Nuclear power is hard. a climate-minded billionaire wants to make it easier.

Outside a small coal town in southwest Wyoming, a multibillion-dollar effort to build the first in a new generation of U.S. nuclear power plants is underway.

Workers began construction Tuesday on a novel type of nuclear reactor meant to be smaller and cheaper than the hulking reactors of old and designed to produce electricity without the carbon dioxide that is rapidly heating the planet.

The reactor being built by TerraPower, a startup, won’t be finished until 2030 at the earliest and faces daunting obstacles. The Nuclear Regulatory Commission hasn’t yet approved the design, and the company will have to overcome the inevitable delays and cost overruns that have doomed countless nuclear projects before.

What TerraPower does have, however, is an influential and deep-pocketed founder. Bill Gates, currently ranked as the seventh-richest person in the world, has poured more than $1 billion of his fortune into TerraPower, an amount that he expects to increase.

“If you care about climate, there are many, many locations around the world where nuclear has got to work,” Gates said during an interview near the project site Monday. “I’m not involved in TerraPower to make more money. I’m involved in TerraPower because we need to build a lot of these reactors.”

Gates, the former head of Microsoft, said he believed the best way to solve climate change was through innovations that make clean energy competitive with fossil fuels, a philosophy he described in his 2021 book, “How to Avoid a Climate Disaster.”

Nationwide, nuclear power is seeing a resurgence of interest, with several startups jockeying to build a wave of smaller reactors and the Biden administration offering hefty tax credits for new plants.

Gates became interested in nuclear power in the early 2000s after scientists persuaded him of the need for vast amounts of emissions-free electricity to fight global warming. He was skeptical that wind and solar power, which don’t run at all hours, would be enough.

One problem with nuclear power, though, is that it has become prohibitively expensive. Traditional reactors are huge, complex, strictly regulated projects that are difficult to build and finance. The only two U.S. reactors built in the past 30 years, Vogtle Units 3 and 4 in Georgia, cost $35 billion, more than double initial estimates.

Gates is betting that radically different technology will help. With TerraPower, he funded a team of hundreds of engineers to redesign a nuclear plant from scratch.

Today, every U.S. nuclear plant uses light-water reactors, in which water is pumped into a reactor core and heated by atomic fission, producing steam to create electricity. Because the water is highly pressurized, these plants need heavy piping and thick containment shields to protect against accidents.

TerraPower’s reactor, by contrast, uses liquid sodium instead of water, allowing it to operate at lower pressures. In theory, that reduces the need for thick shielding. In an emergency, the plant can be cooled with air vents rather than complicated pump systems. The reactor is just 345 megawatts, one-third the size of Vogtle’s reactors, making for a smaller investment.

TerraPower’s design has another unique feature. Most reactors can’t easily adjust their power output, making it hard to mesh with fluctuating wind and solar farms. TerraPower’s reactor will have a molten salt battery that allows the plant to ramp up or down as needed.

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