Nuclear energy, a seemingly sci-fi power source popularized in the mid-20th century before high-profile catastrophes sidelined it, is back in the spotlight.

Demands on the U.S. electrical system have heightened the hype around what some advocates view as a Holy Grail energy generator. Now, strange bedfellows — Joe Biden and Donald Trump, climate advocates and artificial intelligence proponents — agree the country needs more nuclear energy, and fast.

At the center of it all: Baltimore’s only Fortune 500 company.

Constellation Energy, which employs 3,200 people in the state and is headquartered at Harbor Point, could propel and benefit from the country’s nuclear future. Spun off from Exelon in 2022, Constellation is the largest operator of nuclear energy in the United States, the top nuclear-producing country in the world.

The U.S. wants to decrease its diet of fossil fuels even as electric vehicles and power-sucking artificial intelligence data centers strain the grid. Many see nuclear as a beacon of plentiful, carbon-free energy.

Constellation’s investors have taken notice. Despite a recent slide, the company’s share price is worth more than four times what it was three years ago. And Constellation is growing through deals and capital projects.

Last year, the company announced plans to restart a recently shuttered unit at Three Mile Island, 80 miles north of Baltimore in Central Pennsylvania, and acquired Calpine, a giant natural gas generator. It then invested $100 million into its only nuclear facility in Maryland, Calvert Cliffs, partially in an effort to extend the federal licenses for its two reactors.

Former President Biden’s 2022 climate law, the Inflation Reduction Act, offered a decade of tax credits for nuclear plants, and last year he set a lofty goal of tripling U.S. nuclear production by 2050. In a rare concurrence, President Trump’s energy secretary said he plans to “unleash” a “nuclear renaissance.”

Democratic and Republican policymakers alike are pushing for more nuclear plants, including in Maryland, where one proposal would grant new nuclear power a subsidy similar to one the state has used to attract offshore wind farms.

Constellation is active in the statehouse. Last year, it spent more than any other company lobbying in Annapolis, records show.

Skeptics see talks of nuclear growth as a bunch of hot air. Among reasons to be dubious: construction costs in the tens of billion and timelines that stretch beyond a decade. Plus, the country has expressed nuclear enthusiasm before, only to pull back before breaking ground on any new plants.

Among those counseling caution: Constellation itself.

Kathleen Barrón, the company’s chief strategy and growth officer, said Constellation is focused on keeping its current fleet of 21 reactors online and upgrading existing plants.

Building new reactors is challenging, she said, and she’s not ready to call today’s outlook a “renaissance.”

“There is a demand growth here,” she said in a February interview at Calvert Cliffs, “that is causing people to be excited about the potential for that R-word.”

Inside Calvert Cliffs

In a building crowded with tubes and ducts shooting every which way, the floor shook in a mechanical quake.

“It’s like an iceberg,” Roberto Gines, a Calvert Cliffs plant superintendent whose father also worked there, shouted over the din of machinery.

Beneath the grated ground, heat escaped from a generator in the belly of the nuclear plant.

Inside the Calvert County plant’s two massive reactors, uranium atoms are split through a process called nuclear fission. That heats water drawn from the Chesapeake Bay, which flows through a series of pipes, creating steam, spinning the plant’s two turbines and generating the single largest source of energy in Maryland.

Hidden in a corner of Southern Maryland, the recently rebranded Calvert Cliffs Clean Energy Center will mark 50 years of operation this May.

Constellation wants to extend the federal licenses of Calvert Cliffs, which currently expire in the mid-2030s, and other plants, as well as “uprate” facilities to maximize energy production.

Those are measured growth efforts. The only tangible step it has made toward a new reactor is seeking an early site permit at a plant in upstate New York.

In the late 2000s, Constellation made a push to add a third reactor at Calvert Cliffs, before efforts fizzled.

A renewed effort at building another reactor would please some in Annapolis. Amid growing concern about Maryland’s dependence on out-of-state energy generation, top leaders have looked to jumpstart expansions of nuclear power production.

Gov. Wes Moore, who visited Calvert Cliffs earlier this year, introduced legislation this session aimed at fostering new nuclear development, as did Democratic leadership in the House and Senate.

A proposal backed by Sen. President Bill Ferguson and House Speaker Adrienne Jones would cut red tape and establish a ratepayer subsidy to incentivize new nuclear options, including an emerging class of smaller-scale reactors.

Constellation has objected to parts of the bills, though, and in a testimony to lawmakers, the company said the proposed subsidy wouldn’t succeed in developing new nuclear energy.

Though any effort to add a third Calvert Cliffs reactor would be years away, Calvert County Commissioner Earl “Buddy” Hance said: “I think that Calvert County would definitely support any additional capacity.”

With 660 full-time Calvert Cliffs employees, Constellation is the No. 4 employer in Calvert County, behind only the county school system, government and the local hospital.

Hance’s ancestors sailed from England to America in the 18th century, he said, arriving on a dock near where the nuclear plant is today. He now lives 10 miles from the facility and remembers it being built when he was in high school.

“When it was first built, we’d joke with one another about turning the lights out and seeing if we’d glow,” he said of original perceptions.

But the plant has been largely welcomed by the community. Today, a slim majority of Americans are on board with nuclear expansion, and recent polling suggests Marylanders feel similarly.

When The Baltimore Banner toured the facility, workers in hard hats were preparing for a scheduled outage at one unit, a requirement every two years. While the unit is offline, crews, including hundreds of temporary workers, complete needed maintenance, remove used-up radioactive uranium and install fresh fuel over the course of a jam-packed 20 days.

Then, for the next 710 days, the reactor will provide something the U.S. increasingly covets: around-the-clock, carbon-free electricity.

A nuclear renaissance?

The prospect of harnessing more nuclear power has tantalized U.S. leaders before.

Officials and advocates predicted a renaissance 20 years ago, as federal subsidies looked poised to sprout dozens of new reactors around the country.

President George W. Bush visited Calvert Cliffs in 2005 — the first presidential visit to a nuclear plant since the partial meltdown of a Three Mile Island unit in 1979 — declaring it “time for this country to start building nuclear power plants again.”

Then the 2008 financial crash hit. At the same time, a fracking revolution made natural gas prices plummet and the resource’s desirability as an energy source rise.

Suddenly, the economics of nuclear energy became a lot more precarious.

“Saying ‘a nuclear renaissance’ is like a dirty word in the nuclear industry,” said Adam Stein, director of nuclear innovation at the Breakthrough Institute, a California-based energy research group.

But Stein, a proponent of nuclear expansion, thinks this time looks different.

If the U.S. is serious about erasing greenhouse gas emissions from its power grid, nuclear will need to be a big part of the solution, Stein said.

A study he and colleagues at the Breakthrough Institute conducted found that for the United States to meet emissions goals affordably by midcentury, it could need to ramp up nuclear output by nearly fivefold.

For some, such an enormous buildout looks like a devil’s bargain: Does humanity really want to trade the gradual erosion of climate change for the increased likelihood of nuclear disaster?

“The more coal you burn, the more asthma you cause. The more natural gas you burn, the more climate change you cause,” said Catherine Hausman, a professor at the University of Michigan who studies environmental and energy economics. “And the more nuclear sites you have, the higher the probability of an accident.”

The infamous accident at Three Mile Island injured no one, but it caused a national scare. An explosion in 1986 at Chernobyl in the former Soviet Union blew the top off a nuclear reactor and killed 31 people in the immediate aftermath. Some estimates, though, have put the potential death toll from radiation at roughly 4,000 people.

The largest earthquake in Japan’s recorded history hit the Fukushima nuclear plant in 2011, causing three reactors to melt down and release radiation. Deaths from the nuclear disaster are hard to measure, but the government evacuated more than 100,000 people.

Though catastrophic, there have been only a handful of such disasters, and nuclear plants cause significantly fewer deaths on a per-unit basis than the burning of fossil fuels, according to Our World In Data, a publication based at the University of Oxford.

U.S. reactors are protected like military bunkers to guard against worst-case scenarios. A tour of Calvert Cliffs requires a background check, metal detectors, layers of key-card-secured doors and contact with guards in bullet-proof vests and military-style assault rifles.

Cost, even more than safety concerns, has some energy analysts doubting a major nuclear expansion.

The recent completion of two reactors in Georgia began in 2009, took 15 years and 9,000 workers at the height of construction to complete, and cost more than $30 billion.

M.V. Ramana, author of “Nuclear Is Not The Solution” and a University of British Columbia professor, stressed that no large nuclear plants are currently under construction in the U.S.

“That doesn’t sound to me like a nuclear renaissance,” he said.

Constellation’s future

It was on the heels of the near resurgence in 2010 that Barrón, the company’s chief strategy and growth officer, first came to Constellation.

Constellation narrowly evaded bankruptcy at the height of the financial crisis and spent years managing a tough market. It was running nuclear plants at a loss and in 2019, Constellation shut off a reactor at Three Mile Island because of lack of demand.

“Over the last 15 years, what we’ve been trying to do is just keep the fleet operating‚" Barrón said.

She said what has changed recently is the desire for carbon-free energy. Last year, Constellation reached a deal with Microsoft to turn that reactor back on.

Microsoft will pay Constellation for the energy Three Mile Island generates for the next 20 years, and Constellation will spend $1.6 billion — potentially with a federal loan, The Washington Post has reported — to restart the reactor by 2028.

State and federal support are key for nuclear expansion, Barrón said, but deals with companies like Microsoft also give Constellation a low-risk way to grow its fleet.

Many tech companies have pledged to go carbon-zero, making natural gas and coal less desirable options. And artificial intelligence data centers require constant energy, which is difficult for solar and wind sources to provide.

As the U.S. seeks to compete with China to develop AI, many see nuclear energy as the key. Constellation CEO Joe Dominguez has said AI data centers and nuclear plants go together like “peanut butter and jelly.”

Constellation, which has a lease to keep its offices at Harbor Point until 2036, has been busy making its case to lawmakers. It spent $1.1 million last year lobbying in Maryland — on nuclear policy and on new guardrails to retail energy markets — and its federal lobbying efforts have increased in recent years, totaling $4.7 million in 2024.

Meanwhile, Constellation continues to reap the rewards of the nuclear industry’s fanfare.

Last month, the company reported $3.75 billion in 2024 net income — more than double the previous year.