"Solar cells directly convert sunlight into electricity…Ours directly convert radiation into electricity," said Stafford Sheehan, CEO and founder of Project Omega.
DARPA’s Rads to Watts program and the 2027 goal
DARPA’s Rads to Watts effort is explicitly aiming for what the program calls a "30-year battery minimally viable prototype" to be produced by early 2027. The agency has moved from concept toward funded prototypes: a recent $3.37 million contract award is intended to fund a proof-of-concept device that can exceed 10 watts per kilogram while retaining a yearslong shelf life. That target frames the next 18 months of work, during which testing under realistic conditions and risk reduction are priorities, according to a Pacific Northwest National Laboratory (PNNL) statement quoted in Defense One.
Who is building what: Project Omega, Morgan State University, PNNL, and partners
Several organizations have defined roles. Morgan State University is the prime contractor, responsible for basic research. The Pacific Northwest National Laboratory will handle nuclear materials and testing and will host the prototype build. Northrop Grumman and Applied Research Associates (ARA) are assigned computational modeling tasks to ensure the prototype meets performance standards. Project Omega will construct the radioisotope-based generator itself, while Widetronix is designing the semiconductor power converter.
Strontium-90 radioisotopes and the technical approach
The devices under development convert radiation directly into electricity by layering a solid-state "chunk" of radioisotope with semiconductors. Project Omega describes these sources as mini-generators that replace traditional batteries. The isotopes used will come from separated nuclear waste: "we recycle it into two products: one is fuel for reactors…the other are power isotopes," Sheehan said. The program intends to use strontium-90 rather than plutonium-238; Sheehan described strontium-90 as "less hazardous" than the plutonium isotope used in other radioisotope systems.
Project Omega emphasizes temperature resilience: the cells “also work in extreme temperatures—something that would benefit military operations using unmanned systems in harsh environments,” the company said. The team reports having already run small devices, and Sheehan told Defense One that those “specifically designed to meet the DARPA figure of merit are going to come out early next year.”
PNNL’s near-term priorities and technical challenges
A PNNL official summarized the program’s immediate focus: over the next 18 months the effort will reduce technical risk, test system performance under realistic conditions, and generate data to support future development and transition pathways. The official highlighted several "key challenges": improving energy conversion efficiency, validating long-term reliability, managing radiation effects, and ensuring safe, secure handling and deployment. Those constraints set the practical boundary between laboratory prototypes and fielded hardware.
What this means for satellites, unmanned systems, and nuclear waste managers
- Satellites: Project Omega and DARPA frame one clear use case—space systems. “One example is on satellites: if you lose power on a satellite, you lose the satellite, it's gone…if your batteries die and you don't have any sort of backup power,” Sheehan said. A multi-decade power source that produces >10 W/kg could change mission planning for platforms where battery failure ends the mission.
- Unmanned military systems: The Pentagon’s growing demand for drones and other unmanned platforms is a stated driver of the work. The program’s emphasis on extreme-temperature performance and long shelf life speaks to battlefield logistics where charging cycles and generator support are operational pain points.
- Nuclear waste management: Sheehan positioned the program as a way to extract value from existing inventories, noting “there are over 100,000 metric tons of nuclear waste sitting in the 52 reactor sites around the country.” He linked that inventory to an economic and logistical argument: recycling portions of waste into power isotopes while also producing reactor fuel could alter how that material is handled. He also noted a litigative context, saying the federal government “gets sued for billions of dollars every year just because they haven't dealt with the nuclear waste.”
Radioisotope power sources are not new technology—Sheehan noted their use “in everything from smoke detectors to space systems.” What DARPA’s Rads to Watts program and its partners are attempting is to push that class of power source into a different performance envelope: lightweight, relatively high power density (>10 watts per kilogram), and long operational life measured in decades rather than years.
The program’s next concrete milestone is the prototype build at PNNL by early 2027 and the ensuing 18-month campaign of testing and risk reduction. Whether the teams can meet the stated energy-conversion, reliability, and safety thresholds will determine if these radioisotope cells remain a laboratory curiosity or move toward operational use on satellites and unmanned systems—and whether a portion of the nation's reactor-site inventories will be repurposed into long-lived power packages.
