Large upgrade planned at Calvert Cliffs after power deal signed with Amazon

Constellation, the owner of Maryland’s Calvert Cliffs nuclear plant, said Wednesday it plans to move forward with massive upgrades at the facility after signing a 20-year power purchase deal with data center operator Amazon.

While the financial specifics of the deal remain confidential, Constellation officials said that because of the funding pledge from Amazon, the company now plans to spend $3 billion on “state-of-the-art improvements” for the facility, located in Southern Maryland’s Lusby.

The agreement with Amazon will also “help provide Constellation with the revenue certainty to relicense the plant for another 20 years,” according to a company news release. Licenses for the two reactors expire in 2034 and 2036, according to the Nuclear Regulatory Commission.

Beginning between 2030 and 2032, the plant will be able to provide approximately 190 megawatts of additional energy to the grid, enough to power about 147,000 American homes.

“That’s a home run for Maryland,” said David Dardis, Constellation’s senior executive vice president and chief external affairs and growth officer, in an interview with Maryland Matters. “We think it’s a great transaction for our customer — and for us.”

A large deal like this one is a “huge step” toward deciding to continue operating the facility for another two decades, Dardis said.

“Without an agreement like this, and the certainty it provides, you have to make projections about future power prices,” Dardis said. “And one thing we know about future power prices is: We’re always wrong.”

Under the power purchase deal, the energy from Calvert doesn’t flow directly to Amazon data centers elsewhere in the region. All of the power produced by the facility will still flow onto the regional grid for all customers to use, Dardis said.

“Nothing about this agreement changes that,” Dardis said.

But the power deal does give Amazon a degree of certainty about its power costs and supply in the region over the next few decades.

“Amazon is committed to investing in carbon-free energy to strengthen the grid and benefit the communities where we operate,” said a statement from Kerry Person, the Amazon Web Services vice president for global operations and data center delivery.

Less than two months ago, Amazon Web Services backed out of a plan to construct a hyperscale data center campus on the Calvert Cliffs site, amid strong pushback from the community. In June’s primary election, voters ousted all three county commission members who had opposed a data center moratorium.

Constellation is still willing to consider placing a data center or another large customer at Calvert Cliffs, Dardis said, but as of now, “nothing is in the works.”

“We’re open to considering those sorts of arrangements, but we would only do so in partnership with Calvert County and other important stakeholders,” Dardis said.

The Calvert Cliffs Clean Energy Center, located on the western shore of the Chesapeake Bay, accounted for 38% of Maryland’s energy generation in 2025, according to the Energy Information Administration. Still, the state uses five times more energy than it generates, and relies heavily on the regional grid, operated by PJM Interconnection.

“This agreement demonstrates how private investment can strengthen critical energy infrastructure,” said Joe Dominguez, Constellation’s chairman, president and CEO, in a statement. “Amazon’s commitment supports the long-term operation of Calvert Cliffs for generations to come and creates a strong foundation for future investment in both the facility and in advanced nuclear technologies.”

Constellation, a Fortune 200 company headquartered in Baltimore, considers itself the largest private-sector power producer in the world, with power generating facilities that have the capacity to power the equivalent of 27 million homes. Constellation and Amazon have also entered into a related retail supply agreement to support Amazon operations in the 13-state PJM market, according to Wednesday’s news release.

The agreement with Amazon covers 690 megawatts worth of power from the 1,790-megawatt plant — which will expand to 1,980 megawatts after the upgrade.

Constellation will likely continue to seek other long-term contracts with other power users in Maryland, Dardis said. That could include Maryland’s power utilities, who could use power purchase agreements to “hedge” their power costs, he added.

“We think that would be a prudent thing for them to do, at least for a portion of them,” Dardis said. “That’s prudent risk management, and we welcome those conversations.”

Thanks to the funding from Amazon, Constellation also said Wednesday that it plans to evaluate the possibility of new small modular nuclear reactors on the Calvert Cliffs site.

“The only way you can get that done is to have a big company like AWS leaned into those opportunities,” Dardis said.

These power purchase deals are not unfamiliar to Constellation, which plans to reopen the Three-Mile Island nuclear plant, now renamed the Crane Clean Energy Center, in Pennsylvania next year, thanks to a 20-year agreement with Microsoft.

In June 2025, Constellation inked a 20-year power purchase deal with Meta for the Clinton Clean Energy Center in Illinois, which was expected to support its relicensing and add an additional 30 megawatts of capacity to the plant.

That plant had been slated for premature closure in 2017 because of financial losses, before the Illinois legislature stepped in with a zero-emission credit program that was set to last through mid-2027.

And the power deals aren’t just with big tech companies. Earlier this year, Constellation also agreed to a 176-megawatt nuclear power purchase deal in Illinois with Walmart.

But the power purchase agreement with Amazon is “a little bit unique,” Dardis said, because of the large amount of energy involved.

“690 megawatts is a big contract for us — and generally speaking, in the industry,” Dardis said. “A huge value of competitive markets is that customers like Amazon or Walmart … are able to go out into the market and find solutions that work for them.”