The US wind energy industry is now providing enough capacity to power 13 million homes, equivalent to all of Nevada, Colorado, Wisconsin, Virginia, Alabama, and Connecticut combined.

The American Wind Energy Association (AWEA) used the annual National Clean Energy Summit in Las Vegas last week to confirm that the sector had passed the 50GW installed capacity milestone after yet another quarter of rapid growth.

The trade body said the 50GW of capacity was equivalent to the generating power of 44 coal-fired power stations or 11 nuclear power plants, resulting in emission reductions that would equate to taking 14 million cars off the road.

The milestone was achieved thanks to a surge in new wind farms coming online as developers rush to complete projects before the possible lapsing of the US government's crucial production tax credit (PTC) at the end of this year. According to AWEA, over 2.8GW of capacity has now been added during the year to date, while total US wind energy capacity has doubled since 2008.

"This milestone for wind-energy production marks continued success for this clean, renewable and domestically produced energy source," said Republican Senator Chuck Grassley, who helped develop the PTC. "Wind energy has exceeded expectations since I first authored the tax incentive, in 1992, and offers an ideal for expanded production and use of alternative energy sources in the future."

However, growing numbers of wind energy firms are increasingly concerned about the future of the incentive, after Republican Presidential candidate Mitt Romney this month confirmed that if elected he would not extend the PTC when it lapses at the end of the year.

"These truly are the best of times and could be the worst of times for American wind power," said AWEA chief executive Denise Bode. "This month we shattered the 50-gigawatt mark, and we're on pace for one of our best years ever in terms of megawatts installed. But because of the uncertainty surrounding the extension of the Production Tax Credit, incoming orders are grinding to a halt.

"Layoffs have begun up and down our American manufacturing supply chain, which the industry has so proudly has built up in support of the US economy and made-in-the USA manufacturing... Congress must act now to give wind energy a stable business environment to keep producing all this homegrown power, and save 37,000 American jobs by the first quarter of next year."

