As predicted, almost half of the new power-generating capacity installed in the United States last year was renewable.

The Federal Energy Regulatory Commission recently released its December update on the nation’s energy infrastructure [PDF]. When we last checked on the data, it suggested that some 46 percent of new capacity — January through October — was renewable. Well, that ratio improved over the last two months of the year. Ultimately, 49.1 percent of new capacity was renewable.

new generating capacity 2012

Compare that to 2011, when less than 40 percent was renewable.

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new generating capacity 2011 explains that end-of-year boost.

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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.

Around a quarter of this capacity became operational in December alone, as wind energy developers rushed to complete projects before the feared expiration of federal tax credits.

We noted last September the furious rush to bring those projects to completion. Seems like it worked.

The FERC report breaks out the new capacity by type.

new capacity by type

Wind ended up being the biggest new source of capacity, beating even natural gas (which itself had a pretty good year).

The question is: Can this pace be sustained into 2013? The tax credit was extended as part of the fiscal cliff deal, but only temporarily. Our David Roberts thinks 2013 will be another big year for the industry. It will certainly be better than it would have been without the extension — but we’ll have to wait 12 months to see if Roberts is right.