A fusion energy startup is developing a new class of nuclear battery that could help solve one of the biggest challenges in clean energy, turning radiation directly into electricity rather than wasting it as heat.
What Avalanche Energy Is Building
Avalanche Energy, a US-based fusion startup, has been awarded a $5.2 million contract from the Defense Advanced Research Projects Agency (DARPA) to develop compact “nuclear batteries” using advanced radiovoltaic technology.
These devices generate electricity by converting energy from radioactive decay, specifically alpha particles, into electrical power using semiconductor materials. The concept is similar to solar panels, but instead of converting sunlight, they convert radiation directly into electricity.
According to the company, the goal is to produce systems capable of delivering more than 10 watts per kilogram, enough to power a laptop-class device for months from a unit weighing only a few kilograms.
This is a significant step forward compared to traditional radioisotope batteries, which have historically been reliable but very low power.
Why This Matters For Fusion Energy
While the immediate application is compact power systems, the real significance lies in how this technology could support the future of fusion energy.
Fusion reactions generate enormous amounts of energy, but capturing that energy efficiently has proved difficult. Most approaches still rely on heating water and driving turbines, which introduces inefficiencies and limits overall output.
Avalanche’s approach focuses on direct energy conversion, capturing the energy of charged particles before it is lost as heat.
As the company explains, “The direct energy conversion technologies we’re developing under Rads to Watts will be essential for extracting power from fusion reactions efficiently.”
This matters because improving energy capture is one of the key barriers to making fusion commercially viable. Even if a reactor produces more energy than it consumes, that energy still needs to be converted into usable electricity in a practical and efficient way.
A Step Towards Portable, Low-Carbon Power
Beyond fusion, these nuclear batteries could offer a new type of long-duration, low-maintenance power source.
Unlike conventional batteries, they don’t need recharging in the traditional sense. Instead, they produce a steady flow of electricity over extended periods, making them suitable for environments where access to power is limited or unreliable.
DARPA’s interest reflects this potential. The programme is focused on systems that can operate in extreme environments, including space, remote locations, and infrastructure where logistics make refuelling difficult.
In terms of this broader ambition, Avalanche says: “We’re building the capabilities today that will enable tomorrow’s fusion systems to deliver reliable, portable energy for defence, space, and commercial applications.”
In sustainability terms, this could point to a future where certain applications currently dependent on diesel generators or frequent battery replacement could move to cleaner, longer-lasting alternatives.
How This Fits Into The Wider Industry
It should be noted here that Avalanche is not alone in exploring alternative ways to generate long-duration power from nuclear processes.
Companies such as US-based Zeno Power are developing radioisotope power systems designed for remote infrastructure, including maritime and Arctic applications. Zeno focuses on long-life nuclear batteries that can operate for years without maintenance.
Also, organisations like NASA and the US Department of Energy have long used radioisotope thermoelectric generators in space missions, including the Perseverance and Curiosity Mars rovers, demonstrating the reliability of nuclear-based power systems over decades.
In the private sector, firms such as Kronos Advanced Technologies and Arkenlight are also researching next-generation radiovoltaic and betavoltaic systems aimed at improving efficiency and power density.
What makes Avalanche’s approach distinct is its direct link to fusion. For example, rather than treating nuclear batteries as a standalone product, it is using them as a stepping stone towards solving a core technical challenge in fusion energy itself.
This reflects a broader trend in the industry, where companies are focusing on specific bottlenecks such as materials, energy capture, and system design, rather than attempting to solve fusion as a single problem.
What Does This Mean For Your Organisation?
For businesses, this development is less about immediate adoption and more about understanding where energy technology is heading.
The key takeaway is that the future of clean energy is not just about generation, it is about efficiency, portability, and reliability. Technologies that can deliver consistent, low-carbon power in difficult environments will open up new operational possibilities.
In the shorter term, this kind of innovation signals a move towards more resilient energy systems. Businesses operating in remote locations, critical infrastructure, or energy-intensive sectors may benefit from future solutions that reduce reliance on traditional fuel supply chains.
It also highlights the pace at which energy innovation is moving. Fusion is often seen as a distant goal, but the supporting technologies being developed today, including advanced materials and direct energy conversion systems, are already shaping the path towards it.
While nuclear batteries may not be powering offices or factories tomorrow, they represent a step towards a more flexible, sustainable energy landscape where power can be generated and used far more efficiently than it is today.