Seattle-based Endurance Energy has completed a US$54mn fundraiser to progress its plans to develop subsea geothermal power.
The company announced a US$54mn Series A fundraising, led by Founders Fund, in a post published on its Linkedin social media account.
“Our subsea geothermal systems are engineered to deliver gigawatts of always-on, zero-emission power, faster and cheaper than conventional sources,” the statement noted.
“This funding enables us to transition from prototype to full-stack systems and scale our offshore operational capability.”
Alongside Founders Fund, it welcomed new investment from Felicis, Voyager Ventures, Riot Ventures and Construct Capital, as well as continued support from Point72 Ventures, First Round Capital and Ascend.
Presenting its case for subsea geothermal, it noted that most of the world's baseload power still comes from burning fossil fuel, with demand set to climb sharply as AI and re-industrialisation come online.
For many coastal regions around the Pacific, it noted, offshore geothermal represents a completely untapped source of firm, clean power, abundant enough to displace imported diesel and carry baseload at multi-gigawatt scale.
Despite the complexities and challenges involved, it offers a real, long-term solution to rising energy demands.
“Mating a generator to an over 300°C drilled well, holding it on the seafloor for years at a time at depth and pressure, and recovering it for service is hard, but none of it requires new physics,” the company said in its statement.
“The drilling, turbines, and subsea hardware all exist in adjacent industries, and Endurance is integrating them into a single unit you can deploy, operate, and recover on the seafloor.”
It also referenced its “SpaceX heritage” which enables a pace of development that is “unprecedented” for new energy projects.
“In just the past year, we've completed four prototype deployments to deep sea volcanic systems at depths up to 3,300 metres and hydrothermal temperatures up to 386°C, and we're on track to deploy our 100kW 'Adelie' generator to the Juan de Fuca ridge this Fall,” the company said.
Adelie is its first end-to-end system: drilling, generation and offtake in a single deployable unit, powering a co-located subsea compute module and connected to shore via fibre optic cable.
“We build, deploy, learn from real-ocean conditions, and turn the hardware around faster every cycle, with a line of sight to delivering power to the grid in the next two years.”
From its Seattle base, on the north Lake Union waterfront, it can load seafloor drills and generators directly onto vessels that carry them to sea and to where they are required.
In its statement, it also referenced the Endurance Energy leadership team that has scaled multi-billion dollar businesses, built leading-edge energy projects and implemented national energy policy and called on others to join what it termed “a well-capitalised, world-changing energy project with a profoundly kind and talented team operating at full-tilt.”