Last month, the United States added 433 megawatts of new electricity generation. And according to SustainableBusiness.com, all 433 of those megawatts came from renewable sources.

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Five wind projects totalling 300 megawatts (MW) and 18 solar projects for 133 MW were added, according to the latest “Energy Infrastructure Update” from the Federal Energy Regulatory Commission’s Office of Energy Projects.

And renewables account for almost half (43.8%) of all new capacity that’s come online this year so far: 77 wind projects (4,055 MW); 154 solar projects (936 MW); 76 biomass projects (340 MW); 7 geothermal projects (123 MW); 10 water power projects (9 MW); and 1 waste heat project (3 MW).

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That’s a 29% increase from the first nine months of 2011. Renewable energy sources now account for 14.9% (including hydro) of all installed U.S. electrical generating capacity. Excluding hydro, renewables now supply over 5% of US electricity.

EIA.govTotal generation from all sources. Click to embiggen.

EIA.govTotal generation from renewables. Click to embiggen.

So if the United States is generating about 5 percent from renewables each month, we only need … [gets out his calculator] … let’s see … carry the one … about, oh, a lot of years of months exactly like September until we’re finally renewable-only.

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Oh, that’s assuming that the wind production tax credit is renewed. Sigh [gets out his calculator again].