Startup profile · funding coverage
Endurance Energy funding, valuation and investors
Develops modular seafloor geothermal generators for coastal and industrial electricity demand.
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Funding, valuation & investors
Answer-first snapshotLatest funding
Series A
$54M · June 2026
Latest known valuation
Not publicly disclosed
Total disclosed equity funding
$54M
Excludes debt, grants, acquisitions, secondaries, and IPO proceeds.
Current status
private
series a · Seattle, Washington, United States
Overview
Seattle-based geothermal startup founded in 2025 by former SpaceX engineer Andrew Redd. Endurance Energy designs modular generators intended to capture heat from natural hydrothermal vents beneath the ocean. It reported a net-positive Adélie prototype test at Axial Seamount in September 2026 and announced $54 million in Series A funding.
Why Endurance Energy is interesting
The company claims its offshore prototype produced net-positive power from a natural hydrothermal vent in September 2026, a different approach from conventional onshore geothermal. It has disclosed a $54 million Series A.
Product & use cases
Endurance designs equipment to convert geothermal heat found in undersea hydrothermal vent fields into power for coastal electricity and industrial uses. Its Adélie deployment demonstrated an early prototype; commercial power delivery remains to be validated.
- Coastal grids close to viable subsea geothermal resources
- Energy supply for remote island territories
- Long-duration industrial power where a geothermal resource is accessible
Key facts
- June 2026: reported $54 million Series A led by Founders Fund, with Riot Ventures among participants.
- September 2026: deployed Adélie prototype at the Axial Seamount hydrothermal vent off Oregon and reported positive net electrical output.
- Developing a 2 MW commercial-scale generator; first power from a proposed Tonga deployment is targeted for 2027, not yet achieved.
- Expanded into a 25,000-square-foot Seattle R&D and production facility in 2026.
Funding history (newest first)
Series A
2026-06 $54MInvestors in our directory
Funds linked from Endurance Energy's profile — open a fund page for stage focus and related deal articles.
Competitive landscape
Edge: Access to a distinct offshore geothermal resource and a modular generator design; underwater maintenance cost, marine permitting and grid connection remain important risks.
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Fervo Energy adjacent
Enhanced geothermal developer using onshore engineered reservoirs.
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Sage Geosystems adjacent
Onshore geopressured geothermal electricity and storage.
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Eavor adjacent
Closed-loop geothermal systems, primarily terrestrial.
Industries
Market / IPO context
Editorial / static context — not a live quote.
FAQs about Endurance Energy
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