
a bar pressure. Thus a rise of 2oC would occur for a drop in pressure from 80 to 15
bar, which fortunately has no effect on the existing NG infrastructure [87].
[134]
6.6.3.2 Hydrogen embrittlement
Hydrogen embrittlement of pipes is caused by degradation of mechanical
properties; this includes surface cracking and propagation of cracks resulting in
pipe failure. However, causes of embrittlement range from the composition of
pipe material as well as the operating temperature/pressure conditions. The
concentration of hydrogen in a H2/NG mixture also determines the extent of
degradation /embrittlement [88]. Pipeline history specially the intensity and
frequency of pressure fluctuations is an important determinant of embrittlement
predictability. Thus intensive testing of line, weld, and joints only would declare
the existing network’s suitability for Hydrogen fuel gas.
6.6.4 H2-Natural Gas mixtures by % volume
Profile of hydrogen mixtures at low pressures is given in Fig 6.10. It can be
deduced that mixtures of hydrogen and natural gas up to 40% may not require
any major shifts in energy transfer.
The foremost requirement in the initiation of hydrogen economy is to break the
chicken and egg scenario. Hence it may not be logical to expect an overnight shift
of engines, boilers and burners to fuel cells, however a natural propagation is
required to be induced to achieve a full scale penetration of fuel cells in the
market.
[135]
Fig 6.10 Addition of H2 Vs Relative energy flow (NG)
It has been shown (from Fig 6.7 – Fig 6.10) that up to 17% mixture of hydrogen by
volume in NG bulk does not cause any problem [89]. However a mix of higher
percentages requires consideration, though the consequent problems are not
very overwhelming. These include the effects on line pack, pressure drop and
wobbe index (refer to Fig 6.7, 6.9, 6.8).
Wobbe index or number is found by dividing the high heating value of the gas by
the square root of its specific gravity with respect to air. The greater a gases’
wobbe number, the greater the heating value of the quantity of gas that will flow
through a hole of a given size in a given amount of time. Hence it is a measure of
interchangeability of gases as well as its applicability to end use domestic
application [90].
√ (6.23)
For mixtures of H2-NG, the Wobbe number is given by:
√
√
(6.24)
80
85
90
95
100
105
110
115
120
0 10 20 30 40 50 60 70 80 90 100Re
lati
ve E
ne
rgy
flo
w a
s co
mp
are
d t
o 1
00
% N
G
Hydrogen Added % vol
Energy flow in Distribution network
Lean NG
Rich NG
[136]
Table 6.18
Type Wobbe index range
Lean NG
Rich NG
41-47
48-58
For common NG burners, the Wobbe number for rich NG lies between 48-58
MJ/Nm3 while that for a lean NG is in the range 41-47. It is evident from Fig 6.11
that for lean NG value burners, hydrogen injection can be upto 98% by volume,
while for Rich NG it can be within 45% vol. Thus for user ease, it is preferable to
include the complete range i.e. 41-58%, so that the low/high calorific value can be
used with equal convenience. To address the issues of flame detection, burner
heads and sealings, multi-functional devices that can run on entire range of H2/NG
mixtures is suggested [91][92].
Fig 6.11 Wobbe index behaviour with different H2-NG mixtures
From Fig 6.11 it is clear that for low calorific value, the wobbe index is lowest at
72% vol mixture while for high calorific gas, the worst performance range is 75-
85%.
35
40
45
50
55
60
0 10 20 30 40 50 60 70 80 90 100
Wo
bb
e in
de
x M
J/N
m3
Hydrogen Addition % vol
LEAN GAS
RICH GAS
[137]
6.6.5 Transition to 100% hydrogen transport in NG pipelines.
Historically, shift from one form of fuel i.e. city/town gas to natural gas was
almost immediate. However with the present day volume of gas in transit as well
as the number of customers all over the world or any region has multiplied many
times, notwithstanding the network which has inter twined so vastly over the
years, the foreseeable transition is a much daunting task. This transition would
require three fold compatibility:
Distribution network
High pressure grid
End users’ appliances
The transport or high pressure grid may be considered a simple pipeline
infrastructure with compressors and pressure reduction stations, however the
distribution network or the low pressure infrastructure is quite complex, when
considered in terms of its installation, space and investments involved. A parallel
piping network for hydrogen may be a distant feasibility; nevertheless lack of
space is an impediment in distribution networks in populated areas. Thus the
introduction of hydrogen added NG mixtures for a gradual transition is a serious
option.
Technically, the introduction of hydrogen in the network is recommended in the
low pressure grid immediately after the reduction of pressure as shown in Fig
6.12. As no flow takes place from the low pressure to the high pressure side, the
advantages accrued are twofold:
High pressure grid transport network requires the minimum essential
changeover of pipelines, compressors and material.
Transition process can be handled independently for both high and low
pressure network.
[138]
Fig 6.12 Illustration of H2 transport via NG pipelines in Distribution (low-pressure) grid [93].
6.7 Options for transmission & distribution of Hydrogen
The use of natural gas infrastructure for hydrogen transport has been evaluated
in detail in Section 6.6. It has been found that hydrogen can be transported as a
mixture with natural gas only in the low-pressure network i.e. Distribution
network. Transmission network requires higher quantities of hydrogen at larger
pressures over considerable distances. The extent of transport may range up to
several hundred kilometers. Moreover only up to 17% hydrogen by volume can be
mixed in natural gas without carrying out any major modification in the
infrastructural network.
Hydrogen transportation in natural gas pipelines entails major energetic and
material issues, thereby rendering it unfavorable for transportation in large
quantities. Large % age of H2 rich mixtures or pure hydrogen requires a dedicated
infrastructure. Creation of hydrogen demand is a significant pre requisite in the
development and capital investment in new pipeline networks. Further, hydrogen
is to be introduced only in the Distribution network, which necessitates
distributed generation. The effects of stand-alone or distributed generation have
been evaluated in Para 6.6.1, which impedes rapid and quality development of
fuel cell technologies. Moreover spatial considerations give rise to massive
infrastructure issues in terms of availability of space to address the rising demand
[139]
for hydrogen fuel. Alternative means are still required for transporting hydrogen
in Transmission networks.
Nelson et al [94] narrated the public’s opinion regarding the success of the new
energy system, in the words “low failure rates for hydrogen systems”. Hydrogen
economy thus requires a supply chain system that is able to satisfy the consumer
demand in its entirety.
This thesis studies the options available that aid in integration of renewable
sources in the hydrogen economy. In this regard renewable hydrogen can be used
in the form of methane/methanol for direct use as fuel or to regenerate hydrogen
after transportation to the city gate, for use in fuel cell applications with end-
consumers. Salient of the system are discussed in succeeding Paras:
6.7.1 Alternate energy systems
6.7.1.1 Hydrogen storage as Methane:
A major portion of the renewable sources of energy remain untapped because of
geographical remoteness, in comparison with the location of energy users.
However on the other hand, pipeline networks as discussed earlier in this chapter,
pass through several areas where solar, wind and biomass are available in
considerable portions. Also renewable sources are mainly converted into
electricity as an immediate energy vector, whereas the high capacity transmission
lines are also not available to transport electrical energy to the energy
consumption centers. It is needless to mention here that construction of electrical
transmission lines is also quite cost intensive. Thus to fully tap the renewable
sources and integrating it into the hydrogen supply chain, the existing pipeline
networks may be used to transport this energy by converting the renewable
electricity to hydrogen and then hydrogen to methane. Alternatively methanol
can also be generated from methane, which can then be transported in liquid fuel
carrying tankers.
The approach applied here is through the process of hydrogen generation
through renewable electrolysis followed by methanation i.e. chemical reaction
involving H2 and CO2 as reactants. The last step may be considered additional to
[140]
“hydr-icity” exhibiting H2 and electricity, which would be a trading commodity in
the proposed hydrogen economy.
Carbon can be obtained from biomass resources available in majority areas of
Pakistan in the form of wheat, rice, maize, sugar cane and other crop residues.
Biomass estimation can be assessed from various research and statistical studies.
Mirza et al has narrated that during the last decade, fuels derived from biomass
resources amount to about 19500 TOE that comprises almost 28% of total energy
supply [95]. Further breakdown is reported as:
a. Wood form 60%
b. Residual from crops 21%
c. Animal dung 18%
Cropping pattern is shown in Fig 6.13
Fig 6.13 Pakistan Cropping Pattern
[141]
Appendix F is an exhaustive record regarding the availability of biomass feed
stocks in the four provinces in the form of yield per hectare for a variety of
agricultural crops. Biomass energy data book compiled by Oak Ridge National
laboratory of the US Department of energy describes in detail the assessed fuel
value of biomass residues [96]. Chemical characteristics of selected feed stocks is
exhibited in Table 6.19
Table 6.19 Chemical characteristics of selected feedstocks
Considerable feed stocks in the form of crop residue are available for provision of
carbon as a reactant in the methanation process. Alternately carbon can also be
obtained from natural gas fields which is presently being dumped into the
atmosphere in the form of flue gases. Industrial emissions also can be directed to
supply carbon as well as waste heat.
6.7.1.2 Methane formation
The production of synthetic methane may be termed as a reversal of the
reforming process for methane carried out with steam. The reaction is almost a
century old and given by:
[142]
CO+ 3H2↔CH4+H2O (A)
CO2+ 4H2↔CH4+2H2O (B)
The above mentioned reactions require heat and take place in the presence of a
catalytic agent. Reaction A is an industrial process for producing synthetic fuel
while reaction B is commonly used for removal of air exhaled by the astronauts in
space shuttles/aircrafts. This reaction is particularly supported as CO2 is available
in gas fields as well as in the form of residual gases in industrial zones. Moreover
the usage of emission gases would also aid in curbing “climate change” and
environmental degradation.
Methanation diagram is shown in Fig 6.14, which employs reaction B as discussed
in the succeeding para.
Fig 6.14 Flow diagram for Methanation
Hydrogen from electrolysis and CO2 from CNG field/Biomass
(which is otherwise dumped into atmosphere)
[143]
Based on Hashimoto [97] findings it is anticipated that both the reactors would
operate at 90 percent efficiency, which further enhances it to almost 99 percent.
Catalysts being developed by Hashimoto are compounds of Ni and Zi. For the
purpose of this study, several commercial electrolysers for large scale hydrogen
generation were analysed, and electrolyser of 5040 series manufactured by M/S
Hydrogen Technologies of Statoil was assumed for the purpose of this study with
a 19 array unit [28][98]. Salient characteristics are given in Table 6.20:
Table 6.20 Electrolyser 5040
Current input 2.1-2.3 MWe Output 0.135 Nm3/s(485 Nm3/h) DC power 5150 A 19 array output 2.565 Nm3/s
Theoretically 2.565 Nm3/s when reacted with CO2 gives 0.65 Nm3/s of methane.
Applying the conversion factor:
1 cubic meter/second = 3.051187 million cubic foot/day (MMCFD)
results in 1.983 MMCFD or approximately 2 MMCFD for injection in NG grid.
6.7.1.3 Hydrogen storage as methanol
Fuels in liquefied form have several benefits as regards its transportability and
ease of transportation. Although the efficiencies may not be very high in current
status, yet the conversion of H2 gas into methanol provides a relatively easier
energy form which can be conveniently integrated in the established energy
supply chain. In this regard methanol can serve to provide:
a. Means for storing H2
b. Directly as fuel
c. Input for chemical blends
Chemically methanol synthesis is given by [99]:
CO2 + 3 H2 →CH3OH + H2O
[144]
Fig 6.15 Flow diagram for methanol
Methanol is one of the few simple energy carriers, which can be used for storing
hydrogen as well as able to be employed directly as fuel. Practically methanol has
a proportion of 1:1100 in terms of cubic metres of volume, whereas hydrogen in
liquid form can be stored to a maximum of 800 cubic meters. This significant
feature recommends its use as on-board hydrogen systems in FC powered cars
[99]. A comparison of methanol production from biomass gasification and
hydrogenating CO2 from exhaust emissions of fossil fueled power producers has
been carried out based on studies by [100] and [101].
Table 6.21 Comparison of Biomass & carbon-dioxide based methanol
Comparison parameters Biomass generated CO2 based
Electricity consumption (MWh/tonne) Energy conversion efficiency (%) Methanol production cost ($/tonnne)
0.32-7 25-44 300-400
9-12 17-23 500-600
It has been concluded in this study that the biomass based methanol production is the economically cost effective method. The process is represented as:
Fig 6.16 Elements of Biomass to Methanol [101]
[145]
Performance and economic comparisons are given in Table 6.22 and Table 6.23:
Table 6.22
Performance Xistics Ouellete Study Spect Study
Feedstock consumption (ktonne/yr) Electrical consumption (MWh/tonne)
Methanol generation (ktonne/yr)
Percentage Efficiency
10.11 0.34
12.24 44.05
14.38 6.67
17.50 25.62
Table 6.23
Cost comparison Ouellete study Spect study
Capital investment ($) Electricity price/unit Methanol price/tonne
1.45 E 107
0.01 465
3.203 E 107
0.04 573
Preceeding sections have discussed the biomass-based production of hydrogen
and its transportation options as mixture in existing pipeline infrastructure and in
the form of synthetic methane/methanol. The dispersed nature of renewable
resources have to be assessed in conjunction with the natural gas infrastructure
for production of hydrogen from Biomass feed stocks followed by assessing the
modes of delivery for each energy consumption centre.
For instance, as discussed earlier, the lowest flow segment section of SNGPL
identified as Mardan-Mingora has a maximum flow of 16 MMCFD (Table 6.4).
Biomass resources in this region indicate wheat as a major crop in and around
Mingora. Recalling Chapter 4, section 4.3.1 wherein wind corridors in Mardan
have already been identified as major wind resource areas in Northern Indus
valley. Similarly solar potential for Mardan from Jan to Dec, given at Appendix A
at Latitude 34, Longitude 72 indicates a max of 8.94 kwh /m2 /day and an average
6.345 kwh/m2/day, which is considered a very suitable proposition for solar
power potential. Referring to Table 6.19, an electrolyser of 5040 series can
generate up to 2 MMCFD of methane. Simple theoretical calculation indicates a
requirement of 8 similar electrolysers to provide 16 MMCFD of the Mardan-
Mingora segment.
[146]
Thus Hydrogen can be efficiently produced from renewable resources in Mardan-
Mingora region and delivered to the energy consumption centres in the form of
methane/methanol. Similarly other regions/energy consumption centres can be
evaluated each with its own peculiar detail for the production and distribution of
hydrogen. It is once again reiterated that availability of accurate statistical data is
necessary for any integrated energy model that has to be developed by the future
energy planners to ensure sustainability in supply.
6.8 Conclusion
Infrastructure analysis carried out for the renewable hydrogen production has
revealed significant insights into the subject. Firstly, Pakistan is blessed with an
array of renewable resources that are widely available for tapping, both in terms
of quantity and quality. Solar and wind resource are extensively dispersed
however are primarily trappable only in remote locations, owing to urban
development, structural build-up and other land-use limitations. In this regard
alternate options for the distribution and delivery infrastructure are realistically
evaluated by conversion into hydrogen.
Hydrogen being a good storage medium for intermittent resources like wind and
solar is the most preferred energy vector for the medium to long term future
energy scenario.
The road to hydrogen economy strongly rests on a supporting infrastructure that
is able to respond to the energy demands of the consumption centers. In this
regard the production of hydrogen through solar, wind and biomass has been
demonstrated to sufficiently fulfill all energy demands. However the important
aspect of infrastructure for hydrogen transportation from the production plants
to the end users has been evaluated in detail.
In this regard Pakistan being an agriculturally dense country has a very sizable
amount of biomass available in the form of crop residue. Biomass has been
demonstrated to serve not only in the production of hydrogen as exhibited by the
model developed for Faisalabad, but also aids in its transportation. Hydrogen can
[147]
be transported in pipelines only upto 17% by volume, which is only suitable for
the initiation or the transition stage.
Renewable generated electricity from PV and wind resources at remote locations
cannot be provisioned to the local/main grid because of the lack of infrastructure
for power transmission lines. Infrastructural analysis of the gas networks passing
through such locations have been shown to transport hydrogen by conversion
into synthetic methane based on biomass extracted carbon. Similarly methanol
synthesis plant assisted with biomass input can deliver hydrogen as methanol in
liquid fuel carrying trailers. Steam methane reformers or other hydrogen
extracting devices may be used for separating hydrogen for use in fuel cells
applications and other gadgets.
Tool developed to model biomass based hydrogen supply chain demonstrates the
applicability of hydrogen generation from crop residue resulting in an economic
and green path way that is able to deliver hydrogen at competitive rates. All
infrastructural options are to be evaluated in terms of economic benefits for a
complete assessment of the suggested tools. Infrastructure analysis carried out
for Mingora-Mardan section can be expanded to other regions as per the energy
demand/supply scenario and the availability of solar, wind and biomass
resources. It is however emphasized that the distribution and delivery network as
demonstrated (for above mentioned example) has to be integrated with a GIS
system that has updated databases of biomass resources as well as detailed
information on road and pipeline networks.
[148]
7 Summary of Conclusions & Recommendation
7.1 Summary
The dawn of the 21st century saw the “provision of clean and sustainable energy”
as one of the foremost and challenging task. This study does not base any of the
arguments as to how the hydrogen fuel would replace the fossil fuels however it
pre-supposes that eventually hydrogen economy would flourish in an overall
energy scenario of the world. While the hydrogen supply chain may be a
farfetched dream in comparison with today’s fossil fuels yet it is presumed that in
mid-to-far future hydrogen would be a feasible alternative.
7.2 Hydrogen Supply Chain-Infrastructural Analysis
Several studies have concluded that an initiation of Hydrogen Supply Chain (HSC)
would be triggered by the rapid and sustained development as well as economic
availability of fuel cell applications both for stationary and mobile applications.
Infrastructure development would begin when there is a demand for hydrogen
and consequent ease of availability at end user. All the components of HSC need
to be addressed in detail. It has been emphasized in this study that fossil fuels
may be the stepping stone for a full-fledged development of the Hydrogen
Economy; however Renewable Resources are an essential component for any
future fuel supply chain that has to address the issue of Greenhouse gases,
climate change and security of supplies. The conclusions of the study are
numbered as:
7.2.1 Renewable Resource Assessment
The infrastructure analysis identifies the Hydrogen generation potential at
R3 (Renewable Resource Rich) areas pertaining to Solar and Wind
Resource. It has been found that whereas the region is quite rich in solar
potential all along the 800,000 sq km stretch from the Northern
mountainous region to the Southern coastline touching the Arabian Gulf,
the realization is promising. Keeping in view the Energy gap (oil production
and consumption) a fraction of the total potential if realized can fulfill the
energy requirement. The data amply demonstrates the potential for each
sub divisible area and can be employed for energy planning in future.
[149]
Wind resource, although limited with just 9% of the area with good to
excellent wind availability, yet has tremendous potential for growth.
Hydrogen Economy may be a distant future reality; however as a first step
towards the Hydrogen pathways already identified elsewhere, it is
imperative that Sustainable generation of Hydrogen for Pakistan must be
appraised realistically. As imported fossil fuels form a major portion of
Pakistan's Energy mix, hence the foreseeable Hydrogen-based Energy
Infrastructure should preclude any of the existing fossil fuels. Focus in this
study has therefore been on indigenous and sustainable supply of
hydrogen, amounting to several thousand tonnes of hydrogen that can
generate appreciable amounts of electricity. It has been demonstrated that
the solar potential of “Jhelum Division” alone can fulfill the entire energy
needs of the country.
7.2.2 Integrated Renewable Hydrogen Network
Renewable resources are to be integrated in the energy infrastructure for a
feasible model. Infrastructure analysis carried out in this regard resulted in
the development of an integrated framework, which is able to accumulate
renewable energy resources from the available potential regions and
channelizes to the energy consumption centers. An intelligent Just-in-time
power generation system, working at the heart of the proposed system
bases its decisions on reliable feed-back from the various databases.
7.2.3 Gas Networks
Natural gas networks have been identified as the primary energy supply
chain of Pakistan. Infrastructural analysis carried out in this regard
concluded with identification of significant segments of the transmission
and distribution network.
7.2.4 Biomass Based Renewable Hydrogen Model
Infrastructure analysis has been furthered on another major renewable
resource of Pakistan i.e. Biomass. Pakistan being an agrarian economy has
vast amounts of biomass wastes that can be employed for the production
of hydrogen. The mathematical MINLP model demonstrates with the help
[150]
of MATLAB software that hydrogen can be produced from biomass at rates
competitive ($ 3.95-5.14/kg) with steam methane reforming (SMR) which is
presently the most economic method of hydrogen production.
7.2.5 Distribution and delivery
Infrastructural analysis has also developed and investigated three methods
for distribution and delivery of hydrogen. Transport of hydrogen in natural
gas infrastructures has been found to be suitable for only 17% mixture of
hydrogen with natural gas. Hydrogen can also be transported by converting
it into synthetic methane and methanol. With the employment of a
commercial electrolyser such as Series 5040, 0.65 Nm3/s of methane can be
generated which is equivalent of 2MMCFD. Similarly the methanol option
has been evaluated based on studies by Ouellette and Spect.
7.2.6 Model application
Mingora-Mardan segment is the lowest flowing segment of the
transmission network of SNGPL, with a flow of 16 MMCFD. Wheat straw is
extensively cultivated in the region and considered suitable for the biomass
model. It has also been concluded that the wind corridors of Mardan are
suitable for wind power generation. Solar potential is feasible, hence 8
electrolysers of series 5040 type can be employed to meet the natural gas
demands of the segment.
7.2.7 Transition to hydrogen economy
Analysis of the pipeline network has revealed that mixtures of hydrogen
can be transported in the pipeline networks only in the low pressure grid
i.e. distribution network. It has also been shown that as it is practically
infeasible to replace the complete appliances from NG to hydrogen; hence
appliances should have a Wobbe index range from 41-58. It is also
recommended that hydrogen mixed with natural gas is a reasonable option
for the transport of hydrogen in pipeline networks in the transition stage
mainly in the distribution grid due to lack of space. Material aspects and
other elements of the transmission network such as the centrifugal
[151]
compressors also do not favor introduction of hydrogen in the transmission
network.
Hydrogen should be generated from renewable sources with biomass as
the main component in the distribution and delivery infrastructure. An
individual and integrated model is required to be built specific to each
region depending upon the solar, wind and biomass resource. Further as
demonstrated the availability of road networks and the supply/demand
ration would dictate the feasibility of either of the modes of delivering
hydrogen
7.2.8 Recommendations
Ambitious targets for Government sponsored “Stand-alone Renewable
Energy” projects for rural areas.
Cluster mushrooming of micro Renewable Energy projects all over the
country, to enhance public confidence in Renewable Energy technologies.
Sustained efforts for development of Renewable resources at National
level.
Duty-free import of elements/items pertaining to “Renewable Energy
projects” such as small wind turbines, solar panels etc.
Private entrepreneurs be encouraged for Renewable energy based
generation of power and its linkage with the national grid. This will help in growth
of industry based on RE technologies.
Promotion of R&D in Hydrogen based projects in universities and increased
level of public awareness and investment.
Demonstration projects may be pursued with international organizations
such as ICHET under the umbrella of UNIDO.
Industries already producing hydrogen gas such as Oil Refineries, Food
processing units be encouraged to integrate Fuel cell applications and vehicles in
their premises.
Government owned organizations such as Railways, Postal services and
Ministries holding a huge fleet of vehicles may enter into an agreement with
Hydrogen producing industry for running of fuel cell cars.
[152]
Evolution of a Hydrogen Pathway and its modeling for future scenarios in
collaboration with countries already making headway in Hydrogen Technologies.
Timeline must be defined to correlate with gradual phasing out of fossil
fuels, along with the contribution of Hydrogen and/or of other Renewable
resources in the country’s Energy Mix.
Technocrats and Universities must be integrated with the “Energy
modeling” process rather than confining the process to conventional, non-
technical public representatives heading the Energy Ministry.
Energy issues and decisions on its far-sighted development must not be
handled as a political matter. Constitutional protection is ensued to keep the
investors in RE technologies.
The wide spread availability of a wide variety of renewable resources that are well
dispersed over an approximate area of 800,000 sq km require intelligent tapping
of this significant resource. Large amounts of solar energy may be available over
large pieces of land that are uninhabited, however on the other hand heavily
populated areas may not have solar tapping/collecting facility owing to
constructed structures. Thus energy suppliers may be available away from the
energy consumers resulting in a need for development of an intelligent energy
management system. In this regard, an Integrated Just-in-time Power Generation
System has been devised that has an energy Database at the back-end to manage
and channelize the surplus energy to energy consumption centres.
7.3 Infrastructure Analysis & Recommendations
No economy is strong enough to rebuild an entirely new infrastructure for a new
fuel. Thus in order to progress, a transit path has been devised that is based on
biomass and allows for transportation of Hydrogen as a mixture with Natural gas
in the existing pipeline infrastructure.
Pakistan’s pipeline infrastructure owned by Sui Northern Gas pipelines (SNGPL)
and Sui Southern Gas Company Ltd (SSGCL) has been used as a case study to put
forward a pathway for the transmission, distribution of hydrogen gas from the
gas-fields, renewable energy resources to the consumer. The physical and
chemical aspects have also been integrated for a practical solution to the
[153]
concrete problem. It must be realized that transportation of hydrogen is one of
the key challenges in a successful Hydrogen Supply Chain.
MINLP tool developed with Biomass as feedstock has demonstrated that
hydrogen supply chains can be modeled and executed with renewable resources
to achieve sustainability. Costs achieved are compatible with steam methane
reforming of natural gas. It is recommended that in order to plan a realistic
energy supply chain a comprehensive Geographical Information System is very
essential that is able to provide accurate infrastructural information on road
networks, feedstock locations and land use of the region. Moreover a broad
based Database of agricultural output with live feedback must be available for
accurate result oriented energy plans. It is also suggested that Multi-criteria
Decision Making (MCDM) techniques be employed keeping in view the local
availability of biomass feed stocks, infrastructure and other social, economic and
intangible factors. Hence an integrated supply chain is a combination of an
integrated system comprising of:
Modeling tool
GIS
Database
MCDM technique
While considering the energetic and physical aspects it is revealed that the
existing pipe line infrastructure is well suited for transporting mass quantities of
hydrogen over long distances without altering any major elements. The system
also serves as storage to cope up with the difference in demand and supply. The
17% by volume mixture with natural gas is also well compatible with the end use
appliances which do not require any major modification. Hydrogen storage as
methane/methanol generated from remote renewable resources and transported
in liquid tankers and NG pipelines also need to evaluated for economic
compatibility.
Apart from the physical aspects, development of an energy infrastructure must
also have a review of policy and regulations for the new fuel. Not only subsidies
[154]
are required but also encouraging measures are also required for influx of
investment in the new infrastructure.
7.4 Food for thought-Future research direction
Hydrogen economy is a constantly evolving subject and must be followed very
closely to remain abreast with the latest developments. The various models
developed in this study can be expanded to include more geographical, terrain
and spatial data to examine the behavior in different scenarios. Similarly the data
provided as input can be studied for its influence on the optimization techniques
and its points of application.
The proposed mode of transport of hydrogen as a mixture with natural gas needs
to be practically tested with end-use appliances. The results could then be used to
cause modifications at either end i.e. in the pipeline infrastructure or the
appliances. In parallel it is also necessary that standards and regulations must also
be defined and developed for a more practical approach.
As Hydrogen Economy would likely be an International phenomenon in the
coming future, hence other case studies similar to the pipeline network of SNGPL
& SSGCL may also be pursued to have a wider exposure for more infrastructural
dimensions. Economic aspects of the infrastructural developments can also be
studied as Hydrogen economy evolves. Finally an integrated Hydrogen Supply
chain starting from production, transmission, distribution, storage and delivery
can be modeled for a broader picture of a Hydrogen Economy that can then be
evaluated for sensitivity analysis.
[155]
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[163]
8 LIST OF APPENDICES
a. APPENDIX “A” Monthly Averaged clear sky insolation
b. APPENDIX “B” Monthly Averaged wind speed at 50m
c. APPENDIX “C” Province wise solar hydrogen Generation
d. APPENDIX “D” Hydrogen output from wind resources
e. APPENDIX “E” Cost of elements in Biomass supply chain
f. APPENDIX “F” Estimation of biomass feed stock availability
g. APPENDIX “G” Cost comparison of Electrolysers
[164]
Appendix A
[165]
Appendix B
[166]
Appendix C-1
[167]
Appendix C-2
[168]
Appendix C-3
[169]
Appendix C-4
[170]
Appendix C-5
[171]
Appendix C-6
[172]
Appendix D
[173]
Appendix E
Table 6.23 Plant Costs($)
Production plant costs 197,950,000 Biomass storage costs 46.5/tonne Operating cost 9,897,500
Table 6.24 Costs of Terminal (installation/operation)
H2 compressor 153,471,000 Gaseous H2 900 Pipe installation 278,380 Truck ways 1,594,500
Table 6.25 Cost of H2 carriers Compressed gas vehicle cost 265,000 Overhead & maintenance cost 257,544 Liquefied H2 carrier 725,000 Overhead & maintenance cost 257,514
Table 6.26 Equipment cost
Liquefier cost 95,200,000 (100 tonnes daily) Liquid H2 storage 4,400,000 (100 tonnes daily) Dispenser cost 28,000 Pump/piping 2,200,000
Table 6.27 H2 pipeline costs
Rural pipeline 385,000/km Urban pipeline 577,000/km Overhead& maint 23,075
[174]
Appendix F
[175]
Appendix G
Price Comparison of Electrolysers Vs production capacity [102]
* Symbols indicate data obtained from various electrolyser manufacturers.