Calpine Corporation, an independent wholesale power generation company, engages in the ownership and operation of natural gas-fired and geothermal power plants in North America. It generates electricity and produces steam from natural gas-fired combustion and renewable geothermal facilities. The company sells wholesale power, steam, capacity, renewable energy credits, and ancillary services to utilities, independent electric system operators, industrial and agricultural companies, retail power providers, municipalities, and power marketers. As of December 31, 2009, the company had a portfolio of 77 operating power plants with an aggregate generation capacity of approximately 24,802 megawatts. Calpine Corporation was founded in 1984 and is based in Houston, Texas.