Amazon (Nasdaq: AMZN) and Constellation Energy (Nasdaq: CEG) have signed a 20-year power agreement to support the expansion and continued operation of the Calvert Cliffs nuclear power plant in Maryland.
The agreement will help fund more than $3 billion in upgrades across the facility and add about 190 megawatts (MW) of new emissions-free generating capacity. The additional power is expected to come online between 2030 and 2032.
The deal comes as large technology companies seek more reliable electricity to support growing data center and artificial intelligence demand.
The EIA estimates data center servers already accounted for about 7% of U.S. commercial electricity consumption in 2025. By 2050, server electricity use could reach 446–818 billion kWh, depending on how quickly data center power demand grows.
The Deal Supports 190 MW Nuclear Capacity Increase
Calvert Cliffs currently has 1,790 MW of generating capacity, making it Maryland’s only nuclear power plant and its largest source of clean electricity.
- Under the new agreement, Amazon will purchase 690 MW of power through a 20-year arrangement with Constellation. The deal includes the planned 190 MW uprate, which will increase the plant’s output without requiring construction of an entirely new reactor.
Constellation plans to use the investment to modernize equipment and infrastructure throughout the plant. The company also expects Amazon’s long-term revenue commitment to support the process of relicensing Calvert Cliffs for another 20 years.
The companies have also signed a separate retail electricity supply agreement covering Amazon’s operations across the 13-state PJM power market.
Importantly, the electricity generated at Calvert Cliffs will continue to enter the PJM regional grid. Amazon will not receive electricity directly from the plant. Instead, its long-term commitment helps support the economics of maintaining and expanding generation that serves the wider electricity system.
Calvert Cliffs Strengthens Maryland’s Power Supply
Calvert Cliffs plays an important role in Maryland’s electricity system. Constellation says the plant produces about 80% of the state’s clean energy and generates enough electricity to serve more than 1.3 million homes.
The facility also supports more than 800 jobs and contributes approximately $21 million in annual taxes for public services, including schools and roads.
The planned expansion will therefore affect more than the plant’s electricity output. The investment will support upgrades at an existing nuclear facility while helping maintain its workforce and local economic contribution.
Constellation also sees the site as a potential location for future clean energy projects. The company said Amazon’s long-term commitment will help it move forward with additional clean energy development at Calvert Cliffs.
U.S. Nuclear Power Remains a Major Electricity Source
The Calvert Cliffs agreement comes as nuclear power continues to provide a significant share of U.S. electricity.
- According to the U.S. Energy Information Administration’s September 2026 data, U.S. utility-scale nuclear capacity stood at about 98.4 gigawatts (GW) in July 2026. Nuclear power represented roughly 7.5% of total U.S. utility-scale generating capacity at that time.
- Nuclear plants also generated about 460.1 terawatt-hours (TWh) of electricity during the first seven months of 2026, according to EIA data released in September. That was 1.5% higher than the comparable period in 2025.
EIA’s September 2026 Short-Term Energy Outlook also expects nuclear power to account for about 18% of U.S. electricity generation in both 2026 and 2027.
These figures show why extending the operating life of existing reactors can add dependable generation without waiting for an entirely new nuclear plant to be built.
Amazon Builds a Large Clean Energy Portfolio
The Calvert Cliffs agreement adds to Amazon’s growing clean-energy portfolio. In 2025, Amazon said it had more than 700 renewable and carbon-free energy projects across 30 countries, representing more than 40 GW of capacity.
BloombergNEF has also ranked Amazon among the world’s largest corporate buyers of clean energy. The company contracted 10.22 GW of clean energy capacity in 2025.
Amazon’s major clean-energy and nuclear deals include:
- X-Energy: In 2024, Amazon joined a $500 million funding round for X-Energy, which is developing small modular reactors. Amazon expects the partnership to support more than 5 GW of new nuclear capacity in the U.S. by 2039.
- Energy Northwest: Amazon is supporting a planned SMR project in Washington state. The initial project is expected to provide 320 MW, with potential to expand to 960 MW.
- Talen Energy: Amazon signed a long-term agreement to access power from Talen Energy’s Susquehanna nuclear plant in Pennsylvania. The deal can provide up to 1,920 MW through 2042.
The Calvert Cliffs agreement takes a different approach by supporting an existing reactor fleet and increasing its output through an uprate. This can provide additional capacity while preserving an established nuclear facility and its connection to the regional grid.
As U.S. power demand grows, deals like this can help fund nuclear plant upgrades while adding more reliable, emissions-free power to the grid. They also highlight how long-term corporate power agreements can support existing nuclear facilities and help enable new generating capacity.