Remember that whole 'we can make fusion produce more energy than it consumes' breakthrough from 2022? Great. Now fusion startups have to figure out how to turn that into something that doesn't lose money faster than a toddler with a credit card. Realta Fusion, a Wisconsin-based startup, decided to skip the whole 'boil water to spin a turbine' routine and instead just grab electricity directly from the fusion reaction itself. On June 19, they successfully powered a lightbulb using electricity harvested from their WHAM demonstration device. A lightbulb. Take that, Edison.

“We can take power from a plasma,” said CEO Kieran Furlong, which sounds like a threat but is apparently a good thing. The company plans to use direct electricity conversion to heat the plasma in its reactor, a process that normally sucks up a lot of energy. Furlong claims the direct conversion is about 90% efficient, compared to steam turbines' sad 33% in today's fission reactors. That efficiency boost could help fusion reactors finally cross the finish line of producing more energy than they consume.

About 20% of the energy from the deuterium-tritium fusion reactions Realta plans to use comes from charged helium nuclei called alpha particles. So they built a prototype converter, slapped it on the end of their reactor, and harvested enough 'alpha power' to generate multiple amps at 100 volts. That lit a few lightbulbs, but on a commercial scale, it should provide enough energy to heat the plasma itself. “You’re basically able to recirculate the electricity,” Furlong said, which could boost total output by 20% to 30%. Think of it as a very fancy, very nuclear flywheel.

Realta isn't alone in this direct conversion dream - Sam Altman-backed Helion also plans to use the tech, though it hasn't shown off a lightbulb party yet. Realta previously raised $36 million in a 2025 Series A led by Future Ventures, and Furlong says they're raising another round. Because fusion, as it turns out, is expensive.