Three Mile Island Restarts: Microsoft's 20-Year Power Deal Feeds AI Data Centers
On September 20, 2024, Microsoft signed a 20-year PPA with Constellation to restart Three Mile Island Unit 1 — AI demand pulling retired nuclear back onto the grid.
In this story
Per Reuters and the BBC, on September 20, 2024 Constellation Energy announced a 20-year power purchase agreement with Microsoft to restart Unit 1 of Pennsylvania's Three Mile Island plant (renamed the Crane Clean Energy Center), supplying roughly 835 MW of carbon-free power for Microsoft's AI data centers.
Three Mile Island was the site of America's worst nuclear accident; restarting its intact unit for AI demand carried enormous symbolism.
Why Nuclear
AI data centers need 24/7 baseload power that intermittent wind and solar cannot supply alone; nuclear is both carbon-free and steady, making it the workable answer for tech companies balancing climate pledges against compute expansion. Restarting an existing unit is also far faster than building new: Unit 1 was shut down in 2019 for economic reasons but left intact, targeting a return to the grid around 2028 — while a greenfield nuclear plant takes a decade or more.
The Industry Chain Reaction
The deal opened the 'AI plus nuclear' floodgates: Google signed with small modular reactor (SMR) developer Kairos, Amazon invested in X-energy and procured nuclear capacity, and energy stocks re-rated across the board. Constellation later secured federal loan support for the restart (about $1 billion, per NucNet) — policy and capital pulling in the same direction.
In the Compute-Race Big Picture
Read this deal alongside what followed and the scale snaps into focus: Stargate at $500 billion, the Nvidia-OpenAI 10-gigawatt LOI, Oracle's ~$300 billion contract — every one of them implies gigawatt-class power demand, and Three Mile Island's 835 MW covers only a sliver. The binding constraint on AI expansion is becoming electricity, not chip supply (see our Nvidia-OpenAI LOI coverage).
Our Take
AI's energy problem graduated from talking point to industry: the second half of the compute race is about electricity. For observers, tracking tech companies' power purchase agreements (PPAs) has become the leading indicator of their compute roadmaps — the power contracts get signed before the chip orders.
This article aggregates official announcements and public reporting; original sources are linked below.
Source:路透社
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