Wind energy generation was by far the star performer, topping the list at 164 new units totaling 10,689 MW. Solar had 240 new units representing a generation capacity of 1,476 MW, followed by biomass with 100 new units at a generation capacity of 543 MW. Geothermal steam and water units completed the line-up, with 13 new units each, representing generating capacities of 149 MW and 99 MW respectively. New installed renewable capacity increased 51.16 percent from 8,571 MW in 2011, when renewable units accounted for 39.33 percent of total newly built generation capacity. Since legacy fossil-fuel systems still represent most of the total stock of electricity generating capacity in the United States, renewable energy sources only account for 15.40 percent of the total. But this capacity outpaces the generating capacity of both nuclear (9.24 percent) and oil (3.57 percent) combined, and is an improvement over 2011, when renewables accounted for 14.26 percent of America's total generating capacity. It is important to note, however, that generation capacity and actual generation are two different things. Though wind and solar installations, for instance, are rated for a certain maximum capacity, they are not always generating at that nameplate capacity. That is why, according to the Energy Information Administration, renewable energy actually produced 12.7 of America's electricity in 2011, compared to 19.2 percent for nuclear power. Nevertheless, having a larger, more varied stock of renewable energy sources will help address these intermittency issues, by, as it were, spreading eggs over several baskets. Sources
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