NORWAY KNOWS OCEANS, BUILDS DEEP WATER WIND

Seeking Wind Energy, Some Consider the Sea
Henry Fountain, November 18, 2009 (NY Times)

"…[O]ver the next two years [the Hywind project owned by Statoil, the giant Norwegian oil and gas company] will test the feasibility of what some people think may be the next big idea in alternative energy: generating power from the winds over the open ocean, far from land [using the world’s first full-scale floating wind turbine, which was hooked up to a transmission cable and began supplying 2.3 megawatts of electricity to the Norwegian power grid on Sept. 21]…

"Deepwater turbines are meant to solve some of the problems of existing land-based turbines and those that are built on foundations in shallow water…Floating turbines can be located over the horizon, out of sight of land, eliminating aesthetic and noise concerns that have delayed projects…Deepwater farms can be established far from shipping lanes, aircraft flight paths, commercial or sport fishing grounds, and known migratory paths of birds and marine animals, potentially easing the process of obtaining the necessary approvals and permits."

Floating wind - the concept. (click to enlarge)

"And farther offshore, winds are stronger and more consistent, with no surface obstructions to slow the air down. This better-quality wind is also closer to population centers on both coasts. Why pay to transmit power from large wind farms on the Great Plains to the coasts, deepwater proponents argue, when better sources of wind are sitting just a dozen miles or so offshore?

"But the concept of floating wind turbines has its own problems, not the least of which is cost…More than $70 million has been spent on the Statoil project since a couple of employees came up with the idea while out sailing eight years ago…Because it relies on a long ballasted cylinder to keep it stable, the Hywind design has to be assembled in deep water, using floating cranes and large barges…[There are other designs but]…with turbines at 10 miles or more from land, the costs of installation, maintenance and repair would be high. And transmitting power through undersea cables would be expensive…particularly if newer, more efficient methods like high-voltage direct current technology are used."

Floating wind - the reality. (click to enlarge)

"Aside from costs, there are many technical unknowns [and complicated engineering issues] about the performance of wind turbines at sea…Most of the structural technology is borrowed from the offshore oil and gas industry, which has been building floating platforms for decades. But no platform can be made completely stable, and movement caused by ocean swells and storms can create unique stresses on the turbines…[I]f a platform pitches in rough seas, the turbine’s spinning rotor can induce a gyroscopic load on the rest of the system…

"No one knows what the best design will be, but… having a full-scale prototype in the water had helped [Statoil’s] cause…[and] Statoil’s reputation in the oil and gas industry…may help it attract other companies to develop different turbines, assembly ships and the other specialty equipment needed for the technology to develop…"