Constellation Energy is the largest US producer of carbon-free electricity, overwhelmingly from its nuclear fleet, which is the country's biggest. Spun out of Exelon in 2022 and headquartered in Baltimore, it has become one of the corporate beneficiaries of AI-driven electricity demand. Its generation capacity is among the supply that AI data-center buildout competes for, connecting it to AI Infrastructure Capex, to AI Data Centers (the siting and electricity bottleneck), and to Private Credit & AI Infrastructure (the financing of generation consolidation). Its approach to AI load matches always-on, carbon-free nuclear baseload directly to hyperscaler demand through long-term power-purchase agreements.
Microsoft and Three Mile Island
In 2024 Constellation signed a 20-year power-purchase agreement with Microsoft to restart Unit 1 of the former Three Mile Island plant in Pennsylvania, rebranded the Crane Clean Energy Center, to supply Microsoft's data centers. It is among the most prominent instances of a retired or idled nuclear unit being brought back specifically to serve AI compute. As of 2026, the restart faces transmission-interconnection hurdles: PJM Interconnection flagged grid-upgrade requirements that could affect the timeline (Source: industrialinfo.com).
Calpine acquisition
Constellation agreed to acquire Calpine, a large natural-gas and geothermal generator, in a transaction valued at roughly $27B, expanding its fleet and geographic reach to serve rising data-center demand (Source: finance.yahoo.com). The deal sits alongside other AI-power-driven utility transactions: the NextEra Energy–Dominion Energy $67B all-stock merger and BlackRock's ~$39B AES/Allete consolidation (How the AI revolution has turbocharged M&A).
Valuation and demand
Constellation's share price re-rated on the AI-power thesis, and its Q4 2025 results, reported in February 2026, beat estimates on data-center-driven demand (Source: reuters.com). That run-up has drawn scrutiny: analysts question whether the valuation prices in data-center demand growth that depends on the same AI-revenue assumptions underpinning the AI Bubble Debate. The demand-growth and valuation figures are fast-decay and subject to revision on the next earnings cycle.
Relationships
- related: AI Infrastructure Capex
- related: AI Data Centers
- related: Private Credit & AI Infrastructure
- related: Dominion Energy
- related: NextEra Energy
- deploys-in: Microsoft
- supports: How the AI revolution has turbocharged M&A