Amazon, Constellation sign 20-year PPA to expand Maryland nuclear plant

Amazon and Constellation Energy have signed a 20-year power purchase agreement to fund upgrades at Maryland's Calvert Cliffs Clean Energy centre, a 1,790-megawatt nuclear facility. The plant supplies roughly a quarter of Maryland's electricity and is the state's largest source of carbon-free power generation.

The deal represents a direct response to corporate demand for grid-scale zero-carbon energy. Amazon, which has committed to net-zero emissions by 2040 under its Climate Pledge, needs consistent baseload power to run its data centres – a sector where energy consumption remains the primary driver of operational emissions.

Nuclear power purchase agreements have become central to how large tech firms are attempting to meet their scope 2 (purchased electricity) emissions targets. Unlike solar and wind PPAs, nuclear contracts secure long-term, weather-independent capacity – critical for infrastructure operators who cannot afford production variability.

Constellation's willingness to commit capital to plant improvements signals that corporate demand now justifies nuclear investment in the US. This sits at odds with the slow decline of US nuclear capacity over the past two decades – though recent policy shifts, including the Inflation Reduction Act's production tax credits, have reversed some momentum.

The question now is whether this pattern scales. If major tech firms continue signing nuclear PPAs, will utilities across the US accelerate similar upgrades? And crucially: will Amazon's net-zero target actually require independent verification against the GHG Protocol and Science-Based Targets initiative standards, or does the PPA serve primarily as a corporate marketing asset?