Baltimore-based nuclear power company Constellation Energy Corp. and Houston-based Calpine Corp. have entered into an agreement where Constellation will acquire Calpine in a cash and stock transaction with an overall net purchase price of $26.6 billion.

The companies say the agreement has the potential to create America’s “largest clean energy provider,” with what is reported to be the largest fleet of U.S. power stations servicing about 2.5 million customers.

“This is an incredible opportunity to bring together top tier generation fleets, leading retail customer businesses and the best people in our industry to help drive a stronger American economy for a cleaner, healthier and more sustainable future,” Andrew Novotny, president and CEO of Calpine, said in a news release.

Calpine is the largest U.S. producer of energy from low-emission natural gas generation and oversees the largest geothermal generation operation in the U.S. Last year it announced plans to build the Baytown Carbon Capture and Storage Project (Baytown CCS Project), a first-of-its-kind carbon capture demonstration facility, as part of a cost-sharing agreement with the U.S. Department of Energy.

Constellation is considered the top clean energy producer in the U.S., which provides 10 percent of the country’s emissions-free energy. The deal will add to Constellation’s already diverse portfolio of zero- and low-emission sources, including nuclear, natural gas, geothermal, hydro, wind, solar, cogeneration and battery storage.

“Both companies have been at the forefront of America’s transition to cleaner, more reliable and secure energy, and those shared values will guide us as we pursue investments in new and existing clean technologies to meet rising demand,” Joe Dominguez, president and CEO of Constellation, said the release. “What makes this combination even more special is it brings together two world-class teams, with the most talented women and men in the industry, who share a noble passion for safety, sustainability, operational excellence and helping America’s families, businesses and communities thrive and grow. We look forward to welcoming the Calpine team upon closing of this transaction.”

Constellation also announced that it will invest in adding more zero-emission energy to the grid to create “the most reliable generation portfolio in the U.S.” It plans to explore new advanced nuclear projects, invest in renewables and increase the output of existing nuclear plants.

“Together, we will be better positioned to bring accelerated investment in everything from zero-emission nuclear energy to battery storage that will power our economy in a way that puts people and our environment first,” Novotny said in a news release. “It’s a win for every American family and business in our newly combined footprint that wants clean and reliable energy. ECP’s commitment to these goals over the last seven years was critical to the progress we have made as a company and to laying a foundation for future growth.”