Constellation Energy Corporation ( CEG, Financials) said Friday that it will purchase Calpine Corporation ( CPN, Financials) for $26.6 billion in cash and shares, becoming the largest US renewable energy provider. The agreement combines Calpine's low-carbon natural gas and geothermal with Constellation's emissions-free nuclear.

In interesting timing, Friday's announcement came on the silver anniversary of the disastrous AOL/Time Warner merger.

Constellation is buying power natural gas and geothermal power provider Calpine in a cash-and-stock deal valued at approximately $16.4 billion, joining together two of the country’s biggest power companies.