A Futuristic Plan to Make Steel With Nuclear Fusion

In a first-of-its-kind partnership between a major industrial company and a fusion startup, Nucor and Helion Energy plan to develop a 500-megawatt fusion power plant that would be placed at one of Nucor’s U.S. steel mills by 2030, the companies said.

That amount is enough electricity to power a few hundred thousand homes, about as much as a conventional power plant. Nucor is investing $35 million in Helion, which is backed by OpenAI Chief Executive Sam Altman.

The deal is a bet on fusion, a technology that can seem more science fiction than science and hasn’t yet produced electricity.

The agreement shows how Nucor and many other manufacturers are desperate for clean electricity to make greener products but are limited by a lack of abundant wind and solar power.

Many green steelmaking techniques require immense power, creating a need for energy sources such as fusion that address some of the limitations of today’s renewable and battery technologies.

“We don’t want to sit on the sidelines and wait for all these technologies and hope they get developed," Leon Topalian, Nucor’s chief executive, said in an interview.

Fusion powers the sun and has the potential to provide vast amounts of carbon-free power if someone can figure out how to harness it on Earth. No company has proved it can get more energy out of fusion than it takes to create it, and most experts think commercial fusion remains decades away.

Money has poured into fusion following a long-awaited breakthrough in December, when Lawrence Livermore National Laboratory said it had produced more energy from fusion than was delivered through lasers to drive the reaction.

Nucor’s steel goes into the world’s buildings, cars and appliances. In states where Nucor has facilities, it is among the largest electricity consumers.

Customers including General Motors and the heating and cooling equipment maker Trane Technologies are demanding greener steel, pushing Nucor to move faster on clean energy. The company has used recycled material for many years to make cleaner products, but the steel industry needs to address power consumption to meet climate targets and is currently dependent on local utility grids, many of which rely on fossil fuels.

The Nucor fusion plant would be about 10 times the capacity of another facility Helion plans to build to provide fusion-generated electricity by 2028 for Microsoft. The Microsoft deal, believed to be the fusion industry’s first commercial agreement, was announced in May.

Nucor plans to buy power directly from Helion at its steel mill rather than purchasing it from a utility or electricity grid operator. If successful, that approach could provide a blueprint for fusion companies to sign similar deals with power customers. Helion could sell excess power not used by Nucor back to the grid operator, another potential benefit for the developing fusion industry.

“This is moving out of the realm of a federally funded research program and into industrial power development," said David Kirtley, Helion’s chief executive. “This should be the signal that fusion electricity is coming."

Helion is building its seventh prototype, which it says will demonstrate electricity generated from fusion next year.

Current nuclear power plants use fission reactions, which split atoms to create a burst of energy. Fusion merges atoms instead.

In August, the Livermore laboratory said it had replicated its breakthrough. While the achievement doesn’t account for the electricity powering the lasers, it helped boost optimism about the decadeslong pursuit of fusion.

In addition to proving fusion can generate electricity, the companies will have to show a fusion plant can provide power directly to a big user and receive regulatory approvals for the project.

State and local regulations will be a factor in deciding where to put the fusion plant, company officials said. Helion is based near Seattle, while Nucor is based in Charlotte, N.C., and has mills across the U.S. The companies will consider local incentives that could buttress federal subsidies.

Helion has been among the industry’s largest fundraisers, with around $630 million, including the Nucor investment. Altman has invested $375 million in Helion and has said having customers is critical for keeping Helion focused on the realities of business.

Nucor recently invested in the more conventional kind of nuclear power, fission, another carbon-free technology being pursued by startups around the world. Nucor and the fission company NuScale Power are looking at using a small modular reactor to provide power to a steel mill.

The support for nuclear fusion and fission is a blast from the past for Nucor, which was previously called Nuclear Corporation of America in the middle of the 20th century as a nuclear industry services provider before it rebranded and focused on steel.

“Wind and solar aren’t going to be enough," Topalian said. “We’re going to need to look at how we advance the ball in other areas."

Write to Jennifer Hiller at jennifer.hiller@wsj.com and Amrith Ramkumar at amrith.ramkumar@wsj.com