Pacific Northwest tech leaders have shown their support for fusion. Bill Gates’ Breakthrough Energy Ventures has invested in Massachusetts-based Commonwealth Fusion Systems; Amazon founder Jeff Bezos has backed General Fusion; and TAE found support from the late Paul Allen, who co-founded Microsoft with Gates.

Helion’s Series E round was led by Sam Altman, the CEO of OpenAI, former president of Y Combinator and Helion board chairman. His contribution to the round was $375 million — the biggest investment he’s ever made, Altman told CNBC. Existing investors, including Facebook co-founder Dustin Moskovitz, Mithril Capital and Capricorn Investment Group, also participated in the round. The company launched nearly a decade ago and previously raised $72 million in venture capital and $5 million in government grants.

Axios reported that Helion is now valued at $3 billion.

The idea of creating energy on Earth through the fusion of nuclei dates back decades, and the Sun is a massive fusion machine. So what’s taken the technology so long to get here?

“It turned out to just be much, much harder than we thought,” said Chris Hansen, a University of Washington senior research scientist working on fusion. “The conditions that you need to enable fusion to happen and generate energy are just extremely, extremely challenging.”

se A Helion engineer. (Helion Photo)

For years, scientists have predicted that human-made fusion energy was only a few years out, but that day never seemed to arrive.

Kirtley himself predicted in 2013 that he’d have a design that could be commercially deployed by 2019. Limited funding hampered Helion’s efforts, he said. But over the years, Helion kept making progress. It has developed a technology that creates a pulsating, high-strength magnetic field needed to generate the conditions for fusion. Earlier this year, the company said it was the first commercial facility to exceed 100 million degrees Celsius in its prototype generator — an important benchmark for supporting fusion.

There are still challenges ahead. Helion’s fusion system uses deuterium, also called heavy hydrogen, and an isotope of helium as its fuel. The ideal temperature for its fusion is 200 million degrees Celsius, though it works at much lower temperatures. And if that sounds really hot, it is. The center of the sun is a balmy 15 million degrees, by comparison. That said, the company has been able to keep cranking up its heat capacity as it develops new generators.

The bigger technical hurdle, Kirtley said, is with fuel recycling. Helion’s process is to inject the fuel into the system, create fusion that is directly converted into electricity, exhaust the fuel, separate out the helium isotopes and repeat the process. That loop currently takes 10 minutes to complete. The goal is to bring that down to once a second. Helion engineers have been able to speed up the process at a smaller scale, and now have to ramp it up.

The company is also working to build out its ability to manufacture the electronics and materials used in the generators. While that requires a larger real estate footprint and more employees, the hope is the strategy will help Helion avoid supply chain disruptions.

Kirtley expects the current headcount of 63 employees to more than double to 130 by 2024. They’re going to be hiring skilled technical staff, technicians, machinists, engineers and other scientists.

“This funding lets build the team, build the manufacturing and build that Polaris generator system,” he said. Because wind, solar and hydropower aren’t going to be enough to wean the world off fossil fuels.

“We need our data centers and our factories and our Tesla truck charging stations powered by industrial-scale, clean, carbon-free electricity,” Kirtley said, “and fusion, we believe, is that answer.”