Constellation Brand Guidelines: Baltimore’s Nuclear Fleet, the 2022 Exelon Split and Calpine

A utility’s competitive arm, reorganised three times.

Constellation’s roots are in Baltimore utility history. The company’s own timeline says Baltimore Gas and Electric (BGE), which it dates to 1906, created a competitive business called Constellation Power Source with Goldman Sachs in 1997, as electricity markets opened up, and that Constellation Energy Group was formed in 1999 as a holding company with BGE as a subsidiary. English Wikipedia, citing The New York Times of May 1999, gives the same year. The oldest nuclear unit from BGE’s side of the family is Calvert Cliffs Unit 1, on the Chesapeake Bay in Maryland, which entered commercial service in 1975 as BGE’s plant, the company says.

The group grew as a wholesale and retail energy supplier. English Wikipedia records a 2005 merger agreement with FPL Group that was cancelled in October 2006, and a 2008 agreement with MidAmerican Energy that was dropped the same year in favour of a deal with Électricité de France; the company’s timeline shows EDF holding minority stakes in its Ginna, Nine Mile Point and Calvert Cliffs plants until 2021. The timeline also lists the purchase of the R.E. Ginna nuclear plant in New York in 2004 and of the Texas retailer StarTex Power and the supplier MXenergy in 2011.

In 2012 Constellation merged with Exelon, the group formed in 2000 when PECO and Commonwealth Edison’s parent came together, according to the company’s timeline; English Wikipedia dates completion to 12 March 2012. BGE went into Exelon’s utility business, and the competitive supply business continued under the Constellation name, alongside the nuclear fleet run by Exelon Generation. That fleet brought older Illinois and Pennsylvania history with it: the company says Dresden Unit 1, which entered service for Commonwealth Edison in 1960, was the first privately financed commercial nuclear plant in the United States, and that Peach Bottom Unit 1 began service for the Philadelphia Electric Company in 1967.

The 2022 separation and the nuclear fleet.

Constellation became a separate company again on 2 February 2022, when, its release of that day said, it completed its separation from Exelon and began trading on Nasdaq under the symbol CEG, with headquarters in Baltimore. Exelon had announced the split of its utilities from its competitive energy business in 2021, the company’s timeline says, and BGE stayed with Exelon. At launch Constellation described itself as “the nation’s largest carbon-free energy producer,” with more than 32,400 megawatts of capacity, operations in 48 states, Canada and the UK, and about 13,000 employees; those are its own figures.

The fleet is mostly nuclear. English Wikipedia lists plants including Braidwood, Byron, Clinton, Dresden, LaSalle and Quad Cities in Illinois, Calvert Cliffs in Maryland, Ginna, FitzPatrick and Nine Mile Point in New York, and Limerick and Peach Bottom in Pennsylvania, with minority stakes in Salem in New Jersey and in the South Texas Project, where Constellation says it bought NRG Energy’s 44 percent share in 2023. Wikipedia also lists the Conowingo Dam in Maryland and the Muddy Run pumped-storage plant in Pennsylvania, gas and oil plants, and wind and solar projects. On the company’s website several nuclear sites now carry a “Clean Energy Center” name, such as Clinton and Nine Mile Point.

Its recent deals tie that fleet to data centres. On 20 September 2024 Constellation announced a 20-year power purchase agreement with Microsoft that it said would allow the restart of Three Mile Island Unit 1, closed for economic reasons in 2019, as the Crane Clean Energy Center, named after its former chief executive Chris Crane. In September 2026 World Nuclear News reported that the US Nuclear Regulatory Commission had issued its environmental assessment for the restart, and that Constellation said it was on track to return the plant to the grid in 2027; the restart had not taken place at the time of writing. The company’s timeline adds a 20-year agreement with Meta for the output of the Clinton plant in 2025, and a 2025 agreement with the state of Maryland on operational and environmental projects at Conowingo, which English Wikipedia says followed years of litigation over sediment and nutrient effects downstream of the dam.

How power producers present themselves.

Independent power producers sell something nobody can see, so they lean on the places that make it. Their websites and reports tend to draw on a familiar set of pictures: gas turbines in clean halls, cooling towers against a pale sky, the domes of nuclear stations, rows of wind turbines and solar panels caught at dawn, and control rooms where operators watch walls of screens. The plant stands in for the product.

Many of these companies also face households directly. In the competitive retail markets of Texas and parts of the Northeast and Midwest, a single generator may own several retail electricity brands, each with its own name and look, alongside the parent’s corporate name. Vistra and NRG Energy both present themselves this way, as a “family” of brands, and some of those names are older than the parent that now owns them: TXU became the Texas company’s name in 1999, Vistra in 2016.

A newer theme is the long-term power contract with technology companies. In 2026, World Nuclear News reported 20-year agreements under which Amazon Web Services and Meta buy output from Vistra’s nuclear plants, and such deals now sit beside data-centre pages and press releases in the way these companies describe their future.

The rest of the visual record is practical: community and safety pages, plant fact sheets, sustainability reports and investor decks built around capacity charts measured in megawatts and gigawatts. This guide sets out what can be checked about each company — where it came from, who owns it and what it runs — and marks clearly where a statement is the company’s own.

One name over nuclear domes, dams and gas turbines.

The biggest change came in January 2026. Constellation agreed in January 2025 to buy Calpine, the gas and geothermal generator, from Energy Capital Partners, and said on 7 January 2026 that the purchase was complete, calling the combined business “the nation’s largest producer of electricity.” POWER magazine, reporting the closing on 9 January 2026, put the two companies’ combined capacity at 55 gigawatts and said the group would keep its headquarters in Baltimore, with a significant presence in Houston. To settle an antitrust case, the US Justice Department and the state of Texas had said on 5 December 2025 that they would require the sale of six plants in Delaware, Pennsylvania and Texas, POWER reported.

The name itself is a holdover from the 1990s supply business, and it has now outlived one parent company and absorbed a rival generator. Constellation has published no brand book, so this guide does not describe its logo or colours. What its own pages show is a consistent vocabulary: “clean, reliable energy,” plants renamed as Clean Energy Centers, and a history page that runs from Dresden in 1960 to Calpine in 2026.

For a design guide, Constellation shows how a single name can carry a spin-off, a merger and a split, and still sit over a fleet of very different plants. Compare Calpine, now part of the same group, and Talen Energy, another Pennsylvania nuclear operator selling power to data centres. For this guide we use a night blue, a pale silver and a warm amber with a geometric sans, an unofficial interpretation; no product or logo is reproduced.

Keep Constellation’s identity on hand — save it to a board in the Made Good inspiration library.