Key facts
- Realta Fusion announced a successful experiment on June 19.
- The experiment generated electricity directly from a fusion reaction to power a lightbulb.
- Realta Fusion believes it is the first private company to publicly demonstrate this.
- The company plans to use direct electricity conversion, estimating 90% efficiency.
- This method is expected to increase commercial power plant output by 20-30%.
Realta Fusion announced that an experiment conducted on June 19 successfully powered a lightbulb using electricity harvested directly from its WHAM demonstration fusion device. The Wisconsin-based startup believes it is the first private company to publicly demonstrate such a feat, marking a significant step in making fusion power profitable.
Co-founder and CEO Kieran Furlong stated that the company can "take power from a plasma," highlighting the milestone's potential. Realta Fusion plans to utilize direct electricity conversion to heat the plasma in its reactors, a process estimated to be about 90% efficient, significantly higher than the 33% efficiency of steam turbines in current fission reactors. This increased efficiency is crucial for fusion startups to overcome the challenge of producing more energy than they consume.
Approximately 20% of the energy from deuterium-tritium fusion reactions are charged helium nuclei, known as alpha particles. Realta Fusion's prototype electricity converter successfully harvested enough of this "alpha power" to generate multiple amps of electricity at 100 volts, sufficient to power several lightbulbs. On a commercial scale, this direct energy conversion is expected to provide enough energy to heat the plasma, allowing for electricity recirculation and potentially boosting a plant's total output by 20% to 30%.
While Realta Fusion claims to be the first to demonstrate direct energy conversion publicly, other startups, such as Helion, backed by Sam Altman, also plan to deploy this technology. Furlong emphasized that harvesting electricity directly from the fusion reaction "really helps with the economics" of reactor design. Realta Fusion previously raised $36 million in a Series A round led by Future Ventures in 2025 and is currently raising a new round.