Calpine

Calpine Corporation was a very big company based in Houston, Texas. It was one of the largest makers of electricity in the United States. The company made power mainly using natural gas and geothermal energy.

The company was listed on the Fortune 500, which means it was one of the biggest companies in the country. It worked in many places where people buy and sell electricity.

In January 2026, another big company called Constellation Energy bought Calpine for $16.4 billion. After this, Calpine became part of Constellation Energy, meaning it now works under their name.

Operations

Calpine provided electricity to customers in 24 states, Canada, and Mexico. It operated 80 power plants, with the ability to produce nearly 26,035 megawatts of electricity.

In 2019, Calpine made 100.8 million megawatt hours of electricity, mostly using natural gas and geothermal energy. It was the biggest producer of this kind of power in the United States. Besides selling electricity directly to customers, Calpine also sold power to utility companies.

Subsidiaries

Champion Energy

Champion Energy is a part of Calpine and is based in Houston, Texas. It provides electricity to homes, governments, businesses, and industries in places like Texas, Illinois, Ohio, Pennsylvania, New Jersey, and New York. It also serves customers in Delaware, Maryland, and Washington, D.C., and provides natural gas in Illinois.

Fleet

York Energy Center

The York Energy Center is a 565-megawatt power plant that uses natural gas. It is located in Peach Bottom Township, York County, Pennsylvania.

Metcalf Energy Center

The Metcalf Energy Center is a 605-megawatt plant that uses natural gas and combined cycle technology. It is in Silicon Valley, near San Jose, California and Morgan Hill, California. Some of its power travels far away using Path 15, a major power transmission corridor.

The Geysers

The Geysers is the world's largest area for geothermal power, with 15 plants that use steam from deep wells. It is in the Mayacamas Mountains, about 72 miles north of San Francisco, California. In 2019, The Geysers provided about 20% of California's renewable energy. Calpine owned 13 of these 15 plants, which can power 725,000 homes — about the size of a city like San Francisco.

Los Medanos Energy Center

The Los Medanos Energy Center is a 561-megawatt plant that uses natural gas and is located in Pittsburg, California.

Edgemoor Power Generating Station

The Edgemoor Power Generating Station is in Wilmington, Delaware. It was bought in July 2010.

Russell City Energy Center

The Russell City Energy Center is a 619-megawatt plant that uses natural gas. It started operating in August 2013 and is in Hayward, California. It was the first power plant in the nation to receive a special permit to limit greenhouse gas emissions.

History

1984–1999

In 1984, Calpine was started in Silicon Valley, California, by Peter Cartwright and his team. With just US$1 million, it began as a small new company. By 1988, it started making power at its first plant. The name "Calpine" comes from its start in California and “alpine,” after Zürich, where one of its partner companies was based. By 1999, Calpine had bought a big geothermal power area called The Geysers, which helped it grow.

2000–2020

During 2001, California had big energy problems. In 2005, Calpine faced serious money troubles and its leader left. The company worked its way out of these troubles by 2008 and started fresh with new leaders. Over the years, Calpine bought many power plants, growing bigger and reaching new areas. In 2018, it became a private company owned by new investors.

2021–present

In 2023, Calpine shared plans to build a new plant in Freestone County, Texas, and started a project to catch carbon pollution from its plants. In January 2025, another big energy company named Constellation Energy agreed to buy Calpine. By January 2026, the sale was finished, and Calpine became part of Constellation Energy. In 2025, Calpine also made a deal with ExxonMobil to help store pollution from one of its plants.