Realta Fusion Achieves Direct Electricity Generation from Fusion in Industry Milestone

For fusion energy startups, one of the biggest scientific challenges has already been overcome. Following the landmark experiment conducted in 2022, researchers proved that controlled nuclear fusion reactions can produce more energy than they consume. The next major objective for the industry is to demonstrate that commercial fusion reactors can generate enough electricity to be economically viable.

One approach involves increasing reactor temperatures to produce more heat, which can then generate additional steam to drive larger turbines. Another strategy focuses on capturing electricity directly from the fusion reaction itself, a technique widely considered to offer significantly higher efficiency.

Realta Fusion announced that an experiment conducted on June 19 successfully powered a lightbulb with electricity generated directly by WHAM, the company’s demonstration fusion reactor. The Wisconsin-based startup believes it is the first private company to demonstrate direct electricity generation from fusion plasma publicly.

“We can take power from a plasma,” said Kieran Furlong, co-founder and CEO of Realta Fusion. According to Furlong, the milestone highlights “what’s possible” for the future of commercial fusion energy.

The company plans to use direct electricity conversion to power the plasma-heating process in its future reactors, an operation that requires substantial energy. Furlong estimates that the direct conversion system operates at roughly 90% efficiency, meaning it converts approximately 90% of the available energy into usable electricity. By comparison, conventional steam turbines used in today’s nuclear fission power plants typically achieve around 33% efficiency. The more electricity Realta can recover from the fusion process itself, the faster the company expects its commercial reactors to reach profitability.

Like every other power station, fusion facilities consume a portion of the electricity they generate to operate their own systems. One of the industry’s biggest engineering challenges remains building reactors capable of producing substantially more energy than they consume. Realta believes the improved efficiency offered by direct energy conversion could significantly reduce that hurdle.

Approximately 20% of the energy produced during deuterium-tritium fusion reactions—the fuel combination Realta intends to use in its commercial reactors—is carried by charged helium nuclei known as alpha particles. To harness that energy, the startup developed a prototype electricity converter and mounted it at the end of its demonstration reactor. During testing, the system successfully generated multiple amps of electricity at 100 volts, producing enough power to illuminate several lightbulbs.

In a full-scale commercial power plant, Realta expects these direct energy converters to generate sufficient electricity to heat the reactor’s plasma continuously. “You’re basically able to recirculate the electricity,” Furlong explained.

Ultimately, the company estimates this internal energy recycling could increase the total output of a commercial fusion power station by between 20% and 30%. “Spinning a flywheel of electricity, if you like, is very beneficial,” Furlong added.

Although Realta believes it is the first private company to demonstrate direct energy conversion from a fusion reaction publicly, it is not the only startup pursuing the technology. Helion, the fusion company backed by Sam Altman, has also built its reactor strategy around direct electricity conversion, although it has not yet publicly demonstrated the capability.

According to Furlong, harvesting electricity directly from the fusion reaction itself “really helps with the economics” of designing and operating a commercial reactor.

Realta Fusion previously secured $36 million in Series A funding in 2025, led by Future Ventures. Furlong also confirmed that the company is currently raising additional capital to support the next stage of development.