Calpine Corporation is the largest generator of electricity from natural gas and geothermal resources in the United States, with operations in competitive power markets.

A Fortune 500 company based in Houston, Texas, the company’s stock trades on the New York Stock Exchange under the symbol CPN.

Its fleet of 80 power plants in operation or under construction represents approximately 26,000 megawatts of generation capacity.

In 2016, while M.J. Bradley & Associates ranked Calpine as the nation’s 10th largest power producer, it ranked the company 79th, 78th and 72nd with regard to emissions of SO₂, NO_x and CO₂, respectively, with no mercury emissions in its gas-fired fleet. These results reflect efficient operation of a modern fleet with no coal-fired generation.

Calpine’s predominantly gas-fired fleet also benefits from the nations’ abundant and affordable supply of natural gas and the increasing need for dispatchable power plants to successfully integrate intermittent renewables into the grid. The company advocates for responsible environmental regulation, competitive wholesale power markets and market-driven solutions that result in nondiscriminatory forward price signals for investors.

Through wholesale power operations and its retail businesses, Calpine Energy Solutions (formerly Noble Americas Energy Solutions) and Champion Energy, Calpine serves customers in 25 states, Canada and Mexico.

As of 2016, the directors of Calpine are Board Chairman Frank Cassidy, CEO Thad Hill, Laurie Brlas, Jack A. Fusco, Michael W. Hoffmann, David C. Merritt, W. Benjamin Moreland, Robert A. Mosbacher, Jr., and Denise M. O'Leary. The executive leadership team includes President/CEO Thad Hill, EVP/Chief Legal Officer Thad Miller, EVP/Chief Financial Officer Zamir Rauf, EVP/Chief Commercial Officer Trey Griggs and EVP/Power Operations Charlie Gates.

In response to the 1973 oil crisis and the 1979 energy crisis, much legislation was passed that made domestic energy production an attractive enterprise. In 1984, Peter Cartwright and four of his co-workers, the Guy F. Atkinson Construction Company of South San Francisco, and the Electrowatt corporation struck an investment arrangement, and Calpine was born with initial capital of US$1 million. It was essentially a Silicon Valley startup company. The name "Calpine" is derived from the company's original California location and alpine, a reference to the Zürich home base of Electrowatt. Calpine is the largest generator of electricity from natural gas and geothermal resources in the United States.