U.S. wind-energy developers added a record 13,124 megawatts of turbines last year, beating natural gas to become the largest new source of power generation for the first time.

In the fourth quarter alone, 8,380 megawatts of wind farms were completed, more than double that of any prior quarter, according to the Washington-based American Wind Energy Association. That amounted to 42 percent of new power supplies, more than any electricity source including natural gas, coal, solar and nuclear. topping natural gas

Installations accelerated last quarter as developers raced to take advantage of a federal tax credit that was due to expire Dec. 31, and have slumped this year, according to Rob Gramlich, the industry group’s interim chief executive officer. There are 43 megawatts of wind turbines currently under construction in two states. The production tax credit was extended for one year Jan. 1.