Spencer Jackson spent nearly seven years at SpaceX working on some of the most extreme machines ever built: the structures of the Falcon Heavy, the thermal seals that protect Starship during re-entry, and the combustion chamber and nozzle of the Raptor rocket engine. The temperatures and pressures he designed for were those of a rocket firing into orbit. Now he is applying the same engineering to the heat beneath the earth’s surface.
Jackson’s startup, Critical Energy, announced this week that it has raised $22 million to build modular turbines for geothermal power plants. The funding consists of a $19 million seed round led by Susa Ventures and Upfront Ventures, with participation from MaC Venture Capital, Susquehanna Sustainable Investments, Humba Ventures, Scribble Ventures, and Underground Ventures, plus $3 million in venture debt from Silicon Valley Bank. The money is earmarked for the company’s first project: a 2.5-megawatt geothermal plant that will demonstrate the technology at commercial scale.
The company’s insight is that geothermal power has a supply problem that has nothing to do with heat. The earth’s heat is abundant — the technical resource base is measured in terawatts — but converting it into electricity requires turbines, and the turbines available today are large, custom-built, and slow to manufacture. Geothermal developers often wait years for equipment that was designed for other purposes, and the industry has struggled to grow because the supply chain cannot keep up with demand.
Critical Energy’s answer is a turbine designed from scratch for geothermal wells and built like a product rather than a project. By moving most of the manufacturing into factories, the company says it can shrink deployment timelines from years to weeks and cut costs substantially. It has built a pilot facility in Los Angeles and describes itself as the only U.S.-based manufacturer of modular geothermal turbines.
The rocket background is not a gimmick; it is the point. Geothermal turbines operate in environments that are hot, corrosive, and high-pressure, conditions that share DNA with rocket propulsion. Jackson’s work on Raptor, the engine that powers Starship, involved managing combustion at temperatures and pressures that would melt ordinary metals. The thermal management, materials, and precision manufacturing techniques he brought from SpaceX are directly applicable to extracting energy from deep wells.
The timing is favorable. Investment in geothermal has lagged far behind the money flowing into nuclear fission and fusion startups, but the AI boom has changed the calculus. Data centers need enormous amounts of always-on power, and utilities are struggling to supply it; advanced geothermal is one of the few zero-emissions sources that can run around the clock, and analysts project it could supply a meaningful share of new data center power needs by the end of the decade. “Geothermal is going to beat them to it. By a lot,” Jackson told TechCrunch, referring to the nuclear startups targeting their first commercial deployments in the early 2030s. “In four or five years, I hope that we’re doing many gigawatts a year.”
The oil and gas industry, Jackson argues, provides the template for scaling. Drilling companies are extremely good at drilling wells — the industry does thousands of them a year — and that capability can be redirected to geothermal. “They need turbines and there’s going to be a massive shortage of those,” he said. Critical Energy’s wager is that the turbine shortage, not the drilling, is the binding constraint, and that a company that solves it can ride the oil and gas industry’s drilling capacity to scale.
The company’s long-term ambition is large. It aims to deploy more than 300 gigawatts of new geothermal capacity per year by 2045, a figure that would make it one of the largest power equipment makers in the world. For context, the entire global solar industry installed roughly 500 gigawatts last year, and solar took two decades to reach that scale. Jackson acknowledges the target is audacious, but he notes that geothermal’s advantage — reliability — gives it a structural role that intermittent renewables cannot fill.
The startup is also part of a pattern: SpaceX’s alumni network is spawning a wave of energy companies. The IPO of SpaceX this month, which made it the world’s fourth-largest technology company by market value, has focused attention on the broader ecosystem of companies founded by its engineers and executives. From batteries to solar to geothermal, former SpaceX staff are applying aerospace manufacturing discipline to energy infrastructure, and investors have taken notice.
For Critical Energy, the immediate challenge is proving that a 2.5-megawatt plant built with factory-made turbines works reliably, and then proving it can scale. The company’s seed funding is modest by the standards of the energy industry, where a single gas turbine plant can cost more than the company’s entire valuation. But Jackson argues that is the point: if the turbines can be made in factories like rockets are made, the capital intensity of geothermal collapses, and the industry stops being a series of one-off engineering projects. The rocket engines that took him to the edge of space may end up powering the grid instead.
