Wind power is one of the fastest-growing sources of energy around the world. It is popular because it is abundant and provides many communities with a clean, local source of electricity, as opposed to imported fossil fuels. In the United States, which passed Germany to become the country producing the most wind power, the Department of Energy has estimated that wind power could account for 20 percent of the nation's electricity supply by 2030.

Despite a crippling recession and tight credit markets, the American wind power generator industry grew at a blistering pace in 2009, adding 39 percent more capacity. The country is close to the point where 2 percent of its electricity will come from wind turbines.

The American Wind Energy Association said the growth of wind power was helped by the federal stimulus package, which extended a tax credit and provided other investment incentives for the industry.

But the growth could slow. Much of the wind development in 2009 was caused by momentum from 2008, as huge turbines ordered then were delivered to wind farms. In 2009, the recession idled many manufacturers and new orders weakened. And despite a decade of efforts, not a single offshore turbine has been built in the United States. Although in spring 2010, Interior Secretary Ken Salazar approved the the nation's first offshore wind farm, a highly contested project off the coast of Cape Cod.

Developing wind generators has two main problems. First, the wind does not blow all the time, so there must be backup power plants (often fueled by natural gas) ready to turn on instantly if the wind slackens. Secondly, the wind sometimes blows the hardest in remote plains, far from cities that need the energy. In Texas, the leading state for wind power production (followed by Iowa and California), the wind turbine generator is strongest on the mesas and high plains of West Texas, hundreds of miles from big cities like Dallas and Houston. Building transmission lines is expensive and difficult.

The idea of building wind farms offshore, in the sea, is gaining momentum. Putting turbines in the water is expensive, but the advantage is that the wind blows much harder off the coasts, and unlike wind over the continent, which often blows hardest at night, offshore breezes can be strong in the afternoon, matching the time when people are using the most electricity. Offshore turbines can also be located close to the power-hungry populations along the coasts, eliminating the need for new overland transmission lines. And if the turbines are built far enough from shore, they do not significantly alter the view — a major objection from many local opponents.<

Europe has already ventured into offshore wind territory — there are wind turbines off the coasts of Denmark, Britain and seven other European countries. China's first offshore wind farm is a 102-megawatt venture near Shanghai, with more in the pipeline. In the United States, at least half a dozen offshore wind projects have been proposed in the shallow waters off the East Coast and the Great Lakes. But the projects face many hurdles. The proposal to build Cape Wind farm off Cape Cod stalled for nine years before the federal government approved it. The project pitted coastal Indian tribes, business interest and homeowners against the developer and proponents of alternative energy.