Critical Energy builds factory-made geothermal turbines that turn underground heat into always-on electricity. The 2024 startup has now raised $19 million in seed funding because geothermal developers are running into a physical bottleneck: there aren’t enough compatible turbines in the right sizes, especially if they need them built fast instead of assembled on-site over months or years. Founder and CEO Spencer Jackson — a former SpaceX engineering leader — says the money is going toward the company’s first 2.5 MW project. It's a small round by fusion or advanced fission standards, but a telling one for geothermal turbines.
What is Critical Energy and how do its geothermal turbines work?
Here’s the plain-English version. Critical Energy is building modular surface power units for geothermal sites, not drilling rigs and not giant custom plants. Its first product family is called Apex. Those units are factory-assembled in shipping-container modules, can be deployed one at a time or in parallel, and are meant to bring multi-megawatt power online faster than conventional geothermal plant builds.
The workflow is pretty straightforward. A project developer brings the heat source — traditional hydrothermal, enhanced geothermal, or another compatible resource — and Critical supplies the conversion hardware that turns that heat into electricity. Inside the system, geothermal heat vaporizes a specialized working fluid. That vapor spins a turbine and generator, and then the fluid condenses and circulates again in a closed loop. No fuel truck. No combustion.
The manufacturing angle is the real pitch. Critical builds the modules in a factory and ships them in standard containers. It says crews can install them with minimal on-site labor in as little as 2 weeks. That contrasts with the usual large-turbine approach in geothermal, where site-specific equipment and field assembly slow everything down.
And this isn’t just slideware. The company already built a custom turbine and integrated it into a demo system that has generated more than 50 kW in testing. That demo matters. It validates the basic loop — heat exchange, working-fluid cycling, and turbine-driven power generation — before Critical tries to jump to the first commercial-scale units.
Who founded Critical Energy, and can this team actually build it?
The founding story
Critical Energy was founded in 2024 by Spencer Jackson. Before starting the company, Jackson was an Entrepreneur in Residence at NosTerra Ventures, where he focused on low-cost clean energy ideas. His goal for Critical was simple enough: accelerate modular power-plant deployment and make clean, dispatchable energy easier to build.
That sounds broad. But the company’s wedge is narrow. It isn’t trying to solve the whole geothermal stack at once. Jackson is going after the turbine layer — the part that sits above the wellfield and converts heat into electricity. Less glamorous than drilling breakthroughs, sure. But sometimes the boring hardware bottleneck is the whole story.
Why Jackson has real market fit
Jackson spent 7 years at SpaceX, working in engineering leadership across Falcon Heavy, Starship, and the Raptor engine program. Critical’s broader team brings more than 50 years of combined SpaceX experience, plus backgrounds in aerospace, transportation, and energy hardware. That doesn’t make geothermal easy. But it does make the company’s core bet more credible, because turbomachinery, high-performance thermal systems, and rapid hardware iteration are exactly the kinds of things SpaceX people know how to ship.
The supporting cast helps too. Critical lists Steve Kohr as head of engineering. Tyler Rowan handles build and test. Pete Perrone is fractional CFO. Its advisors include Mike Matson, a BCG partner and global geothermal lead, and Greg Leveille, the former CTO of ConocoPhillips. That mix — startup hardware operators plus people who understand geothermal and oil-and-gas scale-up — is probably what investors were buying here.
Traction, fundraising, and where it sits against competitors
Critical is still early, but not pre-everything. The 50 kW demo is already running in testing. The first commercial plant using its turbines is scheduled for completion in 2027, and that initial deployment is planned for an existing geothermal site of the kind Jackson compares to Icelandic projects or The Geysers in Northern California. The company is also designing a larger 5 MW module aimed at enhanced geothermal developers such as Fervo, where hotter and deeper resources can support bigger systems.
Susa Ventures and Upfront Ventures led the $19 million seed round, with MaC Venture Capital, Susquehanna Sustainable Investments, Humba Ventures, Scribble Ventures, and Underground Ventures also participating. Critical also added $3 million in venture debt from Silicon Valley Bank, bringing total early capital to $22 million. Jackson has said he wants the company producing many gigawatts of turbines annually within 4 or 5 years.
Competition makes the story more interesting. Legacy geothermal developers already buy proven binary-cycle systems from incumbents such as Ormat, which has built 190 binary geothermal plants worldwide. Newer geothermal darlings like Fervo and Quaise are attacking the resource-access side — drilling deeper, fracturing hot rock, or repurposing existing sites — and they’ve raised far more money to do it. Critical is taking a picks-and-shovels position between those worlds. Let the drillers open up more heat, then sell them modular conversion hardware that can be manufactured repeatedly instead of custom-built every time. Peregrine Turbine Technologies is one of the few adjacent companies also pushing transportable 1 MW to 10 MW closed-cycle turbine systems.
Why are investors backing geothermal turbines right now?
This round isn’t really about a turbine in isolation. It’s about whether geothermal can scale fast enough to catch a moment when the grid suddenly needs more firm power and can’t wait for a science project. Investors are betting that Critical can move from a 50 kW proof point to a 2.5 MW operating plant without the usual hardware startup stall in between.
There’s also a timing argument in Jackson’s pitch. Advanced nuclear fission startups and fusion companies still largely point to the early 2030s for first commercial deployments, while geothermal projects are already being drilled and interconnected now. Jackson’s blunt version is that geothermal will beat them to market “by a lot.” If he’s right, a company supplying geothermal turbines could benefit from deployment curves long before the nuclear names hit their promised milestones.
The use of funds is concrete. Critical isn’t talking about vague platform expansion. The seed money is meant to get the first 2.5 MW project built, which should tell the company a lot about field installation, maintenance, module performance, and how much custom work still creeps into a supposedly standardized product. That’s what seed investors usually want to de-risk before bigger project finance or later-stage venture money shows up.
How big could the geothermal turbines market get?
The macro case is huge — maybe absurdly huge. The IEA says geothermal electricity at depths of less than 5,000 meters carries an estimated 42 TW of technical potential over 20 years of generation, and that the broader technical potential within 8 km of depth approaches 600 TW. The same IEA analysis argues geothermal’s resource base is second only to solar PV in technical electricity potential. That's why investors have started treating it less like a niche renewable and more like a future industrial power source.
The demand side is changing just as fast. DOE says data centers’ share of total annual U.S. electricity use rose from 1.9% in 2018 to 4.4% in 2023, and projects that figure could reach 6.7% to 12% by 2028. Rhodium’s analysis goes a step further and estimates advanced geothermal could supply nearly two-thirds of new data center demand by 2030. That's why geothermal has gone from a quiet utility topic to an AI infrastructure topic almost overnight.
There’s another structural shift here. Modern drilling is widening the map. Critical itself is designing plants that can work with traditional hydrothermal, enhanced geothermal, advanced closed-loop systems, and hot sedimentary aquifers. If drilling keeps improving — and oil-and-gas supply chains decide geothermal is worth their time — the market for surface equipment could grow much faster than the market for bespoke geothermal plants did in the past.
Will geothermal turbines beat advanced nuclear to market?
That’s still a bold claim. Hardware is hard. Geothermal project development is never clean, and a 2.5 MW first plant is not the same thing as repeatable gigawatt-scale manufacturing.
But Critical Energy is at least aiming at a real choke point. If drilling startups keep making geothermal more available, someone has to provide the conversion hardware at a speed and price the old model can’t match. That’s why this geothermal turbines round matters. Watch the 2027 project. If it works, the company’s line about a “long-term goal” of 300 gigawatts a year in 2045 will start sounding less like startup bravado and more like a manufacturing question.
Read how Pramaana Labs raised a $27M seed round led by Khosla Ventures to build AI verification infrastructure that turns legal, tax, and scientific rules into machine-checkable logic, helping enterprises trust and audit AI-generated decisions.
FAQ
- What funding did Critical Energy raise?
Critical Energy raised a $19 million seed round, then added $3 million in venture debt from Silicon Valley Bank for $22 million in total early capital. Susa Ventures and Upfront Ventures led the equity round, with MaC Venture Capital, Susquehanna Sustainable Investments, Humba Ventures, Scribble Ventures, and Underground Ventures also joining. - How do Critical Energy’s geothermal turbines work?
Critical’s systems use geothermal heat to vaporize a specialized working fluid, which spins a turbine and generator before condensing back into liquid in a closed loop. The company packages that setup in factory-built Apex modules. Its demo system has already generated more than 50 kW in testing. - Who is Spencer Jackson?
Spencer Jackson is the founder and CEO of Critical Energy, which he started in 2024 after serving as an Entrepreneur in Residence at NosTerra Ventures. Before that, he spent 7 years at SpaceX in engineering leadership roles across Falcon Heavy, Starship, and the Raptor engine program. - Is Critical Energy a geothermal developer or a turbine supplier?
It’s primarily a turbine and modular power-plant supplier, not a drilling company. That puts it in a different lane from geothermal developers like Fervo or Quaise, which focus more on opening up the underground resource. Critical focuses on the surface hardware that turns heat into grid power.
