Amazon Signs 20-Year Deal for 690 MW of Calvert Cliffs Nuclear Power, Backing Constellation's $3 Billion Maryland Upgrade

CEG and AMZN signed a 20-year power purchase agreement tied to the Calvert Cliffs Clean Energy Center in Maryland, announced on September 30. Under the deal Amazon contracts for 690 megawatts of the plant's output, including roughly 190 MW of new, emissions-free capacity that Constellation plans to add through an uprate coming online between 2030 and 2032, according to Constellation's announcement. Constellation says the agreement enables more than $3 billion of Maryland infrastructure investment, including improvements across the 1,790-megawatt plant.

The structure matters. The $3 billion is Constellation's investment, which Amazon's long-term contract underwrites, not a payment from Amazon, and the electricity keeps flowing into the PJM regional grid rather than feeding a dedicated data center. A related retail supply agreement supports Amazon's operations across the 13-state PJM market. The Southern Maryland Chronicle noted the announcement came less than two months after Amazon withdrew a contested data center proposal for the same property.

The deal extends a pattern of large technology companies underwriting existing nuclear plants, following Constellation's earlier 20-year agreements with Microsoft and Meta. Constellation shares rose 2.7% in overnight trading after the announcement, according to StockTwits, for a stock that was down more than 30% in 2026.

What to watch: the uprate still requires Nuclear Regulatory Commission approval, and Calvert Cliffs' current licenses expire in 2034 and 2036, so the full 20-year term depends on Constellation securing further license renewals. Pricing per megawatt-hour was not disclosed.