Few energy sources can top geothermal’s potential, with at least 42 terawatts of capacity available worldwide, according to the IEA — more than twice the world's energy use last year. The technology is shaping up to be the energy world’s dark horse, even though investment in the tech pales in comparison to startups in advanced nuclear fission and fusion power.

That makes the $19 million in seed funding raised by a startup called Critical Energy especially notable. Critical Energy hopes to fill a major gap for geothermal power plants by building modular turbines tailored to them. The funds are earmarked to build its first 2.5 megawatt project, the startup exclusively told TechCrunch.

Meanwhile, the darlings of the investment world, those working on nuclear fission and fusion, are targeting the early 2030s for their first commercial deployments. By that time, geothermal startups could be building gigawatt-scale power plants. “Geothermal is going to beat them to it,” said Spencer Jackson, co-founder and CEO of Critical Energy, “By a lot.”

Even modest expansion of geothermal could pay off to serve the world's — and especially the tech industry’s — growing energy needs. A recent report said that advanced geothermal could power nearly two-thirds of new data centers by 2030.

But Jackson said there’s a looming shortage of compatible turbines. Many projects today are specifying large turbines, which can take months to years to assemble on site, he said. “It's still way faster and cheaper to make it the other direction,” he added, “to built it in a factory.”

Critical Energy hopes to fill the gap with modular turbines. To design them, Jackson leaned on his experience at SpaceX, where he worked on Falcon Heavy, Starship, and the Raptor rocket engine. To build them quickly, Critical Energy is working with machine shops to make the turbomachinery and other turbine components, which resemble rocket engines.