Revolutionary Realta Fusion Harnesses Power from Fusion Reactions, Marking a Historic Milestone

For fusion startups, a significant milestone has been reached: A revolutionary experiment conducted in 2022 confirmed that controlled nuclear fusion can produce more energy than it requires. The next challenge for these companies is to demonstrate that their reactors can generate enough electricity to be commercially viable.

One strategy involves increasing the reactor’s temperature, which in turn generates more steam to drive larger turbines. Alternatively, companies can aim to capture electricity directly from the fusion process, a method that has the potential to enhance efficiency.

Realta Fusion has achieved a remarkable feat. On June 19, the company successfully powered a lightbulb using electricity harvested directly from WHAM, its fusion demonstration system. This Wisconsin-based startup claims to be the first private entity to showcase such an accomplishment.

“We can extract power from a plasma,” said Kieran Furlong, co-founder and CEO of Realta Fusion. He emphasized that this achievement illustrates the possibilities that lay ahead.

Realta intends to utilize direct electricity conversion to heat the plasma within its reactor, a process that demands substantial energy. Furlong estimates the efficiency of this direct conversion at around 90%, meaning it could convert 90% of the potential energy into usable electricity. In contrast, conventional steam turbines in fission reactors achieve only about 33% efficiency. The more energy Realta can harness, the sooner it will reach profitability.

Every power facility uses a portion of its generated energy to function, including fusion reactors. The primary challenge these startups encounter is designing reactors that can yield more energy than they consume. The efficiency gained from direct energy conversion should help address this challenge.

Approximately 20% of the energy from fusion reactions powered by deuterium-tritium, which Realta plans to use in its upcoming reactors, is found in charged helium nuclei known as alpha particles. The company created a prototype electricity converter and connected it to the reactor. This enabled them to capture enough “alpha power” to produce several amps of electricity at 100 volts, powering multiple lightbulbs.

In a commercial power plant, these direct energy converters are expected to generate sufficient energy to heat the plasma. “You can essentially recycle the electricity,” Furlong explained.

Furlong also estimated that this circularity could enhance a commercial power plant’s overall output by 20% to 30%. “Using a flywheel of electricity can be very advantageous,” he noted.

While Realta is the first to successfully demonstrate direct energy conversion, it is not alone in exploring this technology. Helion, a startup supported by Sam Altman, also considers direct energy conversion crucial to its plans, though it has not yet publicly demonstrated this capability.

Capturing electricity directly from the fusion reaction significantly improves the economic viability of a reactor’s design, according to Furlong.

Realta previously secured $36 million in a Series A funding round led by Future Ventures in 2025 and is currently in the process of raising additional funds.