Zeno Power’s $50 million Series B was announced on May 14, 2025, led by Hanaco Ventures. The round funds development of radioisotope power systems, which the company describes as nuclear batteries. Those systems turn heat from decaying radioactive material into electricity or heat, and they are built for seabed, space and other remote settings rather than for consumer devices. The company’s 2026 and 2027 targets are still unconfirmed in the sources available as of October 2026.
What the May 2025 round was
The round was a private venture financing. Zeno announced that Hanaco Ventures led it, with participation from Seraphim, Balerion Space Ventures, JAWS, Vanderbilt University, RiverPark Ventures, Stage 1 Ventures, 7i Capital, Beyond Earth Ventures and other investors. The company said total capital raised to that point exceeded $70 million. The announcement is a company source. It is not audited financial reporting, and the sources reviewed do not disclose the valuation or the terms of the round.
The headline uses the present tense, but the financing closed and was announced in 2025. Nothing in the available record indicates a later round.
What the money was meant to support
Zeno said it had more than $60 million in contracts from the U.S. Department of Defense and NASA to develop systems for maritime and space uses. The company named three example applications: seabed infrastructure, highly maneuverable satellites and lunar landers. It said the new capital would go toward team growth and manufacturing capability.
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Co-founder and CEO Tyler Bernstein framed the goal in the announcement this way: “With great power competition rising, the ocean floor, Arctic, and lunar surface are becoming the front lines of global security and economic progress – but they remain energy deserts.” That is the company’s positioning, not independent evidence of market demand.
How radioisotope power differs from ordinary batteries and reactors
A conventional battery stores chemical energy and must be recharged or replaced. A radioisotope power system has no charging cycle. It relies on the steady heat released as an unstable isotope decays. Zeno says its systems use strontium-90 (Sr-90) and americium-241 (Am-241) as heat sources.
The heat is converted in one of two ways. A Stirling engine converts it to electricity through moving mechanical parts. A thermoelectric generator converts a temperature difference directly to electricity with no moving parts. Zeno also builds radioisotope heater units, which supply heat without generating electricity.
These systems are not fission reactors. Zeno does not describe them that way, and nothing in the company’s materials indicates a fission process.
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Zeno’s technical page lists three product families. The output and lifespan figures are company-published development specifications, not independently verified operating results.
| System type | How it produces heat or power | Indicative output (company-published) | Planned lifespan (company-published) | Fuel per system | Intended environment per system |
|---|---|---|---|---|---|
| Radioisotope Stirling generator | Stirling engine converts heat to electricity via moving parts | 15 W electric to hundreds of W electric | Five years or more | Not stated per system (Sr-90 and Am-241 named across the product line) | Not stated per system; company lists seabed, satellite and lunar uses overall |
| Radioisotope thermoelectric generator | Thermoelectric generator converts temperature difference directly to electricity, no moving parts | 1 W electric to hundreds of W electric | Five years or more | Not stated per system | Not stated per system |
| Radioisotope heater unit | Provides heat directly | Under 10 W thermal | Five years or more | Not stated per system | Not stated per system |
The sources do not state which fuel or environment applies to each product, so the table reflects only what Zeno has published.
Milestones and what remains unconfirmed
- 2018: Zeno says it was incorporated and received a $50,000 National Science Foundation grant and a $50,000 investment from 1517 Fund.
- 2022: The company reports a $20 million Series A led by Tribe Capital.
- 2023: NASA selected Zeno for a $15 million Tipping Point award to develop a radioisotope Stirling generator for future lunar surface missions. Zeno also says it demonstrated its first Sr-90 heat source at Pacific Northwest National Laboratory that year.
- 2024: Zeno says it secured initial Department of Energy fuel supply by recycling a historic radioisotope thermoelectric generator, and partnered with a commercial radiological facility to fabricate its systems.
- May 2025: The $50 million Series B was announced.
- 2026 (target): A full-scale heat-source demonstration. The company’s May 2025 announcement said it was on track for this year.
- 2027 (target): Delivery of the first commercially built nuclear batteries, and a first full-scale seabed system deployment according to the company’s history page.
The sources reviewed do not confirm whether the 2026 demonstration was completed, and they do not independently verify that the 2027 delivery target is still on schedule. Readers should treat both dates as company targets, not outcomes.
What the government award record shows
The U.S. Small Business Administration’s SBIR award record lists a 2022 Department of the Air Force STRATFI award of $7,155,899, with a period running from August 16, 2022 through July 20, 2026. The record describes the proposed system as providing always-on, resilient power in the watt-to-kilowatt range for years. That language comes from the proposal abstract, not from test data. The award amount is a government record. The performance claims are not.
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The round is a private investment in a company building specialized power hardware for government and institutional customers. The announcement offers no consumer product, no retail purchase channel and no public way for individual readers to invest. Nothing in the reviewed sources indicates a public offering or secondary market.
For households, the practical takeaway is limited. Zeno’s technology may matter to the space and maritime programs that buy it, but it does not change the cost or availability of batteries or electricity for anyone outside those programs. Any future financial relevance depends on the 2026 and 2027 milestones being met, and on reliable public data about performance that is not yet available.
No independent market-size figure or independently validated performance figure is available for this company. The $50 million, $60 million and $70 million numbers all come from the company’s own announcement.
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