As energy companies work to cut carbon emissions, some are turning to nuclear power.

Nuclear energy will be crucial in the push to decarbonize the U.S.—no matter how controversial it may be—Dominion Energy CEO Robert Blue said Tuesday.

In the U.S., fossil fuels like coal and natural gas accounted for about 60% of the electricity that was generated in 2020, according to the Energy Information Administration. Renewables and nuclear power, by comparison, each represented about 20%.

Yet, with a carbon footprint on par with wind and solar, a far smaller physical footprint, and the ability to be generated at a near-nonstop rate, nuclear power stands to represent a key component in the energy grid in the coming years as the U.S. looks to cut down its reliance on fossil fuels, Blue said during Fortune's Global Sustainability Forum.

"There's only one source of round-the-clock, carbon-free electricity that exists today, and it's nuclear," Blue said.

Nuclear energy has been a source of tension for about as long as it has been a source of electricity.

A survey conducted by Gallup in 2019 found that Americans are evenly split on whether they favor the use of nuclear energy; however, in years past, as much as 62% of people surveyed have expressed they are in favor of its use. But with high-profile incidents like the nuclear meltdown at Japan's Fukushima Daiichi nuclear power plant, consumers, lawmakers, and the like have had a long-standing hesitancy about it.

Even former Nuclear Regulatory Commission Chairman Gregory Jaczko has raised concerns: "Two years into my term, an earthquake and tsunami destroyed four nuclear reactors in Japan. I spent months reassuring the American public that nuclear energy, and the U.S. nuclear industry in particular, was safe," Jaczko wrote in an op-ed for The Washington Post in 2019. "But by then, I was starting to doubt those claims myself."

The infrastructure beneath the nuclear power grid has been known to be aging for years. The average age of the 94 commercial nuclear reactors that were in operation at the end of 2020, for instance, was 39 years old, according to the Energy Information Administration. And only one new reactor has been built since 1996.

President Joe Biden's administration has acknowledged that nuclear will play a role in the White House's efforts to cut down on carbon emissions. In May, Gina McCarthy, the White House national climate adviser, said "existing nuclear, as long as it's environmentally sound and it's permitted, is going to be absolutely essential," according to Reuters. U.S. Energy Secretary Jennifer Granholm is not worried, either. Speaking at Fortune's Global Sustainability Forum, Granholm reiterated that "nuclear is safe" and that the U.S. has a "gold standard" of regulation around it.

Dominion operates four nuclear stations today that are currently licensed to run until the mid-2030s, said Blue, who also expressed an interest in developments around small modular reactors. These so-called SMRs, which offer more flexibility than larger nuclear plants and distinct security measures, have been heralded by the Energy Department as a "key part" of its goal to develop an affordable and safe nuclear power option. Nonetheless, Dominion is still looking to extend its nuclear plants' lifecycles by another 20 years as it views nuclear as critical to its ambitious $72 billion push to decarbonize by 2035.

Currently, Dominion generates about 10% of the electricity used by its customers from coal, which Blue says is down from more than half in 2005. Another 45% comes from natural gas today, while the remaining 45% is generated by a mix of zero-carbon sources, including nuclear, hydro, and other renewable energy sources. But Dominion wants to slash its use of coal even further to around 1% in the next 15 years, while placing an even greater emphasis on those less carbon intensive sources like nuclear, Blue said.

"For our company, nuclear has been in that mix the entire time," Blue said. "And we expect it's going to have to be for us to meet [our] climate goals."