The power source for the next frontier of exploration and defense won't be a solar panel or a diesel generator. It will be a sealed metal cylinder, about the size of a fire extinguisher, converting the steady heat of radioactive decay into electricity for a decade or more without refueling. Zeno Power, a Seattle-based startup founded in 2018, is betting that its radioisotope power systems are the only viable answer for long-duration missions in the dark, whether on the ocean floor or the surface of the moon.
Zeno’s near-term market is the U.S. government, a customer with a clear and urgent need for persistent power in environments where conventional energy fails. The company has secured anchor contracts worth over $60 million with the Department of Defense and NASA, providing a stable revenue foundation as it moves from prototype to production [YouTube interview, 2025/2026]. Its roadmap calls for full-scale system demonstrations in 2026 and the first commercially built units in 2027 [Perplexity Sonar Pro Brief, Unknown].
The bet on two isotopes
Zeno’s technical strategy hinges on using two specific radioisotopes, each matched to a distinct operational environment and customer.
- Strontium-90 for the seabed. The Pentagon is funding development of a strontium-90 fueled system to power seabed sensors and infrastructure for the U.S. Navy. Strontium-90 is a byproduct of nuclear fission, and Zeno has already successfully demonstrated a prototype heat source using the material [Zeno Power, Unknown].
- Americium-241 for the moon. For NASA’s Artemis program, Zeno is leading a team to develop an americium-241 radioisotope Stirling generator. NASA awarded Zeno a $15 million Tipping Point contract for this work in 2023 [Zeno Power, July 2023]. The company has also made a multi-million dollar investment for priority access to americium-241 supplies from a nuclear recycling site in France [World Nuclear News, September 2025].
Why the government is writing checks
Zeno’s $50 million Series B round, closed in May 2025, reflects investor confidence in this government-led path to market [SpaceNews, May 2025]. The round brought Zeno’s total disclosed private funding to approximately $70 million, backed by firms like DCVC, Hanaco Ventures, and Seraphim. The capital is earmarked for scaling its team, now around 80 people, and moving its two product lines toward demonstration and delivery [leadiq.com, December 2025].
| Product Line | Primary Customer | Fuel Isotope | Key Milestone |
|---|---|---|---|
| Seabed Power System | U.S. Department of Defense (Navy) | Strontium-90 | First full-scale demo targeted for 2026 |
| Lunar Surface Power System (Harmonia) | NASA | Americium-241 | Final design review completed; targeting 2027 delivery |
The path to a commercial model
While government contracts de-risk the early technology, Zeno’s founders have outlined a longer-term vision that includes commercial models. CEO Tyler Bernstein has described three potential business approaches: direct sales of hardware, a power-as-a-service model, and revenue-sharing partnerships [YouTube interview, 2025/2026].
Where the wheels could come off
Zeno’s bet is technically sound and commercially logical, but its timeline faces predictable pressures from the inherent complexity of its work. Regulatory friction, supply chain scaling, and the demonstration gap represent the primary hurdles to moving from a validated prototype to a reliable, manufacturable product.