While the use of solar, wind and other renewable energy continues to grow, hydroelectric energy continues to account for the lion's share of U.S. renewable energy, at 70 percent.
Biomass accounts for nearly 15 percent of U.S. renewable energy, while wind accounts for 10 percent and large-scale solar less than 1 percent, according to the National Renewable Energy Laboratory.
The U.S. lags other nations such as Germany and Spain in adding solar.
For instance, Germany is expected to add a record 2.5-3 gigawatts of solar capacity this year, and it already had a third of the world capacity for solar.
U.S. solar electricity generation increased 12.72 percent, from 542,760 MWh to 611,793 MWh between 2001-2007.
During the same period, U.S. wind electricity generation increased 411 percent, from 6,737,337 MWh to 34,449,927 MWh.
