Earth Equity News

Norway Installs First Major Floating Turbine. Economist, September 3, 2009. "StatoilHydro, a Norwegian energy company, and Siemens, a German engineering firm, have first of their floating offshore turbines [for] a two-year test period generating about 1 megawatt of electricity -- enough to supply 1,600 households. The Hywind is the first large turbine to be deployed in water more than 30 metres deep. The depth at the prototype's location, 10 kilometres (six miles) south-west of Karmoy, is 220 metres. But the turbine is designed to operate in water up to 700 metres deep, meaning it could be put anywhere in the North Sea. Three cables running to the seabed prevent it from floating away. It is an impressive sight. Its three blades have a total span of 82 metres and, together with the tower that supports them, weigh 234 tonnes. That makes the Hywind about the same size as a large traditional offshore turbine. Even though it is tethered, and sits on a conical steel buoy, the motion of the sea causes the tower to sway slowly from side to side. This swaying places stress on the structure, and that has to be compensated for by a computer system that tweaks the pitch of the rotor blades to keep them facing in the right direction as the tower rocks and rolls to the rhythm of the waves. That both improves power production and minimises the strain on the blades and the tower."