Fusion Startup Realta Fusion Generates Electricity Directly from Reactor for the First Time
Claire Weston
On June 19, US fusion startup Realta Fusion extracted electricity directly from a fusion reaction and lit up light bulbs — a milestone that shifts the fusion conversation from 'can we sustain a reaction' to 'can we turn that reaction into usable power efficiently.'
What exactly did it achieve?
At its WHAM device in Wisconsin, Realta Fusion used a prototype direct energy converter to extract electricity from charged helium nuclei (alpha particles) produced by a fusion reaction.
The output reached 100 volts and several amps — enough to light multiple bulbs. The company says this is the first public demonstration of its kind by a private firm.
This means → fusion has moved past just "burning" plasma in a lab; for the first time, energy from a reaction was turned directly into usable electric current.
Why not use a steam turbine like a nuclear plant?
Conventional fission plants drive steam turbines at roughly 33% efficiency — two-thirds of the heat is wasted.
Realta's direct energy converter skips steam entirely. CEO Kieran Furlong estimates its efficiency at about 90%, capturing nearly all kinetic energy as electricity.
In plain terms = a steam turbine is like "boiling water to spin a wheel"; direct conversion is like "catching the energy straight from the flame" — fewer steps, far less loss.
What does higher efficiency mean for commercialization?
The central challenge in fusion today is building a reactor that produces more energy than it consumes. Higher conversion efficiency lowers that breakeven bar.
In Realta's planned commercial plant, electricity from the converter would heat the plasma itself, creating an internal power loop that could boost total output by 20% to 30%.
This means → the same reactor, paired with this technology, could squeeze out nearly a third more power — a meaningful step closer to profitability.
Where do competitors and funding stand?
Helion, backed by Sam Altman, lists direct energy conversion as a core technology path but has not yet demonstrated it publicly.
Realta previously closed a $36 million Series A led by Future Ventures and is currently raising a new round.
This reflects a shift in fusion capital: investor interest is moving from "proof of concept" to "who can put electricity on the grid first" — teams that can demonstrate actual power generation hold stronger fundraising leverage.
Content is for reference only, not financial advice.