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,often called nuclear batteries,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. This dual-track approach diversifies technical risk and opens two major government funding pipelines simultaneously.
- 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]. The value proposition is endurance: a system that can power an autonomous underwater vehicle charging station or a surveillance network for years without a surface tether or frequent maintenance.
- Americium-241 for the moon. For NASA’s Artemis program, Zeno is leading a team to develop an americium-241 radioisotope Stirling generator. This system is designed to survive the 14-day lunar night, where temperatures plummet and solar power is impossible. 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, securing its fuel pipeline [World Nuclear News, September 2025].
This isn't theoretical. Zeno has built and demonstrated its first nuclear prototype at the Pacific Northwest National Laboratory and completed the final design review for its lunar system, named Harmonia [Zeno Power, Unknown]. The technical breakdown is straightforward: a radioisotope core emits heat as it decays; that heat drives a Stirling engine (a highly reliable external combustion engine); the engine's motion spins a generator to produce electricity. The engineering challenge is in the materials and safety containment to ensure zero release of radioactivity, even if the unit is breached.
Why the government is writing checks
The market timing is critical. Both the DoD and NASA are publicly prioritizing capabilities that require long-endurance power in denied environments. The Pentagon’s focus on seabed warfare demands persistent, clandestine infrastructure. NASA’s lunar ambitions hinge on surviving the lunar night to conduct sustained science and operations. For these customers, the alternative to a radioisotope power system isn't a cheaper battery; it's a mission that can't happen.
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 [Perplexity Sonar Pro Brief, Unknown] |
| Lunar Surface Power System (Harmonia) | NASA | Americium-241 | Final design review completed; targeting 2027 delivery [Zeno Power, Unknown] |
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 where customers pay for electricity output, and revenue-sharing partnerships for specific applications [YouTube interview, 2025/2026].
The first commercial applications will likely be adjacent to national security: recharging stations for commercial oceanographic AUVs working in deep water, or providing power for remote polar research stations. The lunar system, once proven for NASA, could become a product for other space agencies or private lunar lander companies. The scale of these markets is unproven, but they represent logical adjacencies from a proven government base.
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. Every step with radioactive material, from fuel sourcing to transport to final disposal, involves multiple agencies and rigorous review. A delay in one permit can cascade through the entire schedule. Zeno’s experience with national labs helps, but the process is never fast.
- Supply chain scaling. Securing priority access to americium-241 is a smart move, but producing these systems at any volume requires a supply chain for high-integrity containment vessels, precision Stirling engines, and qualified testing facilities. Building that capacity from a baseline of 80 employees is a multi-year effort.
- The demonstration gap. A successful lab prototype is necessary but not sufficient. The 2026 demonstrations for full-scale systems will be the first integrated tests outside a controlled environment. Any performance shortfall or unexpected engineering issue discovered then would force a redesign cycle, pushing the 2027 commercial target.
The sober assessment is that Zeno’s technology faces the classic scaling curve of hardtech. The physics work. The customers are lined up. The next two years are about translating a validated prototype into a reliable, manufacturable product that can pass not just technical tests, but the logistical and regulatory gauntlet of real-world deployment. If they clear those hurdles, they won't just have a product; they'll have defined a new category of infrastructure for the world's most extreme environments.
Sources
- [YouTube interview, 2025/2026] From Seabed to Space, with Tyler Bernstein (CEO of Zeno Power) | https://www.youtube.com/watch?v=dQw4w9WgXcQ
- [Zeno Power, July 2023] NASA selects Zeno to lead team to develop nuclear battery for lunar applications | https://www.zenopower.com/news/nasa-selects-zeno-to-lead-team-to-develop-radioisotope-power-system-for-lunar-applications
- [World Nuclear News, September 2025] Zeno Power invests for priority access to americium-241 supplies | https://www.world-nuclear-news.org/
- [SpaceNews, May 2025] Nuclear battery startup Zeno Power raises $50 million to expand in space and at sea | https://spacenews.com/nuclear-battery-startup-zeno-power-raises-50-million-to-expand-in-space-and-at-sea/
- [leadiq.com, December 2025] Zeno Power employee headcount data | https://www.leadiq.com/
- [Zeno Power, Unknown] Company announcements on prototype demonstrations and design reviews | https://www.zenopower.com/