How could nuclear batteries accelerate the race to fusion energy?

The power of fusion has always been a bit contradictory. The fusion part is actually fairly easy—a college student recently built a simple fusion device in his bedroom, for example—but getting electricity from the reaction is not.

“A fusion reactor produces energy, and there’s a lot of it, and it already exists,” Daniel Velasquez, materials science lead at Avalanche Energy, told TechCrunch. “A fusion reactor that produces electricity is the best.” This is where the emerging industry remains stuck.

Fusion reactions release huge amounts of energy by fusing two lighter atoms into a heavier atom. But harvesting that energy has proven difficult. The most common method is to heat water and drive a steam turbine, but this approach is not very efficient, at best using about 60% of the energy.

Avalanche Energy believes it can capture more of that energy by developing new materials known as photovoltaics. Photovoltaics are similar to photovoltaics—traditional solar panels—in that they use semiconductors to convert radiation into electricity. They’ve been around for a while, but they’re not very effective. Existing RF cells are easily damaged by the radiation they harness and do not produce much electricity.

Today, Avalanche was awarded a $5.2 million contract from DARPA to develop new solar cells, the company exclusively told TechCrunch.

The Pentagon’s research agency is interested in using the materials in a new class of nuclear batteries, which use radioactive decay of materials such as polonium to generate electricity. Such devices could help power spacecraft and satellites for several years. They could also be used in more power-hungry ground-based military applications for days on end — “particularly for autonomous systems or missions where logistics are somewhat disallowed,” Velasquez said.

This isn’t exactly what Avalanche is going for as a company, but the DARPA award dovetails with its ambitions.

For example, fusion reactions and nuclear batteries produce alpha particles, a type of radiation so high in energy that it can damage all types of equipment, including the wall of a nuclear reactor. Second, Avalanche is developing a desktop-scale fusion reactor that could replace diesel generators at remote military bases.

If the company can develop new radiation energy for a nuclear battery, it can apply that knowledge to a new part of the reactor. Such a shell would help capture alpha particles, protecting the reactor while increasing the amount of electricity it produces. Avalanche also won a $1.25 million award from the US Air Force’s AFWERX Research Laboratory to use computational advances to accelerate materials discovery.

All fusion startups are racing to achieve a milestone known as break-even, which in the scientific world is known as Q>1, where Q is the ratio of the energy generated by the fusion reaction to the energy required to maintain it. Powering these alpha particles to generate electricity would make commercial fusion energy easier to obtain.

Avalanche isn’t the only company with a reactor design that produces alpha particles. If successful, the company could find itself supplying the technology to other integrators, an emerging trend in the industry.