Realta Fusion produces electricity directly from the fusion reaction, which is visible first

With the start of fusion, the hard part is over: Thanks to a basic test in 2022, we know that a controlled nuclear fusion reaction can create more energy than it uses. But now companies need to prove that their reactors can make enough electricity to make a profit.

Another option is to simply increase the temperature, generating more heat to produce more steam to spin a larger turbine. Another is to harvest electricity directly from the fusion reaction itself, a method that promises to be very efficient.

Realty Fusion announced that a test it conducted on June 19 successfully powered a lamp using electricity harvested directly from WHM, its display fusion device. The Wisconsin-based startup is believed to be the first private company to publicly demonstrate such action.

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

Realta plans to use direct current 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. In comparison, the steam engines in today’s reactors are about 33% more efficient. If a company is able to harvest more energy, it quickly becomes profitable.

All power plants use some of the energy they produce to operate, and fusion reactors are no exception. The biggest challenge facing fusion reactors today is building reactors that can produce more energy than they use. The efficiency boost from the direct power conversion should make clearing that hurdle easy.

About 20% of the energy from deuterium-tritium-fueled fusion, the type Realta plans to use in its commercial reactors, is charged helium nuclei known as alpha particles. The launcher built a prototype transformer and attached it to the end of its reactor. There, it was able to harvest enough “alpha energy” to generate several amps of electricity at 100 volts, powering several light bulbs.

In a commercial scale power plant, direct current converters must provide enough power to heat the plasma. “You’re basically able to recirculate electricity,” Furlong said.

Ultimately, Furlong estimates that circularization could increase the amount of commercial-scale power plant emissions by 20% to 30%. “Spinning the electric flywheel, if you will, is very profitable,” he said.

While it may be the first to demonstrate a direct power conversion, Realta isn’t the only startup planning to use that technology in its wallet. For Helion, a startup backed by Sam Altman, direct energy conversion is key to its plans, though not yet publicly visible.

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

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