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| Offshore sites | Graph showing increase in windpower off shore from 750 megawatts in 2008 to 2,300 megawatts in 2015 and then to 4,000 megawatts in 2030 |
Power From The Sea - The Offshore Revolution
National Action Plan
Offshore Advantages
Reducing Costs
Local environmental effects
Europe Moves Offshore
Quotes
...gift to the earth quote (to be found precisely)... Svend Auken, Danish Minister for Environment and Energy
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| Offshore sites | Graph showing increase in windpower off shore from 750 megawatts in 2008 to 2,300 megawatts in 2015 and then to 4,000 megawatts in 2030 |
Building wind farms out to sea could dramatically transform the Danish power supply system. A national action plan shows how more than 4,000 megawatts of wind power could be installed off the coast of Denmark by the year 2030. Meeting 40 per cent of electricity demand, this would take the country firmly into the lead in the world wind power league.
Improved technology should enable the offshore schemes to be built just as cheaply as on land. By saving millions of tonnes of carbon dioxide emissions from coal-fired power stations they will also make a major contribution to the fight against global warming.
Denmark's ambitious plans for offshore wind power were drafted following a major series of studies undertaken by the Danish Energy Agency and the two main electricity companies, Elsam and Elkraft[1]. The action plan focuses initially on four specific sites around Denmark's coastal waters. Each of these will contain large wind parks of between 80 and 100 large turbines.
In a phased programme starting in the next two years, the aim is to have at least 750 megawatts (roughly 500 turbines) of offshore wind power in place by 2008. These will mainly be developed by the two large utilities, the first time they have taken such a prominent role in Denmark's wind industry.
The first five utility wind farms, with a total capacity of 670 megawatts, are expected to involve an investment of over DKK 7,800 million (US$ 1157 million). Apart from ongoing support programmes for renewable energy (see Briefing 5), no additional government funding will be made available.
A further batch of large wind farms could bring the offshore capacity up to 2,300 megawatts by 2015. After that, a second list of sea areas will be exploited, building up to a total of 4,000 megawatts by 2030. The first large offshore scheme should be in place soon after the millennium.
Making the first announcement at a United Nations conference on climate change in New York last summer, Danish Environment Minister Svend Auken described the offshore wind plan as his "gift to the earth". Because the wind is stronger, savings of carbon dioxide, the main greenhouse gas, are up to 50% more than on land.
The first 750 megawatts of offshore capacity will save 2.1 million tons of carbon dioxide every year, contributing 17.5% to the national reduction target for 2005 (see Briefing 5)
The main attraction of going offshore is the enormous wind resource available. Average wind speeds can be 20 per cent higher, and the resulting energy yield up to 70 per cent greater than on land. The lack of obstacles such as hills, and the generally smooth surface of the sea, also makes the wind more reliable.
The other incentive is the difficulty of finding enough suitable wind turbine sites on land, especially in the densely populated and relatively flat countryside of a country like Denmark.
Denmark already has experience of offshore wind development. Two pilot wind farms of 5 megawatts capacity each were built at Vindeby in 1991 and Tuno Knob in 1995. Both have performed extremely well and provided valuable feedback for the new action plan.
Two factors will help reduce the construction costs of offshore schemes, up to
now considered the main stumbling block to major expansion. One is the use of
wind turbines up to three times larger than the 500 kilowatt models in use at
Tuno Knob. Such 1.5 megawatt turbines have already been installed successfully
in substantial numbers in several European countries. By building wind farms of
100 machines or more, economies of scale are achieved and much better use made
of expensive cabling needed to transfer the electricity back to shore.
The other factor is an important breakthrough in the method of constructing the
all-important foundations. New engineering studies monitored by the Danish
Energy Agency suggest that foundation costs could be cut by over a third if
steel is used rather than concrete. Steel has the advantage of being lighter
and therefore easier to transport and install. Foundations accounted for 23% of
costs at Tuno Knob.
Economic studies by the utilities and engineering companies also show that it will be possible to install turbines at sea depths of up to 15 metres without any significant cost increase. This opens up a much wider area of the sea to development.
Since the bigger turbines produce more power, the cost of electricity from the new large scale parks is expected to compare favourably with a coal-fired power station. In the long term, offshore prices should fall even further as the technology is optimised for conditions at sea, even larger turbines are used, and already established grid connections to the shore are used for "add-on" wind farms.
Rather than have scattered small scale developments close to the coast, where they might clash with leisure interests, the Danish action plan recommends a small number of very large wind parks further out to sea. The new wind farms will be built in general at a distance of between seven and ten kilometres from the coastline.
The impact on sea birds, especially diving ducks which use shallow coastal waters to find food in winter when other water is frozen, has also been studied. The results from Tunø Knob show that the eider ducks which live and breed in this area have not been frightened away by the presence of turbines. At Vindeby, the turbine foundations have even encouraged fresh colonies of marine animals for birds to feed on.
Offshore wind is moving ahead in other European countries apart from Denmark.
In the Netherlands two wind farms have already been built in the shallow waters of the Ijselmeer. The Dutch government has now approved a 100 turbine wind park off the North Sea coast. This would generate enough power for up to 100,000 households.
Sweden's first offshore wind park, with five 500 kilowatt Danish turbines, was built near the island of Gotland last year. An industrial consortium now has plans to construct a 48 megawatt wind farm in the sea near the port of Malmo, whilst another company is aiming for as much as 750 megawatts offshore.
Several offshore projects are being planned off the United Kingdom coast, and the government is discussing with the wind energy industry how to progress such schemes. The British Wind Energy Association predicts there will be "turbines in the water" by early 2001.
"Offshore wind energy is a little more expensive than conventional power in Denmark. But if you take the environmental costs of fossil fuels and internalise them, it's very competitive indeed." Svend Auken, Minister for Environment and Energy.
[1] "Action Plan for Offshore Wind Farms in Danish Waters", Danish Energy Agency, June 1997.