Floating wind farms placed far offshore could lead to affordable electricity -- without cluttering the view. GE has announced a $27 million partnership with the U.S. Department of Energy to develop 5-7 megawatt turbines by 2009, each of which could power well over 1,000 homes. Supplanting the company's current 3.6 megawatt turbines, these giant energy factories should make wind power more economical, since the major cost of building and installing offshore wind farms does not depend primarily on a turbine's size, but on the number of them that need to be erected. By 2015, GE could have even bigger, 10-megawatt turbines, according to Jim Lyons, leader of advanced technology for GE's wind energy business. Based on wind-speed measurements, researchers at MIT, led by Stephen Connors, director of the Analysis Group for Regional Electricity Alternatives, calculated that large turbines located far offshore could ultimately cost less per power generated than either land-based turbines or near-offshore ones, even factoring in extra costs, such as much longer underground electricity transmission cables. The upside: much more fast and steady wind, which would allow the turbines to generate power at 50 percent capacity on average throughout the year, compared with 30 percent or less with on-land turbines.
Offshore wind farms could also have the advantage of being close to big cities, unlike wind farms in remote areas, which require significant power grid upgrades to transport the power to places where it's needed. Making the technology cheap enough to be feasible will not be easy. "You've got to push all the buttons to get the costs down," Lyons says. Using a combination of far-offshore and land-based farms, however, one day it may be possible to provide 20 percent of U.S. energy from wind, he says.
the article was describing plans for 95m tall towers and 140m rotors. So 300+ ft tall for the 3.6MW version. the diagram of wind towers.
The 5MW plan has tower height of 120m. Or almost 400 feet. The tip of the rotor would reach 180m. A 10 MW version planned for 2015 will probably be 200m tall for the tower which is an over 650 feet tall tower.