Constellation, the country’s biggest producer of nuclear power, agreed to buy the private- equity-owned Calpine , a major generator of natural-gasfired and geothermal power for $16.4 billion, plus debt.
It is part of a remarkable turnaround for Constellation, Calpine and other power producers, which have emerged from years of ho-hum electricity demand as the newly popular kids. Constellation’s stock has risen roughly 575% since the spinout.
The industry’s glow is due in large part to the boom in demand for electricity-hungry artificial- intelligence computing. That trend has sent the wealthy tech sector on a desperate hunt for city-sized amounts of power for new data centers.

ECP liked Calpine’s geothermal assets, including The Geysers complex with 13 plants in Northern California. It also has developed large battery-storage and solar projects.
In the past year, the consensus on how much natural gas will be needed has increased sharply with electricity demand forecasts.
Discussions between Constellation and Calpine leaders had been going on for about two years, though they picked up last fall.
Constellation said it could sell some assets in markets that overlap with Calpine, especially in the PJM Interconnection, the regional transmission organization and electricity market serving Washington, D.C., and all or part of 13 states.