Tens of kilometers from shore, the wind blows faster and more steadily than it does on land. But offshore wind farms are expensive and complicated to build and maintain. The Danish company Dong Energy is constructing what will be one of the world’s largest such farms, a 367.2-megawatt, $1.5 billion project off the coast of England. It will use Siemens wind turbines as tall as a 30-story building.
Under threatening skies, ships lay power cables between the 150-meter-high turbines and an offshore substation (left), where the voltage of the current they generate is increased before it’s transmitted the 45 kilometers to shore. The turbines can produce 3.6 megawatts each, twice as much as those commonly used on land.