The densely populated U.S. East Coast could meet close to half its current electric demand by relying on offshore wind turbines, a study by an ocean conservation group found.

North Carolina, South Carolina, New Jersey, and Virginia offer the most potential for easily captured wind energy, according to the Oceana study, which estimates that the 13 coastal states could together generate 127 gigawatts of power.

That represents the potential for far more wind power than the United States currently generates. At the end of 2009, the nation's land-based turbines were capable of producing some 35,000 megawatts of power--enough to meet the needs of 28 million typical American homes.

Investment in new wind turbines has surged in recent years, boosting sales at turbine makers including General Electric, Vestas Wind System, and Siemens.

However, all the U.S. wind farms built so far are on land. Advocates of offshore wind installations, led by backers of the Cape Wind facility proposed off the Cape Cod beach area in Massachusetts, have been working for almost a decade to try to win approval to build offshore turbines.

Opponents of Cape Wind argue that it could harm fisheries as well as sully views in a region dependent on tourism.