what is a comparison of energy output with energy input
Energy conversion efficiency Energy conversion efficiency (Î·) is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be chemical, electric power, mechanical work, light (radiation), or heat.[citation needed]
Energy in the United States Most of this energy comes from fossil fuels: in 2010, data showed that 25% of the nation's energy originates from petroleum, 22% from coal, and 22% from natural gas. Nuclear power supplied 8.4% and renewable energy supplied 8%,[5] mainly from hydroelectric dams and biomass; however, this also includes other renewable sources like wind power, geothermal, and solar energy.[6] As of 2006, energy consumption had increased more rapidly than domestic energy production over the last 50 years in the nation (when they were roughly equal). This difference was largely met through imports.[7]