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Friday, November 04, 2005

Floating Wind Farms? Why Not, it Works for Oil Rigs

Green Car Congress reports today that the Norwegian energy and aluminum company, Hydro, is working to develop floating wind turbines for use in offshore power generation. The company, which has experience in offshore oil rigs, will base the design on the same type of floating concrete structure technology applied in the North Sea oil industry for offshore rigs. The floating turbines, dubbed the Hywind system, are designed to work in sea depths of 200–700 meters (656–2,297 feet).

Hydros system entails mounting a regular offshore wind turbine on top of a 120 meter high floating concrete cylinder with ballast that will be fastened to the sea floor with three sturdy anchor lines [see accompanying graphic]. The electric power generated by the turbines will be transported to shore by buried power lines or, according ot Hydro, possibly to offshore oil platforms.

According to Hydro, who has measured wind speeds in the North Sea for more than 30 years, the average wind speeds at sea are higher than on land, and they expect the offshore Hywind to be exceptionally energy efficient. The Hywind system will potentially allow deployment of offshore wind farms in depths deeper than traditional offshore wind farms or perhaps will offer a lower cost alternative to such traditional farms who's towers must be sunk into the sea bed.

The Hywind system is currently undergoing model testing is at the Norwegian R&D institute Sintef Marintek’s ocean basin laboratory in Trondheim. According to Alexandra Bech Gjørv, Hydro’s director of new energy forms,

Hywind is a future-oriented project combining our offshore oil industry experiences with our knowledge of wind power to take advantage of wind resources where it blows most: at sea. If we succeed, this can become an important part of our future energy supply.

Hydro is planning a demonstration project based on 3 megawatt wind turbines scheduled to commence in 2007. The turbines will have hub heights 80 meters above the sea’s surface and will have a rotor diameter of about 90 meters [see accompanying graphic].

The company eventually plans to develop wind turbines with a power capacity of 5 MW and a rotor diameter of approximately 120 meters. They plan to be building these turbines in 10-15 years. Again, Hydro's Alexandra Bech Gjørv:
The future goal is to have large-scale offshore wind parks with up to 200 turbines capable of producing up to 4 terawatt hours (TWh) per year and delivering renewable electricity to both offshore and onshore activities. This goal is far in the future, but if we’re to succeed in 10-15 years, we have to start the work today.

Hydro has already invested some NOK 20 million (US$3 million) into developing the Hywind concept over the past three years and further realization of research as well as the demonstration project will require at least another NOK 150 million (US$22.8 million). According to Hydro, for the concept to work, the turbines must be light which will require further technological developments.

The Energy Blog reported Thursday that Thomas Lee has also invented a floating wind-hydrogen platform. This version consists of several wind turbines are mounted on a floating platform, much like an oil rig, and makes use of battery storage. By storing the energy in batteries it is available continuously or in response to peaks. His proprietary hydrogen production system does not employ electrolysis, but involves batteries. Not all platforms would necessarily produce hydrogen. [What the heck does this mean? How can you make hydrogen out of batteries? Anyone?]. The navigable unmanned platform would be controlled remotely and by pulling up its anchors could be navigated out of the way of approaching storms. Lee's company, Stanbury Resources Inc., has approached U.S. companies for licensing agreements, but has not found much interest. A large Asian conglomerate and an European group both would like exclusive agreements.

The U.S. Department of Energy's National Renewable Energy Laboratory has aparently also conducted a feasibility study on floating turbine farms and found that they could be built using existing technology and provide electricity at approximately $0.05/kWh.

An innovative idea. It seems like these turbines would likely have less of an environmental impact than turbines who's towers are sunk into the seabed. However, the teathers may be harder to sense and avoid for aquatic animals. I guess we'll have to wait for an environmental impact study.

Regardless, these turbines offer the potential to open up larger areas of offshore wind resources for development. Each of these technologies may also allow the deployment of wind farms far enough off shore to avoid NIMBY criticisms about the turbines spoiling oceanfront views.


  • Hydro pdf on Hywind floating wind turbine system

  • "Sea-based windmills could blunt eyesore criticisms", Reuters, November 2, 2005

  • "Floating offshore wind energy and hydrogen fuel generating company tipping to Europe and Asia", Open Source Energy Network, November 31, 2005

  • US DOE's National Renewable Energy Lab feasibility study on floating wind farms

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