EVERETT — Helion received $425 million in new funding to expand its goal to build nuclear plants using fusion energy, the Everett fusion energy company announced Tuesday.

This boosts the overall total to more than $1 billion for its efforts to deliver carbon-free electricity without the drawbacks of traditional nuclear power, such as radioactive waste.

A who’s who of tech investors for Helion include Open AI CEO Sam Altman, Japanese investment firm’s SoftBank Vision Fund 2, Lightspeed Venture Partners, Facebook co-founder Dustin Moskovitz through the Good Ventures Foundation, Mithril Capital and the Capricorn Investment Group.  

Altman is the Everett company’s biggest investor, already contributing at least $375 million.

”We are on the brink of delivering a transformative energy solution that can meet the world’s increasing electricity demands while preserving U.S. energy leadership,” David Kirtley, Helion’s co-founder and CEO said in a statement Tuesday.

Kirtley said the new money from investors means the company will be able to increase its 450-person workforce in Everett by at least 100 employees toward its goal to provide fusion power to customers.

But skeptics maintain the technology, which began development in the 1950s, is still years away from being implemented.

In a 2003 report by the General Accounting Office, one key challenge to achieve fusion power is the physics of plasma, the state of matter needed for fusion.

“Researchers do not fully understand the burning of plasmas, those who main source of heat is from the fusion reaction itself rather than an external source,” the GAO report said.

Helion agreed in a May 2023 contract with Microsoft to provide a minimum of 50 megawatts for Microsoft’s data centers starting in 2028.

“It’s an extremely ambitious date given technical and engineering challenges to the implementation of commercial fusion power,” said Brain Bothwell, director of Science, Technology Assessment and Analytics for the GAO, said in an interview.

Helion also agreed to develop a 500-megawatt power plant for steel company Nucor in the 2030s.

Robert Rosner, a professor of astrophysics and astronomy at the University of Chicago, estimated the soonest a fusion power plant could be built is the last 2030s.

He said scientists have been attempting to develop nuclear fusion since the 1950s.

In a telephone interview Monday, Kirtley said skeptics don’t understand the enormous progress the company had made in harnessing fusion power for commercial use. He said the company is on track to build a power and provide power to Microsoft by 2028.

He said three locations in Washington are being considered for the power plant, but did not provide more specifics.

Last year, Helion signed a letter of intent with the Chelan Douglas Regional Port Authority in Central Washington for a one-year feasibility period to conduct due diligence on part of a 25-acre plot in Malaga.

Kirtley declined to name the two other locations under consideration.

He said the construction of the plant would ultimately require a permit from Washington state officials.

Randy Diamond: 425-339-3097; randy.diamond@heraldnet.com