tom winkler wave energy potential for ki

8/8/2019 Tom Winkler Wave Energy Potential for Ki

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UNIVERSITY OF SOUTH AUSTRALIA

School of Advanced Manufacturing and MechanicalEngineering

Bachelor of Engineering

Final Year Project

Wave Energy Potential for Kangaroo Island

Tom Winkler

I.D. No: 100005269Supervisor: Dr Brian Kirke

2005


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Abstract

Renewable energy technologies offer power for a sustainable future and there are two

key factors driving their development. Firstly is the growing awareness of the need to

reduce the destructive effects of conventional energy use on humanity and the

environment. The second factor is to reduce the heavy reliance society has on burning

limited fossil fuel reserves, oil in particular. Of the new renewables, Wind energy is

leading the charge by being the most economically viable form of renewable energy

technology at present. However, other forms of renewable energy are emerging

including harnessing the power of the ocean in the form of wave energy generation.

Ocean wave energy is an abundant and highly concentrated form of renewable energy

that up until very recently has been virtually unexploited. Wave energy now looks set

to become an important addition to the renewable energy mix.

Local renewable energy developer Wind Prospect is exploring the use of a specific

wave energy generation technology, the Pelamis P-750 Wave Energy Converter,

developed by Ocean Power Delivery Ltd in the UK. The Pelamis is viewed by Wind

Prospect as the leading contender in commercially available wave energy generation

technology and having the potential to become a valuable supplement to wind power

for supplying Australia with renewable electricity and possibly desalinated water.

The original purpose of this project was to assess the feasibility of installing a wave

farm to contribute to the electricity demands of Kangaroo Island, South Australia.

Wind Prospect required an investigation into the use of Pelamis wave energy

converters in a specific offshore location. After it was discovered that the feasibility

for Kangaroo Island was not as good as anticipated, the scope broadened significantly.This project explores the available wave energy resources and bathymetry of the

entire coastline of southern Australia. As a result it has identified Australias best

locations for offshore wave energy projects. Portland in Victoria was identified as the

most promising and its feasibility is outlined in a case study.


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Research was undertaken to establish the nature of ocean wave energy and the long

term wave climatology arriving at southern Australia. Over 10 years worth of wave

data was analysed and combined with Pelamis specification data to model and predict

the power output of the Pelamis at specific sites. Investigation is made into issues

associated with grid connection, electricity demand and local Pelamis manufacture

and assembly. A brief life cycle analysis is undertaken to estimate the embodied

energy of a Pelamis and other environmental impacts.

Wind Prospect has recently become interested in the potential for renewable energy to

desalinate water on an industrial scale. This is an emerging area of research and Wind

Prospect required a conceptual investigation into the feasibility of offshore sea water

desalination using the Pelamis. A number of different configurations are proposed for

using the mechanical pumping power of the Pelamis to drive saline water through

Reverse Osmosis units within its structure.


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Disclaimer

I hereby declare that this thesis is my own work and contains no material, which has

been accepted for the award of any degree or diploma from any tertiary institution. To

the best of my knowledge and belief, this thesis contains no material previously

written or published by another person, except where due reference is made in the

text.

Signed: ..

Tom Winkler

7th November 2005


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Acknowledgements

I would like to thank my project supervisor Dr. Brian Kirke for all the guidance, input

and help throughout the project. You have helped me gain a much better

understanding of renewable energy technology and improved my project management

skills. Our sometimes overly lengthy discussions, which moved off topic, were not at

all a waste of time in my opinion. I would also like to thank Michael Vawser,

Managing Director of Wind Prospect and Andrew Dickson, Development Manager.

Thank you for developing and supporting the project and for having the time for

meetings, emails and for providing general help and sourcing information. Special

thanks to Andrew, who provided great help during the latter 2/3 of the project, for the

endless search for wave data, and for proof reading the entire thesis only a couple of

days before the submission date.

I also sincerely acknowledge the assistance provided by the following individual and

organizations:

Vincenzo Bellini (Vinni) from Ocean Power Delivery for answering my

questions on his trip to Adelaide. Its unfortunate that the trip to Edinburgh

didnt eventuate.

Edward Mackay and Helen Plowman at Ocean Prospect, Bristol, for the

teleconference and emails, even if I could not get you data and the MCP

was not able to be used in my project.

Mike Lewis, General Manager of Air Ride Wind, for giving us a tour of

the wind turbine tower plant, it a very interesting and useful experience.

Paul Driver and the team from ETSA Utilities for the meeting regarding

the connection enquiry for Kangaroo Island.

Osmoflow for data on reverse osmosis units.

Powercor for offering assistance with the Portland connection enquiry.

I would also like to mention the support of my parents, family, friends (the dudes I

live with who had to put up with ****) without which would have made life much

harder. Also my experience at the Whyalla steelworks which helped me gain an

appreciation for energy use in industry, an appreciation of embodied energy and agreater respect for the impacts of energy use on the environment.


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Contents

Abstract................................................................................................................... 2

Disclaimer .............................................................................................................. 4

Acknowledgements............................................................................................... 5

Contents.................................................................................................................. 6

List of Tables........................................................................................................ 12

1 Project Background and Significance ....................................................... 13

1.1 Aim of the Project.................................................................................. 13

............................................................................................................................ 14

1.3 Project Scope.......................................................................................... 18

1.4 Identifying Audience............................................................................ 20

1.5 The Energy Industry and Renewables ................................................ 21

1.5.1 Climate Change and Environmental Concerns................................. 21

1.5.2 Energy Demands, Global and Local.................................................. 24

1.5.3 South Australias Energy Snapshot.................................................. 25

2 Literature Review and Project Plan........................................................... 27

2.1 Renewable Energy Technologies......................................................... 27


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2.1.1 Common Issues with Generating Renewable Power ......................... 27

2.1.2 Overview of Renewable Energy Technologies ................................... 30

2.1.2 Energy Storage and Transportation Technology............................... 35

2.2 The Power of Sea Waves ...................................................................... 40

2.2.1 Oceanic Wave Formation and Climatology ...................................... 40

2.2.2 Wave Energy Characteristics ........................................................... 44

2.3 Wave Energy Converters...................................................................... 49

2.3.1 Study of Different Designs............................................................... 49

2.3.2 Projects at Advanced Development Stage......................................... 52

2.4 The Pelamis Wave Energy Converter ................................................. 54

2.4.1 Design Concept and Features........................................................... 54

2.4.2 Performance and Specification.......................................................... 552.5 Project Discussion and Methodology.................................................. 57

3 Southern Australian Wave Energy Resources ............................................ 59

3.1 Australia's Long Term Wave Climate ................................................. 59

3.2 Study of Waves Arriving at Cape Du Couedic .................................. 62

3.2.1 Data Description.............................................................................. 62

3.2.2 Statistical Analysis and Wave Climate Trends................................. 64

3.2.3 Wind to Wave Correlations and Directional Climate........................ 73

3.3 Study of Waves Arriving at Cape Sorell ............................................. 75

3.3.1 Data Description.............................................................................. 75

3.3.2 Statistical Analysis and Seasonal Climate Trends ............................ 76

3.4 Survey of Australian Coastline Bathymetry ....................................... 79

3.5 Measure Correlate Predict Model for Waves ..................................... 82

3.6 Conclusions ........................................................................................... 83

4 Case Studies for Potential Wave Farms .................................................... 85

4.1 Kangaroo Island Wave Farm Study .................................................... 85

4.1.1 Summary of KI Energy Review ........................................................ 86

4.1.2 Grid Connection and Location Bathymetry ...................................... 87

4.1.3 Pelamis Performance Model at Cape Du Couedic ............................. 89

4.1.4 Recommendations ............................................................................ 92

4.2 Portland Wave Farm Study.................................................................. 93

4.2.1 Location Bathymetry and Grid Connection ...................................... 93

4.2.2 Resource and Performance Prediction .............................................. 96


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4.2.3 Recommendations ............................................................................ 97

4.3 Other Potential Pelamis Projects.......................................................... 98

4.3.1 Cape Sorell and other Tasmanian locations ...................................... 98

4.3.2 West Coast of Eyre Peninsula .........................................................100

5 Pelamis Production and Development ....................................................102

5.1 Local Pelamis Construction.................................................................102

5.2 Developments in Desalination............................................................103

5.2.1 Overview of Reverse Osmosis Technology.......................................105

5.2.2 Pelamis Design Integration.............................................................109

5.2.3 Offshore Desalination Plant Concepts.............................................112

6 Life Cycle Analysis.....................................................................................114

6.1 Embodied Energy for a Locally Manufactured Pelamis...................1146.2 Energy Balance.....................................................................................120

6.3 Conclusion............................................................................................122

7 Conclusions and Recommended Further Works..............................................123

References ...........................................................................................................126

Appendix A .........................................................................................................133

Ocean Power Delivery ......................................................................................133

Pelamis P-750 Brochure...................................................................................133

Appendix B .........................................................................................................134

Statistics of World Energy Use.......................................................................134

Appendix C .........................................................................................................137

Summary of Wave Energy Information Resources ....................................137

Companies and other Non-literature Resources...........................................137

Literature Resources Explored .......................................................................139

Appendix D .........................................................................................................143

Descriptive Coastal Wave Photographs .......................................................143

Appendix E..........................................................................................................145

ERA-40 Wave Atlas Plots .................................................................................145

Appendix F..........................................................................................................148

Extracts from BOM Cape Du Couedic Buoy Report...................................148

Data Buoy Cooperation Panel : Scientific and Technical Workshop XVII ..............................................149

The South Australian Wave Rider Buoy and ......................................................149

Some Preliminary Comparisons of Wind and Wave Data. ................................149Andrew Watson ...........................................................................149


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1. Introduction ...............................................................................................150

2. Wave Rider Buoy Description.....................................................................151

Appendix G .........................................................................................................152

Description of Wave Data Fields ....................................................................152

Appendix H .........................................................................................................153

Bathymetric Image of Australia and the Southern Ocean.........................153

Appendix I ...........................................................................................................154

Geography of Cape Du Couedic to Cape Sorell..........................................154

Appendix J ..........................................................................................................155

Comparison of Embodied Energy Values ....................................................155

Appendix K .........................................................................................................156

Environmental Impact Assessment - Generic Scoping Study .................156Appendix L..........................................................................................................157

Industrial Experience Report............................................................................157


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List of Figures

Chapter 1Figure 1.1 Artists impression for a 40 Pelamis, 30 MW wave farm 13

Chapter 2

Figure 2.1 The Vestas V120 31Figure 2.2 Concentrating solar thermal collector types 32Figure 2.3 Current Hydrogen consumption 36Figure 2.4 Illustration of wave fetch area to Cape Sorell 40Figure 2.5 Annual average wave power in kW/m of crest length for various

locations around the globe41

Figure 2.6 Monthly mean 500 hPa wind speed (m/s) and direction, SouthernHemisphere, July 2005

42

Figure 2.7 Gravity Waves 43

Figure 2.8 An idealized sinusoidal ocean wave 44Figure 2.9 Plot for equation (2.4) empirically relating wind speed to wavepower

44

Figure 2.10 Illustration of approximate particle orbits 45Figure 2.11 A typical record from a Wave Rider Buoy 46Figure 2.12 Evolution of UK Wave Power Devices 48Figure 2.13 Configurations of Wave Energy Converters 49Figure 2.14 Energetechs WEB Design 52Figure 2.15 Pelamis Performance Matrix 54Figure 2.16 Relative efficiency of a Pelamis 55

Chapter 3Figure 3.1 Global ERA 40 Plots for yearly mean Hs and Tz 59Figure 3.2 Sample of wave rider buoy data 61Figure 3.3 Series of plots from combined monthly mean values 64Figure 3.4 Plot of monthly means for all 3 years of Hs and Tz data 65Figure 3.5 Daily mean values for winter 02 (left) and summer 01/02 (right) 65Figure 3.6 2003 Histograms for Hs 67Figure 3.7 2003 Histograms for Tz 67Figure 3.8 2003 Histograms for Power flux 67Figure 3.9 Overall Histograms for Hs 69Figure 3.10 Overall Histograms for Tz 69

Figure 3.11 Overall Histograms for Power flux 69Figure 3.12 Scatter Diagram for all year 2003 recordings 70Figure 3.13 24 hour distributions from mean hour values 71Figure 3.14 Hs and wind speed against time 73Figure 3.15 Hs and wind direction against time 73Figure 3.16 Hs (m) against wind speed and direction 73Figure 3.17 Combined monthly mean plots and comparison 76Figure 3.18 Monthly means over the 7 years of data 77


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Chapter 4Figure 4.1 Kangaroo Islands Electricity grid network 84Figure 4.2 Coastal bathymetry of the region south of American River 86Figure 4.3 Pelamis performance curves for various Tz values 88

Figure 4.4 Near linear property of Tz curves 89Figure 4.5 Mean monthly Pelamis output over the whole 3 years 89Figure 4.6 Annual Comparison of Mean Pelamis Outputs 90Figure 4.7 Coastal bathymetry surrounding Portland with depth in metres 93Figure 4.8 Cape Duquesne Location 93Figure 4.9 Electricity Grid Surrounding Portland 94Figure 4.10 Comparison of Pelamis performance from combined monthly

means96

Figure 4.11 Satellite image of Cape Sorell 98Figure 4.12 Satellite image of Cape Du Carnot 99

Chapter 5Figure 5.1 Basic components of a RO plant 105Figure 5.2 Hollow Fibre RO membrane configuration 106Figure 5.3 The Aquadam Concept 112

Chapter 6Figure 6.1 Energy used by Bluescope to make steel 115


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List of Tables

Chapter 1

Table 1.1 The Worlds Proven Fossil Fuel Resources 23

Chapter 2Table 2.1 Annually Averaged Extractable Energy Flux 33Table 2.2 Energy Densities of Various Fuels 37

Chapter 3Table 3.1 Total number of recordings per month 2001-2003 62Table 3.2 Summary of Mean Values at CDC 63Table 3.3 Total number of recordings per month 1998-2004 75Table 3.4 Summary of Mean Values at Cape Sorell 75

Chapter 4Table 4.1 Summary of Mean Capacity Factors for Pelamis at CDC 90


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1 Project Background and Significance

1.1 Aim of the Project

Wind Prospect is in the business of expanding the renewable energy industry both in

the UK and in Australia. A recent endeavor by the company is to explore the use of a

specific wave energy generation technology, the Pelamis P-750 Wave Energy

Converter, developed by Ocean Power Delivery Ltd. (OPD). The Pelamis is viewed

by Wind Prospect as the leading contender in commercially available wave energy

generation technology and having the potential to become a valuable supplement to

wind power for supplying Australia with renewable electricity and possibly

desalinated water. The aim of this project is to asses the feasibility of developing

projects using the Pelamis and the wave energy resource so abundant along the

southern coasts of Australia.

Wind Prospect decided that Kangaroo Island has particularly good potential for off-

shore wave energy production, a potential worthy of greater and more detailed

investigation. Initially the scope of this project focused on assessing the feasibility of

a 4 unit wave farm (see Figure 1.1) demonstration off the shores of Kangaroo Island.

Since then the scope has been modified and broadened to include other potential sites

and to focus investigation into other aspects of local wave energy development. The

case study approach was adopted and Kangaroo Island is the first to be investigated.

This project is industry-based and is primarily intended to cater for the interests of

Wind Prospect. Ultimately Wind Prospect has the goal of convincing outside

investors and manufacturers to join in supporting development of real wave energy

projects. This report was to be completed with sufficient detail and supportingevidence to greatly assist Wind Prospect in reaching their goal.

This project is the first investigation into wave energy undertaken by Wind Prospect

in Australia and many aspects of the research to be undertaken are completely new.

The purpose of this report is to not only outline the feasibility of producing potential

wave farms but to provide a knowledge resource for Wind Prospect. Each of the

components included in the scope (section 1.3), and in particular the study into wave


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energy resources, will become a valuable reference for current and future work by

Wind Prospect in the field of wave energy.

Due to the heavy research nature of this project compared to a conventional

mechanical engineering final year thesis, the scope has been subject to continuous

change and review. As new developments occur, the focus has moved toward new

targets and priorities. Incorporated into the aim of this project is for research to be

initially relatively flexible and for continuous consultation with Wind Prospect to be

sought in the interests of best project management. In this way, the project will be of

far greater value to industry.

Figure 1.1 Artists impression of a 40 Pelamis, 30MW wave farm (OPD 2005)

More images of and information on the Pelamis can be found in the Ocean Power

Delivery brochure, APPENDIX A and in section 2.4.


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convince governments and venture capitalists that the technology is worth investing in

real projects. Again, this is a costly and time consuming process. This is why Wind

Prospect has sought the resources of the SEC and a University student project

dedicated to providing this service at a minimal cost.

Wind Prospect is a wind farm developer that was established in the UK in 1988. The

Australian division, Wind Prospect Pty Ltd., is currently based at Christies Beach,

South Australia. Wind Prospect claims an unrivalled success rate in securing planning

consents and is a leading wind farm developer in Australia. They undertake all aspects

of development including feasibility studies, design, construction and operation. With

the aim of maximizing the cost-effectiveness of every project, all ventures of Wind

Prospect remain independent of manufacturers. Wind Prospect has been involved with

over 1,300 MW of wind energy developments worldwide, including 700 MW in

Australia. Using experience gained with onshore projects, Wind Prospect established

SeaScape Energy Ltd. to develop offshore wind energy projects in the UK. It must be

noted that Wind Prospect and all other renewable energy developers depend greatly

on government inscentives to make their projects financially viable.

Ocean Prospect is a recent venture established by Wind Prospect in the UK to developmarine renewable energy projects. Wave energy is seen by Wind Prospect as an

important part of the future mix of renewable energies. Ocean Prospect is currently

focused on working with OPD to develop projects using the Pelamis off the shores of

the UK. Following the initiative of Ocean Prospect in the UK, Wind Prospect now

wants to explore wave energy opportunities in Australia.

Ocean Power Delivery Ltd. (OPD) is the designer and manufacturer of the Pelamis P-

750 Wave Energy Converter and is based in Edinburgh, Scotland. They employ a

wide range of engineering expertise and have 40-50 cumulative years of staff

expertise in wave energy. They are a world leader in ocean wave energy analysis and

modelling. OPD have produced and tested a full scale prototype Pelamis, claimed to

be the most advanced wave energy converter available. It is a result of 6 years of

development, modelling and testing and OPD claim at least an 18 month lead over

rival companies. The Pelamis technology is proven and ready for commercialization

and OPD are sourcing developments across the globe. OPD are a manufacturer and


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rely on developers such as Wind Prospect to develop projects using their machines.

The Pelamis design is protected by OPD under a group of patents and patents

pending. A significant component of the cost of a Pelamis is the steel, structural

manufacturing and labour costs. OPD prefer that as much of the manufacture of these

components is outsourced to local specialized manufacturers, such as those that build

steel wind turbine towers. Only certain groups of internal components are to be

manufactured by OPD and then shipped to the location of assembly. Once a Pelamis

is completely assembled, it is then thoroughly inspected by OPD before deployment.

Air-Ride Wind Pty. Ltd. is a business dedicated to manufacturing wind towers and

was established in 2003. It is a South Australian owned and operated company based

at Kilburn North in Adelaide. They are involved with all assembly and manufacturing

from supplied steel plate, through to fully assembled and painted wind tower

components with internal structuring that are ready for final on site assembly. They

are able to manufacture tapered welded steel tubes up to 4m diameter that can be

transported using rail and road freight. Air-Ride work closely with wind farm

developers including Wind Prospect. They also work closely with industry leading

European wind turbine designers to ensure that all standards and specifications are

met. All steel plates are currently supplied by Bluescope Steel, based at Port Kembla,NSW. Air-Ride prides themselves on quality welding procedures and inspection and

on meeting target delivery schedules. It is through companies like Air-Ride that

renewable energy projects can be seen positively contributing to our local SA

economy.


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1.3 Project Scope

As stated in the project aim, the scope of this project has been under continuous

change and review. This scope is effectively the last major revision which occurred on

the 4th

August. Information in this scope refers only to work done beyond the

literature review, Chapter 2.

This project deals only with analyzing the feasibility of the Pelamis designed by OPD,

not with any other wave energy converter. No attempt will be made to redesign the

Pelamis, its manufacturing and construction procedures, its component specification

or its installation and mooring design. The only exception is for the desalination study

(section 5.2) where a redesign of the existing internal layout of the power moduleswill be investigated to incorporate reverse osmosis units.

For the study of wave energy resources (Chapter 3), only the southern coast of

Australia is investigated. This is done in the order of SA, VIC, TAS and WA. The

study should result in identifying Australias best wave energy resource locations

ready for further development. Wave data from Cape Du Couedic is analysed using

statistical methods only; no advanced mathematical wave modelling is attempted. The

task of creating the measure correlate predict (MCP) mathematical model (see

section 3.4) for wave resources in Australia is left to Ocean Prospect in the UK.

Case studies of potential wave energy projects (Chapter 4) will contain all work

undertaken on the Kangaroo Island study. This then forms a template model for later

case studies, which are less in-depth. The case studies use the information from

Chapter 3 to predict wave energy levels and then investigate aspects of project

development including: localized bathymetry, demand load, grid connections,

political and integration issues such as docking and maintenance. The Pelamis output

at the Cape Du Couedic buoy is also modelled to determine a likely Capacity Factor

and output trends. The result is a basic design of a wave farm to suit each case

study.


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Chapter 5 deals with Pelamis production and development explores three areas:

construction, component sourcing and desalination. The local feasibility of

construction of a Pelamis is investigated although no planning for production is

undertaken, as that work will be left to the manufacturer(s) (Air-ride, Bluescope etc.)

All internal components that are to be sourced locally are identified and listed. Effort

will go towards finding suppliers willing to provide components to the designed

specifications. The study into desalination, as mentioned above, is a design

investigation to lay the path for potential future research by Wind Prospect and OPD.

A basic lifecycle analysis is undertaken for a locally manufactured Pelamis based on

one of the case studies (either KI or Portland). A calculation is made, stating all the

assumptions, to determine a realistic figure for the embodied energy of a Pelamis unit

and the consequent energy and CO2 payback periods. Comparisons are then made

with the lifecycle analysis of a Vestas wind turbine. An environmental impact

assessment is then produced for the case studies using the OPD EIA as a template.


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1.4 Identifying Audience

Aside from UniSA (contents subject to the confidentiality agreement possibly

modified), the full project thesis will be read by and is directed to the following list of

companies or groups in order of importance:

Wind Prospect Pty. Ltd. (Australia) and Wind Prospect (UK) including all

their venture businesses

Subject to confidentiality agreement with Wind Prospect, a special version(s) of this

report may be compiled (even if by Wind Prospect) for viewing by:

Ocean Power Delivery Ltd.

Various grant agencies

Air-Ride Pty. Ltd.

ETSA Utilities

KIDB Kangaroo Island Development Board

ESIPC Electricity Supply Industry Planning Council

SENRAC South Australian Energy Research Advisory Committee

ESCOSA Essential Services Commission of South Australia

BOM Bureau of Meterology

Separate investors linked with Wind Prospect

Various other relevant government departments and authorities

A version of this report may eventually be made freely available - ie. published on a

website subject to the removal of copyrighted content and confidential information.


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1.5 The Energy Industry and Renewables

In its simplest definition, renewable energy is any form of energy that can be taken

from a renewable source. All of the energy on Earth and most of its matter originated

from the Sun our solar systems giant thermonuclear power plant. The only possible

exception to this is matter from outside our solar system, maybe distant meteorites.

The sun is considered to be the only true renewable energy source even though its

energy is not limitless because the sun wont last forever. For this reason sometimes

the term solar energy is used to cover all the forms of renewable energy including

wind, wave, hydro and biomass, because they did originate from the sun. Geothermal

energy is usually considered to be renewable although some individual sources have

been weakened from heavy exploitation. Tidal energy is renewable but is generatedby the gravitational pull of the moon as well as the sun, so could be termed lunar

energy. All fossil fuels such as coal, oil and natural gas are the heavily compressed

remains of hundreds of millions of years of biomass. The energy needed to grow this

biomass and store chemical energy in their long hydrocarbon chains was all provided

by the sun. However, fossil fuel sources are definitely finite and are not renewable.

For an investigation into the global renewable energy sources see section 2.1.2.

A lot of study and debate has gone into the idea of using renewable energy over the

last few decades. There are a lot of factors involved but there are two main reasons

why renewable energy has become important. Firstly there is a growing need to

reduce the destructive effects of energy use on human and environmental health. The

second is to reduce the heavy reliance society has on burning fossil fuel resources, oil

in particular. An appreciation of these issues must be gained in order to understand

the appeal behind using energy generated from ocean waves rather than by current

conventional methods.

1.5.1 Climate Change and Environmental Concerns

The expansion of the human species has brought about massive changes to our planet.

The global human population is now over 6.476 billion inhabitants (IPC 2005), a

growth of about 10 times the population existing just 300 years ago and the number is

projected to climb even further. In meeting the demands of our population, the earths

ecology has endured the effects of widespread habitat destruction and land clearance,


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pollution and climate change. Great concern is growing over the state of our ancient

natural ecosystems and their suffering biodiversity. Of particular threat are the

imminent effects of climate change due to global warming.

Global warming or the greenhouse effect is an important phenomenon and has been

required for sustaining life on earth for hundreds of millions of years. The earths

atmosphere is a very complex system and there are many factors that contribute to the

atmospheres ability to trap the suns heat. Contrary to popular understanding, water

vapour is by far the most powerful contributor to the greenhouse effect. Water vapour

along with aerosols, clouds and ice reflectivity can further amplify any small

increases in global warming (NAS 2005). A great deal of research is yet to be done in

order to gain a comprehensive yet irrefutable understanding of the process and status

of global warming. The fact is, our planet is experiencing a growth in atmospheric

temperature and this research is a critical tool for addressing solutions to this problem.

Numerous scientific authorities support evidence that suggests recent human activities

are contributing to global warming in a harmful way. After water vapour, carbon

dioxide (CO2) is the gas next most responsible for trapping the suns heat in our

atmosphere, and it can remain there for very long periods. Studies show (IEA 2002)that since 1750 the atmospheric concentration of CO2 has grown 31 percent. Increases

in global temperatures have already been detected and during this century, the global

average surface temperature is projected to increase by 1.4 to 5.8 C (IEA 2002,

p.19). The magnitude of this temperature change could be compared to that during the

last Ice Age over 20,000 years ago. The projected increase in global temperature

would have devastating results. Sea levels will rise due to melting ice at the poles.

Severe weather including droughts and floods will increase due to altered weather

patterns and ocean currents. Also there would be shifts in climate zones of hundreds

of kilometres, which could cause mass extinctions and damage vast ecosystems. The

threat posed to humanitys future is enormous.

The other significant contribution to global warming is the effect of wholesale land

clearance for agriculture and for wood products. Forests are still being cleared at the

fastest rate in history, much faster than they can be replaced. Trees and all other plants

take up CO2 and place it into the soil and use the carbon in new growth. About 2.6


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1.5.2 Energy Demands, Global and Local

Our current system of economics promotes meeting the unlimited demands of the

population by exploiting finite resources. Since the dawn of the industrial age over

150 years ago, the pace of technological development has accelerated to this day

largely fuelled by fossil fuelled energy. As a result of this our demand for resources

and energy is growing endlessly. Importantly, the worlds current energy consumption

rate greatly exceeds what is required to sustain a good quality of human life for all

populations. Fossil energy comes into all aspects of modern human life including

goods, services, comfort, transport and industry. The International Energy Agency has

published a report (IEA 2004) outlining statistics for the worlds energy usage. Some

pages from this report can be found in APPENDIX A showing the worlds energy

supply and electricity generation grouped by fuel. From this data it is very easy to see

modern societys reliance on fossil fuels (coal, oil and natural gas) as an energy

source. Looking at electricity alone, total of 16.1 percent of all consumed energy was

converted to electricity globally in 2002 (IEA, 2004). Fossil fuel sources accounted

for 65.3 percent and the rest being mostly nuclear and hydro. Of that total, only 1.9

percent was produced from renewable sources (excluding hydro, including all wind,

geothermal, solar electricity etc.), which comprises 0.31 percent of primary energy

consumption.

Table 1.1 The Worlds Proven Fossil Fuel Reserves (IEA 2000)

Fuel Reserves (*Q)1995 Consumption

(Q/y)

Rate of Growth

(%/y) 1987-1997

Lifetime (y)

No Growth

Lifetime (y)

with Growth

Coal 24,000 93 0.8 258 140

Oil 9,280 141 1.1 66 50

Gas 6,966 78 2.5 90 50*Q = 1 Quad = 1 Quadrillion British thermal units (Btu) = 2.9037 E+11 kWh

The figures displayed in Table 1.1 provide an indication of how much longer we can

expect to continue using fossil fuels for energy. The price of oil and gas is likely to

rise dramatically within the next few decades demanding a full scale transformation of

the transportation industry, the highest relative consumer of oil. Once oil and gas

reserves are depleted or become too valuable, the various forms of coal reserves might

serve the populations energy needs past 2100. If the population is to continue its


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energy consumption patterns, alternative sources of energy including nuclear fission,

possibly nuclear fusion, geothermal, unconventional fossil fuels and renewables will

become far more important in the future. Realistically from a sustainable perspective,

the relative monetary cost of energy should be far higher than it is now, reflecting its

true cost to humanity. Eventually the relative cost of energy will rise as fossil fuels

deplete. This will place enormous stress on the fundamentals of modern economics,

particularly the necessity for growth.

Australias contribution to global energy production is only about 2.5 percent of the

world total (IEA 2004). Per head of population, though, Australia is one of the worst

emitters of greenhouse gasses in the world. The Australian government has failed to

ratify the Kyoto protocol yet it has established a mandatory renewable energy target

(MRET) of generating 9,500GWh by 2010. This is a relatively tiny target and will

mostly be met by existing hydro schemes. According to a report (PMSEIC 2002), the

current government seems highly favorable on continuing to use coal to meet future

energy demands by developing clean coal technology. This involves the large scale

gasification of coal and sequestration of CO2 as an effort to suppress climate change,

which is also an outlook of the US government. On a positive note, developing

renewable energy technologies can generate wealth and employment, adding valuewithin local economies. The amount of funding allocated to develop new renewable

energy technologies with the aim of sustainability, is mostly a political issue, which is

in part a reflection of public opinion in the Australian democracy. Environmental

concerns can change energy policy, which can push growth in renewable energy.

1.5.3 South Australias Energy Snapshot

The state of South Australia is one of the most sparsely populated places on earth and

is very rich in renewable energy sources. With 1.1 million people (73% of the States

total), metropolitan Adelaide is the States largest energy consumer. SAs largest

annual generation comes from the power stations at Port Augusta (Northern 530MW

and Playford 120MW) owned by NRG Flinders. They are fuelled by coal mined at

Leigh Creek and transmit power 300km to Adelaide. Burning coal produces the

highest amount of polluting emissions and carbon dioxide per unit energy output

compared to the other major fossil fuels. There are also a few large natural gas-firedpower plants in South Australia including Torrens A&B (1,228MW combined


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capacity) and Pelican Point (460MW). These gas plants usually operate at only a

fraction of their output capacity, ~37% for Torrens B and ~10% for Torrens A,

whereas the Northern coal plant usually operates at ~93% (ESIPC 2004).

The Electricity Supply Industry Planning Council releases an annual planning report

(ESIPC 2005). It describes in great detail South Australias current electricity supply

system, usage, demand and projections so that planning can be made to secure supply.

The following are a list of facts outlining the energy snapshot of SA, many of which

are sourced from this annual planning report.

Contributes about 6.5% of Australias Total Primary Energy Consumption

Peak electricity demand during 2004-05 is in the order of 3,050MW during

summer around midday, with huge power demand from air-conditioning.

Average electricity demand is in the order of 1,500MW.

During 2004 it was calculated about 100 MW or ~7% is lost through heating

transmission cable (ESIPC 2004).

Olympic Dam mining operations in the States north typically consume about

one fifth of the states total electricity.

On average about 15% of SAs electricity is imported from Victoria, but

sometimes up to 35%, where it is produced cheaply with brown coal (lignite).

Fossil fuels constituted 98% of all energy used in 2003 (DEH 2005)

In 1998, less than 0.1% of electrical energy was derived from renewable

sources (DEH 2005); this figure is now approaching 10% of average demand.

First major wind farm was opened at Starfish Hill near Cape Jervis in October

2003 with a 34.5MW capacity, developed by Tarong Energy and with wind

towers built by Air-Ride in Adelaide

As of October 2005, with the new Canunda and Wattle Point wind farms there

is 252MW (AusWEA 2005) wind power capacity connected to the grid and

2209MW capacity proposed at different stages.

SA is currently one of the fastest growing wind farm locations in the world but

is now effectively limited to about 500 MW installed capacity due to a recent

ESCOSA review of wind energy.


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Developers of renewable energy are now finding it desirable to have several

independent sources. Successful connections into the electricity grid are also now

becoming more difficult due to network regulators demanding a high quality,

uninterrupted, reliable and predictable source. This is why a developer like Wind

prospect wants to explore wave energy generation. When there is no wind there may

be plenty of wave energy, as waves may be generated by winds thousands of

kilometres away (see section 3.2.3 and Figure 3.14).

The term Capacity Factor is often used in the power industry. It is usually expressed

as the ratio of energy produced by a given plant in a year out of the energy that could

be produced by that plant running at full capacity over a year. A low capacity factor

does not necessarily indicate low reliability or lack of efficiency, it simply means than

on average the plant spends little time operating at its rated capacity. When new

renewable energy projects are built the power output capacity is often quoted. It is

important to multiply this value by the capacity factor to get a realistic view of the

plants designed average output. For example Starfish Hill has a rated capacity of 34.5

MW but a capacity factor of 34.5% (ESIPC 2004) so it would produce about 12 MW

on average. The firm capacity that can be relied on with 95% confidence, has beenestimated at 8% of rated capacity for SA wind farms (ESIPC 2004). According to

OPD, the Pelamis is able to achieve a capacity factor of up to 50%.

Conventionally generated electricity is currently sold to Adelaide residents for about

16-20 cents per kilowatt hour (c/kWh) and the price is expected to steadily rise in

future. Renewably generated electricity can only attract a slightly higher price because

a small but devoted proportion of the population will pay for it. In the Australian

electricity market, Green Power can be purchased by the public with guarantees that

it is generated using renewable energy sources. When planning a new power plant, it

is desirable to minimise the payback period of the project by building a plant with the

maximum power delivery for the lowest capital cost. This is where most renewable

energy technologies find it difficult or impossible to compete with new fossil fuel

plants. Plants with long payback periods dont get built because the financial risk is

just too high and no one is prepared to carry that risk. Often it is a case of whether the

government is prepared to recognise advantages and offer subsidies to the technology.


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In the case of wind and wave energy, variable supply combined with relatively low

capacity factors has led to restrictions in the amount of power connected to the grid.

Additionally, a grid connection can represent a large proportion of the capital cost of a

wind farm. For a wave farm, the proportion of the capital cost is potentially much

higher still particularly due to the cost of the undersea cable. The submarine cable

between Cape Jervis and Penneshaw is about 13kms long and can carry

approximately 10MW and its value was estimated at about $4-6m in the KI Energy

Review Report (SWWES 2003). ESTA Utilities made an estimation of the total

replacement value being more like $15-20m. This suggests that the cost of a 33kV

10MW submarine cable may cost up to $1m per kilometer, compared to the figure of

a 33kV land cable being $50,000-$80,000 per kilometer (SWWES 2003). It is clear

that a wave farm should be as close as practicable to the shore, consistent with a good

wave resource.

Some renewable energy technologies require rare materials or large amounts of

materials and even require energy intensive manufacturing. If many of the current

renewable energy schemes were used to provide power for hundreds of millions of

people, vast expanses of land and gigantic amounts of resources would be needed.

Biomass has a limit to the amount of power that can be generated sustainably for thearea of land used (~0.5W/m2 thermal, see Table 2.1) and environmental damage must

be closely monitored. For other renewables, land usage this isnt such an issue: for

example wind turbines dont prevent cows grazing under them. Photovoltaic solar

panels require the use of silicon crystals that are expensive to grow and cut, which has

limited their wholesale use. The Pelamis does not occupy land as such and but will

require several hundred tons of steel per MW. This project includes an investigation

into all these issues specific to the Pelamis in the Life Cycle Analysis in Chapter 6.

Some types of renewable energy projects have either been protested heavily or even

stopped because of their adverse environmental impacts, direct or indirect.

Construction of hydroelectric dams, such as those in Tasmania, left environmentalists

enraged by the destruction of vast areas of wilderness and this was the centre for

ongoing political turmoil. Aside from environmental issues, aesthetics can also be a

source of disturbance. Wind farms have been criticised for visual pollution, noise


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pollution and effect on birdlife (and bats). The Pelamis has a very minimal direct

environmental impact; see section 6.3 and APPENDIX K.

2.1.2 Overview of Renewable Energy Technologies

This section contains an overview of all established or promising renewable energy

technologies for use in generating electricity on a relatively large scale. These are the

technologies that have been successful enough to evolve to the stage of being

deployed in big engineering projects. Key factors including the scale, effectiveness

and state of technological advancement are outlined for each technology. This is done

in order to make simple direct comparisons between each technology and wave

energy technology, in particular the Pelamis. Given that the Pelamis is a very recently

deployed technology, it is important to asses where wave energy stands within the

renewable energy industry.

Biomass is the most heavily consumed form of renewable energy and is listed in

APPENDIX A as combustible renewables and waste. It includes all forms of recently

produced matter as a result of photosynthesis. It wasnt long ago when biomass was

mankinds primary energy source. Most of this energy source is used in combustion

processes to produce heat, generating CO2 and other emissions. A very small

proportion of total biomass energy is currently being converted to electricity. Biomass

is completely renewable but if it were to replace all current fossil energy use, it would

be far from sustainable using current proven technologies. Biomass can be converted

into other fuels such as biodiesel or alcohols on a large scale, many of which offer

cleaner emissions than petrochemicals. Biomass energy extracted from waste will

become more important in the future.

Hydro power is the only renewable source of energy that produces electricity on a

large scale today. It represented 89.5% of all renewably generated electricity

produced in 2002 (IEA 2004). Hydro electricity is sourced from the natural

evaporation of water by the sun. Principally the sun performs all the work in lifting

millions of tonnes of water above sea level and depositing it in hydroelectric dams.

The water is then released through water turbines, which turn generators. Dams are

built across flowing bodies of water in order to raise the hydraulic head and act asenergy storage. Hydros main advantage is producing power quickly at any time of


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demand with minimal emissions. It is now becoming clear that some dams produce

considerable greenhouse gas emissions, methane in particular (Boyle 2004).

Geological and terrain features limit the amount the hydropower can be exploited and

most of the worlds largest hydropower sites are, or are soon to be, in use. A giant

hydropower plant is under construction in China and is due to be finished in 2009.

The Three Gorges Dam on the Yangtze River will be a mile wide, 172m high and able

to generate 18,200MWe (IRN 2005), making it by far the biggest single renewable

electricity project in the world. Its construction will require the demolition of several

towns and the displacement of over 1.9 million people (IRN 2005). Many believe the

dam will help prevent chaotic flooding of the Yangtze, such as the disaster in 1998

resulting in the evacuation of millions and a staggering death toll. Others think that it

may only compound the problem; however this issue was certainly a major factor that

went into approving its construction.

Extracting geothermal energy is essentially the process of mining geothermal heat. It

is the only energy source that is classified as renewable that supplies constant non-

cyclical energy independent of the sun. Global geothermal electricity generation

capacity approached 8 GWe in 2000 (Boyle 2004) and a further 16GWt heat was

extracted for a variety of processes. Deep within the earth there is a vast amount ofenergy, almost limitless, but on the surface there are definite limits to what can be

feasibly extracted. The best sites for high-enthalpy geothermal power generation are

typically located at boundaries of tectonic plates or fault lines. Aside from volcanic

activity, hot dry rocks created partly by radioactive decay are now being explored in

detail. Central Australia has such a resource in great abundance. The technology

deployed is simple in concept, one or more boreholes are drilled into the heat

reservoir and then heated fluid is pumped to the surface to conventional steam

turbines or heat exchangers. However it is located very far from urban centres of

consumption and the deep drilling required is very expensive. It could however be

used as an energy source for regional Australia and in energy intensive industrial sites

such as Olympic Dam, SA.


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Wind power has been used for thousands of

years for sailing ships and windmills. Winds are

driven by the suns differential heating of the

ground. Modern methods of large scale

electricity generation from wind utililise a

number of efficient wind turbines combined in a

wind farm. The turbines are massive structures;

manufacturers are now producing turbines with

hub heights and rotor diameters over 100m. One

such machine, the V120 developed by Vestas

Wind Systems, has a rated output capacity of

4,500kWe, see Figure 2.1. Larger wind turbines

can collect more energy per disk area due to

greater wind velocities available higher from the

surface. Wind power is one of the most rapidly

advancing energy markets and is experiencing aFigure 2.1 (Vestas 2004)

growth in development projects worldwide. In the 70s and 80s there were a range of

different wind turbine designs and configurations on the market, including vertical

axis wind turbines. Eventually the 3 blade horizontal axis turbine design matured andestablished itself as the market leader. Recently there has been a lot of investment in

offshore wind energy particularly in Europe. As of writing this report the worlds

largest approved wind farm will be constructed off the shores of Ireland on the

Arklow Sandbank. With 200 turbines, it will have an output capacity of 520MWe.

All life on earth depends on energy received from the sun. Our planet continuously

receives solar energy at about 9,000 times the current total primary energy

consumption (IEA 2002). Of course this amount is far greater than can be technically

be captured and harnessed. In the tropics up to about 1kW/m2 makes it to the surface

at noon. Solar electricity represented only about 0.05 percent of total electricity from

renewable energy sources in 2000 (IEA 2002). Two groups of technologies,

photovoltaic (PV) solar panel systems and solar-thermal power plants, each have a

roughly even share of that production. Energy produced by PV systems is still

relatively expensive but has advantages in small plants in remote areas. Large solar

power plants use solar-thermal technologies that generate power from the heat of solar


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radiation. As with most coal, nuclear or geothermal power plants utilizing heat

energy, electricity from concentrating solar thermal makes use of the Rankine cycle

(or variations) to provide work for steam turbines. This process has inherent losses

and limits of efficiency in the order of 40%. The concept behind the three main solar

thermal technologies is illustrated in figure 2.2.

Figure 2.2 Concentrating solar thermal collector types (Johansson et al. 1993)

Each of these configurations makes use of reflective mirror-like surfaces to

concentrate the suns energy. The largest solar power plant currently in operation is the

SEGS built by LUZ international situated in the Mojave Desert, California. The SEGS

is a 100 acre (0.4km2) field of parabolic trough mirrors and can generate a maximum

power output of 355MWe. This plant currently constitutes nearly 90% of the worlds

direct solar electricity; however its capacity factor is about 22% (Hayden 2001).

There is research being undertaken around the world using the parabolic dish

configuration to power advanced Stirling engines and high temperature photovoltaics.

In this way some of the highest levels of direct solar capture efficiency have been

achieved, over 30% (peak of about 300W/m2 of collector) at temperatures as high as

1000C (Boyle 2004).

The ocean has very large sources of renewable energy that have remained virtually

unexploited. This is because the energy is often widely dispersed and located far from

where consumption takes place. Tidal or lunar energy moves great bodies of water

through many different cycles and is produced by the gravitational attraction of the

moon and sun. The most well established technology uses a tidal barrage that is like a

big, low head, hydroelectric dam which use turbines to generate significant amounts

of electricity. The largest tidal barrage was built in France in 1966 and can generate

up to 240MWe. Tidal barrage projects can be very costly and can and adversely effect


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the environment. Ocean tidal current turbines are like under water wind farms and

would counter these problems. The energy density is often too low to become cost

effective, but tidal turbine technology is advancing. Ocean thermal energy conversion

exploits the temperature differences between the surface and the floor of the sea. This

is a giant source of solar thermal energy but due to such poor energy density,

enormous structures would need to be built to produce sizeable amounts of power.

Other interesting ocean energy technologies include exploiting salinity gradients by

osmosis of fresh water meeting the sea; again this has low energy density.

Table 2.1 Annually Averaged Extractable Energy Flux (Fay & Golomb 2002)

Source Area Heat (W/m2) Work (W/m2)

Solar thermal Collector 150 20

Solar photovoltaic Cell 30

Wind Turbine disk 40

Tidal current turbine Frontal area 750*

Ocean wave Frontal area 10,000+ (W/m crest)

Biomass Field 0.5 0.1

Geothermal Field (underground) 0.1 0.02

Tidal barrage Tidal pond 1

Hydropower Drainage basin 0.01

* This is an estimation for Backstairs Passage, South Australia (Kirke, pers. comm)

Each renewable energy source has a feasibly extractable energy flux or power

available from a certain area of resource. A comparison of these values averaged

annually is provided in Table 2.1. The first five sources in this table can be compared

relatively easily regarding energy density and give some indication of the area of

structure required for collection. The last four sources in this table are a little more

difficult to compare and greatly depend on location, geography and a number of other

factors. For these four sources typical values have been provided for the surface area

of the resource. Low energy flux values help explain why hydroelectric dams & tidal

barrages typically need to be such giant structures to produce large amounts of power,

even if they dont cover the whole basin. Solar and wind power have comparable

energy density although wind power is currently significantly more cost effective andhas the advantage of extracting energy already in kinetic form.


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forms of energy storage including thermal storage, chemical batteries (Vanadium

Redox battery technology is promising for large scale), ultra-capacitors, salinity

gradients and compressed gas systems. Two other promising forms of energy storage

technology involve using advanced flywheels and hydrogen fuel cell technology and

will be discussed briefly here. In concept neither is new, but both technologies are

rapidly advancing and can provide compact and high quality energy.

A spinning flywheel is a compact form of kinetic or mechanical energy storage. For

high density energy storage the flywheels material tensile strength relative to its

density is most important, not so much the weight or the size of the flywheel. The

most advanced flywheels make use of modern composite materials shaped with high

precision and rotate at extremely high velocities. To minimise losses, the flywheel is

suspended by a magnetic bearing and enclosed in a chamber with a partial vacuum or

an inert low viscosity gas. Coupled to the shaft are the latest high power and

efficiency brushless motors and generators. The result is a unit that offers many

advantages over batteries including being able to deliver a wide range of power, with

relatively tiny losses for an almost indefinite number of cycles. NASA is even

researching their use in spacecraft (NASA 2005). The cost of this technology is still

very high for the amount of energy stored, mainly due to the flywheel material and thehigh powered magnets. If the cost approached that of conventional batteries, units

could be purchased for individual household or industrial use. At this scale they could

make much better use of renewable energy by smoothing out and improving the

quality of supply from cyclical energy sources such as direct solar. Batteries for small

scale photovoltaic power plants are a continually expanding market.

Much speculation exists about the prospects of a future hydrogen economy where

pure hydrogen energy is to become a major component of primary energy,

particularly for transportation. Extensive research is being undertaken into producing

hydrogen gas and then converting it to electricity using different types of fuel cells or

even combustion in turbines and internal combustion engines. It must be stressed that

Hydrogen is not a source of fuel as it does not occur naturally in a pure state and

always requires more energy to produce than can be extracted from it. The attraction

lies in the fact that fuel cells can convert hydrogen into energy in a way that is very


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efficient, clean and environmentally friendly and that hydrogen is the most abundant

element in the universe.

Figure 2.3 Current Hydrogen consumption (Kruse, Grinna & Buch 2002)

Global production of Hydrogen is over 45 million tones per year and over 90% of this

is from reformed raw fossil fuels (Kruse, Grinna & Buch 2002). The distribution of

Hydrogen consumption is shown in Figure 2.3 where the majority of it goes to

Ammonia production, mainly for the use of fertilizer, and most of the rest goes

towards refining fossil fuels. Ideally Hydrogen could be produced on a large scale

from the electrolysis of water using renewable electricity. The leading technology for

this is alkaline electrolysis where manufacturers are now quoting efficiencies of 4.2

kWh/Nm3 (Stuartenergy 2005), which equates to an energy return on energy invested

(EROEI) of 71%. There is considerable research taking place on using thermal energy

to dissociate water to obtain hydrogen, also photoelectrolysis and biological

production. Proponents of nuclear power expect that the hydrogen economy will be

largely nuclear driven and thermal dissociation is a potential means of production.

Even though hydrogen is being discussed here as storage for renewable energy, thestorage and transportation of hydrogen is regarded as a major flaw of the hydrogen

economy. Although it has very high energy density, its volumetric energy density is

very low, see Table 2.2. Hydrogen must be compressed to achieve acceptably high

energy storage density. Liquid hydrogen requires a cryogenic temperature of -253C

needing up to 40% of its energy content (Kruse, Grinna & Buch 2002). Large scale

storage could be achieved underground under pressure. Natural gas infrastructure

could be upgraded to store and deliver hydrogen at significant cost.


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Table 2.2 Energy Densities of Various Fuels (from various sources)

Fuel State Thermal Energy

Density (MJ/kg)

Volumetric Energy

Density (kWh/L)

Hydrogen -253C (liquid) 120 2.33

Ammonia -33.5C (liquid) 20.9 4

Gasoline (liquid) 1 bar, 20C 43.2 8.6

Issues with hydrogen storage for transportation have limited the growth of the

industry. Many compact storage solutions have been proposed for vehicles, including

compressed gas tanks, cryogenic LH2 tanks and storage in solids. Studies have been

done by Chahine & Bernard (2001) and Pradhan et al. (2002) suggesting there may be

storage solutions in using carbon nanofibre technology. The cheapest and most

effective storage of hydrogen is with its natural energy carriers, the hydrocarbons

(especially methane), alcohols and ammonia.

The idea of using ammonia, one of the most mass produced chemicals in the world, as

a carbon free hydrogen carrier is not new. A great deal of infrastructure is already in

place to store and distribute ammonia, which in a liquid state (needing only -33.5C

or 8 bar) has half the volumetric energy density of gasoline (Kordesch et al. 2003). A

simple ammonia cracker and an alkaline fuel cell can be used to provide electrical

energy or it can be used directly in specially designed internal combustion engines.

The main drawbacks are that it is toxic and that the energy needed to produce

ammonia from hydrogen by the Haber Process is approximately 70% of its energy

content.

In the short term, mass production of Hydrogen could occur through the gasification

and reforming of fossil fuels, especially coal or even biomass, and then controlling

CO2 emissions by sequestration technology. From there efforts could be made to

develop the required infrastructure for hydrogen manufacturing and supply using

renewable or possibly nuclear energy.

Hydroelectric dams are currently unparalleled in their ability to store large amounts of

renewable energy with minimal losses and can respond to demand in less than one

minute. The idea of transporting excess energy into pumped hydro storage has greatmerits if excess capacity is available. Building renewable energy plants with


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2.2 The Power of Sea Waves

The waves in our oceans are very effective at storing, transporting and concentrating

large amounts of energy. A strong yet brutal example of this ability is the devastation

caused by the Asian tsunami disaster of December 2004 created by powerful

earthquakes beneath the Indian Ocean hundreds of kilometers from shore. With the

exception of geologically driven tsunamis, almost all of the energy in ocean surface

waves originated from the sun. Anyone who has experienced conditions in the open

ocean, or witnessed coastlines during severe weather holds an appreciation of the

power of ocean waves. Estimations have been made for the feasibly extractable global

wave power resource from 1TW (Johansson et al. 1993) to 2TW as estimated by the

World Energy Council, mentioned in Duckers (2004). Considering the current globalelectricity demand has just exceeded 1TW (IEA 2004), the power available in waves

is a very large untapped resource. Given enough technological development these

figures could be attainable.

This section contains a review of wave energy resource theory; an in-depth study of

southern Australias wave energy resource is undertaken in Chapter 3. APPENDIX C

contains a compilation of all wave energy information resources used throughout this

project (excluding energy converter technologies).

2.2.1 Oceanic Wave Formation and Climatology

Waves on the surface of the ocean are generated by sea winds that were generated by

solar energy. Wind energy represents less than one percent of the solar energy that

arrives at our planet and only a tiny fraction of that energy is transferred to waves

(Boyle 2004). Exactly how this process is initiated is complex and not completelyunderstood. There are three processes that describe the formation of ocean waves

(Duckers 2004).

1. Air flow creates tangential stresses on the surface of the water,

spawning the initial growth.

2. Air flow becomes turbulent at the water surface and wave development

is caused by fluctuating stress and pressure oscillations in phase with

existing waves. These are called capillary waves.


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than half way around the Earth. The difference between short fetch chop created by

local winds and long range swell can be identified in the images in APPENDIX D.

It is possible to estimate the long term wave climate of any part of any coast given

enough data and analysis. The meteorological study of wave climate is a complex

process involving many factors. Wave energy is strongly variable in time and space,

involving a lot of chaos; energy levels can be estimated and predicted as accurately as

weather can be. An important factor to determine is the directional climate of long

fetch swell that contains most of the energy. At present there are a number of

computer models available which supply calculated information about waves at any

time and location in the ocean. Some of the most well established models are the

NOAA Wavewatch III and the ERA-40. Details of these and other models are listed

in APPENDIX C. Data input for these models include a host of information collected

from satellites, also wind data (from anemometers etc.) and wave rider buoy data

collected from various sites around the world. Calculations are made by the models

which make correlations between each of the data inputs and the measured wave rider

buoy data.

Figure 2.5 Annual average wave power in kW/m of crest length, for various

locations around the globe (Duckers, 2004).


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2.2.2 Wave Energy Characteristics

Figure 2.7 Gravity Waves (Nave 2005)

Ocean waves are complex phenomena

and rarely resemble perfectly

monochromatic or smooth sinusoidal

shaped waves. They are usually

described as gravity waves or waves

that are mainly controlled by gravity

and inertia. At higher amplitudes for a

given wavelength the peaks of ocean

waves tend to become narrower as

illustrated in Figure 2.7 (Nave 2005).

Experiments done in wave tanks

(Soreneson 2000) show that the limit

of amplitude against wavelength, or

steepness, is about 1 to 7 and a

minimum wave peak angle of 120.

Beyond this the top of the wave is traveling too fast and becomes unstable then

breaks. Waves observed in the oceans are typically composed of many gravity

waves traveling in various directions. Much of the surface of the waves is covered in

newly forming capillary waves from wind turbulence. Large and powerful long swell

waves will travel hundreds kilometers to the shore through short fetch waves traveling

in any direction. This is best shown in Image A ofAPPENDIX D.

The physical properties of sinusoidal waves can be used to model ocean wave

characteristics. Most of the theory outlined here is sourced from literature by Duckers

(2004) and Fay & Golomb (2002). Wave power is normally expressed as the amount

of power per length of wave crest (kW/m). Figure 2.8 illustrates an idealized

sinusoidal ocean wave and its characteristics.


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H= wave height = wave lengthd= mean water depthT= period

= density of water (1000kg/m3)g = gravitational acceleration (9.8m/s

2)

Figure 2.8 An idealized sinusoidal ocean wave.

Wave power/length

32)(

221 THg

WmP == (2.1)

The above equation gives the wave power for an idealized ocean wave. It shows that

the power of a wave is proportional to the square of its amplitude. It is also useful to

know that 95% of the energy of a wave is contained between the surface and a depth

equal to a quarter of the wavelength (d= /4).

Oceanographers have developed the following equations that relate wave properties

empirically to wind speed, V(Fay & Golomb 2002).

2

42

)2(19.2g

VEH = (2.2)

V

g

T

70.02=

(2.3)

These two relations can be substituted into equation (2.1) to give:

Wave power/length =g

VEkWmP

51 )3(89.3)(

=

(2.4)

0

25

50

75

100

125

150

175

200

4 5 6 7 8 9 10 11 12 13 14V (m/s)

P(kW/m)

Figure 2.9 Plot for equation (2.4) empirically relating wind speed to wave power


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In Figure 2.9 a quick plot generated using Excel is displayed for equation (2.4); it

shows a strong exponential trend. This was done to visualize how this empirical

relationship was derived. This type of formula would have great accuracy limitations

in its application because fetch distances vary and wind rarely flows in a straight line

for long. It would have its uses in determining simple correlations when initially only

wind data is supplied, such as wind strengths for an upcoming storm.

The greatest wave energy levels exist in deep water where waves travel at speed with

minimal losses. Once they move into depths of about 50m the energy losses from

bottom friction begin to accumulate resulting in a reduction in wave velocity. Figure

2.10 shows how particle motion below the surface can interact with the seabed in

shallow water. In deep water the particle orbits are circular, but in shallower water the

orbits are elliptical applying frictional forces to the seabed. All kinds of factors and

wave properties come into play as waves interact with shoreline bathymetry, making

for complicated modeling. Eventually all of the energy is lost on the shore when the

waves break and then interact with themselves. As wave speed reduces the effect of

energy conservation increases their amplitude, bringing about the phenomenon

described in Figure 2.7. It is for these reasons that offshore wave energy (>50m

depth) devices have a clear advantage over shoreline device. Offshore wave energyconverters can access more energy, more predictably and without being subjected to

the rough forces of breaking waves.

Figure 2.10 Illustration of approximate particle orbits for: a) deep water whereH, b) in shallower water where 2.5H(Brooke 2003)


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Another important phenomenon of waves moving into a coastline is known as

refraction. Interactions with coastline bathymetry give waves a tendency to arrive at

the shore with the crest parallel or close to parallel to it. This is created by reduced

wave velocities forcing a change in directional orientation over a length of crest.

Images B and C ofAPPENDIX D both illustrate this property. Depth contours affect

the wave velocity of long fetch waves and concentrate their energy at headlands,

capes or points. These headlands also have a great sheltering effect for regions in the

shadow of the long swell direction. Such areas are fetch limited and have much

reduced wave energy levels that are difficult to model. The importance of this will be

seen in the KI Case Study in Chapter 4.

Two important values that will be used throughout most of Chapter 3 are those of

significant wave height (Hs) and zero crossing period (Tz). The surface of the ocean is

irregular and composed of a number of different waves that cant be measured

individually. In order to measure them an averaging process is required. The average

water height will always be zero and this is used as reference point for other

measurements. Squaring all instantaneous elevations makes them positive, and then a

mean height of a given number of waves is taken. The significant wave height is

calculated as the square root of this mean multiplied by 4 (Duckers 2004). Throughobservation, the value for significant wave height closely approximates the average of

the highest one third of the waves. The zero crossing period is given by the average

time between upward movements of the wave surface thought the mean level. An

example of how these values are calculated is illustrated in Figure 2.11.

Figure 2.11 A typical record from a Wave Rider Buoy (Duckers 2004)


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2.3 Wave Energy Converters

Wave energy was first explored in detail as a major source of energy during the

1970s energy crisis. Most of the investment into wave energy research has been in

Europe and this is where many of the wave energy converters have been developed.

This is because Europe has become increasingly reliant on importing its energy and is

now focusing on renewables in an effort to improve energy security. Wave energy

converters are currently still going through an evolutionary stage in much the same

way wind turbine technology did in the 70s and 80s. A different set of challenges

apply to wave energy converters and many of the technologies are still evolving fast.

Figure 2.12 shows the evolution of some wave energy technologies on the basis of

cost per performance output. A number of different contending technologies arenamed, with the Pelamis currently taking the lead. These figures are estimates by

Duckers (2004) from a range of sources, but they provide a clear trend that wave

energy devices are dropping in cost. Duckers (2004) provides a concise overview of

different wave energy converters.

Figure 2.12 Evolution of UK wave power devices (Duckers 2004)

2.3.1 Study of Different Designs

Every wave energy converter consists of some form of structure that has the goal of

extracting the mechanical energy from the waves. There are devices built into the

shoreline or offshore devices which are typically designed to be located in depths

greater than 50m where losses of long swell energy are minimal. Offshore structures

can be rigidly or flexibly moored to the sea bed or the entire vessel can be designed tofloat. In order to extract a waves energy there must be some relative movement


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between the structure and the wave motion. A number of mechanisms have been

devised for this purpose. A diagrammatic illustration of the main families of

configurations is shown in Figure 2.13. Wave energy converters can be classified into

5 different groups, but for some designs this can be difficult task.

Figure 2.13 Configurations of Wave Energy Converters (Johansson et al. 1993)

Tapered channels can be effectively built into the shoreline and work by concentrating

waves up a channel to create a static hydraulic head in a storage reservoir. Much like

a small dam, the water then returns to the sea through a turbine built into the structure.

A surge device using the flexible bag and spine mechanism was developed by

Coventry University in the 1980s called the circular Clam.


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Ocean waves repeatedly apply rough and highly variable loads to wave energy

converters and some expensive prototypes have been destroyed as a result of powerful

storms. In the end the most important thing to determine is the commercial viability

and readiness for a given technology. A thorough assessment of all available offshore

wave energy conversion devices has been undertaken in the US by the Electric Power

Research Institute, or EPRI (Prevesic 2004). The report, released on June 16 2004,

identified only 8 technologies on the market ready for demonstration by 2006 and

assessed them using an extensive list of criteria; design for survivability being a key

requirement. In summary the EPRI believed only one of the devices was acceptable

for use in a pilot plant in the US, the Pelamis by OPD. Three other devices, namely

Energetech (see Figure 2.14), Wave Dragon and Waveswing could be used if a few

remaining issues were addressed.

2.3.2 Projects at Advanced Development Stage

On May 19th 2005, OPD made the announcement of the worlds first commercial

wave farm to be located 5km off the Portuguese coast. Three Pelamis are to be

installed having a capacity of 2.25MW and is expected to meet the average electricity

demand of more than 1,500 Portuguese households. Subject to the satisfactory

performance of the first stage, an order for a further 30 Pelamis machines (20MW) is

anticipated (OPD 2005). The cost of the first stage of this project is 8m

(~$AUD13m). This is good indication that the cost of a locally developed Pelamis

would be in the order of $AUD4m per unit until more units are ordered for production

significantly reducing the cost.

Ocean Prospect in the UK is working on developing a wave farm for a wave energy

project called the Wave Hub. The Wave Hub concept is to build an electrical grid

connection point approximately 10 miles off the UK shores into which wave energy

devices would be connected. It will provide a well defined and monitored site with

electrical connection to the onshore electricity grid and will greatly simplify and

shorten the legal consents process for developers. Wave Hub would reduce the risk

for developers of the first pre-commercial wave machine arrays. If it goes ahead,

Wave Hub could be commissioned by 2006 (OP

tom winkler wave energy potential for ki

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