DARPA is funding the development of batteries that could last 30 years on a single charge by harvesting energy from radioactive strontium-90 recovered from nuclear waste, with a minimum viable prototype targeted for early 2027.
The program, called Project SYMPHONEE (Strontium-Yttrium Multi-junction PIN-based High-Density Output Nano-system for Extreme Environments), operates under DARPA’s broader Rads to Watts initiative. It uses a multi-junction silicon carbide PIN semiconductor structure to convert beta radiation from strontium-90 and yttrium-90 directly into electricity, bypassing traditional thermal conversion methods.
The isotopes are recovered from used nuclear fuel and legacy Cold War nuclear waste. Project Omega handles the chemical separation and extraction, while Pacific Northwest National Laboratory oversees laboratory validation. Northrop Grumman leads AI-driven simulations and survivability analysis under intense radiation fluences.
Professor Michael Spencer of Morgan State University, the project’s technical lead, said the team is “pushing the boundaries of radiovoltaic technology, developing high-power, long-life systems that were not previously achievable.”
The primary goal is a step-change improvement in power density, measured in watts per kilogram. Achieving high power density while maintaining a long operational lifetime would enable applications that current battery technology cannot support: persistent military drones that stay aloft for years rather than hours, deep-space probes operating beyond solar range, autonomous undersea surveillance infrastructure, and remote tactical sensors that require no refueling or battery replacement.
“Our mission is to turn what has historically been treated as waste into a strategic energy asset,” said Dr. Stafford Sheehan, CEO of Project Omega. “Rads to Watts provides a clear demonstration of how recovered isotopes can power critical systems for years, without needing to manage the logistics around constant battery replacement.”
The technology builds on decades of research into betavoltaic power sources but aims for dramatically higher power densities than previous implementations. While betavoltaic batteries have existed in niche applications like pacemakers and space probes, their low power output has limited broader adoption. SYMPHONEE’s multi-junction SiC design seeks to overcome that constraint.
If successful, the program could redefine the operational limits of unmanned systems and remote infrastructure, replacing the logistics chain of battery swaps and refueling with a single installation that outlasts the equipment it powers.
Sources: DARPA plans 30-year endurance nuclear waste batteries to power next-gen drones (Tom’s Hardware, July 5, 2026); DARPA backs radiovoltaics project (Nuclear Engineering International, July 2026)