Realta Fusion generates electricity directly from a fusion reaction, apparently for the first time

For fusion startups, the hard part is over: Thanks to a groundbreaking experiment in 2022, we know that controlled fusion reactions can generate more energy than they consume. But now the companies have to prove that their reactors can produce enough electricity to be profitable.

One option is to simply increase the temperature, generating more heat to produce more steam to turn a larger turbine. Another is to harvest electricity directly from the fusion reactions themselves, an approach that promises to be more efficient.

Realty Fusion announced that an experiment it conducted on June 19 successfully powered a light bulb using electricity collected directly from WHAM, its demonstration fusion device. The Wisconsin-based startup believes it is the first private company to publicly demonstrate such an achievement.

“We can take energy from plasma,” Kieran Furlong, co-founder and CEO of Realta Fusion, told TechCrunch. The milestone shows « what’s possible, » he added.

Realta plans to use direct electricity conversion to heat the plasma in its reactor, a process that requires a lot of energy. Furlong estimates that direct conversion is about 90% efficient, meaning it will convert 90% of the potential energy into electricity. By comparison, the steam turbines in today’s fission reactors are about 33% efficient. The more energy the company is able to collect, the faster it will reach profit.

Every power plant consumes some of the energy it produces just to run, and fusion reactors are no exception. The big challenge facing fusion startups today is building reactors that can produce more energy than they consume. Increasing efficiency from direct energy conversion should make it easier to overcome this hurdle.

About 20 percent of the energy from deuterium-tritium-fueled fusion reactions, the kind Realta plans to use in its commercial reactors, is charged helium nuclei known as alpha particles. The startup built a prototype electricity converter and attached it to the end of its reactor. There he was able to collect enough « alpha power » to generate several amperes of electricity at 100 volts, powering several light bulbs.

In a commercial-scale power plant, direct energy converters must provide enough energy to heat the plasma. « You can essentially recirculate electricity, » Furlong said.

Ultimately, Furlong estimates that circularity can increase the total output of a commercial-scale power plant by 20% to 30%. « Spinning a flywheel with electricity, if you will, is very useful, » he said.

While it may be the first to demonstrate direct energy conversion, Realta isn’t the only startup planning to implement this technology in its reactor. For Helion, the startup backed by Sam Altman, direct energy conversion is key to its plans, although it has yet to demonstrate it publicly.

Harvesting electricity directly from the fusion reaction « really helps the economics » of the reactor design, Furlong said.

Realta previously raised $36 million in a Series A led by Future Ventures in 2025. Furlong said the company is in the midst of a new round.