The Energy Source the World Has Been Overlooking
Beneath the surface of the Earth, an almost incomprehensible amount of heat is waiting to be used. The planet's core burns at roughly 5,000 degrees Celsius — hotter than the surface of the sun — and that thermal energy radiates steadily outward through rock and sediment. Unlike solar panels that go dark at night or wind turbines that stand idle on calm days, this heat never stops. It is consistent, enormous in scale, and theoretically available almost anywhere on Earth. So why isn't geothermal energy already powering our cities?
The answer, in short, is that getting to that heat is extraordinarily difficult and expensive. But a new wave of energy start-ups believes that advances in drilling technology, materials science, and data-driven engineering may be about to change that equation. The question investors, policymakers, and climate advocates are all asking is the same: will the economics ever truly work?
What Is Geothermal Energy and How Does It Work?
Geothermal energy is heat derived from the Earth's interior. In its most traditional form, it relies on naturally occurring hydrothermal reservoirs — pockets of hot water or steam trapped in permeable rock close enough to the surface to be reached with existing drilling equipment. Countries like Iceland, Kenya, and New Zealand have long exploited these geological gifts, generating reliable baseload electricity with relatively low operating costs once a plant is up and running.
The process is straightforward in principle. Wells are drilled into a geothermal reservoir. Hot fluid or steam rises to the surface, drives a turbine to generate electricity, and the cooled fluid is often reinjected into the ground to sustain the reservoir. The result is a closed-loop system that produces clean electricity with a remarkably small land footprint and minimal emissions compared to fossil fuels.
The problem is that these ideal hydrothermal reservoirs are geographically rare. Most of the world sits on top of hot rock, but not necessarily hot rock that is also permeable and water-saturated in the ways traditional geothermal plants require. That limitation has historically confined geothermal to a handful of geologically fortunate regions, leaving most of the planet's vast underground heat untapped.
Enhanced Geothermal Systems: A New Frontier
This is where modern start-ups are placing their bets. Enhanced geothermal systems, or EGS, represent the most promising new approach to unlocking heat from rock formations that would otherwise be unusable. Rather than searching for a natural hydrothermal reservoir, EGS technology creates an artificial one by injecting high-pressure water into hot dry rock, fracturing it to create permeability, and then circulating fluid through those fractures to extract heat.
The United States Department of Energy has called EGS a potential game-changer, with estimates suggesting the technology could provide more than 90 gigawatts of clean electricity to the American grid — enough to power tens of millions of homes. Companies like Fervo Energy and Quaise Energy are among those leading the charge, combining techniques borrowed from the oil and gas industry with cutting-edge engineering to push the boundaries of what's geologically possible.
Fervo Energy, for example, has adapted horizontal drilling methods — the same approach behind the shale oil revolution — to dramatically improve the efficiency of geothermal well production. Early projects in Nevada have shown promising results, with the company successfully delivering geothermal power to the commercial grid. Meanwhile, Quaise Energy is pursuing an even more audacious path: using high-powered millimeter-wave energy, similar to that produced by fusion reactors, to vaporize rock and drill to depths far beyond what conventional drill bits can reach, potentially accessing temperatures above 500 degrees Celsius.
Why the Costs Remain a Stubborn Problem
Despite the excitement, the economics of next-generation geothermal remain challenging. Drilling deep wells is extraordinarily expensive. A single geothermal well can cost anywhere from $5 million to $20 million or more, and a commercial-scale plant may require dozens of them. Those upfront capital costs dwarf those of solar and wind projects, which have seen costs fall by more than 90 percent over the past decade due to mass manufacturing and supply chain maturation.
Geothermal has not benefited from the same kind of scaling effect, largely because each project is highly site-specific. Unlike a solar panel that performs predictably wherever it is installed, a geothermal well must be carefully designed around the unique characteristics of the subsurface geology at a given location. That variability makes it harder to standardize processes, drive down costs through repetition, or attract the kind of commodity-market financing that has turbocharged solar and wind deployment.
There is also the issue of risk. Subsurface geology is notoriously difficult to predict, even with sophisticated modeling. A project can look excellent on paper and deliver disappointing results once drilling begins, which makes investors cautious and financing terms expensive.
The Case for Optimism
Nevertheless, there are genuine reasons to believe the tide could turn. The oil and gas industry spent decades and hundreds of billions of dollars perfecting deep drilling technology, and much of that expertise is now directly applicable to geothermal projects. Many laid-off petroleum engineers are finding new careers in geothermal start-ups, bringing irreplaceable practical knowledge with them.
Government support is also growing. The Inflation Reduction Act in the United States introduced tax credits that apply to geothermal power, reducing the financial burden on early projects and signaling long-term policy commitment. Similar support is emerging in parts of Europe and Asia as nations race to decarbonize their electricity grids.
Perhaps most importantly, the unique characteristics of geothermal power — its ability to generate electricity around the clock regardless of weather — make it an increasingly valuable complement to the intermittent renewables that now dominate new energy investment. As grids fill with solar and wind capacity, the need for firm, dispatchable clean power becomes ever more acute, and geothermal is one of very few technologies that can fill that role.
A Long Game Worth Playing
Geothermal energy is not going to replace fossil fuels overnight, and the start-ups chasing this opportunity face real and significant hurdles. But the resource itself is undeniably vast, the environmental case is compelling, and the technology is advancing faster than at any point in history. Whether the economics ultimately bend in geothermal's favor may depend less on geology and more on continued investment, policy support, and the relentless ingenuity of the engineers now pointing their drill bits downward — toward one of the most promising and underappreciated energy sources on Earth.