Amazon.com (NASDAQ: AMZN) has signed a 20-year power purchase agreement with Constellation Energy (NASDAQ: CEG) tied to Maryland’s Calvert Cliffs nuclear plant, the companies confirmed on 30 September. The Amazon nuclear power deal covers 690 megawatts of output from the 1,790-MW facility, Maryland’s only nuclear plant.
Constellation said the agreement unlocks more than $3bn in infrastructure investment at the site, including roughly 190 MW of new emissions-free generating capacity due online between 2030 and 2032, according to its official statement.
No data centre attached this time
The structure marks a shift from how Amazon pursued nuclear power a year earlier. In August 2026 Amazon Web Services withdrew a conceptual plan to build a hyperscale data centre on the Calvert Cliffs campus itself, after local opposition in Calvert County, according to Maryland Matters.
This time there is no campus, no co-location and no site-specific construction for Amazon. Instead, Amazon buys power at arm’s length through the PJM wholesale market, which spans 13 states, alongside a retail supply agreement for its own operations in the region, Reuters reported. Financial terms of the power purchase agreement itself were not disclosed; Constellation has said only that the revenue certainty it provides supports the $3bn capital programme, the Baltimore Sun reported.
Constellation chief executive Joe Dominguez said the arrangement “demonstrates how private investment can strengthen critical energy infrastructure,” according to the company’s announcement.
Relicensing now on the table
Calvert Cliffs’ two reactor licences run to 2034 and 2036 under Nuclear Regulatory Commission terms. Constellation has described the Amazon agreement as a significant step toward seeking another 20 years of operation at the plant, Maryland Matters reported, with the company also weighing next-generation small modular reactor technology at the same site.
The 190 MW of added capacity promised by 2030-32 would be enough to power roughly 147,000 American homes, Constellation told Maryland Matters.
The deal follows a separate, troubled attempt by Amazon to pair a data centre directly with a nuclear plant: its 2024 agreement with Talen Energy to co-locate at Pennsylvania’s Susquehanna facility hit a regulatory setback after the Federal Energy Regulatory Commission rejected the proposed interconnection arrangement, CNBC reported at the time. The Calvert Cliffs structure avoids that specific regulatory exposure by routing power through the grid rather than a direct interconnection.
Muted reaction in Amazon shares
Amazon stock closed at $250.16 on 30 September, down 0.51% on the day and down 1.01% over the prior 20 trading sessions, with volume running at 1.49 times the 20-day average. The modest move suggests investors treated the agreement as incremental infrastructure news for Amazon’s cloud and AI capacity plans rather than a standalone catalyst for the stock.
Constellation shares, by contrast, rose more than 2% in reaction to the announcement, reflecting the long-term revenue visibility the agreement hands the plant operator.
The deal lands against a backdrop of still-elevated borrowing costs: the 10-year US Treasury yield stood at 5.26% as of 29 September, up marginally from 5.24% the prior session, according to Federal Reserve data. Higher long-term rates raise the cost of the kind of multi-decade infrastructure spending Constellation is now committing to, making the 20-year revenue certainty from Amazon’s offtake commitment more valuable to the project’s financing.
Why electricity demand is driving these deals
Data centre power demand has become the defining constraint for cloud providers racing to build out AI infrastructure, and Amazon has pursued nuclear supply through several routes rather than one template. The Calvert Cliffs agreement is explicitly framed by Constellation as AI-driven: the company has said rising compute demand from hyperscale customers is the reason it now plans to expand capacity at a plant that, until this year, had no expansion plans attached to it.
For Constellation, the agreement effectively pre-funds plant upgrades that would otherwise compete for capital against other priorities. For Amazon, it secures a fixed, long-dated supply of carbon-free power without the planning and political friction that sank the original campus proposal. Markets will next watch for any formal relicensing filing at Calvert Cliffs, and for whether Constellation discloses pricing terms when it next reports results.
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