According to FERC’s Office for Energy Projects, biomass, geothermal, solar, hydro and wind power accounted for 49.10% of all new power generating capacity installed in 2012 - a total of 12.9 GW. More than a quarter of that new capacity 3.3GW came on-line in the month of December 2012 alone, the report added.

Wind led the way in 2012 with over 10.6 GW installed, while solar saw 1.5 GW installed. Biomass added 100 new units with a total capacity of 543 MW while geothermal steam and water each had 13 new units with installed capacities of 149 MW and 99 MW respectively.

“If there were still any lingering doubts about the ability of renewable energy technologies to come on-line quickly and in amounts sufficient to displace fossil fuels and nuclear power, the 2012 numbers have put those doubts to rest,” said Ken Bossong, executive director of the Sun Day Campaign, a group set up to promote the use of renewables in the US. “Not only has renewable energy become a major player in the US electrical generation market, but it has also emerged in 2012 as the reigning champion.”

The figures represent an increase of 51% compared to 2011, when renewables accounted for 39.33% of all new generation capacity.

By comparison, there was 8.7 GW of new gas generation installed in 2012, 4.5GW of new coal, 125 MW of new nuclear and 49 MW of new oil-fired power stations.

Renewable sources now account for 15% of total installed US operating generating capacity, with hydro accounting for 8%, wind 4.97%, biomass 1.3%, solar 0.34%, and geothermal - 0.32%. This is more than nuclear (9.24%) and oil (3.57%) combined, FERC added.