Introducing the Hydrographer to Offshore Wind Farms

S Keedwell
The Geocon Group, Axminster, UK

Abstract

The development of a renewable and sustainable energy source is fundamental to many European Government Energy policies. There are many types of renewable energy source, of which wind power is one. Wind power has been developed in many onshore locations. However, land for new developments is relatively scarce, and this is compounded by the objections of local residents, necessitating developers to look at the marine offshore environment. Careful consideration must be given to the environmental factors when building an offshore wind farm. The hydrographer and geoscientist will play a crucial role in these developments. This paper introduces the subject of offshore wind energy and provides an overview of what will be required of hydrographers and geoscientists.

Renewable energy comes in many forms: bio-energy, municipal solid waste (MSW), hydrogen, ocean, geothermal, hydropower, solar and wind. The latter of these, wind power, has been utilised as a source of energy since the dawn of time. Today it is used in several guises - from propelling sailing vessels to drying our laundry. More importantly, onshore wind power has been providing electricity to domestic and commercial users for over 25 years and can be traced back to developments in the early twentieth century. This technology is now being transferred offshore, and many wind farms are planned for construction around the coastlines of the United Kingdom, Ireland and Northern Europe in the next ten years. This is because wind power is now economically viable and represents the most direct route by which to satisfy the Renewable Energy Directive that was set by the European Union in September 2001. Support for renewable energy projects in the United Kingdom has come from the very highest levels of the Government:

“I want Britain to be a leading player in this coming green industrial revolution. We have many strengths to draw on. [We have] Some of the best marine renewable resources in the world - offshore wind, wave energy and tidal power.”

Tony Blair, [UK] Prime Minister,
‘Environment: the Next Steps’, March 2001

The decline in western oil and gas supplies, combined with increasing concern over the security of overseas resources for future utilisation, is also escalating the requirement for renewable and sustainable energy supplies. Support from European governments and investment from the oil and gas majors is increasing the number and profile of renewable projects. It must be noted that wind power alone is not sufficient to provide for our energy requirements. In countries such as Canada, hydroelectricity has been developed to provide 60% of the energy needs.

In real terms, every megawatt of electricity produced by an offshore wind farm will equate to the energy requirements of 685 UK homes. However, the reduction in emissions such as carbon dioxide, sulphur dioxide and nitrogen oxide into the atmosphere will play an important role in reducing the Greenhouse Effect.

The hydrographic surveyor or geoscientist will play a crucial role in the site investigation, installation and monitoring of offshore wind farm projects. This paper will provide an overview of renewable energy, the history of wind power up to its migration offshore and a review of current and future projects.

The Growing Need for Renewable Energy

The requirement for a renewable and sustainable energy source is based on several factors, of which the following are most notable:

• Growing concerns over the security of oil and gas supplies
        o       Increase in the possibilities of Middle Eastern conflicts
        o       Problems with the utilisation of the hydrocarbon resources in Venezuela
        o       Most major future energy sources are in politically unstable areas
• Huge long-term growth in energy demand forecast
        o       Production in the North Sea and Gulf of Mexico offshore in decline
        o       Forecasts assume that Saudi Arabia can double oil production by 2020
        o       The demand for gas is exceeding oil, especially in Europe and the USA
• Growing environmental pressures
        o       Global Warming and the Greenhouse Effect
        o       The general public becoming more environmentally aware
• Growing world population
• The cost of renewable energy decreasing to become competitive against fossil fuels

Source: Douglas Westwood

Given the above listed points, the continuing growth of world population, especially in developing countries is a major concern. At the time of writing this article [June 2002] the US Bureau of the Census estimated the world population to be 6,229,941,925. The population will continue to grow at a staggering rate, refer to Figure 1. Energy supplies will need to match the population growth. Thus a continuing reliance on the current oil and gas reserves would not be prudent.

Fig. 1: Estimated world population growth

Supply from Middle Eastern oil and gas reserves may be possible, however this could conceivably be at a premium price. The following succinctly describes the position of OPEC with regard to supplying other countries with oil and gas:

“OPEC simply cannot produce such amounts of crude, whatever the circumstances or the price of oil.”

A M S Bakhtiari, Senior Corporate Planner,
National Iranian Oil Company
Source: Douglas-Westwood

The current energy mix and future projections are shown in Figure 2. Please note that renewable energy is included (this refers to all sections of the renewable industry), however the consumption of oil, gas and coal increases exponentially, whereas renewable energy maintains a steady increase and is expected to double by 2020. The author considers this to be a conservative estimate.

Fig. 2: Historical, current and future world energy mix

Source: EIA 2002 p 11

The increasing use of fossil fuels leads to an increase in the release of carbon dioxide into the atmosphere. The information provided in Table 1 indicates that the increase in energy consumption will be 17% per decade; the equivalent increase in carbon dioxide emissions will be under 16%. The use of renewable energies will help to increase the margin between energy consumption and carbon dioxide emissions, and this is an important step in alleviating the Greenhouse Effect and Global Warming.

Table 1: Past and future world energy consumption and carbon dioxide emissions by region

Source: Energy Information Administration, Dept of Energy US Government.
Report # DOE/EIA-0484 (2002), 26 March 2002, http://www.eia.doe.gov/

Greenhouse Effect

Continual reliance on fossil fuels in the production of electricity leads to the production of carbon dioxide gas, which is the main catalyst for the Greenhouse Effect thus leading to an increase in the temperature of the planet. It is not in the scope of this paper to discuss the effects of an increase in temperature on the planet, however, it must be noted that this is another driving factor behind the interest in renewable energies. The utilisation of renewable energies as an energy source will help to significantly decrease carbon dioxide emissions. Figure 3 illustrates the world’s top six carbon dioxide polluters.

Fig. 3: The world’s top six carbon dioxide polluters by global region

Source: EIA 2002 p 8

Wind energy is only one of several renewable energy sources. Each country will choose an energy source that will suit its environment, economy and natural renewable energy sources. An exemplary illustration is the use of hydroelectricity in Canada. In 1999 60% of the 551 billion kilowatt hours generated was supplied by its network of hydroelectric dams (EIA, 2002). Similarly, Bangladesh is implementing a system of biomass electricity plants to support its energy needs. As a large portion of the indigenous population is from an agrarian background, this will help to enhance the economy, whilst helping to build an electricity infrastructure in the rural areas. (Biomass electricity plants would be based within the production areas of the biomass crops and would supply electricity to the local population).

In Western Europe, hydroelectricity [generally] has been fully developed. The following succinctly states the current position of the UK on the production of renewable energy:

“Today, less than 3 percent of the UK’s energy needs come from renewables. And, as I never tire of saying at gatherings like this, that even most of that 3 percent figure has got nothing to do with what has happened in the 90s, the 80s and the 70s. It goes right back to the halcyon days when people had the vision to build hydroelectric stations in the 1940s and 50s. So that’s where most of our 3 per cent comes from right up to the present day, and there’s a long way to reach the target of 10% in 2010 and so on, and 20 per cent by 2020 as suggested by the PIU*.”

*PIU is the acronym for the newly formed Cabinet Office for the Performance and Innovation Unit.

Brian Wilson MP, Energy Minster,
UK Offshore Wind 2002
Offshore Wind: The UK Government View -
Keeping up the pace and providing the basis for major expansion

Table 2 compares the cost of fossil fuels, renewable and nuclear energies. As discussed previously, hydroelectricity has been utilised where possible and new projects are planned in developing countries such as China, India, Malaysia, Central and South America. The Three Gorges Hydroelectric Dam in China, which will produce a massive 18,200MW of electricity when construction and commissioning is completed, has come under pressure from environmental groups. Dam construction has resulted in the flooding of land, and this in turn has led to the loss of habitats for indigenous animals and the relocation of thousands of people (EIA, 105). Therefore careful consideration has to be given to the construction of [all] renewable energy projects so that their impact on the environment is minimal. Thus, it has been necessary to carefully develop and monitor offshore wind farm construction, to ensure the environmental impacts are minimal.

The UK has many options available for the development of renewable and sustainable energy supplies. Relying on wind alone is not a solution - a renewable energy mix will be developed. At this present time wind energy is the most favourable option to meet EU directives in the current time-frame and the UK Renewables Obligation.

Table 2: Cost comparisons between different energy sources

Source: Douglas-Westwood, The World Renewable Energy Report

*Direct studies for offshore wind farm construction costs indicate that the cost would be 5.0 cents/kWh over a planned 20-year period and 4.0 cents/kWh for 25 years. This includes all installation and maintenance costs, including grid reinforcement. Please note that the foundations would be expected to have a lifetime of 50 years (Krohn, 1997).

In 2001 the European Parliament approved a Renewables Directive that obliges European Union members to double their renewable share of total energy consumption by 2010. In real terms, this means that the share of total inland energy consumption met by renewable energy resources should be 12% in 2010 from the current estimated level of 6%.

The United Kingdom Renewables Energy Obligation required electricity suppliers to derive 3% of their electricity from renewables at the start of 2002. This will rise to 10% by 2010. To obtain these targets electricity suppliers are looking at several options, of which offshore wind energy is currently the most attractive, as it is the most economically viable and, if the development is managed correctly, will meet the requirements of the UK Energy Obligations in 2010.

The UK [and Europe] has a vast wind resource, but onshore sites are being utilised quickly and the development of onshore wind farms frequently comes into conflict with local communities on the use of the limited land resources. The next step is to move offshore, which will help to alleviate these problems. The UK is in an excellent position to move the production of wind energy offshore. Key factors are:

• The UK territorial waters offer a wind rich resource environment
• Established offshore companies that would easily adapt to the construction of offshore wind farms
• A large manufacturing skills base
• Service companies that will be able to provide support to offshore wind farm construction, maintenance and operation
• An understanding of the risks associated with working and investing in the offshore environment
• All the above may also give the UK a potential to export these skills

Source: BWEA Meeting 2002

A study by the Risoe National Laboratory produced the wind resource map for Western Europe, as shown in Figure 4.

 + > 9 ms^-1   + 8-9 ms^-1      +7-8 ms^-1     +5.5-7 ms^-1  +< 5.5 ms^-1
Fig. 4: European Offshore Wind Resources Map

Source: Risoe National Laboratory (1989)

Moving wind farms offshore also offers further benefits:

Higher wind speeds
Theoretically, the available wind potential (based on a height of 60m above sea level and a average wind speed of 8m/s) around the coast of the UK would match current demands three times over. The wind potential offshore Germany would provide half of their current energy requirements. Research and development into the modification to offshore wind modelling software has indicated that these estimates may increase by 5 to 10% as more data is collected. The installation of anemometer masts on proposed offshore wind farm sites will provide information to refine the model.

Low wind shear
When considering wind shear, the low sea state offshore compares very favourably with uneven onshore environments and may result in the height of wind towers decreasing by a factor of 0.75 of the rotor diameter. Onshore wind towers are typically the height of the rotor diameter - rotor diameters can range from 50m up to 100m.

Low turbulence intensity
The turbulence of the wind above the sea is less than that onshore. This is due to the temperature variations at different altitudes in the atmosphere above the sea, which are notably smaller than above land. The penetration of sunlight into the sea is significantly higher and heat is absorbed, whilst on land the penetration and absorption of heat is appreciably less.

Turbulence intensity affects the lifespan of a wind turbine and its components, leading to greater maintenance and hence operational downtime on land-based units.

Wind shade
The surrounding terrain and upwind obstacles cause wind shade. During a site study software packages such as WindPro™ or WaSP™ are used to model the wind resource. For onshore studies, the surrounding environs (eg building, trees and terrain) are surveyed and entered into the wind resource-modelling package.

Studies of offshore sites have shown that modelling the wind resource is far more complicated than onshore. This is due to the surface roughness of the sea, which is complicated to model due to the following varying parameters:

• Wind speed
• Water depth
• The distance of the site from the surrounding shoreline
• Tidal flows
• Atmospheric conditions

As more research and development is completed, the wind models will be modified to the marine environment.

Land use and planning conflicts resolved
As previously mentioned, the development of onshore wind farms can come into conflict with the local population over the use of land. Moving offshore will help to alleviate this problem, however, it is envisaged that planning conflicts will continue. Offshore wind farms will require onshore support facilities for the transmission cable. From these facilities a cable will have to be connected into the National Grid system, it will therefore be important and necessary to assess the level of impact of the facilities and subsequent transmission lines to the National Grid.

Visual impact and noise
The construction of wind farms offshore will decrease their visual and noise impact, which has been one of the greatest areas of opposition for onshore projects.

Offshore Wind Power – History

Modern wind power is based on a relationship charting several thousand years. Onshore windmills have been an integral part of economic and social progress. In the nineteenth century working windmills were only eclipsed by the onset of the Industrial Revolution, as were commercial sailing vessels. Converting wind power to electrical energy was pioneered by Charles F Brush (1849-1929) and Poul la Cour (1846-1908).

Charles F Brush invented an extremely efficient DC (direct Current) dynamo, and more importantly he pioneered the design of the first automatic wind turbine in the winter of 1887-88 (Danish Wind Industry Association). The rotor diameter was 17m and it had 144 rotor blades constructed from cedar wood. It had an operational life span of 20 years and was utilised to power batteries in the cellar of his mansion. Despite its size, the turbine produced only 12kW –owing to the slow rotation of the blades – and was thus an inefficient unit. The Frenchman Poul la Cour experimented with various blade configurations and discovered that fast rotating wind turbines with fewer blades are far more efficient at producing electricity. By 1918 approximately 120 utility companies in Denmark had a wind turbine from 20 to 35kW producing a total of 3MW, meeting an estimated 3% of the then Danish energy consumption at that time.

The wind energy industry grew slowly from the early twentieth century. The first oil crisis in 1973 prompted several countries to look for alternative energy sources. In Denmark, power companies immediately looked at the manufacture of larger wind turbines. This was mirrored in Germany, Sweden, UK and the USA. The manufacture of these large turbines was expensive and thus the high price demanded to cover the cost of construction was deemed too high for the energy market to sustain. However the advent of the Nordtank 55kW wind turbine was the catalyst for the great Californian wind rush in the early 1980s. This was enabled by the technological and industrial manufacturing breakthroughs – essentially the commercial manufacture of the Nordtank 55kW wind turbine – which decreased the cost of producing electricity by 50% per kilowatt-hour. At that time, in California, the economic and political conditions were also favourable, until the support mechanisms were removed in the mid-1980s and new projects disappeared (Danish Wind Industry Association).

In Europe, especially in Denmark, engineering ingenuity, the experimentation of several individuals and the formation of the Risoe National Laboratory supported the utilisation and development of wind energy.

The development of the Rilsager, Tvind and Bonus wind turbines helped to develop the modern wind turbine. As wind farm developments move offshore, further work will be required in developing wind turbines that can withstand the corrosive and damaging effects of the marine environment. A comprehensive study of the effects of the marine environment was reviewed in the Concerted Action for Offshore Wind Energy in Europe and the Offshore Wind Energy Network workshop on Structure and Foundation Design of Offshore Wind Installations. Both papers are available on the internet (see the list of references).

Offshore Wind Farm Site Investigation and Environmental Impact Assessment

A preliminary desktop study will first assess a site. Primarily, this will be to assess the wind potential of the site. The developer will refer to the wind atlas developed by the Risoe Laboratory for baseline information on the site (see Figure 4). Consideration will also have to be given to the following:

• Access to the local and national grid
• Visual impact – Is the site sufficiently far enough from shore that visual impact is at a minimum?
• The potential for local conflicts – Is the proposed site within a local fishing area? Would the construction of wind farm cause interference to commercial or military radar sites?
• The proximity to sites of scientific interest and breeding/spawning grounds of birds and fish

A review of the local environs will help in further qualifying the site and at this point the developer will then decide on the route he will take when applying for an offshore wind farm consent. There are two options currently available to developers:

1.   Electricity Act 1989/FEPA¹/CPA² and also the following possible consents depending on the site and location:

1. Town and Country Planning Act 1990 – Sections 57 or 90 (eg Onshore substation)
2. Electricity Act 1989 – Section 37 (Onshore overhead power lines)
3. Water Resources Act 1991 – Section 109 (If erecting structures in a water course)

2.   Transport and Works Acts (TWA)/FEPA and other possible consents:

      Offshore wind farm developers can choose to obtain an order under the TWA. Using Section 3 (1)(b) of the TWA, the Secretary for State for Trade and Industry (or in Wales this would be the National Assembly) can make an Order relating to, or to matters ancillary to, the carrying out of works which interfere with rights of navigation in waters within or adjacent to England and Wales up to the seaward limits of the territorial sea (Crown Copyright 2001).

      However, the making of such an order does not confer planning permission for any development, but the developer can at the same time request that planning is deemed to be granted. Alternatively the developer can apply for planning permission from the Local Planning Authority (LPA).

Both FEPA and CPA Acts require developers to assess the potential and magnitude of harmful effects when considering the exploitation of the marine environment. Cumulative impacts from multiple projects within the same area would also have to be considered. It is most probable that when making and supporting an application for the development of an offshore wind farm an Environmental Impact Assessment (EIA) would be required.

Environmental Impact Assessment (EIA)

The term EIA describes the procedure for compiling the environmental information relating to a site (and surrounding environs) and measuring its predicted effects on the environment and the scope for ensuring that they are kept to a minimum. An offshore wind farm EIA within UK Territorial waters will have the following information within it – both site and project specific:

Sedimentary and Coastal Processes

The scope of the sedimentary processes study will be to assess the magnitude and cumulative impacts of the construction of the wind farm within the local site, but it will also consider far-field impacts such as the local coastline, Special Sites of Scientific Interest (SSSIs) and areas of conservation interest. This will include:

• Sediments (particle size, distribution within the water column and geochemical composition)
• Hydrodynamics (eg waves, local tidal flows and seabed topography)
• Sedimentary environment (eg sediment transport, re-suspension of sediments and deposition of sediments within the long-shore and cross-shore environment)
• Sedimentary structures (eg channels, banks and stability thereof)
• Suspended Sediment Concentrations (SSC)

Source: Crown Copyright 2001

Information from the above should be used in addressing the following issues:

• Scour around the subsea foundation of the wind turbine and cables and to quantify the basis for scour protection – if needed – including free-span analysis.
• The design of the wind farm array and the subsequent effects it will have on waves (constructive and destructive), and the effect this will have on sediment spatial distribution. The designed array will also affect the diffraction of waves onto the surrounding coastline, thus potentially causing alternate regions of high erosion and sediment deposition. Quantification of the change in wave energy and angle of approach and the subsequent impact on the coast, especially in sensitive areas (SSC), must be assessed.
• Assessment of the potential impact the wind farm array will have on the mobilisation of seabed sediments during non-linear interaction, such as storms, and the subsequent deposition of the sediments within the local environs.
• Measurement of the near-field sediment depth and quantifying its impact on foundation stability and the turbine structure; the requirement for foundation material, if necessary, and the impact on cable burial.
• Measurement of localised sediment transport and enhanced SSCs during seabed preparation (dredging) and cable burying (ploughing and water jetting) operations.

Marine Benthos
Marine benthos studies would be completed to support an EIA. The study would be site-specific and would involve seabed surveys and sampling to quantify the baseline population and species. Techniques such as grab and core sampling for macrobenthic infauna and epifauna using trawls and dredges would be used. Samples of the seabed should also be collected at each sample site. An ROTV or diver survey may also be required to record visual data in support of the EIA. Sampling design, practices, frequency and Quality Assurance (QA)/Quality Control (QC) procedures must be adopted prior to the survey work.

The planning of the benthic study must take into account the envisaged effects of the construction of the wind farm. The following should therefore be taken into account when planning the survey:

• The physical effects of construction (ie seabed preparation) on the water quality and the deposition of sediments on benthic colonies.
• Effects of and level of scour on the seabed environment and the ameliorative action taken.
• The colonisation of structures and subsequent effects, such as modification to biodiversity and the increase in the level of food available for shellfish and fish communities. Attention must also be paid to the de-commissioning of structures and the effect that will have on benthic biota.
• The cumulative effect of man-made activities within the marine benthic environment that may have a cumulative effect on benthic biota.

Analysis of the data must take into account the patterns and trends and incorporate a plan for future studies to measure the effects of the wind farm on the marine benthic communities.

Fisheries resource (including commercial fishing)
The wind farm may adversely affect the local fisheries resource, disrupting local spawning grounds and patterns, such as inhibiting the movement of adult and juvenile fish. The study should incorporate not only the site, but also a reasonable area surrounding the vicinity of the site. The following fisheries resources will need to be described:

• Fish spawning grounds.
• Juvenile fish nursery grounds and seasonal migration areas, such as over-wintering areas for crustaceans.
• Migratory routes for shellfish and fish.

The site will also have to be assessed with regard to the impact on commercial fishing operations. The impacts of the wind farm construction on commercially exploited fish and shellfish populations, access to fishing grounds; interference to commercial fishing activities and implications during the construction phase will have to be quantified. Commercial claims and reimbursement for loss in revenue may also have to be taken into account.

Commercial and recreational activity
Construction of wind farms may impinge on local commercial and recreational activities, such as sailing, power boating and marine shipping traffic travelling to and from commercial ports etc. A full risk assessment will have to be conducted prior to the construction of the wind farm; this would include traffic frequency and collision risk analysis. A design for marking the offshore wind farm (ie navigation lights) would have to be designed prior to construction. The effects of the marine lights on marine birds would need to be considered (CA-OWEE, p7-7).

Archaeology
The site will have to be assessed to ensure that it will not be constructed on historically important wreck site, war graves or palaeontological/palaeogeological features.

Marine mammals
The site will be assessed for the proximity of marine mammals. The effects of noise, vibration, physical intrusion, visual disruption and interruption to known migratory routes/feeding grounds must be assessed. The internal cables between wind turbines and the shore connection will also have to be assessed to ensure the impact of their electromagnetic noise distortion on the biological sonar of marine mammals is minimal (CA-OWEE, p7-26).

Birds
As part of the EIA the site will be assessed to ascertain the impact on birds. This will address both the local sea-bird population and seasonal migration. Research into bird collision with onshore wind farms has concluded that the impact on birds is minimal. However, the incident at the Øresund Bridge between Denmark and Sweden, in which 600 birds were killed in a single day due to collision with the bridge caused considerable public outrage. The cause of the incident was attributed to the illumination of lights during a foggy day. Thus, careful attention must be paid to navigational lighting to ensure a similar incident does not re-occur in the future (CA-OWEE, p7-26). Research in this area has suggested that the layout of the wind farm array should be shaped into bird friendly corridors (CA-OWEE, p7-6)

The Role of the Hydrographer/Geoscientist in Offshore Wind Farm Development

The hydrographer/geoscientist has supported and continues to support the development of the following industries:

• The oil and gas industry (eg exploration and production)
• Submarine cable industry (telecoms and electrical)
• Port infrastructure and shipping channels
• Sea defence programmes
• Precious mineral extraction
• Dredging

Many of the skills developed in supporting the above industries will be brought to bear on the development of offshore wind farms. The types of data required for an offshore wind farm development are listed in the Table 3.

Table 3: Data types and acquisition methods

The data described in Table 3 will be used for the following:

• In support of the EIA application.
• Installation of meteorology mast for site-specific wind resource assessment.
• Subsea transmission cable engineering, including onshore landing sites. This will also be extended to mapping the local environs for onshore facilities for planning application purposes.
• Benthic survey workscope.
• Planning of the geotechnical survey.
• In support of the installation of the wind turbines, ie identifying seabed hazards for jack-up/specialised installation vessels is critical.

The general consensus is that site survey data acquisition should be completed at an early stage.

Currently Installed and Planned Offshore Wind Farm Developments

Table 4 lists the currently installed and operational wind farms in Europe.

New offshore wind farms which are planned for construction in Europe and North America, between 2002 and 2005, are shown in Table 5. The construction of these wind farms will be phased, and may take an additional 5 years to build, taking completion dates up to 2010. There will be a massive programme to obtain licenses for sites, complete EIA for planning permission and construction of offshore wind farms.

In the UK there are currently 13 sites applying for consents to build an offshore wind farm. Currently each site is at a different stage in the project; refer to Figure 5 for their locations around the UK coastline.

Conclusion

The future development of offshore wind farms is crucial in the development of a renewable and sustainable energy mix that is friendly to the environment. Careful consideration must be given to the development of offshore wind farms so that their impact on the environment is minimal during installation, operation, maintenance and de-commissioning. The next ten years will see many new developments that will require and utilise the skills developed by hydrographic surveyors and geoscientists.

Table 4. Installed and operating offshore wind farms in Europe

Table 5: Planned offshore wind farm construction in 2002 to 2005

Source: Henderson A, (2002) British Wind Energy Conference and  http://home.planet.nl/~windsh/offshoreplans.html

Fig. 5: Planned UK offshore wind sites

Source: www.offshorewindfarms.co.uk

Please note that the go ahead for the Scroby Sands development has now been given.

References

All URL addresses for articles from online sources were correct on the 27/06/02

Krohn, S. (1999). Offshore Wind Energy: Full Speed Ahead. www.windpower.org

Carryer, R and Deeming K. (Undated). ‘Environmental risk for offshore wind farm developers: lessons from other industries’. www.owen.eru.rl.ac.uk/documents/bwea20_40.pdf

Cheshire, J H. (2001). Cabinet Office PIU Energy Policy Review. Summary of key themes and points in the submissions. www.cabinet-office.gov.uk/innovation/2001/energy/SumKeyPoints.pdf

Crown Copyright (2001). Offshore Wind Farms: Guidance note for Environmental Impact Assessment in respect of FEPA and CPA requirements. www.cefas.co.uk/publications/Windfarm-guidance.pdf

Danish Wind Industry Association, DWIA (2002). The Wind Energy Pioneer – Poul la Cour. www.windpower.org

Danish Wind Industry Association, DWIA (2002). Offshore Wind Conditions. www.windpower.org

Danish Wind Industry Association, DWIA (2002). The Great Californian Wind Rush.  www.windpower.org

Danish Wind Industry Association, DWIA (2002). The Wind Energy Pioneers: The Gedser Wind Turbine. www.windpower.org

Danish Wind Industry Association, DWIA (2002). The Wind Energy Pioneers – 1940-1950. www.windpower.org

Danish Wind Industry Association, DWIA (2002). Wind Turbines From the 1980s. www.windpower.org

Danish Wind Industry Association, DWIA (2002). Modern Wind Turbines.  www.windpower.org

Energy Information Administration, EIA, (2002). World Energy Consumption. www.eia.doe.gov/oiaf/ieo/world.html

Energy Information Administration, EIA, (2002). Hydroelectricity and Other Renewable Resources. www.eia.doe.gov/oiaf/ieo/world.html

European Wind Energy Association, EWEA, (2002). www.ewea.org

Grainger, W and Jenkins, N. (Undated). ‘Offshore Wind Farm Electrical Connection Options’ www.owen.eru.rl.ac.uk/documents/bwea20_46.pdf

Hendersn A R, (2002). ‘What’s Being Built Elsewhere?’ Proceedings of British Wind Energy Conference, British Wind Energy Association.

Henderson, A R and Patel, M H. (Undated). ‘Floating Offshore Wind Energy’ www.owen.eru.rl.ac.uk/documents bwea20_48.pdf

Lange, B and Hojstrup, J. (2000). Evaluation of the Wind Resource Estimation Program WasP for Offshore Applications, October 2000 Revision. Special Issue of the Journal of Wind Engineering and Industrial Aerodynamics. ehf.uni-oldenburg.de/wind/download/jweia2001/ICWE-Wasp-paper-revised.pdf

Pincott, N. (2001). Offshore Wind Farms – Construction and Operational Issues (Norton Rose Seminar).  www.nortonrose.com/Wind%20Farm/Wind%20Farm/papers.html

Weatherill, Jennie (2000). First International Workshop on the Feasibility of HVDC Transmission Networks for Offshore Wind Farms, 30-31 March 2000, KTH, Stockholm, Sweden. www.ekc.kth.se/ees/workshop/workshop-00.html

Westwood, J. (2002). Renewable Energy World Market Prospects 2002 Douglas-Westwood Associates. www.dw-1.com

Williams, W. (2001). Blowin’ in the Wind: Offshore wind farms may prevent an energy crisis. The American Prospect Online. www.prospect.org/webfeatures/2001/10/williams-we-10-18.html

Wind Directions (2001). Offshore Wind: The advantages and challenges, p 12-17.