Because the winds are strongest several miles offshore, the turbines would be mostly out of sight of land, built on floating platforms anchored some 12 to 20 miles off the coast in waters 100 to 200 meters, or 330 feet to 660 feet, deep.
That should pose no problem. "The oil industry has been using floating platforms for 20 to 30 years," Dagher said. Two main designs exist - the tension-leg platform and the spar buoy. The platform has horizontal "legs" attached to a buoyant central structure and secured by tensioned cables to gravity anchors - essentially heavy weights - on the ocean floor. "The tension, fighting against the buoyancy of the platform on top, keeps it stable even in storms or heavy waves," Hart said.
A spar buoy "looks like a large pencil floating in the water, point down toward the ocean floor," Hart said. Up to 300 feet long, and mostly submerged, the underwater section acts like a ship's keel to stabilize the structure, which is anchored with mooring lines only "because you don't want it waltzing around the ocean," he said.
Thursday, November 27, 2008
The start of something big
Now this is what I'm talking about: Matthew Simmons wants to build a 5-Gw wind farm using massive, far-offshore turbines that haven't exactly, uh, been designed or built yet.