Helion bags $425M in fresh funding despite fusion power still being a distant dream

Microsoft-backed startup now valued at $5.4B

Fusion energy startup Helion has yet to prove it can generate electricity, but that hasn't stopped investors from dumping another $425 million into the venture.

Helion, whose board is chaired by OpenAI CEO Sam Altman, announced an "oversubscribed and upsized" Series F funding round yesterday. With the addition of $425 million to its coffers, the startup claims it's now worth $5.4 billion - despite failing to produce net-positive energy after more than a decade. 

This latest round included more cash from Altman, Peter Thiel-founded Mithril Capital and others, also brought in new investors like the SoftBank Vision Fund, Silicon Valley funding giant Lightspeed Venture Partners, an unnamed "major university endowment" and more. 

"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," Helion cofounder and CEO David Kirtley said. 

Always on the brink, but never beyond

Helion acquired its first customer in Microsoft in 2023, with Redmond agreeing to host a 50MW fusion power plant at one of its datacenters in Washington State by 2028. Never mind the fact that some of Microsoft's current and planned datacenters likely consume more energy than that - Helion is still nowhere near that point, and it's questionable whether it'll get there in the next three years. 

The fusion energy that Microsoft has agreed to purchase from Helion relies on a fundamentally different approach than the fusion experiment conducted by scientists at Lawrence Livermore National Laboratory (LLNL) in 2022, which briefly achieved net energy gain.

In that case, LLNL boffins at the National Ignition Facility managed to accomplish an energy output of 3.15 megajoules after bombarding a fuel pellet with lasers outputting 2.05 megajoules of energy. While this marked a net energy gain at the fusion reaction level, it did not account for the total energy input, including the 322 megajoules required to power the laser system.

Helion, on the other hand, wants to generate electricity from fusion reactions using electromagnetic fields that accelerate plasma generated from deuterium hydrogen and helium-3 gases to speeds so fast they exceed 100 million degrees Celsius. By colliding two plasma blobs in the center of a field-reversed configuration (FRC) reactor, energy is supposed to be released; magnetic fields are generated. Theoretically, this allows Helion to extract power via induction. 

In theory, anyway. Helion said in 2014 that it was going to be able to commercialize its tech by 2019, and in 2018 claimed its yet-to-materialize 50MW reactor would be online by 2021. While the outfit did manage to achieve the 100 million degrees Celsius benchmark using its sixth-generation reactor prototype, it missed another self-imposed milestone last year of generating net-positive energy using its seventh generation prototype, Polaris. 

"We achieved our goal of beginning operations in Polaris before the end of 2024," a Helion spokesperson told The Register. "This year, we will accelerate our testing program with the goal of demonstrating our ability to create electricity from fusion."

It's running late, but the startup told us that it was seeing "great progress." As for why it hasn't made it further - this is complicated work, we're told. 

"We want to be absolutely certain of our data before we share more," Helion told us in an email.

Beyond the 50MW plant that's supposed to come online in three years, which we're told the company is "still on track" to achieve despite its net-positive energy setback last year, Helion said in its press release announcing the Series F funding that it intends to get a 500MW power plant online in the 2030s for steel manufacturer Nucor. 

When asked why we should believe Helion could manage a 10x increase in power output between 2028 and the following decade when it can't even manage positive energy output, Helion reiterated the complexity of what it's trying to achieve. "We're developing a brand-new technology," the spokesperson said. 

"[Fusion is] a highly complex undertaking that involves cutting edge science, novel engineering, and supply chain considerations, some of which are out of our control," Helion explained. "But with each prototype we've built we have learned more and remain confident that we can meet our commitments to our customers."

"After extensive due diligence, we're very confident in Helion's technology and leadership as the company moves from research and development into commercial production," Lightspeed Venture Partners cofounder Ravi Mhatre said of his firm's investment in Helion. Investors, at least, still seem convinced. ®