Microsoft signs 835 MW power deal

Microsoft and Constellation signed a 20-year power purchase agreement on September 20, 2024, that underpins the planned restart of Three Mile Island Unit 1 in Pennsylvania. Constellation said the deal would support the relaunch of the reactor under a new name, the Crane Clean Energy Center, and add about 835 megawatts of carbon-free power to the PJM grid. Microsoft said the electricity would help back its data-center load in PJM, the regional grid operator covering 13 states and the District of Columbia. The agreement was one of the clearest examples yet of a large technology company lining up long-duration firm power as AI-related electricity demand rises. ### Why is Microsoft tied to Three Mile Island at all? Microsoft said on September 20, 2024, that it had signed the PPA with Constellation to enable the restart of an 835-megawatt nuclear facility in Pennsylvania that had been retired in 2019. In its announcement, the company said the contract would bring “net-new, reliable, carbon-free electricity” to PJM and support its effort to match data-center demand with clean power. (constellationenergy.com) Constellation said the agreement was its largest-ever power purchase deal and that Microsoft would purchase the output generated from the renewed plant as part of its goal to help power data centers in PJM with clean energy. A Constellation filing with the U.S. Securities and Exchange Commission used the same description and said the reactor had been retired in 2019 because of economic conditions. (microsoft.com) ### What exactly is being restarted in Pennsylvania? Three Mile Island Unit 1 is the unit covered by the restart plan, not Unit 2, the reactor associated with the 1979 accident. Constellation said Unit 1 had operated for decades before shutting in 2019 and would be renamed the Crane Clean Energy Center after Chris Crane, the former CEO of Constellation’s previous parent company. (constellationenergy.com) The U.S. Nuclear Regulatory Commission materials on the project say Constellation announced the restart plan and Microsoft PPA on September 20, 2024, then laid out the regulatory path in an October 25, 2024 presentation. NRC documents describe the project as a return of Unit 1 to commercial service, with emergency-planning and licensing work still required. ### Why does the 835-megawatt number matter? (constellationenergy.com) The 835-megawatt figure is the approximate output Constellation and Microsoft attached to the plant in their September 2024 announcements. That is large enough to stand out against the incremental power needs of hyperscale data-center campuses, which utilities and grid operators have increasingly linked to AI computing growth. (nrc.gov) Microsoft framed the deal as part of a broader clean-energy procurement strategy rather than a one-off transaction. In the same September 2024 post, the company said the nuclear agreement would complement a 34-gigawatt contracted renewable-energy portfolio across 24 countries. ### Has Microsoft changed its climate target? (constellationenergy.com) Microsoft said in its February 18, 2026 sustainability update that it had achieved a milestone of matching 100% of its annual global electricity consumption with zero-carbon energy purchases. The company also reiterated its 2030 goal to become carbon negative and said it remained committed to that target. (microsoft.com) Microsoft has not, in the official materials reviewed here, announced that it is delaying its hour-by-hour or 24/7 carbon-free energy ambitions. In a January 2025 policy post, the company said it regularly assesses progress and adjusts strategies, but the published sustainability pages and reports still describe the 2030 commitments as in place. (blogs.microsoft.com) ### How far along is the restart now? Constellation said on February 19, 2025, that it was ahead of schedule on several workstreams tied to the Crane project, including hiring, inspections, building upgrades, permitting and licensing. The company also cited an economic-impact study estimating 3,400 direct and indirect jobs and more than $16 billion in state and federal economic activity. (blogs.microsoft.com) A September 2025 company update said the project remained ahead of schedule one year after the announcement. Constellation said then that the plant would help strengthen grid reliability and restore jobs while adding emissions-free electricity to the grid. ### What comes next before the plant can sell power again? (constellationenergy.com) NRC documents identify licensing and emergency-planning approvals as part of the path back to service for Unit 1. Constellation’s public updates say equipment inspections, workforce hiring and site upgrades are continuing as it works toward restarting the reactor. The next concrete milestone is commercial restart of the renamed Crane Clean Energy Center after the regulatory process is completed. (constellationenergy.com) Constellation’s project materials and updates remain the primary public source for timing, while Microsoft’s role is defined by the 20-year agreement to buy the plant’s output for PJM data-center demand. (constellationenergy.com) (nrc.gov)