The name says it all -- NRG Energy is all about energy. NRG is a leading power producer with a generating capacity of 49,287 MW (including 1,489 MW of solar power assets). The vast majority of NRG's power plants are in North America, but it also has one in Australia and one in Turkey. Its portfolio includes more than 150 generation units at about 90 power plants. It also markets natural gas, oil, and other commodities, NRG's retail units (including Reliant Energy and Green Mountain Energy) distribute power to about 3 million customers across the US. In 2015 the company announced plans to spin off its renewables businesses to pay down debt.