A historic milestone for fusion energy has been achieved by Realta Fusion, a startup based in Wisconsin. On June 19, the company announced it had powered a lightbulb using electricity generated directly from its experimental WHAM reactor. This marks the first public demonstration by a private company of direct conversion of fusion energy into electrical current, a step that could revolutionize the economics of future fusion plants.
Founder and CEO Kieran Furlong told TechCrunch, "We can take power from a plasma," emphasizing how this milestone shows "what's possible." The experiment successfully harvested energy from positively charged alpha particles, which account for about 20% of the energy released in deuterium-tritium fusion reactions, the type of fuel Realta plans to use in commercial reactors.
Direct conversion achieves over 90% efficiency versus 33% for steam turbines
Realta Fusion's system generated several amperes of current at 100 volts, enough to power a few lightbulbs. The key lies in the high efficiency of direct conversion, estimated by Furlong at around 90%. This is significantly higher than the 33% efficiency of traditional steam turbines used in today's fission reactors. Greater efficiency means significantly less wasted energy and faster profitability for commercial plants.
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Every power plant consumes some of the energy it produces to operate; fusion reactors are no exception. The main challenge for fusion startups is building reactors that produce more energy than they consume. Direct conversion offers a decisive advantage by reducing losses and increasing net available energy.
Harvested electricity will heat the plasma and improve reactor economics
The electricity generated directly from fusion is not only for external use. Realta plans to use it to heat the plasma inside the reactor, a process that requires large amounts of energy. Furlong explained that "you are basically able to recirculate the electricity," creating a virtuous cycle that could boost a commercial plant's total output by 20 to 30 percent. "Spinning a flywheel of electricity, if you like, is very beneficial," he added.
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This energy circularity is a key design element. While other startups, such as Sam Altman-backed Helion, also target direct conversion, Realta was the first to demonstrate it publicly. Competition is heating up, but Realta's demonstration marks a turning point: the path to economically viable fusion reactors becomes more tangible. The company, which raised $36 million in a Series A round led by Future Ventures in 2025, is already working on a new funding round.
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Realta's progress fits into a broader landscape of innovation in artificial intelligence and energy. To better understand how emerging technologies compare, check out our comparison of AI chatbots. Additionally, the use of AI in creative fields raises questions, as seen with the AI-generated voice for Willy Wonka. Fusion, on the other hand, promises a clean and abundant energy future, one that comes ever closer thanks to these experiments.
For more on nuclear fusion, see the Wikipedia page on nuclear fusion.
