innovation in global power
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A technicaljournal by
ParsonsBrinckerhoff
employeesand colleagues
Issue No. 68 August 2008
http://www.pbworld.com/news_events/publications/network/
Also in this Issue: PB Redesigns Composting Machine;
Laying out a Swim Lane Diagram Using Microsoft Powerpoint or Visio;
Working with Text in Adobe Acrobat
Innovation
in Global
PowerNuGas Steam Cycles
HeatMap of
HotRocks
3 MW Mini Hydro Station
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Guest Editors for thisissue: Katherine Jack-son and Arthur Ekwue.
Guest Technical Reviewers:John Douglas, Ferrel Ensign,Steve Loyd, Chris Meadows,Brian Van Weele, andJohn Wichall .
Special thanks to Paul Kenyonand Matthew Chan for theirassistance.
Cover photo (lower right):Tony Mulholland
Note: Soon after distribution,this issue will be availableon the Web athttp://www.pbworld.com/news_events/publications/network/Issue_68/68_index.asp
PB Network #68 / August 2008 2
Innovation in Global PowerInnovation in Global PowerIntroduction (Burton) ...........................................................3
GENERATION
THERMAL ACHIEVING NEW EFFICIENCIES,REDUCING CARBON EMISSIONS
Best Practices Across a Range of Technologies (Kenyon)..4
The Effect of Carbon Capture and Storage andCarbon Pricing on the Competitiveness of GasTurbine Power Plants (Cook)..................................................5
The NuGasTM Concept: Combining a Nuclear PowerPlant with a Gas-fired Plant (Willson, Smith).................8
PB Inspections Help To Ensure Power Plant Safety(Gray) .................................................................................................11
Project Brief: Using Monte Carlo Techniques toSize a Power Station (Emmerton).....................................13
Project Brief: Energizing Singapores Economy (Gill)........13
Combined Heat and Power for USAs LargestResidential Development (Bautista, Swensen)............14
Ensuring Continual Power Supply for New York
City Hospitals (Krupnik, Andrews) ....................................16Changes to Chiller, Boiler and HVAC Lower Energy
Consumption at a University Campus (Choi)............18
Power Terminology: Units and Conversions(Ebau) .................................................................................................20
HYDROPOWER NEW TECHNOLOGIES, NEWCONSIDERATIONS
Does Hydro have a Future? (Wichall).......................................21
Pumped Storage Technology: Recent Developments,Future Applications (McClymont, Reilly)........................22
Planning for Mini Hydro in Distributed Generation(Mulholland)....................................................................................25
Developing, Engineering and Licensing a NewHydropower Dam (Chan, Schadinger)...........................27
Developing Hydropower Resources in Greenland(Kropelnicki,Tucker, Shiers).....................................................30
Successful Relicensing of a Federally RegulatedHydropower Project (Bynoe, Shiers, Williamson,Plizga)..................................................................................................32
Using OASIS Software to Model Water Allocationfor Hydropower Generation Projects(Shiers, Williamson,Tsai) ..........................................................35
Dam Safety: State-of-the Art MethodologyDemonstrates that Costly Dam Remediation isNot Needed (Greska, Mochrie) .........................................38
Deck Slot Cutting and Tainter Gate RemediationExtend Safe Operations of a HydroelectricDam (Buratto, Plizga, Shiers).................................................41
RENEWABLES THE RISKS, CONCERNS ANDPOTENTIAL
The Growing Power of Renewables (Loyd) .............44
Renewable EnergySustainable Economy? (Cook)........45
Test Bed to Turnkey: Introducing New ThermalRenewable Energy Technologies (Burdon) ...................48
Realising the Power Potential from Hot Rocks(Curtis) ..............................................................................................51
Project Brief: Tidal Power (Kydd) .........................................53
Converting Landfill Gas to High Btu Fuel (Lemos)...........54
Photovoltaics,With a Focus on Spain* (Lejarza)..........56
TRANSMISSION AND DISTRIBUTION
TRANSPORTING POWER ACROSS THE GRID
Electricity Transmission, Building on 120 Years ofExperience (Ekwue)...................................................................58
Meeting the Need for Reliable, Cheaper and Non-polluting Electricity in Cambodia (Parkinson,Roe).........59
Rehabilitation and Reconstruction of Abu DhabiTransmission Network (Jayasimha)...................................62
HVDC Transmission Strengthening in SouthernAfrica (Tuson)......................................................................................63
Assessing Transmission Network Condition: 3DData Capture and Reporting (Reynolds)......................66
DISTRIBUTING POWER TO USERS
The Wide Range of Distribution (Douglas)....................68
Research & Innovation: Using Dynamic ThermalRatings and Active Control to Unlock DistributionNetwork Capacity (Neumann)...........................................69
Upside Down! How Innovation in DistributionNetworks is Challenging Tradition (Neumann) .........72
A Survey of Power System Packages for DistributionNetwork Analysis (Ekwue, Roscoe, Lynch) ..................75
Improving 11 kV Network Performance in Al Ain(Nikolic).............................................................................................77
Energy Demand Management Programs inWestern Sydney (Duo)............................................................79
PLANNING AND THE ROLE OF REGULATORS
Planning and Regulating Power Infrastructurein a World of Change (Stedall) ...........................................81
Asset Replacement: The Regulators View (Douglas)...........82
New Zealand Energy StrategyA Plan for aSustainable Nation (Barneveld)...........................................86
Power Articles in PB Network, NOTES, andPowerlines (Chow) ...................................................................89
DEPARTMENTS
Networking: PB Redesigns a Composting Machinefor Improved Operations (Alts)* ....................................91
Water Factory Will Help to Address Water
Shortage Concerns (Hodgkinson) ....................................94Swim Lanes Part 2: Laying Out a Swim Lane Diagram
using Microsoft PowerPoint or Visio (Sloan)................94
Computer Tutor: Working with Text in AdobeAcrobat Pro: Copy text to other softwareapplications, use built-in OCR, make correctionswith the TouchUp Text tool (Hinshaw) ..........................99
PlanetWise: Going Green: Walking the Walk!!(Sammut).......................................................................................101
In Future Issues/Call for Articles................................102
The Net View: Fishing Power (Clark)....................104
TABLE
OF
CO
NTE
NTS
* La edicin en lengua espaola del presente artculo est disponible en la direccin Web de PB Network.
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Innovation in Global Power
http://www.pbworld.com/news_events/publications/network/
3 PB Network #68 / August 2008
I
NTR
ODUCT
ION
This issue ofPB Networkfocuses on the power expertise that PB provides to clients around the
world. There continues to be a rapid rate of change in the global power industry as it responds
to a range of external drivers, including governmental and regulatory targets, fuel price changes,
rising equipment costs and environmental pressures. These changes are happening at the same
time that the demand for electrical power world-wide continues to accelerate at unprecedented rates.
PBs ability to innovate has become increasingly important to power clients looking for solutions
and a competitive advantage in this rapidly changing environment. Reducing carbon emissions
through using more efficient and lower carbon forms of generation, a greater interest in extending
the l ifetime and capacity of existing power assets, and a requirement to squeeze more into
existing land space must all be key to helping ensure a sustainable future
One of PBs stated values is to work with our clients to contribute to their success, and
a number of the articles demonstrate how we are using innovation to do this, including:
Information about the advice we are currently providing to the UK government on carbon
capture and storage
The creation of the NuGas concept that can improve thermal efficiencies to unprecedented
levels by combining nuclear power generation with a small combined cycle gas fired plant
The development of designs for high-temperature hot dry rock power generation in Australia
PBs role in the research and development of a distribution network active thermal controller
that uses local meteorological data to calculate real time equipment ratings and control network
power flows.
Other articles demonstrate how PBs engineers have successfully applied novel thinking to solving
problems on a range of projects, including:
Increasing the lifetime of hydropower dams
Ensuring that New York City hospitals continue to operate during power blackouts
Developing a 3D asset data capture system for transmission networks; and developing demand
reduction strategies.
Another of PBs stated values is to share knowledge with our colleagues to deliver profes-
sional excellence. PB Networkand the Practice Area Networks (PANs) all assist with achieving
this goal, and I would like to thank all of the PANs, authors, reviewers and the editing team who
have contributed to this issue. In the spirit of sharing knowledge with our non-power colleagues,
we have included a list of standard power terminology, definitions, and conversion factors (Ebau,
page 20). Colleagues have shared over 30 other power articles in recent PB Networks, NOTES,
and Powerlines (see list on pp. 89-90).
Katherine Jackson and Arthur Ekwue were the guest editors who compiled all the articles and
developed the framework for the publication. The guest reviewers who helped hone the technical
content were John Douglas, Steve Loyd, Chris Meadows, John Wichall, Paul Kenyon, Brian Van
Weele, and Ferrel Ensign. This issue was sponsored by PBs Power business units globally and
by four of PBs power PANs (conventional thermal generation; high voltage transmission and
distribution; power system planning, analysis, and restructuring; and renewable energy sources).
Eric Burton
Managing Director, Power International
Newcastle, UK
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The public awareness of climate change and energy issues has risen dramatically in the last two to
three years. There appears to be growing acceptance of the need to be energy smart and to
reduce carbon emissions.
An example is the identification of energy savings by finesse of thermal cycle. The NuGas
concept and the energy efficiency projects at Co-op City and the SUNY campus in Brockport,
New York combine an already efficient plant in a way that gains an extra advantage. The process
for cleaning the steam and evaporator units at the Keppel Energy Plant in Singapore reduced
on-site time and improved steam and water quality during commissioning. These are elegant
no-cost or low-cost solutions that were developed by thinking that went the extra step.
The demand for increasing thermal efficiencies in our power plants is pushing up temperatures,
making it even more important to ensure safe design and operation of these facilities. Stewart
Gray has developed an expertise in hazardous areas engineering due, in part to having witnessedmany instances of people not understanding the rules and vocabulary involved, and he knows of
the severe consequences that can result. His ar ticle highlights some of the steps engineers can
take a various stages to help ensure such disasters do not occur.
The paper on carbon capture and storage gives insight to a dilemma facing many of PBs clients.
The world-wide management of carbon dioxide emissions to the atmosphere is crucial to slowing
the rate of global warming. This can be achieved by combinations of improved efficiency in
combustion of fossil fuels, moves to low-carbon or carbon-free fuels, or carbon capture. At present
carbon capture is not mandated but this may arise, just as happened with reduction of nitrogen
oxides emissions (NO and NO2). As with Renewable Energy Certificates, a market may develop
to provide incentives to clean operators, funded by penalties on those with less clean processes.
PB is well placed to assist its clients in this topical and important area of technology.The use of Monte Carlo techniques is a novel approach to optimize generation capacity for a
random load profile. The team went beyond traditional engineering analysis, reduced uncertainty
and provided the client with increased confidence in PBs appraisal. Other PB teams can adopt
this approach to determine the most economical technical solution yet minimize the risk of a
shortfall in installed capacity.
The emergency power generation project for hospitals in New York City applied PB expertise
and good practice to solve a real and serious issue with old and inadequate life-safety
equipment. The projects required improvement work to progress on old, dispersed,
sometimes poorly documented infrastructure without disruption to essential services.
These articles illustrate projects and technologies with a range of complexity, but each team hasa depth of expertise and knowledge to assist clients in its sector.
Please see page 89 for a list of many additional thermal generation and carbon reduction articles
from past PB publications.
Paul Kenyon
Engineering Manager, Newark, New Jersey
PB Network #68 / August 2008 4
GENERATION:Thermal Achieving New Efficiencies, Reducing Carbon Emissions
Best Practices Across a Range of Technologies
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5 PB Network #68 / August 2008
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
Current thinking is that atmospheric CO2 concentrations must be stabilised at 450 parts per
million by volume if we are to at least slow down, if not stop, global warming. This goal will
require a reduction in greenhouse gas emissions by a factor of four to five in the industrialised
nations. Whilst there is a continued and necessary focus on the development, improvement
and implementation of renewable and carbon-neutral power generation technologies and the
adoption of energy efficiency measures, there is a large gap in the short and medium terms
in the level of carbon reductions that can be delivered through these routes alone.
The power generation industry produces about half the worlds CO 2 emissions, so it offers
considerable opportunity for introducing large-scale emission reduction technologies. Current
global debate is focussing on the development of carbon capture and storage (CCS), which
can extract 85 percent to 95 percent of the CO2 produced by a fossil-fuel power generation
facility. Even though carbon capture reduces a plants thermal efficiency, meaning that the use
of fuel per unit of electricity produced increases, the overall carbon reduction is still highabout 80 percent to 90 percent. The effectiveness of carbon capture technology on power
plant emissions is illustrated in Figure 1.
CCS technologies impact the cost of electricity generation, however, so if we are to move
forward with this technology, it is important that we consider the impact of carbon pricing on
lifetime costs, the attractiveness of the technology to investors, and how varying the carbon price
will affect the competitiveness of gas turbine plant with other methods of power generation.
Carbon Capture Technologies
The main carbon capture technologies under development are classed as either
pre-combustion or post-combustion. The one pre-combustion and two post-combustionoptions available, which represent the first generation of commercial carbon capture, are
shown in Figure 2 and reviewed below.
Pre-combustion. The fuel is first reformed into more basic constituents by its reaction
with oxygen. The fuel can be solid, such as coal, petcoke or biomass; liquid, such as a heavy
fuel oil; or gas, such as natural gas. The resultant product, known as syngas (synthetic
gas), contains mainly carbon monoxide and hydrogen. Other constituents include some
methane, some carbon dioxide, hydrogen sulphide and many other minor compounds
including ash if a solid fuel is used. Ash is usually in a fused form and easily separated
from the syngas. The syngas is treated to convert the carbon monoxide to carbon dioxide
that is removed in a chemical absorption process, leaving a predominantly a high purity
hydrogen gas stream suitable for compression, transportation and long-term sequestration.
The main plant components of the pre-combustion reformation and capture stages are considered
to be proven technologies, although there will be some process engineering required to bring
these to the scale required for large scale CCS. Some further operational
proving of the gas turbine for use on hydrogen fuel is required before
the process can be regarded as being a normal operational procedure.
Post Combustion. A post combustion carbon capture plant can
use the same fuels as a pre-combustion capture plant. The fuels are
combusted in either conventional boiler plant or, if suitable, in gas
turbine plant. The flue gases are treated to remove particulate matter
The Effect of Carbon Capture and Storage andCarbon Pricing on the Competitiveness of GasTurbine Power Plants By Dominic Cook, Newcastle-upon-Tyne, UK, 44 191 226 2203, [email protected]
Carbon capture and storage
presents an opportunity for
the continued use of fossil
fuel in power generation
whilst mitigating its contri-
bution to carbon emissions.
But at what cost? Will elec-
tricity still be affordable?
Will the technology be
attractive to investors?
The author explains thecapture and transport/
storage processes, explores
the answers to these ques-
tions, and tells about some
considerations clients will
face when deciding whether
or not to implement CCS.
Figure 1: Effectiveness of CarbonCapture.
Figure 2: Carbon Captureand Storage Schematic.
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1 A number of possible chemicals can be used. Amine, ammonia, and potassium bicarbonate are just a few.2Imperial College, Potential for Synergy between renewables and Carbon Capture and Storage.
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PB Network #68 / August 2008 6
and sulphur dioxide, and to reduce nitrogen oxides before
entering the carbon capture process. The carbon dioxide is
absorbed into a chemical solution1to remove it from the flue
gas,which is then emitted to atmosphere. The carbon dioxide
gas is removed from the absorbent, compressed and trans-
ported for long-term sequestration. The challenge with this
technology is the need to scale up to utility-size capture.
Oxyfuel. An oxyfuel plant is one in which the fuel is
combusted in oxygen supplied by an air separation plant
rather than air. The resulting flue gases are purified to remove
particulate matter and sulphur dioxide, and to reduce nitrogen
oxides. Some of the captured carbon dioxide is recycled and
mixed with the oxygen feed to the boiler plant to control
combustion temperature. The remaining carbon dioxide is
then purified, compressed and transported to long-term storage.
The aim of oxyfuel development is to use as much of the
existing and proven equipment as possible; although some
issues remain relating to the control of combustion tempera-tures within the boiler and the scaling up of air separation
plant to the size necessary for use in power plant applications.
Carbon Dioxide Transport and Storage
Transport. Captured carbon dioxide is transported to a long-
term storage location by either pipeline, truck, train, or boat,
although only pipeline would be feasible for the quantities
resulting from large-scale power generationmillions of tonnes
per year. The pipeline could transport carbon dioxide in the
gaseous phase, at pressures below 71 bar, or at higher pres-
sures where the carbon dioxide is present as a supercritical
fluid giving benefits from lower frictional losses. The scale issuch that a new pipeline infrastructure would be needed.
Storage. Storage of carbon dioxide is assumed to be in
geological formations, such as depleted oil and gas reservoirs,
deep saline aquifers and unmineable coal seams. These
formations need to provide storage with negligible leakage
to ensure that the carbon is sequestered over geological
timescalesthousands, if not tens of thousands of years.
The estimated global potential for the storage of CO2 in
these various sinks is detailed in Table 1. As would be expected,
the capacities for the oil/gas and coal storage options areconsiderably smaller than those for the saline aquifers.
Even with the present global carbon dioxide emissions of
about 25 billion tonnes per year, the available storage capacity
extends for about 55 years to about 435 years. Whilst
this is not a solution, it does provide us with a temporary
breathing space in which to find and implement alternative
means of energy provision to satisfy human, social and
economic aspirations.
TechnologyAnalysis andLifetime Cost ofGeneration
For the purposes of
reviewing the position
of gas turbine technol-ogy within a carbon
constrained world, it was
necessary to identify those
power generation technologies where gas turbines will
continue to have a use and, importantly, the competitor
technologies. The technologies reviewed included:
Coal supercritical pulverised fuel plant with flue gas
desulphurisation with and without carbon capture
Coal integrated gasification combined cycle plant (IGCC)
with and without carbon capture
Gas fired combined cycle plant with low NOx burner
technology with and without carbon capture New generation nuclear power plant.
Our analysis considered the impact of carbon and capital
on the lifetime cost of electricity generation. The extent to
which carbon pricing feeds through to the cost of electricity
generation depends on the amount of free allocations
provided by government to individual plants. Given that
different allocation methodologies will be adopted in different
countries globally, it was considered to be of more value to
assume no allocations and that the full cost of carbon flows
through to the end electricity generation cost.
The level of carbon captured within the carbon captureoptions will be specific to each plants detailed design. The
costs associated with the transport and storage of carbon
were based on various reference sourcesan indicative
value of $10/ton CO2 sequestered was used.2 The Capital
costs and operation and maintenance costs were based on
those observed in the market and included adjustments for
the recent increases in the underlying materials costs, such as:
Steel: 35 percent increase since 2002
Copper: 400 percent increase since 2002
Nickel: 400 percent increase since 2002.
The analysis showed that the addition of carbon captureand associated transport and storage charges added about
35 percent to 63 percent to the lifetime cost of electricity
generation. Introducing a carbon cost payable by the
generation plants for all CO2 emitted increased the electricity
costs across the board, as would be expected. For example,
if a $25/ton charge were placed on all CO2 emissions, the gap
between non-carbon capture and carbon capture would be
narrowed to 6 percent to 22 percent due to the proportion-
ately larger impact the carbon cost has on the non-CCS plant.
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
Table 1: Estimated Capacity ofCO2Storage Options.
(Source: IEA-GHG, 2004)
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7 PB Network #68 / August 2008
Figure 3 shows that the carbon costs incurred by unabated
generation increase the cost of generation significantly whilstmaintaining the mix of generation technologies to coal, gas
and nuclear. There did not appear to be a clear winner.
Where Are We Now?
A number of CCS projects of varying sizes are underway
around the world. The European Union (EU) projects are
shown in Figure 4. As can be seen, only three are identifiedas being operational with the bulk being in the planned stage.
These projects will be implemented at various times up to
2015, with the majority scheduled for delivery around 2010.
The fact that these development projects are moving forward
is a step in right direction; however, there is a need to accelerate
this if we wish to contain the global concentrations of
atmospheric CO2 below the 450 ppmv level that is presently
given as our target.
Other Opportunities
A carbon capture plant had been considered to date as
being inflexible in its operation and less able to respond to
short-term changes in electricity demand. This view is changing,
however, with recent studies considering the specific capabilities
of the power generation plant and the carbon capture plant
separately. With this new view comes the potential to
include additional carbon storage on post-combustion capture
plants, a change that will allow additional power to be provided
from the generator in response to system events, such astransmission system faults, power station forced outages, or
spikes in demand. This change could provide valuable flexibility
services to the transmission system operator when rapid
response to system events is required.
In the case of pre-combustion plant, whether the fuel is coal
or gas, the hydrogen fraction of the syngas could provide the
beginning for establishing a hydrogen economy. This would
be prior to the commercial realisation of nuclear fission. It
would also be applicable in countries that do not have sufficient
insolation (incident solar radiation) or available land area to
drive large solar plant that could be used to generate hydrogen.
Summary
The technology relating to carbon capture is progressing
and reaching a point where it is at a pre-commercial stage.
The mechanisms to allow the costs associated with carbon
emissions to incentivise investment in carbon capture plant
are beginning to emerge, but they will need a strong political
will to ensure that the costs associated with carbon emissions
become sufficient to tip the balance in favour of carbon
capture. This political decision will need to take into
account the extent to which the end customer incurs
additional charges and the rate at which any additional costsare introduced into the economy. This is a balancing act
and it will have a time constant associated with it. It must
be remembered, however, that:
CCS IS NOT A SOLUTION ITS A STOP GAP!
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
Figure 3: Relative costs of plant with and without carbon capture.
Figure 4: Carbon Capture projects in the European Union.
Dominic Cookhas 20+ years of utility and consultancy experience in the power industry. He has been involved in regulatory audits and the development of powergeneration plant, and in providing advice to financial institutions. His publications included Powering the Nation in June 2006 and he is presently involved with theUK government on the carbon capture competition.
Note: This article was adapted from a paper presented at the annual conference of the Institute of Diesel and Gas Turbine Engineers (IDGTE) in November 2007.
across the board, as would be expected. For example, if a
25/ton charge were placed on all CO2 emissions, the gap
betweennon-carbon capture and carbon capture would be
narrowed to 6 percent to 22 percent due to the proportion-
ately larger impact the carbon cost has on the non-CCS plant.
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PB Network #68 / August 2008 8
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
PBs power specialists in the UK have developed and patented a completely new concept
for high-efficiency electricity generation. This ground-breaking development, called NuGasTM,
combines the advantages of nuclear power generation with a smaller combined cycle gas turbine
(CCGT)-based power technology to create a low-cost, highly reliable hybrid system that:
Increases output and thermal efficiencies to levels that are far higher than even the most
ambitious forecasts
Achieves a simple, safe and effective interface between the cycles.
Improved performance comes from better use of heat in the steam cycles of the CCGT and
nuclear plant where currently unavoidable large temperature differences prevent the maximum
work being obtained from the heat. By linking a CCGT with the low-temperature steam cycle
typical of a nuclear power plant, these temperature differences can be reduced significantly,
releasing additional power output without going outside conventional design conditions.
Because NuGasTM enhances thermodynamic cycle design rather than changing operating conditions
to improve efficiency, it introduces no new technology risks in its implementation. This is a
significant advantage over the more complex and unproven technologies being introduced for
new gas turbine designs as engineers pursue ever higher temperature operation.
NuGasTM can be used either for retrofitting existing nuclear stations or for new-build installations.
While the new-build design allows for maximum optimization, the retrofitted option will
enable rapid return on investment with minimal impact on normal day-to-day operation
of the existing nuclear plant during construction of the CCGT unit.
Improving Thermal Efficiency
When analyzing a nuclear power station design, the question often asked by non-engineers or
scientists is why cant you convert all the heat generated in the reactor into electricity? For
example, the thermal efficiency of the latest pressurized water reactors (PWRs) is just 37 percent.
Even if there were no losses in the system, the maximum Ideal Efficiency would still be well
below 100 percent. For a PWR operating at an upper steam temperature of 540F (280C),
the maximum possible efficiency would be just 45 percent. The way to push the Ideal Efficiency
up is to increase the upper temperature in the cycle, which is why gas-cooled high temperature
reactors are again being considered.
Temperatures have been pushed up also in fossil fuelled power plants, and the most modern
coal-fired super-critical boilers can achieve a thermal efficiency of 44 percent. This level is now
being exceeded when two cycles are combined, such as the CCGT, where temperatures are
around 2300F (1200C) and a thermal efficiency of 57 percent can now be achieved. Thedesire to raise system efficiencies beyond current levels has proven challenging, however.
Despite considerable investment in research and development, it appears that significant
incremental improvements are becoming more expensive and harder to achieve without
sacrificing reliability.
By combining current nuclear and CCGT technologies. NuGasTM raises thermal efficiencies to
unprecedented levels. Under this concept, the two separate power generation systems can operate
in tandem as a single combined unit on the same site. In the case of breakdown or planned
maintenance, either the nuclear plant or the gas turbine-powered unit can revert to independent
operation, thereby maximizing availability of power and minimizing upset to the power networks.
The NuGasTM Concept: Combining a Nuclear PowerPlant with a Gas-Fired PlantBy Paul Willson, Manchester, UK, 44 161 200 5210 [email protected]; andAlistair Smith, 44 161 200 5114, [email protected]
Nuclear power is experi-
encing renewed interest
around the world because
of its low carbon emissions
and affordability. As with
other thermal generation
technologies, however, its
thermal efficiency is limited.
PB has developed a new
concept that combines
current nuclear technologywith combined cycle gas
turbine technology to
achieve unprecedented
levels of thermal efficiency.
The authors explain how
it works and how it can be
implemented in new instal-
lations or in retrofitting
existing nuclear stations.
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9 PB Network #68 / August 2008
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
The basic concept would allow a large nuclear power plant
with a typical output of 800 to 1700 MWe to be combined
with a 300 MW CCGT generating unit. Linking the steam-
cycles of the two plants enables them to operate as an
integrated power production unit and reduces losses of
potential output, increasing total efficiency. Cycle efficiency
gains enable the CCGT to contribute an increased output for
no additional fuel, with the efficiency of converting the energyin the gas to electricity increased to about 62 percent.
How NuGasTMWorks
Although a CCGT system has a high thermal efficiency, it
relies on using the heat from the exhaust gases of the gas
turbine to boil water to produce steam that drives the
turbine. As the exhaust gases cool, water is evaporated in
the boiler tubes but temperature differences of up to 400F
(200C) arise in the boiler due to the large amount of heat
needed to evaporate the water. These temperature differences
limit the potential work that can be extracted from thesteam, reducing the output of the steam cycle.
The NuGasTM cycle overcomes this limitation by borrowing a
small proportion (typically 10 percent) of the steam from the
nuclear steam cycle (point A on Figure 1). The dry saturated
steam is superheated using the exhaust heat of the gas
turbine. The high temperature steam (B) is then used to
drive a separate conventional condensing steam turbine to
provide additional output from the plant. Superheating steam
rather than boiling water enables a much lower temperature
difference to be maintained in the heat recovery system,
maximizing the value of the energy recovered.
The heat in the gas turbine exhaust flow between about
570F and 320F (300C and 160C) is recovered via a high
temperature economizer (C) to generate high temperature
feedwater, which is returned to the nuclear cycle (D),
ensuring that the inlet temperature to the steam generator
is maintained close to the design value.
The heat in the gas turbine exhaust below about 320F (160C)
(E) is used to heat part of the condensate from the high
temperature steam turbine (F) before it is deaerated and
returned to the nuclear cycle feed pumps (G). The remainingcondensate from the high temperature steam turbine is
returned to the nuclear cycle condensate system (H).
The flows of energy around the cycle differ somewhat to
those in a conventional CCGT. Figure 2 shows a simplified
Sankey diagram for the NuGasTM cycle, including the energy
exchanges between the CCGT and PWR cycles shown along
the lower edge of the diagram.
Identifying the separate performance of the CCGT cycle
when it is linked to the PWR cycle requires that the design
PWR energy balance be maintained. Thus, the CCGT returns
power to the PWR to compensate for the reduction in
output due to the borrowed steam and returns rejected
heat in the CCGT cooling water to the PWR to account
for the reduced heat rejection from the nuclear turbine
condenser. The diagram therefore shows the additional
energy input, the additional losses and the additional power
generated by the cycle, demonstrating its high efficiency.
Safety Considerations
Downstream failure is limited. The extraction of steam
from the main steam system has the potential to disturb
reactor operating conditions. However, the PWR system isdesigned to allow for a 10 percent step change in flow to the
main steam turbine without exceeding the appropriate limits
for a frequent operating condition. It is likely, nevertheless,
Figure 1: Schematic Combination of the Steam Cycles. Figure 2: Simplified Sankey Diagram for NuGas Cycle.
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PB Network #68 / August 2008 10
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
that a suitably qualified shut-off valve and additional bypass
valves would be needed to limit the potential impact of any
downstream failure in the NuGasTM cycle.
Installation risks are minimized. The interconnection
design minimizes installation risks and ensures that the main
plant is unaffected by maintenance of the NuGasTM plant and
that CCGT operation can continue independently of reactoroperation. This is fundamental, as significant costs would be
charged by the grid operator for increasing the loss of gener-
ation resulting from a single fault. In addition, the project
economics would be adversely affected if the availability of
either plant was to be degraded by the linking of the cycles.
Safety case is maintained. NuGasTM raises overall efficiency
by enhancing the thermodynamic cycle rather than changing
operating conditions, so in addition to being inexpensive, it
introduces no new technology risks in its implementation.
The plant design incorporates additional systems to control
high temperature steam flows linking the nuclear and CCGTunits, ensuring that the integrity of the nuclear safety case is
maintained.
To ensure that all the additional hazards associated with the
introduction of the CCGT are assessed, a full HAZOP has
been carried out to ensure that risks are well within the
currently assessed fault scenarios.
New Build
Currently, the two leading candidate PWR designs for new
nuclear construction are the Evolutionary Pressurized Water
Reactor (EPR) from AREVA with a nominal power rating of
1600 MWe and the Westinghouse AP1000 reactor with an
output of around 1140 MWe. Either the EPR or AP1000
could be integrated with a NuGasTM cycle to offer extra
capacity with the highest possible efficiency for fossil fuel
conversion without significantly increasing the loss of output
in the event of a reactor trip.
If the NuGasTM concept was applied to an AP1000 with a
nuclear plant electrical output of 1140 MW, the combined
plant would have an output of approximately 1470 MW for an
additional capital cost of around $250 million ($800 to $1000
per incremental kW). The cost of the NuGasTM integration is
approximately $50 million, which can be considered to offer
additional capacity with no additional fuel burn. Pessimistically
at a fuel price of $7/MMBTU, a cost that is conservatively
below current levels and below recent longer term forecasts,
the investment to combine the plants would have a typical
payback time of less than three years. At higher gas prices,
the benefits are increased and the payback period
correspondingly reduced.
Backfit
The renaissance of interest in new nuclear power plants will
mean that by 2015 and beyond more nuclear plants will be
brought on-line, but for the next seven years utilities waiting
for their new nuclear plants to be licensed and built may be
faced with a generating capacity gap. Some utilities are,
therefore, considering building interim plants with a low capital
cost and rapid construction times, characteristics of the
CCGT. Building a CCGT and combining it with an existing
nuclear power plant can provide a rapid method for increasing
power generation capacity with exceptionally high thermalefficiency, making it far more profitable than stand-alone
CCGTs. The necessary connections to the nuclear steam
cycle can be readily made during the refuelling outages on
the nuclear plant, thereby minimizing disruption and cost.
A further key advantage for the NuGasTM concept arises
where the nuclear plant has increased operating margins
such that more heat can be emitted by the reactor. In some
cases this extra output cannot be converted to electricity
as the existing steam system cannot operate at significantly
higher rates. Because the NuGasTM cycle increases steam
utilization capability by at least 10 percent, it can use excesssteam without expenditure or shutdowns for costly steam
cycle upgrades, making the NuGasTM conversion even more
attractive financially.
Conclusion
By re-examining power generation options and focusing on
improving efficiency to reduce carbon emissions, it has been
possible to developing a novel concept that brings together
the best aspects of nuclear and gas-fired power generating
technologies. The concept is now being developed with
utilities and plant vendors, with a target of going into servicebefore 2013.
Paul Willson, Deputy Director of Engineering, Generation within PBs power and energy business in Manchester, has worked for PB and its predecessors for more than 25years. He leads the Development and Emerging Technology Group, which is responsible for independent power and water project development and for innovations. Paul
is co-inventor of the NuGas technology.
Alistair Smith, Director of Nuclear Services for PB based in Manchester, has worked in the nuclear power industry for 27 years and has worked on all phases of thenuclear plant li fecycle covering design, construction, operation and decommissioning. He is the chairman of the UK Institution of Mechanical Engineers Nuclear Power
Committee, chairman of the Nuclear Industry Associations industrial group, and is a spokesman for the UK nuclear industry.
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11 PB Network #68 / August 2008
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
In modern thermal power plants fuelled by either oil or gas, fuel handling processes give rise
to situations where electrical equipment could cause an explosion due to a hot surface or a
spark. Indeed, there have been several incidents in the past where lives have been lost and
plant destroyed. Places where these situations arise are termed hazardous or classified areas.
Special engineering practices designed to prevent explosions in these areas are available.
These practices are often misunderstood and applied incorrectly, however, expert supervision
should always be used at a project start-up to ensure such engineering practices are imple-
mented properly. The following information is based on the experiences of some of PBs
workers in this field, particularly our assessments of power plant installations and our ensuring
that relevant codes and practices, local statute and insurance requirements are adhered to.
Applicable Codes or Practice
The code or practice applicable to each installation is normally determined by its locality,
although the several different practices applied worldwide have many similarities. The mostcommonly applied codes are International Electrotechnical Commission (IEC) 60079 Electrical
apparatus for explosive gas atmospheres and National Fire Protection Association (NFPA) 70
National Electrical Code. Both define sets of special precautions (types of protection) required
for electrical equipment in hazardous/classified areas using some very definite vocabulary.
Choice of Types of Explosion Protection
It is important to establish the extent of hazardous areas that exist at an early stage of any
plants design. These areas are customarily delineated using a plan called a hazardous areas
layout drawing. While it is always best to install the electrical equipment elsewhere, doing so
is often unavoidable.
All electrical equipment installed in a hazardous area requires explosion protection. IEC60079 defines nine types of such protection. Of these, the three types of protection most
commonly found in modern power plant are:
Flame proof enclosure (type d). This technique limits the effect of an explosion. Parts
that could cause an explosion are placed inside a special enclosure that is strong enough to
contain an internal explosion (Figure 1). The resulting hot gasses exit through a specially
machined path that is relatively long and narrow. As they exit they are cooled sufficiently
to avoid spreading the explosion outside.
The main uses for this type of protection are electrical power equipment, switches, etc.
While this is a well known technique, it is somewhat less readily available than other s. It
is also expensive and requires special installation rules.
Increased safety (type e). This technique (Figure 2) prevents explosions. Parts that could
cause an explosion are made with a superior degree of safety, including long creepages and
clearances, and temperature limitations. Its main use is for junction boxes. This technique is
well known, readily available, and inexpensive. Its use requires observation of special design
and installation rules.
Intrinsic safety (type i). This technique (Figure 3) also prevents explosions. The circuit
is arranged so the amount of energy that can flow into the hazardous area is limited and
incapable of causing an ignition. Normally, energy limiting barrier devices used in the safe
area contain zenner diodes or optical isolators to achieve the energy limitation. Care needs
to be taken to ensure that the hazardous area part of the circuit cannot store large amounts
of energy (i.e., use of low capacitance cables).
PB Inspections Help to Ensure Power Plant SafetyBy Stewart Gray, Bangkok, Thailand, 66 (0) 2343 8866, [email protected]
The author provides some
insight into the application
of engineering to prevent
explosions and fire in highly
hazardous areas of power
plants fuelled by oil or gas.
Acronyms/Abbreviations
IEC: Internat ionalElectrotechnicalCommission
Figure 1: Schematic of theprinciple of a flameproofenclosure.
Figure 2: Schematic of theprinciple of increased safety.
Figure 3: Schematic of theprinciple of intrinsic safety.
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PB Network #68 / August 2008 12
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
The main uses of type i are for instrumentation, telecom-
munication devices, and similar equipment. It is well
known, inexpensive and readily available, but special design
and installation rules need to be followed. Two categories
of intrinsic safety are available. Category ia, which provides
the highest degree of explosion protection available,
ensures safety under two faults. Category ib ensures safety
under a single fault.
Design and Assembly Stage Inspections
Inspections of the installation need to be conducted through-
out the stages of its life cycle in accordance with IEC 60079.
Design Stage. Inspections should start at the design stage
by means of design review because mistakes identified at this
stage are almost always easier and less costly to rectify.
Factory Assembly Stage. When factory assembly of skid
mounted equipment is completed and after the factory has
conducted its own inspection, an inspection done by our
team is advantageous. Whilst this does not present a
comprehensive picture of the final installation, it can often
show mistakes, and corrective measures can be planned
during shipping to the construction site.
Final Construction Inspection
A final construction inspection, along with possible rectifica-
tion of any mistake, is mandatorybefore explosive fluid can
be introduced to the plant. The objective of the inspections
is to verify the installation complies with the applicable code
of practice. In the case of IEC 60079, this requires ensuringthat the appropriate components were selected and that
they were installed correctly. Discovery of an installation
mistake at this stage may lead to project time delay.
Verification of Explosion Protection. The first part of
any inspection work is to make sure that the equipment is
explosion protected in conformance with IEC 60079. Whilst
it may be labelled with compliance information, a visual check
of labelling is not enough. It is necessary to obtain a copy
of the original certificate of conformance and use this as
the inspect ion star t-point . The inspector should check
the cer tif icate validi ty, cross check the cer tificate againstequipment labels and verify the installation method complies
with the requirements as stated in the certificate.
Use of Check Sheets. It is good practice to record the
outcome of the inspection using check-sheets. The minimum
points to be considered are peculiar to each type of protection,
as summarised in the box below. In addition, the check-sheets
should contain a record of each items certificate number.
The methods used are straightforward; however, each item of
plant has its own peculiarities and some of these are often
overlooked. The importance of this matter dictates that an
expert lead the inspection at this stage.
Minimum Check Points for Installation of
Three Common Types of Explosion Protection
Flame proof enclosure installation (type d). The EEx d label is correct. The cover has been fitted correctly. The serial number on the cover and base unit match (if applicable). Cable entries are by means of EEx d certi fied gland (special rule
for enclosure > 2 litre size), EEx d certified plug or stopper, EEx dcertified cable bushing/termination or sealed conduit.
All conduits are wrench-tight with at least five full threads engaged. Any reducer used is certified.
Increased safety installation (type e).
The EEx e label is correct. Any breather is of an approved type (see certificate schedule).
Any breather is installed in correct face.
Any unused cable hole is sealed properly.
All terminal screws are tightened, including spare terminals.
Insulation is within 1 mm (0.04 inch) of the terminal throat.
If mineral-insulated copper clad (MICC) cable is used, an EEx egland is applied.
The glanding technique maintains IP54 (washers may be used).
There is no more than one conductor per clamp, unless a specialjoint is used.
Terminal creepages and clearances are within specifications.
Terminal temperatures will not exceed the temperature of thecomponent certificate.
All terminals and accessories have been installed per themanufacturers recommendations.
Terminal ratings do not exceed their label.
Intrinsic safety installation (type i).
The barrier is installed in safe area (may be in zone 1 area if insideEEx d enclosure).
The EEx marking is correct on the barrier and device, if applicable.Wiring has been segregated. Enclosures are protected to at least IP20.
Earthing has been connected in accordance with the EEx certificate.
Wiring properties are consistent with EEx cer tification. If a colour code is applied, the colour used is light blue.
Related Web Sites:
Additional information about the use of electrical equipment inhazardous areas is publicly available at numerous certification body
and specialist manufacturers Web sites, including: http://www.baseefa.com/ http://www.mtl-inst.com/ http://www.ptb.de/index_en.html http://www.stahl.de/en/start.html
Stewart Grayis a principal engineer with more than 30 years project engineering experience, including 10 in a construction-based consulting role. With his detailed knowl-
edge of the subjects of safety and inspections, he has identified a variety of hazardous area installation errors on behalf of several clients before their plants went into service.
In most cases, these errors were attributable to incorrect material selection or inappropriate installation techniques.
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13 PB Network #68 / August 2008
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
In early 2007, PB was selected to assist one of the worlds largest port owner-operators to
determine the least-cost approach to meeting the power needs of a proposed container port
development in Pakistan. The major electrical loads of a container port are the quay cranesused for loading and unloading container ships. The client required our power specialists to
determine whether a stand-alone power station would be more economical than using on-board
quay crane diesel motors. The key challenge in sizing the power station was to deal with the
uncertainty associated with the loading pattern of 16 quay cranes. The electrical loads of
these cranes var y with their duty cycles, and the total load varies with the number of cranes
in operation In turn, this, is dependent on the rate of arrival/departure and the capacity of the
container ships.
Our team combined engineering and Monte Carlo techniques to successfully deal with this
problem. Monte Carlo is a method of analyzing stochastic processes, which are those governed
by laws of probability, that are so difficult that a purely mathematical treatment is not practical.1
Client feedback indicated that this technique was the most convincing method they had seen
used in the industry, whereas solutions based on traditional engineering methods only were
judged to be unreliable or conservative.
Project Brief: Using Monte Carlo Techniques toSize a Power Station By Mike Emmerton, Hong Kong, 65 6290 0737, [email protected]
1 Two earlierPB Networkarticlestell how Monte Carlo techniques
were used in risk management.Please see:
Project Risk Management andMadrids New Airport by PaulCallender, Issue 51, January 2002,pp. 56-58 and on line at http://www.pbworld.com/news_events/publications/network/issue_51/51_24_callenderp_madridairport.asp.
A Risk Assessment and Analysisfor an Existing Water ConveyanceTunnel by Kyle Ott and Joe Wang,Issue 51, January 2002,pp. 38-40, 43 and on line athttp://www.pbworld.com/news_
events/publications/network/issue_51/51_17_ottk_riskassessmentanalysistunnel.asp
Mike Emmerton is a management consultant who has been with PB since 2004.
PB acted as owners engineer to Keppel Energy for its development of the Keppel Merlimau
Cogen power plant, a 500 MW combined cycle facility on Jurong Island in southwest Singapore.
The plant now supplies power to the Singapore grid, and has provision to feed process steam
to chemical plants that are due to be part of the evolving petrochemical industry on the island.
Construction began in March 2005. Our management team ensured that everything was in
place well ahead of the schedule set by the turnkey contractor, an effort that helped lead to
the plant seeing provisional acceptance in April 2007.
The project adopted the acid cleaning method, which replaced the usual steam-blow procedure.
This resulted not only in a shortened timetable, but in improved qualities of steam and waterfor commissioning.
Our team also helped to meet stringent regulatory requirements. The plant was the first
independent power project to comply with Singapores Energy Market Authority (EMA) rules
following deregulation of the countrys electricity market in 2003.
Project Brief: Energizing Singapores EconomyBy Kamaljit Gill, Singapore, 65 6533 7333, [email protected]
Kamaljit Gill is a senior mechanical engineer who has been with PB since 2005. He was the lead mechanical engineer supervising the installation and construction of GTs,ST, HRSG, piping, tanks and balance of plant equipment on site, including chemical cleaning, steam blowing and performance testing of turnkey systems. He was also review-ing engineering design documents and drawings from contractors, monitoring schedules and quality of execution during site implementation to ensure that the plant complieswith contractual requirements. Kamaljit was also a member of the commissioning team, supervising, internal commissioning activities - conducting internal and regulatorytesting, reliability runs and performance guarantee testing.
Related Web Sites:
http://www.keppelenergy.com/
http://www.ema.gov.sg/
http://www.pbworld.com/
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PB Network #68 / August 2008 14
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
PB was engaged as prime consultant to upgrade the central boiler/chiller plant at the largest
cooperative residential development in the USA, which is named Co-op City. Located inNew York Citys borough of the Bronx, Co-op City is home to approximately 55,000 residents.
It consists of 15,372 residential units in 35 high-rise buildings and seven clusters of townhouses,
three shopping centers, parking garages, schools, and houses of worship (Figure 1).
Riverbay, the corporation that manages Co-op City for the residents, wanted to make a number of
improvements for greening the complex. These included: upgrading the central plant, improving
the buildings energy efficiency, extending the existing waste recycling schemes, and introducing
water-conserving technologies. The objectives of the central plant upgrades were to reconfig-
ure the systems to optimize steam and energy utilization during peak and off peak seasons;
make the development self-sufficient for heating, cooling, and power; and lower emissions.
The Existing Boiler/Chiller Plant
The existing plant had been configured as a thermal plant with electric generation to provide
for the parasitic loads of the plant. As studied, the plant comprised the following, all of which
were fired on No. 6 (residual) fuel oil:
A central boiler plant with combined gross steam generating capacity of approximately
442 tonne/hour (975,000 lbs/hr).
One high-pressure boiler 34.5 barg (500 psig) with rated capacity of 138 tonne/hour
(305,000 lbs/hr).
Two low-pressure boilers.
Four multistage steam turbine driven centrifugal chillers, each with original rating of
6,250 tons refrigeration.
During spring and fall when there is li ttle requirement for heating or cooling, the steam
demand may be as low as from 4,536 kg/hr to 13,608 kg/hr (10,000 lbs/hr to 30,000 lbs/hr),
while winter peak heating demand can be more than 226,800 kg/hr (500,000 lbs/hr). Steam
is used for domestic water heating all year round, chilled water production in the summer,
and space heating in the winter. The old 7.5 MVA steam turbine generator (STG) had not
been operational since 1996, and the superheated steam from the high-pressure boiler was
now directed to the pressure reducing/de-superheater station and
low-pressure header to supplement the low pressure boilers
steam supply.
The electrical loads were supplied from Consolidated Edison
Company of New York, Inc. (Con-Ed), the local utility. The loadranged from an annual average demand of 12 MWe to a peak
demand of 23 MWe.
Configuration Study and Critical Analysis
PB provided a configuration study and critical analyses that
recommended installation of combined cycle gas turbine (CCGT)
cogeneration plant to replace the existing electrical supply from
Con-Ed and to meet the thermal demand of the complex.
Included were a combined heat and power (CHP) study, chiller
upgrade study, cooling tower study and miscellaneous plant upgrades.
Combined Heat and Power for USAs LargestResidential DevelopmentBy Dennis Bautista and Eric Swensen, New York, New York, 1-212-613-8840, [email protected]
The project described inthis article started as
refurbishment of a central
heat/chill plant to include
combined heat and power
(CHP) for a baseload of
approximately 26 MWe.
The majority of CHP in USA
is heat matched with top-up
electrical power from the
utility provider. Our teamidentified benefits for an
over-size (40 MWe) CHP
plant able to export up to
16 MWe to the utility grid.
Figure 1: View from the refurbished cooling tower showingsome of the Co-op Citys 35 high rise buildings in thebackground.
Related Web Sites:
New York State EnergyResearch and DevelopmentAuthority (NYSERDA):
http://nyserda.org/default.asp Riverbay Corporation:
http://www.riverbaycorp.com/newrb
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15 PB Network #68 / August 2008
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
The CCGT system selected by the client from options
presented by PB went beyond the straight replacement of
plant. It was designed for flexibility of operation and retained
usable equipment where possible. Although the majority of
CHP in the USA is heat matched, an oversize (40 MWe)
plant with power-export capability was selected. This oversize
system (Figure 2) included:
Two new 13 MWe gas turbine generators, each with a
heat recovery steam generator (HRSG), fired on natural
gas as primary fuel or No. 2 (distillate) oil as back up fuel.
A new 15 MWe extraction condensing steam turbine
generator. This generator uses the existing condenser,
which has a maximum steam capacity of 29,483 kg/hr
(65,000 lb/hr). Consultation with the original equipment
manufacturer confirmed sufficient capacity.
The two existing central plant low-pressure boilers, which
will continue to operate on No. 6 (residual) fuel oil.
A new dual fuel (gas/oil) packaged boiler rated at 68 tonne/hr
(150,000 lbs/hr) that will provide further flexibility.
The PB CHP study started in May 2004 and was completed
in October 2004. Following the study and configuration
analysis, PB performed owners engineering services to procure
the gas turbine and award an engineer, procure, construct
(EPC) contract. The contract was awarded April 2006 and
construction commenced in June 2006. The installation was
completed in early 2008 and, at the time of writing, was
ready for testing and final Con-Ed approval of the intercon-
nection arrangements. The final EPC cost was $67 million.
Chiller Upgrade
The other major component of our plant work was a
configuration study and engineering services to upgrade
the existing central chil ler plant. The goals were to
increase efficiency and reliability with construction that
minimized the impact on the existing system. The primary
features of the existing central chiller plant were:
Chillers. Four Worthington multistage steam turbine
driven, centrifugal chillers, each with original rating of
6,250 tons refrigeration.
Turbine Drives. The multistage steam turbine drivers
were each rated 2,289.3 kW (3,070 hp), designed for10.3 barg (150 psig) steam supplied from the existing
central boilers.
Performance. Design chilled water flow rate was 37 8
liter/minute (10,000 gpm) each.
The main components of the chiller plant upgrade were:
Replacement of the chiller unit driveline to a more efficient,
single-stage turbine. The new driveline lowered the output
of each chiller to 5,000 tons (total combined capacity of
20,000 tons), but improved chiller efficiency by 33 percent.
New high efficiency tubes for the evaporators, condensers
and steam condensers. A new digital control system.
The chilled water plant configuration study and engineering
was undertaken in September 2004. The upgrade of the
chiller plant commenced in summer of 2006 and was completed
a year later. The final EPC cost was $12 million. The chiller
plant efficiency was improved from the existing steam rate
consumption of approximately 15 lb/ton-hr to 10 lb/ton-hr
Other Supporting Tasks
Several other tasks included in our scope supported Riverbay
Corporations goal to increase efficiency and reduce emissions.
Some of them are discussed here briefly.
Cooling Tower. The existing five-cell Marley mechanical
draft evaporative cooling tower was refurbished to address
the additional heat rejection from the new cogeneration plant.
Switchgear. A short circuit and protection relay coordination
study indicated that upgrading of the existing switchgear was
required. The new 13.2 kV switchgear includes individual
generator circuit breakers, connection to the new plant
switchgear and parallel operation with the Con-Ed utility.
The switchgear was installed by the client.
Financial Grants. We investigated the availability of grants
and successfully applied to the New York State Energy
Research and Development Authority (NYSERDA), a public
benefit corporation created in 1975 to help reduce New
York States fossil fuel consumption.
Figure 2:Combined cyclegas turbine(CCGT) plantrepresentativeof installationat Co-op City.
Dennis Bautista was lead mechanical engineer on the Co-op City project. He is a former PB employee.
Eric Swensen, an assistant vice president and senior engineering manage, has extensive experience in power engineering, ranging from initial feasibility studies and
conceptual design, through detailed design, construction, and commissioning.
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PB Network #68 / August 2008 16
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
The Northeast Blackout of 2003, the largest power outage in North American history, revealed
poorly performing stand-by emergency generators and emergency power distribution systemsat some of New York Citys hospitals. This event led NYC Health and Hospital Corporation
(NYC HHC), the owner, to have feasibility studies performed for upgrading emergency power
systems at several of its major hospitals and diagnostic and treatment centers. The following
year the Dormitory Authority of the State of New York (DASNY), which acts as NYC HHCs
agent, retained PB to validate the aforementioned feasibility studies and to develop design and
construction documents for upgrading the emergency systems at nine hospitalsBellevue,
Coler, Elmhurst, Goldwater, Gouverneur, Harlem, Lincoln, Queens and Woodhulland three
diagnostic and treatment centersCumberland, Segunda Ruiz Belvis, and Morrisonia.
Bellevue, Elmhurst, Harlem and Lincoln Hospitals received priority over the other facilities
because they serve as Level 1trauma centers.1 At the time of writing (May 2008), Bellevue
and Elmhurst Hospital projects were in the middle of the contractor bidding process.
PBs role was similar for each hospital:
Investigate the site.
Measure and record existing running loads.
Perform load analysis.
Provide a study report to document findings and recommendations to address system
deficiencies.
Meet and correspond with local utility companies to request upgrades in utility services.
Provide bid documents and construction support services to upgrade emergency
systems, including replacing and adding generators; synchronizing generator switchgear;
and incorporating bypass isolation type transfer switches, emergency distribution
switchboards and panelboards. Provide bid documents and construction support services to address code violations
associated with the existing emergency systems and to connect code-required HVAC
equipment to emergency power.
Design Challenges
General Challenge. Implementing electric power upgrades within active hospital facilities
is challenging, and it is essential that electric power be maintained during construction. Even a
partial loss of power can cause severe operational problems along a chain of activities:
Power loss to lighting systems can make it impossible to dispense medicine accurately,
carry out precise medical laboratory work or perform surgical procedures.
Power loss to refrigerators storing tissue, bone or blood can leave the facility without
crucial resources.
Power loss to essential life support equipment, such as heart pumps, medical vacuum
pumps, dialysis machines, and ventilators, can result in loss of life.
Developing design and construction documents that virtually eliminate interruptions to
electric power during construction was paramount. Thorough up-front planning was essential
so that these documents incorporate effective strategies for minimizing the impact of
construction on hospital operations.
We exercised just such careful planning for the NYC HHC facil ities, and included language for
sequencing construction into design and construction documents for each one. During the
Ensuring Continual Power Supply for New YorkCity Hospitals By Ross Krupnik, New York, New York, 1-212-613-8889, [email protected]; and
Warren Andrews, Atlanta, Georgia, 1-404-364-2650, [email protected]
Several of New York Cityshospitals and diagnostic
and treatment centers
needed upgrades to their
power systems to ensure
they would maintain services
during power outages. The
author tells about much of
the research and planning
PB conducted for these
upgrades and, equallyimportant, for ensuring that
interruptions to power
were minimized during
construction.
Ross Krupnik, an electrical engineer,has a B.S. degree with a double major-electrical and computer engineering,and biomedical engineering. Hecompleted his advanced studies inelectrical engineering in June 2008.Ross joined PB in 2006 and served as
an engineer on the hospital studiescovered in this article.
Warren Andrews, a senior engineeringmanager and PB vice president, wasprogram manager for the New YorkCity hospitals project. He specializesin power design. Warren has beenwith PB since 1997.
1 Level 1 trauma centers offer themost comprehensive emergencymedical and surgical servicesavailable to patients sufferingtraumatic injuries.
Related Web Sites:
Dormitory Authority of theState of New York:www.dasny.org
New York City Health and
Hospitals Corporation:www.nyc.gov/hhc
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17 PB Network #68 / August 2008
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
planning phase, our team:
Performed detailed surveys and consulted with facility
administrators, maintenance and operation staff and other
personnel to gain a thorough understanding of specific
functions in each area of each facility
Identified and documented the location of all essential
equipment, and critical and life-safety loads Identified the local source of normal and emergency power
serving all these loads
Identified areas in each facility that would serve as swing
space for locating temporary power distribution equipment.
This planning allowed us to produce drawings specifying
construction phasing for accurate, detailed equipment
removals and relocations and for temporary power. It also
enabled us to identify windows of opportunity for scheduled,
short-duration interruptions of power to minimize impacts
on facility operations.
Bellevue Hospital. After our analysis of the existing and
planned electrical loads, we discovered that the hospitals
existing four 400 kW generators and one 600 kW generator
could not accommodate a total failure of the normal electrical
power feed from the local utility. We proposed:
Replacing the 400 kW generators with four new 725 kW
generators and one 1500 kW generator to provide
enough power for the existing and future loads. These
would be installed and synchronized with the remaining
600 kW generator.
Replacing the existing emergency switchgear.
Modifying and upgrading 35 of the 47 existing automatictransfer switches (ATSs) to accommodate future loads.
Upgrading various systems, including the fire pump, fire
detection system, fire alarms, and alarms for medical gas
and vacuum systems.
Various components of the emergency electrical equipment
are located throughout the hospital rather than at centralized
locations. Further, Bellevue Hospital is Americas oldest
public hospital, and now has little room for larger equipment.
We collaborated with facility management and the manufacturer
of the switchgear, ATSs, and generators to fit the equipment
in the available space. (For example, once we determinedhow much space was available for switchgear, manufacturers
worked within those restrictions to develop switchgear
frames (boxes) that fit.) The four 725 kW generators will
be installed on the 13th floor close to the existing 600 kW
generator, while the 1500 kW generator was planned to be
installed in the sub-cellar. The paralleling switchgear for these
generators is on the 13th floor.
Toward the end of the design process, DASNY asked that we
revise our design for the sub-cellar 1500 kW generator to
offer it more protection against flood damage. We raised the
generator six feet (2 m) and placed it on a new platform. It will
be supported in an areaway next to an on-ramp along the
FDR Drive, a heavily traveled highway on Manhattans east side.
The 47 ATSs are located in electrical rooms throughout the
hospital. Our engineers had to arduously examine the available
riser space to determine where the replacement switchescould be located. This effort required the engineers to visit
each floor of the hospital and venture into areas that required
special security by the hospital or NYC Department of
Corrections because of the patients that occupied those areas.
Elmhurst Hospital. As was the case at Bellevue, Elmhurst
Hospitals current generators could not accommodate a total
failure of the normal electrical power feed from the local utility.
We proposed installing generators at three locations, each with
different setups, and making additional upgrades, as follows:
Replacing one 350 kW generator with a new 600 kW
generator and synchronizing it with an existing 400 kWgenerator
Replacing another 350 kW generator with a new 600 kW
generator
Synchronizing three existing 600 kW generators with one
new 1500 kW generator
Upgrading 16 of the 30 existing ATSs and adding five new
ATSs to accommodate future loads
Upgrading various systems, including the fire pump, fire
detection system and fire alarms.
The generators at the three locations will be activated basedon the particular load that was lost and the size of the
power outage. If for some reason the local generator cannot
supply enough load, it will activate and synchronize with the
1500 kW generator. This built in redundancy helps to assure
that patients, doctors, and hospital staff will not notice the
change from normal to emergency power.
While Elmhurst is not as tall a building as Bellevue and has its
emergency power equipment at three centralized locations,
these locations are located at nearly opposite ends of the
hospital. This configuration requires that cable between the
generators and paralleling switchgear be run through the
cable support system in the sub-basement. The conduit runs
are layered many times over and noticeably reduce the height
of portions of the sub-basement corridors. An electrician at
this hospital told us that the supports for the conduit had to
be replaced recently because the weight of the conduit caused
the supports to buckle. This reduced the available space for
new conduit and made it more challenging to run new feeders.
PB worked closely with facility management and its electricians
to make the most efficient use of the hospitals remaining
space for new feeders and equipment.
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PB Network #68 / August 2008 18
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
PBs power specialists have been working with New York Power Authority (NYPA) for more
than a decade to undertake energy conservation designs for college campuses, municipalitybuildings and state office buildings throughout New York State. At the State University of New
York (SUNY) campus at Brockport, New York, we developed improved systems and plant that
reduced energy consumption, enhanced the reliability of campus systems and increased the
comfort and safety of building occupants. Some of the key features of this work included:
Introducing a distributed chilled water loop that linked individual chillers in various
buildings to increase part-load efficiency
Linking boilers in individual buildings to improve their use and extend boiler life by
reducing cycling.
Getting Started
The Brockport campus is comprised of 40 buildings, most of which are 30 to 50 years old.
We assessed these buildings and their chiller, boiler, and heating, ventilation and cooling
equipment for potential energy conservation measures. Our team conducted an extensive
data collection on the campus equipment to perform cooling and heating load calculations.
An economic analysis (life-cycle cost analysis) was performed using Building Life-Cycle Cost
(BLCC) 5.2 software, which was developed by the National Institute of Standards and Technology
under the Federal Energy Management Program (FEMP). The software methodology complies
with American Society for Testing and Materials (ASTM) international standards related to
building economics as well as FEMP guidelines for economic analysis of building projects.
We developed a number of energy conservation measures (ECMs) that were subsequently
ranked based on payback and client preference. The college approved seventeen of them,and PB provided the detailed design and construction management for the work.
Distributed Chilled Water Loop
A key energy savings was obtained on the chiller system providing air conditioning (AC) for
the buildings. The campus had eight electricity-driven water-chillers located in individual buildings.
Many of the chillers were either oversized or inadequate for the required duty. By their nature,
constant speed chillers operate most efficiently when the cooling load is close to the chiller
capacity. They become less efficient in part load use, which is the majority of the cooling season.
We designed an underground chil ler water loop running in concrete tunnels to connect the
individual chillers into a distributed chilled water plant. This technique, normally adopted onlyin centralized plant systems, improved utilization of the installed capacity and increased the
seasonal efficiency. Fewer chillers run during partial load conditions, so the lives of individual
machines will be prolonged and efficiency increased. System redundancy improved also, and it
was possible to install additional air handling units without the addition of new chillers.
Installation of underground piping is always a challenge and this case proved to be no exception.
Although we had the campus underground utility records, we asked the contractor to investigate
pipe routing with ground penetration radar. We had to confirm that we would not encounter
abandoned asbestos piping that was not shown on any drawings, gas distribution lines that
were not active, or stone foundations of old houses along the way.
Changes to Chiller, Boiler and HVAC Lower EnergyConsumption at a University CampusBy Damee Choi, New York, New York, 1-212-613-8835, [email protected]
New York State has a goalof cutting energy use
in schools and other
government facilities by fif-
teen percent by 2015. Our
work at the State
University of New York
campus in Brockport illus-
trates how PB is helping
the state meet this goal.
Improvements to the boilersystem and other energy
saving measures resulted
in a six percent reduction
in energy consumption.
Acronyms/Abbreviations
AC: Air conditioning
ECM: Energy conservationmeasures
HVAC: Heating, ventilation, airconditioning
LED: Light-emitting diode
NYPA: New York PowerAuthority
SUNY: State University ofNew York
VAV: Variable air volume
VFD: Variable frequencydrive
Related Web Sites: http://www.brockport.edu/
http://www1.eere.energy.gov/femp/
http://www.astm.org/
http://www.nyserda.org/programs/state.asp
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19 PB Network #68 / August 2008
Thermal Achieving New Efficiencies, Reducing Carbon Emissions
Improving Kitchen Steam Boiler Operation
The original boiler was sized to meet the kitchen load
demand, but over time part of the steam kitchen equipment
had been converted to direct gas or electric fired equipment,
so the boiler had become oversized, resulting in extreme
short cycling and a drop in efficiency. We installed a steam-
to-water heat exchanger up stream of a direct fired gasdomestic hot water heater serving the kitchen. The system
was arranged to meet the kitchen steam demand first and,
if steam was available, to then feed the new heat exchanger.
Cold water to the domestic hot water heater passes first
through the new heat exchanger and is heated there by the
excess steam. It then flows to the direct fired heater. If the
available steam is adequate for domestic hot water production,
then the heater does not fire. If the steam boiler capacity
cannot meet the demand at this moment, then the heater
fires and heats the water to the desired temperature.
Wide Range of Additional Energy ConservationMeasures
The following energy conservation measures that we imple-
mented can often be applied to other projects.
Water Pump Control. In a number of buildings, we installed
variable frequency drives (VFDs) on the water pumps and
outside air fans to minimize the water pumping cost and
outside air conditioning costs. For example, the Tuttle North
building had five constant speed pumps that served the
heating system. VFDs were installed at these pumps and
the three-way heating coil control valves were converted tooperate as two valves to support the variable flow operation.
During the occupied hours, the pumps modulate flow to the
coil, which reduces power consumption particularly at partial
load conditions. When the building is unoccupied, the flow is
maintained at 20 percent to avoid coil freezing.
CO2 Sensors. The majority of buildings featured air handling
units that operated with a fixed amount of fresh air intake
that was independent of the building occupancy. This mode
of operation, common for building design until several years
ago, results in unneeded energy consumption. We introduced
CO2 sensors (indoor air quality sensors) that reduce thefresh air intake, and consequently, the heating and/or cooling
energy consumption, particularly when the building is only
partly occupied.
The CO2 sensors are located in the return air ducts of 56 air
handling units. They have automatic controls to modulate
their outside air dampers and exhaust dampers to suit building
occupancy. The CO2 sensor readings fluctuate depending on
building occupancy levels. The outside air is set to a minimum
rate required for the building minimum exhaust.
HVAC Upgrade. At the Metro Center, which has class rooms
and lecture halls, the HVAC system was upgraded to include a
new variable air volume (VAV) system with summer economizer.
This replaced the old high pressure air handling units and
window mounted direct expansion (DX) units. Fin tube radi-
ation installed at the building perimeter improved occupant
comfort and eliminated the need for costly reheating systems.