# Constellation Energy

> Source: https://aiwiki.ai/wiki/constellation_energy
> Updated: 2026-06-23
> Categories: AI Energy, AI Infrastructure
> From AI Wiki (https://aiwiki.ai), a free encyclopedia of artificial intelligence. Quote with attribution.

**Constellation Energy** (Nasdaq: CEG) is the largest operator of nuclear power plants in the United States and the central electricity supplier to the [artificial intelligence](/wiki/artificial_intelligence) buildout, running about 21 reactors across 12 sites with roughly 22,000 megawatts of capacity, close to a quarter of all U.S. nuclear output. [1][3] In September 2024 the Baltimore-based company signed a 20-year power purchase agreement with [Microsoft](/wiki/microsoft) to restart [Three Mile Island](/wiki/three_mile_island) Unit 1 as the [Crane Clean Energy Center](/wiki/crane_clean_energy_center), the first time a previously retired U.S. commercial reactor has been brought back specifically to power [AI data centers](/wiki/ai_data_center), and in January 2026 it closed a roughly $22 billion acquisition of [Calpine](/wiki/calpine) to become the nation's largest power producer at about 55 gigawatts. [3][4][14] Because hyperscale computing needs firm, around-the-clock power and nuclear plants are among the few large carbon-free sources that can supply it, Constellation's reactors have become a binding input to [AI infrastructure](/wiki/ai_infrastructure) rather than an ordinary commodity. [19]

Constellation was created on February 1, 2022, when [Exelon](/wiki/exelon) spun off its competitive generation and retail business into a separate public company, leaving Exelon as a pure regulated utility. [1][2] Constellation sells electricity and natural gas to roughly two and a half million homes and businesses, and its September 2024 deal for Microsoft plus its January 2025 agreement to buy Calpine turned the company into a primary lens through which investors view the link between nuclear power and AI. [3][13]

## History

### Spinoff from Exelon

Constellation traces its corporate roots to Baltimore Gas and Electric and to the old Constellation Energy Group, which merged with Exelon in 2012. [20] For a decade the nuclear and competitive-generation assets sat inside Exelon. On January 20, 2022, Exelon set the record date for a tax-free separation, and the distribution took effect at 12:01 a.m. Eastern Time on February 1, 2022. Exelon shareholders received one share of Constellation common stock for every three Exelon shares they held, with cash paid in lieu of fractional shares. [2] Constellation began trading as an independent company on the Nasdaq under the ticker CEG, describing itself at launch as the largest producer of carbon-free energy in the United States, supplying about 10 percent of the country's emissions-free electricity. [1]

The company is led by president and chief executive [Joseph Dominguez](/wiki/joseph_dominguez), a former federal prosecutor and longtime Exelon executive. Under Dominguez, Constellation has pursued a strategy of extending the operating lives of its reactors, increasing their output through equipment upgrades known as uprates, and signing long-term contracts that lock in premium prices from technology companies and the federal government.

## What does Constellation's nuclear fleet include?

Constellation owns and operates the largest nuclear fleet in the United States: about 21 operating reactors across 12 sites, with total generating capacity of roughly 22,000 megawatts (about 22 gigawatts). [1] That is close to a quarter of all U.S. nuclear capacity. In 2025 the fleet ran at a capacity factor of 94.7 percent and produced approximately 182 million megawatt-hours of electricity, a level of reliability that is central to the company's appeal to data-center customers. [16] Most of the reactors sit in Illinois, with additional sites in Maryland, New York, and Pennsylvania, plus minority interests in plants in New Jersey and Texas.

| Plant (site) | State | Reactors | Notes |
|---|---|---|---|
| Braidwood | Illinois | 2 | PWR |
| Byron | Illinois | 2 | PWR |
| LaSalle | Illinois | 2 | BWR |
| Dresden | Illinois | 2 | BWR |
| Quad Cities | Illinois | 2 | BWR |
| Clinton | Illinois | 1 | BWR; full output contracted to [Meta](/wiki/meta) |
| Calvert Cliffs | Maryland | 2 | PWR |
| Nine Mile Point | New York | 2 | BWR |
| Ginna | New York | 1 | PWR |
| FitzPatrick | New York | 1 | BWR |
| Limerick | Pennsylvania | 2 | BWR |
| Peach Bottom | Pennsylvania | 2 | BWR (co-owned) |
| Salem | New Jersey | minority interest | operated by PSEG |
| South Texas Project | Texas | minority interest | |
| Crane (Three Mile Island Unit 1) | Pennsylvania | 1 | retired 2019; restart targeted 2027 |

## Why did Microsoft restart Three Mile Island as the Crane Clean Energy Center?

On September 20, 2024, Constellation announced a 20-year power purchase agreement with Microsoft that would fund the restart of Three Mile Island Unit 1, a reactor the company had shut in 2019 for economic reasons. [3][4] The deal was, at the time, the largest power purchase agreement Constellation had ever signed, and it was the first time a previously retired U.S. commercial reactor was slated to be brought back specifically to serve a corporate buyer. Microsoft agreed to take the plant's full output, roughly 835 megawatts of carbon-free electricity (the 837-megawatt pressurized water reactor's rated capacity), to match the growing power consumption of its data centers in the [PJM](/wiki/pjm) region. [4][3] Constellation said the project would create about 3,400 direct and indirect jobs and generate more than $3 billion in state and federal taxes. [3]

The company framed nuclear as the only generation source able to meet AI's constant load. "Powering industries critical to our nation's global economic and technological competitiveness, including data centers, requires an abundance of energy that is carbon-free and reliable every hour of every day, and nuclear plants are the only energy sources that can consistently deliver on that promise," Constellation chief executive Joe Dominguez said when the deal was announced. [3] Microsoft vice president of energy Bobby Hollis called the agreement "a major milestone in Microsoft's efforts to help decarbonize the grid in support of our commitment to become carbon negative." [3]

Constellation renamed the facility the Crane Clean Energy Center, after Chris Crane, the former Exelon and Constellation nuclear executive who died in April 2024. [3] The company expects to invest about $1.6 billion to refurbish and restart the unit, a cost of roughly $1,900 per kilowatt that is a small fraction of new-build nuclear economics. [7] The restart was originally targeted for 2028 but was accelerated to the second half of 2027 after PJM granted expedited interconnection approval; by September 2025 the site was about 80 percent staffed, with around 500 full-time employees. [5][6] Constellation also plans to seek a license extension to operate the plant to at least 2054. The project received a $1 billion loan from the U.S. [Department of Energy](/wiki/department_of_energy), which closed on November 18, 2025, under the Trump administration's push to expand nuclear output. [8][9]

An important distinction: the reactor being restarted is Unit 1, which operated safely and independently from Unit 2. Unit 2 is the reactor that suffered a partial meltdown in 1979, the most serious accident in U.S. commercial nuclear history; it has been permanently closed since then and is owned by a separate company (EnergySolutions subsidiary TMI-2 Solutions) that is decommissioning it. The Crane restart does not involve Unit 2 in any way. Restart of Unit 1 still requires approval from the [Nuclear Regulatory Commission](/wiki/nuclear_regulatory_commission), which is reviewing the plant under a dedicated restart panel. [5]

## What other AI and data-center power deals has Constellation signed?

The Microsoft agreement was the first of a series of large contracts tied to AI-driven [electricity demand](/wiki/ai_energy_consumption). On June 3, 2025, Constellation signed a 20-year deal with Meta for the full output of its Clinton Clean Energy Center in Illinois, about 1,121 megawatts, with deliveries beginning in June 2027. [10][11] The contract is a market-based replacement for Illinois's expiring zero-emission credit subsidy, preserves roughly 1,100 jobs, supports relicensing the plant for another two decades, funds a 30-megawatt uprate, and delivers about $13.5 million in annual tax revenue. [10] In 2025 Constellation also won what it called the largest energy procurement in the history of the U.S. General Services Administration: a 10-year, $840 million contract to supply more than a million megawatt-hours of nuclear power a year to more than a dozen federal agencies, partly from planned uprates. [12] In early 2026 the company added a 380-megawatt supply agreement with [data center](/wiki/data_center) developer [CyrusOne](/wiki/cyrusone) in Texas and entered roughly 5 gigawatts of new nuclear-uprate, gas, and battery capacity into the PJM interconnection queue.

| Counterparty | Asset | Capacity | Term | Start | Announced |
|---|---|---|---|---|---|
| [Microsoft](/wiki/microsoft) | Crane (Three Mile Island Unit 1) | ~835 MW | 20 years | 2027 (target) | Sep 20, 2024 |
| [Meta](/wiki/meta) | Clinton Clean Energy Center | ~1,121 MW | 20 years | Jun 2027 | Jun 3, 2025 |
| U.S. General Services Administration | fleet nuclear | >1M MWh/yr | 10 years | 2025 | 2025 |
| [CyrusOne](/wiki/cyrusone) | Texas data center | 380 MW | n/d | n/d | early 2026 |

## Calpine acquisition

On January 10, 2025, Constellation agreed to acquire Calpine Corporation, the largest U.S. generator of electricity from natural gas and the largest operator of geothermal capacity in the country through its Geysers complex in California. [13] The equity purchase price was about $16.4 billion, made up of 50 million Constellation shares plus $4.5 billion in cash, and the deal carried roughly $12.7 billion of assumed Calpine net debt, for a total enterprise value of approximately $26.6 billion at announcement. [13] Constellation framed the acquisition as the creation of the nation's largest producer of clean and reliable energy and a major expansion into Texas, the fastest-growing U.S. power market. [13]

The transaction closed on January 7, 2026, after the Department of Justice required the divestiture of several power plants to LS Power to resolve antitrust concerns; the company reported total consideration of approximately $22 billion (50 million newly issued shares plus $4.5 billion in cash) at closing. [14][15] The combined company has about 55 gigawatts of generating capacity spanning nuclear, natural gas, geothermal, hydro, wind, solar, and battery storage, and serves roughly 2.5 million retail and commercial customers across markets including Texas, California, Illinois, Maryland, New York, and Pennsylvania. [15] Calpine added a mostly gas-fired fleet of about 28 gigawatts. [14] Management said the deal would add roughly $2 per share of annual earnings accretion, and on closing Constellation raised its dividend by about 10 percent. [14][16] The acquisition gave Constellation a portfolio of dispatchable gas plants to pair with its nuclear baseload, useful for serving data centers that need both firm capacity and the ability to ramp.

## Behind-the-meter and co-location debate

A central regulatory question for Constellation and its peers is how data centers should connect to power plants. In a "co-location" or "behind-the-meter" arrangement, a data center plugs directly into a generator and draws power without flowing it across the public transmission grid, which can let the load avoid some grid charges. This model became contentious in November 2024, when [FERC](/wiki/ferc) rejected an amended interconnection agreement that would have let [Talen Energy](/wiki/talen_energy) expand a behind-the-meter sale from its Susquehanna nuclear plant to an [Amazon](/wiki/amazon) Web Services data center, freezing a wave of similar deals across PJM. [17] Days later, on November 22, 2024, Constellation filed its own complaint at FERC arguing that PJM's tariff was unjust because it lacked rules for what Constellation called "fully isolated co-located load."

The Microsoft and Meta deals are structured differently from the Talen arrangement: Constellation sells the reactors' output to the grid while the technology buyer purchases a matching quantity of carbon-free power, a front-of-the-meter contract that sidestepped the co-location dispute. [3][10] The broader fight continued at FERC. On December 18, 2025, the commission ordered PJM to create new rules for co-locating large loads at power plants, directing the grid operator to establish several new transmission services and to revise its behind-the-meter generation rules within 60 days. [17][18] Analysts described the order as a victory for plant owners such as Constellation, [Vistra](/wiki/vistra), and Public Service Enterprise Group. [17] Even so, Constellation said in early 2026 that some data-center customers had paused contract talks pending final clarity on PJM's co-location and capacity-auction rules.

## How does Constellation make money?

Constellation reports a volatile GAAP bottom line because of non-cash mark-to-market accounting on its hedging contracts, so management guides to "adjusted operating earnings." For full-year 2025, reported on February 24, 2026, the company posted GAAP net income of $7.40 per share and adjusted operating earnings of $9.39 per share on revenue of about $25.5 billion, up roughly 8 percent year over year from $23.6 billion. [16] GAAP earnings were lower than 2024's unusually high $11.90 per share, a swing driven mainly by mark-to-market effects rather than operations. [16] At its Business and Earnings Outlook call on March 31, 2026, after closing the Calpine deal, Constellation set full-year 2026 adjusted operating earnings guidance of $11.00 to $12.00 per share, including roughly $2 per share of Calpine accretion. [21] First-quarter 2026 results, the first to include Calpine, showed revenue of about $11.1 billion, GAAP net income of $4.49 per share, and adjusted operating earnings of $2.74 per share, up 44 percent from a year earlier, with the company affirming the $11.00 to $12.00 guidance. [21]

| Metric | Q4 2025 | FY 2025 | Q1 2026 | FY 2026 guidance |
|---|---|---|---|---|
| Revenue | n/d | ~$25.5 billion | ~$11.1 billion | not disclosed |
| GAAP net income per share | $1.38 | $7.40 | $4.49 | n/a |
| Adjusted operating earnings per share | $2.30 | $9.39 | $2.74 | $11.00 to $12.00 |
| Nuclear capacity factor | n/d | 94.7% | n/d | n/a |

## Why does Constellation matter for AI?

Training and serving large AI models requires enormous, steady electricity, and the constraint on building new data centers has shifted from chips to power. [19] Nuclear plants are attractive to hyperscalers because each reactor delivers hundreds of megawatts of firm, carbon-free output that runs around the clock, matching the constant load of a data center far better than intermittent wind or solar. [19] Constellation owns more of that capacity than any other U.S. company, which is why [Microsoft](/wiki/microsoft), Meta, and others have signed multi-decade contracts with it rather than waiting for new generation to be built. [3][10] The company's strategy of restarting Crane, relicensing and uprating existing reactors, and using Calpine's gas fleet for additional firm capacity positions it as a key supplier to the AI buildout. The same demand has revived interest in [small modular reactors](/wiki/small_modular_reactor) and developers such as [Oklo](/wiki/oklo), but those technologies remain years from large-scale deployment, leaving Constellation's existing reactors as some of the only near-term carbon-free firm power available at gigawatt scale.

Dominguez has also publicly questioned whether all of the announced data-center demand is real. On the company's first-quarter 2026 earnings call he warned, "I just have to tell you, folks, I think the load is being overstated. We need to pump the brakes here," a note of caution from the executive whose reactors stand to benefit most from the boom. [22]

## Timeline

| Date | Event |
|---|---|
| Feb 1, 2022 | Separation from Exelon completed; Constellation begins trading as CEG |
| Sep 20, 2024 | 20-year Microsoft PPA to restart Three Mile Island Unit 1 (Crane Clean Energy Center) announced |
| Nov 22, 2024 | Constellation files FERC complaint against PJM over co-located load rules |
| Jan 10, 2025 | $16.4 billion agreement to acquire Calpine announced |
| Jun 3, 2025 | 20-year Meta PPA for Clinton Clean Energy Center (1,121 MW) signed |
| Nov 18, 2025 | $1 billion Department of Energy loan for Crane restart closes |
| Dec 18, 2025 | FERC orders PJM to create co-location rules for data centers |
| Jan 7, 2026 | Calpine acquisition closes; combined fleet about 55 GW |
| Feb 24, 2026 | Full-year 2025 results: $9.39 adjusted operating earnings per share |
| Mar 31, 2026 | 2026 guidance set at $11.00 to $12.00 adjusted operating earnings per share |

## See also

- [Crane Clean Energy Center](/wiki/crane_clean_energy_center)
- [Fermi America](/wiki/fermi_america)
- [Oklo](/wiki/oklo)
- [Small modular reactor](/wiki/small_modular_reactor)

## References

1. "Constellation Launches as Largest U.S. Clean Energy Company After Completing Separation From Exelon." Constellation Energy, February 2, 2022. https://investors.constellationenergy.com/news-releases/news-release-details/constellation-launches-largest-us-clean-energy-company-after
2. "Exelon Corporation Form 8-K (separation of Constellation)." U.S. Securities and Exchange Commission, February 2022. https://www.sec.gov/Archives/edgar/data/0001109357/000110465922010604/tm224978d1_8k.htm
3. "Constellation to Launch Crane Clean Energy Center, Restoring Jobs and Carbon-Free Power to The Grid." Constellation Energy, September 20, 2024. https://www.constellationenergy.com/news/2024/Constellation-to-Launch-Crane-Clean-Energy-Center-Restoring-Jobs-and-Carbon-Free-Power-to-The-Grid.html
4. "Constellation Energy to restart Three Mile Island and sell the power to Microsoft for AI." CNBC, September 20, 2024. https://www.cnbc.com/2024/09/20/constellation-energy-to-restart-three-mile-island-and-sell-the-power-to-microsoft.html
5. "Constellation plans 2028 restart of Three Mile Island unit 1, spurred by Microsoft PPA." Utility Dive, September 20, 2024. https://www.utilitydive.com/news/constellation-three-mile-island-nuclear-power-plant-microsoft-data-center-ppa/727652/
6. "One Year Later: Crane Clean Energy Center Still in the Spotlight and Ahead of Schedule." Constellation Energy, September 23, 2025. https://www.constellationenergy.com/newsroom/2025/09/one-year-later-crane-clean-energy-center-still-in-the-spotlight-and-ahead-of-schedule.html
7. "Three Mile Island Unit Eyes $1.6B Revamp, Restart in Microsoft Deal." Engineering News-Record, 2024. https://www.enr.com/articles/59329-three-mile-island-unit-eyes-16b-revamp-restart-in-microsoft-deal
8. "DOE loans Constellation $1B to restart Three Mile Island nuclear unit." Utility Dive, November 2025. https://www.utilitydive.com/news/doe-loan-constellation-crane-nuclear-restart/805923/
9. "Trump administration backs Three Mile Island nuclear restart with $1 billion loan to Constellation." CNBC, November 18, 2025. https://www.cnbc.com/2025/11/18/trump-nuclear-three-mile-island-crane-loan-constellation-ceg.html
10. "Constellation, Meta Sign 20-Year Deal for Clean, Reliable Nuclear Energy in Illinois." Constellation Energy, June 3, 2025. https://investors.constellationenergy.com/news-releases/news-release-details/constellation-meta-sign-20-year-deal-clean-reliable-nuclear
11. "Meta, Constellation ink 20-year nuclear power deal to support AI goals." Utility Dive, June 3, 2025. https://www.utilitydive.com/news/meta-constellation-illinois-clinton-nuclear-ppa-support-ai-goals/749992/
12. "Constellation Wins Record-Setting Federal Government Clean Nuclear Energy Procurement." Constellation Energy, May 2025. https://www.constellationenergy.com/newsroom/2025/constellation-wins-record-setting-federal-government-clean-nuclear-energy-procurement.html
13. "Constellation's $16.4B purchase of Calpine would create largest US power generator." Utility Dive, January 10, 2025. https://www.utilitydive.com/news/constellation-acquires-calpine-in-164b-mega-deal/737012/
14. "Constellation Energy Corp Form 8-K (Calpine merger completion, total consideration ~$22 billion)." U.S. Securities and Exchange Commission, January 2026. https://www.sec.gov/Archives/edgar/data/1868275/000110465926001780/tm2532248d1_8k.htm
15. "Constellation Completes Acquisition of Calpine; Groups Have 55 GW of Generation Capacity." POWER Magazine, January 2026. https://www.powermag.com/constellation-completes-acquisition-of-calpine-groups-have-55-gw-of-generation-capacity-2/
16. "Constellation Reports Fourth Quarter and Full Year 2025 Results." Constellation Energy / Business Wire, February 24, 2026. https://www.businesswire.com/news/home/20260223802465/en/ADDING-and-REPLACING-Constellation-Reports-Fourth-Quarter-and-Full-Year-2025-Results
17. "FERC orders PJM to craft large load colocation rules." Utility Dive, December 19, 2025. https://www.utilitydive.com/news/ferc-pjm-colocation-data-center/808368/
18. "FERC Directs Nation's Largest Grid Operator to Create New Rules to Embrace Innovation and Protect Consumers." Federal Energy Regulatory Commission, December 18, 2025. https://www.ferc.gov/news-events/news/ferc-directs-nations-largest-grid-operator-create-new-rules-embrace-innovation-and
19. "Data center owners turn to nuclear as potential electricity source." U.S. Energy Information Administration, 2024. https://www.eia.gov/todayinenergy/detail.php?id=63304
20. "Constellation Energy." Wikipedia, accessed June 2026. https://en.wikipedia.org/wiki/Constellation_Energy
21. "Constellation Reports First Quarter 2026 Results." Constellation Energy, May 2026. https://www.constellationenergy.com/news/2026/05/constellation-reports-first-quarter-2026-results.html
22. "Utilities grapple with a multibillion question: How much AI data center power demand is real." CNBC, October 17, 2025. https://www.cnbc.com/2025/10/17/ai-data-center-openai-gas-nuclear-renewable-utility.html