European Offshore Wind Projects Confront Challenging Seas

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Rødsand 2 offshore windRødby, Denmark--As the winds blowing over Lolland Island turned a morning drizzle into a cold shower, Bjarne Haxgart told his crew that, as on many days this past August, they would stay indoors.

"This year we have had an awful lot of wind," said Haxgart, site manager of the Rødsand 2 offshore wind farm. "It's a big difference for the people who are out there doing the work. If it's a little windy, they would be green in the face by the time we got there."

Rødsand 2, a 90-turbine project sited three kilometers from Denmark's southern coast, is scheduled to supply 200,000 households with electricity by next September as part of the country's drive for wind energy to supply at least 50 percent of electricity consumption by 2025 [PDF].

The project is still in the installation stage, and costs climb for every day that construction crews sit idle. Poor weather conditions prevented crews from working for almost twice the number of days in August than the project owner, German energy company E.ON, had predicted.

"We damn the wind because we can't go out there if the waves are more than 75 centimeters high," Haxgart said.

E.ON is not the only developer frustrated by the challenges of establishing offshore wind farms. Project developers across Europe have found that mastering turbulent seas and harsh weather is more difficult than many expected, especially as projects are sited farther from the coast and are built with larger turbines.

Denmark's Horns Rev 2, the largest offshore wind project in the world, was inaugurated this September following two months of installation delays due to bad weather. The London Array, a 1 gigawatt (GW) project set to be the largest offshore project when it is completed, is still on track with a €2.2 billion ($3 billion) initial investment despite nearing financial ruin on several occasions. Alpha Ventus, Germany's first offshore wind farm, went online in August after a year of delays that led the project's budget to increase from $270 million to $357 million.

"Wind projects are lagging behind. There should be offshore wind by now, but it isn't there yet," said Malte Kreutzfeldt, environment editor of the German newspaper Die Tageszeitung. "It turns out it's a lot more expensive than people thought, a lot more complicated."

Regardless, several European governments are betting that offshore wind will prove to be affordable. Denmark plans to expand from its existing and approved 825 megawatts (MW) of offshore wind to more than 3 GW by 2025. The British government has proposed 14 GW of offshore wind by 2020. The German government has set a goal of 25 GW by 2030.

Across Europe, seven offshore wind farms were installed last year, with a combined capacity of 1.47 GW. The European Wind Energy Association (EWEA) expects offshore wind to reach 2 GW continent-wide by the end of 2009, and an additional 1 GW to be installed in 2010. According to the 2010 projection [PDF], offshore wind would supply 0.3 percent of the European Union's electricity demand.

"This is the big potential for the future and we want to do it," said Sascha Müller-Kraenner, the Berlin-based European representative of The Nature Conservancy. "The future of wind in Europe will be off the coast."

Even with the recent acceleration of offshore wind projects, the industry has only installed as many turbines as the onshore wind industry had in the early 1990s. While turbine manufacturers have found the optimum size and technology for onshore installations, the offshore devices still require considerable progress.

Most offshore wind farms are found 20 kilometers from shore, at depths of 20 meters. As projects move to windier areas even farther offshore - German developer Geo GmbH has proposed a 4 GW project 200 kilometers into the North Sea - the costs for equipment, installation, and maintenance will rise.

Ultimately, the EWEA envisions projects on the scale of 200-300 MW and beyond. Such a large investment would encourage more streamlined construction processes and the manufacturing of advanced installation vessels and technologies.

In the meantime, however, installing 2 GW of offshore wind per year may lead to a shortage of installation equipment, such as crane-equipped vessels, after 2011, according to New Energy Finance, an energy analyst.

Projects also lack trained personnel to operate the installation boats and perform regular maintenance. Rødsand 2 requires 100 workers on a given day, most of whom are trained to construct harbors, not turbines.

"There is a whole range of issues to be tackled," said Paolo Berrino, an EWEA information officer. "Installation and maintenance, specific wind turbines for the offshore environment, maritime spatial planning, development of sub-structures for deep water installations, and most importantly, the construction of an offshore grid and interconnectors that would integrate the huge potential of offshore wind into the European electricity system."

Europe is beginning to address these larger questions. The United Kingdom, Germany, Denmark, Belgium, and the Netherlands have zoned offshore wind areas. Offshore grid plans are under development for the North Sea and the Baltic Sea.

On a project-level, smaller questions are providing enough of a challenge. Turbine structures must be placed at exact depths to avoid damage during the winter ice. Fiber cables must not bend as they are placed delicately under the seafloor. The effect on the offshore environment - sediment flow and sea life - must be kept to a minimum.

For the Rødsand 2 crew, the financial costs of delay have sunk in, Haxgart said.

"It's very costly. You have to do an awful lot of planning," he said. "If you go out there and you forget the wrench, it's not very popular to go back."

Reporting for this story was made possible courtesy of funding provided by the German and Danish foreign ministries.

Ben Block is a staff writer with the Worldwatch Institute. He can be reached at

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