Floating wind

Hywind

Two of the five floating wind turbines, in Norway, before being floated to Scotland

This summer marks a new era in wind power. The world’s first commercial scale floating offshore wind farm is taking shape off Peterhead in Scotland. The Hywind project is just 30MW, so small for a commercial wind farm, but groundbreaking in that the turbines are floating rather than standing on the seafloor. This is hugely significant. Offshore wind has so far been restricted to shallow continental shelf areas such as the North Sea. Many areas of the world wish to develop more diverse renewable energy portfolios but do not have much in the way of suitable shallow waters. Japan and Korea, California and Hawaii, France and many other countries look set to develop floating offshore wind systems over the next decade or so. Currently the cost is higher than for traditional offshore wind, but it is projected to fall as systems are scaled up.

Norwegian oil and gas company Statoil has designed and built the system, using five Siemens 6MW turbines, and a range of other companies for various parts of the supply chain. The towers will have a total height of 258 metres, 178 metres above water and 80 metres below. The base will be filled with iron ore to give ballast and be tethered to the seabed. The turbines are assembled on the Norwegian fjord of Stord and floated in their vertical state across the North Sea. This allows very fast deployment, about seven weeks for the whole wind farm. As things are scaled up this will become a very important area of cost saving. Compare this to the decade or so involved to build a typical nuclear power station. The Hywind project is 75% owned by Stadoil and 25% by Masdar. Stadoil refer to this as a pilot project. If it works well in the testing conditions off North East Scotland global orders will come in, which will trigger falling costs and more orders. I think it likely that very large floating windfarms in the deep water off Japan, Korea, California and the Breton coast of France will be built over the next decade. Will it be Stadoil who builds them or will rival firms emerge with better and cheaper designs?

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