Harvesting Offshore Wind

In recent years, there has been steadily growing interest in placing wind turbines in the waters off the world’s coasts to generate electricity. The first major American offshore wind farm was recently proposed for Cape Cod (see sidebar). There is also considerable interest in developing wind energy off of Long Island. To see how possible project in these locations relate to the development of maritime wind farms worldwide, this article looks at the global picture.

Trends in Wind Power Development
Wind power is being developed at a rapid pace worldwide. By the end of 2001, a total of 24,000 megawatts of wind generating facilities had been installed—both on land and off shore. Most of this is in Europe, which has a wind power capacity of 17,000 megawatts producing enough electricity for the equivalent of 10 million households. Germany, Spain, and Denmark contribute the lion’s share of Europe’s wind generation. Elsewhere in the world, the US with 4,300 megawatts of wind power capacity and India with 1,500 megawatts are two other important centers of wind development.

Up to now, relatively little electricity has been produced offshore but this is starting to change. The existing operating offshore farms, in the North and Baltic Seas, have a capacity of only 86 megawatts. In 1991, Denmark built the first offshore project, Vindeby.  It was constructed one mile off the Danish coast and had a total project cost of $13.8 million, with the European Union contributing 10%. Holland, Sweden and the UK followed with other projects. More recently, in 2000, the UK built Blyth Offshore, which was the first offshore wind farm exposed to the full forces of the North Sea.

The biggest maritime wind farm, Middelgrunden in Denmark, came online in 2001 with a capacity of 40 megawatts. Another Danish project will soon overshadow all the previous ones. Horns Rev is planned to start operating later this year and will have a capacity of 160 megawatts.

There are many more European projects in the works for the North and Baltic Seas. Last year, about 21 German projects were proposed. The UK has identified 13 potential offshore sites near the British coast that could collectively offer a capacity of more than 1,000 megawatts. By the year 2005, 2500 megawatts of offshore wind capacity could be in place in Europe, generating enough electricity for two million households and providing roughly 50,000 new jobs.

Looking to the longer-term future, the European Wind Energy Association estimates that in 20 years 10% of the electricity needs worldwide could come from wind energy generated by offshore farms. Specific countries could get an even higher percentage of their electricity from offshore wind. The German Wind Energy Association  suggests that by 2030 20% of that country’s electricity could come from 5,000 offshore turbines with a capacity of five megawatts each.

Northern Europe’s Advantages
The early concentration of offshore wind development in northern Europe stems in part from the strong commitment governments in that region made to renewable energy in general and to wind in particular. But Northern Europe also has some important geographical advantages. Research by the German Wind Energy Institute reveals that the UK, the Netherlands, Belgium, Denmark, and Germany collectively have a wind resource at sea equivalent to three times their electricity needs. The offshore wind resources are considerably more powerful than the available wind resources on land in Europe. Moreover, because the North Sea is relatively shallow, with a depth of only 131 feet, construction of wind turbines offshore is less expensive than in many other possible maritime locations around the world.

Another advantage is that noise and visual intrusion is often less of a concern for offshore farms than for those built on land. In fact, many of the future offshore installations in Europe will be constructed beyond the horizon, so they will be nearly invisible from the coast.

So, given these advantages, why hasn’t there been more offshore wind development in Europe? For one thing, construction costs remain higher than on land, although they are likely to fall as there is greater experience with offshore construction. . In addition, some environmental organizations, such as the World Wide Fund for Nature (WWF), believe that more basic research needs to be conducted to make sure that large wind farms don’t pose a threat to the environment. Up to now, there has been relatively little study of the effects offshore wind projects will have on birds, fish, sea mammals, and animals on and below the seabed floor. Various groups have raised concerns are potential problems. In Denmark, for example, the fishing industry has demanded compensation in case their fish stocks decrease. Some inhabitants of North Sea islands worry about the safety of ships and effects on tourism, if the seascape gets filled with wind turbines.

Although such concerns deserve close attention and careful investigation, it currently appears highly likely that significant further offshore wind development can take place in Europe without causing major environmental or economic dislocations. Offshore wind farms seem poised to provide not only Europe but other parts of the world with large quantities of safe, clean, renewable electricity.

If you would like further information about offshore wind development, visit the website of the German Wind Energy Institute at www.offshore-wind.de/en/facts/ or the website of the Danish Wind Energy Industry Association at www.windpower.org. The latter site includes pictures and information on the Middelgrunden project. For information on the Horns Rev project, including geographical and environmental issues, download www.ens.dk/nyt/Hoeringer/VindHornsRev/Resume_eng.pdf. More general information on wind energy is available from the American Wind Energy Association and the US Department of Energy.

Bea Kölle was an intern at NESEA. She lives near Stuttgart, Germany.