Realta Fusion generates electricity directly from the fusion reaction, an obvious first

For merged startups, the hard part is over: thanks to A pioneering experience in 2022We know that controlled nuclear fusion reactions can generate more energy than they consume. But companies now need to prove that their reactors can produce enough electricity to be profitable.

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

Realty Fusion She announced that her experiment on June 19 had successfully powered a light bulb using electricity obtained directly from WHAM, her experimental fusion device. The Wisconsin-based startup believes it is the first private company to publicly demonstrate this feat.

“We can get energy from plasma,” Kieran Furlong, co-founder and CEO of Realta Fusion, told TechCrunch. He added that this achievement shows “what is possible.”

Realta plans to use direct conversion of electricity 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 potential energy into electricity. By comparison, the steam turbines in today’s fission reactors are nearly finished 33% efficiency. The more energy a company can harvest, the faster it can achieve profitability.

Every power plant consumes some of the energy it produces just to operate, and fusion reactors are no exception. The big challenge facing nuclear fusion startups today is building reactors that can produce more energy than they consume. The increased efficiency resulting from direct energy conversion would make removing this obstacle easier.

About 20% of the energy from fusion reactions fueled by deuterium and tritium, the kind Realta plans to use in its commercial reactors, is charged helium nuclei known as alpha particles. The startup built a prototype of an electrical transformer and attached it to the end of its reactor. There, she was able to gather enough “alpha power” to generate several amps of electricity at 100 volts, to power a few light bulbs.

In commercial-scale power plants, direct power converters must provide sufficient power to heat the plasma. “You’re basically able to recycle the electricity,” Furlong said.

Ultimately, Furlong estimates that recycling could boost a commercial-scale power plant’s total output by 20% to 30%. “Rotating the electric flywheel, if you will, is very useful,” he said.

Although it may be the first company to demonstrate direct energy conversion, Realta is not the only startup planning to deploy this technology in its reactor. For Helion, the Sam Altman-backed startup, direct energy conversion is central to its plans, although it has yet to prove it publicly.

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

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