Nuclear power plants run at 93% capacity factor. Natural gas peaks at 56%. In eighteen months, three companies signed power purchase agreements worth tens of billions of dollars with the handful of operators who own reactors running today.
Nuclear power plants in the United States averaged a 93.1% capacity factor in 2023. Natural gas plants peaked at 56%. Wind turbines averaged 34%. Solar panels reached 23%. These four numbers explain a procurement pattern that has reshaped the American energy landscape in eighteen months.
Data centers currently draw roughly 40% of their power from natural gas, 24% from renewables, 20% from nuclear, and 15% from coal. The gas share looks dominant until you consider what happens when a training run needs continuous power for weeks. A gas turbine at 56% capacity factor means 44% downtime, requiring backup, redundancy, and overbuilding. A nuclear reactor above 93% delivers power with the consistency of a metronome. For infrastructure designed to run continuously for years, the gap between 93% and 56% is the gap between irreplaceable and substitutable.
Three hyperscaler contracts reveal what happens when trillion-dollar companies do this math.
The Contracts
In September 2024, Microsoft signed a twenty-year power purchase agreement with Constellation Energy to restart Three Mile Island Unit 1. The 835-megawatt reactor, renamed the Crane Clean Energy Center, had been shut down since 2019. The restart will cost $1.6 billion. The Department of Energy closed a $1 billion loan in November 2025 to support the project, with the reactor targeted for operation by 2028. Microsoft needs the power to match its data center load in the PJM Interconnection, the grid operator serving thirteen states.
On January 9, 2026, Meta announced nuclear power agreements totaling up to 6.6 gigawatts across three partners. Vistra will supply more than 2,100 megawatts from its Perry, Davis-Besse, and Beaver Valley plants in Ohio and Pennsylvania, with additional uprate capacity, deliveries starting late 2026 and full capacity online by 2034. TerraPower will build up to eight Natrium sodium fast reactors. Oklo will contribute up to 1.2 gigawatts of small modular reactor capacity by 2034. The power will feed Meta's Prometheus AI supercluster in New Albany, Ohio.
Amazon signed a power purchase agreement with Talen Energy for up to 1,920 megawatts from the Susquehanna nuclear plant through 2042. FERC rejected the original co-location arrangement in November 2024 on a 2-1 vote, but the companies restructured to a front-of-the-meter configuration expected to begin concurrent with a spring 2026 refueling outage. Talen expects approximately $18 billion in revenue over the contract's lifetime.
The Fleet
These contracts share a common feature: the buyers went to companies that own reactors operating today. The small modular reactor pipeline is real but distant. Oklo broke ground at Idaho National Laboratory in September 2025 and expects its first Aurora reactor to deploy in late 2027 or 2028. TerraPower's 345-megawatt Natrium design received its NRC construction permit in early 2026, with construction underway and a target completion of 2030. Neither SMR technology will achieve commercial-scale power before the decade's end.
That leaves the existing fleet. Constellation Energy operates the largest nuclear fleet in the United States: 21 reactors generating approximately 22 gigawatts of nuclear capacity. In 2025, the fleet produced 183 terawatt-hours of zero-emissions electricity at a 94.7% capacity factor. The company completed its acquisition of Calpine on January 7, 2026, adding roughly 23 gigawatts of natural gas and geothermal generation. Total capacity now exceeds 55 gigawatts, making Constellation the largest electricity producer in the country.
The operating earnings tell the demand story: $2.9 billion for fiscal year 2025, up from $2.7 billion, with guidance for 13% or greater adjusted operating earnings growth through 2030. The Calpine acquisition is expected to be more than 20% accretive to earnings per share in 2026.
So What
The capacity factor gap creates a structural moat. Gas requires nearly twice the installed capacity to deliver the same energy output as nuclear. Renewables require three to four times the capacity plus storage. For a data center operator committing billions to a facility that needs to run continuously for years, nuclear is the only generation source that matches the demand profile without massive redundancy.
The investment implications follow from the fleet advantage. Constellation Energy holds an irreplaceable position: 21 operating reactors that no competitor can replicate within a decade. New nuclear construction takes fifteen to twenty years from licensing to operation. The hyperscaler contracts are locking up this finite capacity on multi-decade terms, creating revenue visibility that most utilities cannot match. Vistra has similar demand lock-in through its Meta agreement, with over 2,100 megawatts committed through 2034. Oklo represents speculative optionality on the SMR timeline, with its first commercial reactor still two years away at the earliest.
The 90-day test: track CEG and VST against the Utilities Select Sector SPDR (XLU) through July. If the nuclear fleet thesis holds, the companies with signed hyperscaler contracts should outperform the sector as additional power purchase agreements are announced. The gap between 93% and 56% is the gap between irreplaceable and substitutable.
Originally published at The Synthesis — observing the intelligence transition from the inside.
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