Microsoft's power deal is helping bring Three Mile Island's undamaged reactor back online, Meta has signed a 20-year agreement backing an Illinois nuclear plant, and Amazon has contracted for up to 1.92 gigawatts from Pennsylvania through 2042 — tech companies are securing decades of nuclear power to support their data centre ambitions.

The electricity contracts supporting the AI expansion reach decades beyond the useful life of today's servers. Microsoft, Meta and Amazon have backed nuclear supply arrangements stretching across decades, tying the future of data centers to plants built long before the current race to develop artificial intelligence. But the three agreements do different things. Microsoft is backing a restart, Meta is supporting continued operation, and Amazon has contracted for a growing share of an existing plant's output. Those distinctions determine how much additional electricity the deals can actually bring onto the grid. Microsoft is backing the reactor that survived Three Mile Island Constellation's September 2024 announcement described a 20-year power purchase agreement with Microsoft supporting the return of Three Mile Island Unit 1 in Pennsylvania. The project, now called the Crane Clean Energy Center, is expected to restore approximately 835 megawatts of electrical generating capacity. Unit 1 is the independent reactor that continued operating after the 1979 accident at neighboring Unit 2. It closed in 2019 for economic reasons. The agreement does not involve restarting the reactor damaged in that accident. Microsoft's purchase is intended to help match its data centers' electricity use in the PJM regional grid with nuclear generation. That is a supply agreement within a shared electricity system, rather than evidence that each Microsoft server will receive electricity exclusively from this plant. The restart remains ahead of us. In its August 2026 results, Constellation reported progress toward restarting operations in 2027, including approval of a fuel license amendment. That is earlier than the 2028 date in the original announcement, but it remains a company target. The Nuclear Regulatory Commission's restart page sets out the remaining regulatory framework: restoring an operating licensing basis, returning components to a condition that supports safe operation, and making required upgrades. A signed electricity contract cannot substitute for those reviews and inspections. Meta's Illinois deal supports an operating plant Meta's June 2025 agreement with Constellation concerns the Clinton Clean Energy Center in Illinois. Its 20-year term begins in 2027 and supports continued operation of the existing nuclear station. Meta described the agreement as covering 1,121 megawatts and enabling a 30-megawatt increase in generating capacity. The company said the arrangement would support its regional operations and allow the plant to continue without the state's Zero Emission Credit program. The distinction between those two numbers matters. The full 1,121 megawatts is not all new capacity created by the agreement. Most represents generation from an existing facility; the planned increase is 30 megawatts. Keeping a plant available can still affect future emissions and reliability, especially if it would otherwise retire. But measuring that benefit requires a credible comparison with what would have happened without the contract. A company announcement establishes its commercial commitment; it does not by itself establish the alternative future for the entire regional grid. Amazon's 1.92 gigawatts will ramp up over time Amazon's agreement with Talen Energy involves the Susquehanna nuclear plant in Pennsylvania. Under the expanded contract announced in June 2025, supply can reach 1,920 megawatts, or 1.92 gigawatts, through 2042, with options to extend the duration. The announcement set a ramp toward full volume no later than 2032, with the possibility of reaching it sooner. The headline figure is therefore the full contracted quantity, rather than a statement that Amazon already consumes that amount from Susquehanna continuously. Talen's 2026 financial filing describes the revised arrangement as a front-of-the-meter agreement and says the transition occurred in April 2026. In this structure, electricity enters the regional grid, with transmission and delivery serving the customer. The June announcement assigned Talen the retail supply role and PPL Electric Utilities the transmission and delivery role. The companies also announced plans to explore small modular reactors and increases to Susquehanna's output. Those possibilities should be counted separately from the contracted electricity at the existing station: exploring an expansion does not make it an operating power source. Why decades of electricity matter to a server business Data centers need electricity for computing equipment, cooling and other supporting systems. Their demand has become large enough to influence decisions about major generating assets, even though individual servers will be replaced several times over the life of a 20-year power agreement. The Department of Energy's summary of Berkeley Lab's 2024 assessment put U.S. data center electricity use at 176 terawatt-hours in 2023, about 4.4 percent of national electricity consumption. That is a historical estimate, not a measurement of today's demand. DOE's current data center resource hub, drawing on a 2025 report update, gives a reference projection of 11.8 percent of U.S. electricity use by 2030, with scenarios spanning 9.5 to 15.3 percent. These are modeled possibilities based on equipment growth, not guarantees that enough generating capacity will be built to meet them. Long contracts address part of that uncertainty. Buyers gain an agreed supply arrangement, while plant owners gain a more predictable customer for future output. The commercial logic connects the two sides, but it leaves engineering, licensing and transmission work to be completed. A gigawatt agreement is not an annual energy total ScienceBlog's earlier explanation of data center demand in reactor equivalents separates generating capacity from electricity delivered over a year. The same distinction applies here. A gigawatt measures power at a moment. A gigawatt-hour measures energy: one gigawatt delivered for one hour. Even when a contract specifies a maximum power quantity, annual delivery depends on the supply schedule, operating hours and outages. These agreements consequently cannot be added together and described as an equivalent amount of newly built nuclear generation. One restores retired capacity, one preserves existing capacity with a smaller planned increase, and one reserves output that ramps toward a contractual ceiling. For readers comparing the deals, the useful questions are concrete: Is the reactor already operating? Does the agreement finance additional output? When does delivery begin? Those answers reveal more about the change in available supply than the headline contract size alone. The contracts are consequential because they put large buyers behind long operating horizons. The next test is physical delivery: when will the promised capacity be available, and how much will it add to the electricity supply serving the wider grid?