The latest Energy Infrastructure Update report from the Office of Energy Projects, part of the Federal Energy Regulatory Commission (FERC), lists just shy of 13GW of green energy projects coming online last year, a more than 50 percent rise on the 8.5GW of capacity added in 2011.
Wind projects led the way in 2012 with 164 new developments totalling over 10.5GW of capacity, a figure that dwarfed the 8.7GW of new natural gas generation capacity and 4.5GW of coal added in the same period.
In addition, around 1.5GW of new solar capacity was added, along with 0.5GW of biomass and 0.1GW of geothermal projects.
As a result, wind power for just under five percent of the United States' total electricity capacity, which is still well short of the 42 percent provided by natural gas and 29 per cent from coal. Of the other green energy sources, hydropower contributes almost 8.5 percent, biomass 1.3 percent, and solar 0.3 percent to the power mix.
The increase in capacity will come as good news for the renewable energy sector, which saw investment fall for the first time during 2012.
Ken Bossong, executive director of non-profit research organization the SUN DAY Campaign, said: "If there were still any lingering doubts about the ability of renewable energy technologies to come online quickly and in amounts sufficient to displace fossil fuels and nuclear power, the 2012 numbers have put those doubts to rest."