Geothermal energy, long a niche power source accessible only in volcanically active regions, is on the verge of a major expansion. Advances in drilling technology now allow engineers to reach the Earth’s heat almost anywhere, a shift that industry leaders say could reshape the global energy landscape. Cindy Taff, chief executive of geothermal company Sage Geosystems, described the moment in February of 2025 as “the decade of geothermal.” The sector still accounts for a tiny fraction of the global energy mix, but momentum is building.
From Ancient Baths to Modern Power Plants
Harnessing heat from the Earth’s crust is not new. The heat itself comes from two sources: the planet’s original formation and the ongoing decay of radioactive elements.
People have used this energy directly for millennia—bathing in hot springs since Paleolithic times and piping warm water through Roman underfloor systems. The world’s oldest known district heating network dates to the 1400s in Chaudes-Aigues, France. Industrial exploitation began in 1827, when steam from geysers in Larderello, Italy, was used to extract boric acid from volcanic mud.
The first geothermal power plants appeared in the early 20th century. In the United States, geothermal energy was already heating buildings by the late 1800s in Boise, Idaho, and Klamath Falls, Oregon.
The Hot Lake Hotel in Oregon, dating to 1907, became the first known building to rely on geothermal as its primary heat source. Over subsequent decades, technology improved and the cost of generating geothermal power declined sharply. The underlying resource is vast; geothermal reserves are theoretically more than enough to supply all of humanity’s energy needs. But for most of the 20th century, extraction was practical only in geologically unusual places—near tectonic plate boundaries where heat naturally rises to the surface through geysers and hot springs.
That limitation kept geothermal to a small share of the global energy mix.
Drilling Deeper, Expanding Access
What has changed is drilling technology. By going deep enough, engineers can now access that heat almost anywhere, regardless of surface geology. The U.S. Department of Energy estimated that power from a newly built geothermal plant costs roughly the same as many fossil-fuel sources.
Advances continue to reduce costs and expand the amount of economically viable resources. The technology is now feasible in nearly any geological context, and the electric grid is preparing to integrate more of this steady power source.
Unlike wind or solar, geothermal does not flicker off when the weather changes; it runs day and night, unaffected by time of day or cloud cover. That constant, always-available output is a key advantage. Geothermal has also proved politically popular, a rare point of agreement in an often divided energy landscape. None of this means the path is easy.
The upfront costs of drilling and development are significant, and the industry still faces real headwinds. But the competitive edges are becoming harder to ignore.
What has unfolded over the past year is a story of momentum. Taff’s prediction is proving prescient. The technology’s feasibility in nearly any geological context, combined with falling costs and a grid ready for more reliable clean power, suggests geothermal may finally shed its status as a geological curiosity.
For those involved, the stakes are personal. The appeal is not just that geothermal is clean—it is constant.
And that constancy, together with its growing economic viability, positions it to play a far larger role in the energy systems of the coming decades.
