U.S. wind power accounted for 6 percent of the nation's total electricity generation capacity after developers rushed to finish projects before expiration of a subsidy, Bloomberg New Energy Finance said.

The threat that the U.S. Production Tax Credit would lapse on Dec. 31 prompted developers to complete as many projects as they could last month, the London-based research group said. A record 13.2 gigawatts of turbines were installed last year including 5.5 gigawatts in December, the most ever for a single month. Total wind capacity is about 60 gigawatts.

“It’s clear that the economics, aided by the Production Tax Credit, drove wind growth in 2012,” said Amy Grace, lead analyst on wind in North America for New Energy Finance. “Capacity was built without any near-term state mandated demand. This means that in most areas, utilities are buying wind power because they want to, not because they have to.”

The credit has been extended for a year to cover wind farms that start construction in 2013. Previously it only covered projects that started working by the expiration date.

Uncertainty about whether the credit would be extended meant developers and investors haven’t built up a backlog of projects for 2013.

Asset financing for U.S. wind farms dropped to $4.3 billion in the second-half from $9.6 billion in the first six months of last year. This has hurt component makers such as Vestas AS, Gamesa Corp Tecnologica SA and Clipper Windpower Ltd., which is owned by Paltinum Equity LLC.

Share Drops

Vestas declined as much as 41 percent in the past year and Gamesa by 39 percent.

Equipment prices for wind have dropped by more than 21 percent since 2010, and the performance of turbines has risen. This has resulted in a 21 percent decrease in the overall cost of electricity from wind for a typical U.S. project since 2010, New Energy Finance said.

Last year’s numbers are especially “striking” given the current price of natural gas which sank below $2 per million British thermal unit in April, the lowest in a decade. At this price, natural gas plants present “stiff” competition for wind projects, the research company owned by Bloomberg LP said.

Copyright 2013 Bloomberg

Lead image: Wind turbines via Shutterstock