The Department of the Interior is proposing a large expansion of U.S. efforts to make energy from offshore winds, with a plan centered off the Massachusetts coast. Here, a 2010 photo shows a sunrise over Nantucket Sound. Julia Cumes/AP hide caption

itoggle caption Julia Cumes/AP

The offshore wind farm in the North Sea near Borkum, Germany, is nearly complete. The Riffgat facility, seen here on June 23, includes 30 turbines, each with a generating capacity of 3.6 megawatts. David Hecker/Getty Images hide caption

itoggle caption David Hecker/Getty Images

A maintenance worker looks out over an off-shore wind farm in Liverpool, England in 2008. Some people are concerned about the potential health effects of noise from wind turbines. Christopher Furlong/Getty Images hide caption

itoggle caption Christopher Furlong/Getty Images