Geothermal energy could power nearly half of Europe's electricity

Earth's heat is constant, reliable, and mostly untapped. A new analysis from the energy think tank Ember found that geothermal energy could theoretically replace 42% of the European Union's electricity currently generated from coal and natural gas — and do it at the same cost.

The catch: most of Europe's geothermal potential lies deeper underground than traditional geothermal sites, in places where the Earth's heat isn't already bubbling to the surface. But newer drilling techniques are changing what's economically possible.

How Deep Geothermal Works

Traditional geothermal works in volcanically active regions where heat rises close to the surface. Engineers drill down, pump water through hot rock, and the heated water powers turbines above ground. It's elegant and it works — but only in specific places.

Advanced geothermal flips the script. Drillers go deeper — several miles down — where the planet's molten core keeps temperatures high everywhere. They also fracture rock at depth to create pathways for water to flow through and absorb heat. The technique borrows heavily from oil and gas engineering, which is both practical and, as Tatiana Mindeková, the policy advisor at Ember who led the report, notes, "a bit ironic."

The deeper you drill, the harder and more expensive it gets. Equipment must scale up to handle the load and pressure. But as more geothermal projects come online, costs will fall — a pattern we've seen with solar and wind. David Victor, co-director of the Deep Decarbonization Initiative at UC San Diego, points out that European deployment will bring innovation costs down globally: "To the extent that we see more deployment of advanced geothermal in Europe, we're going to see that bring down the cost of applying the innovation in lots of other places in the world."

Heating Homes, Not Just Grids

The electricity story is compelling, but it misses half the picture. In the EU, more than three-quarters of household energy goes to heating homes and water. Geothermal can address this more directly through networked geothermal systems.

A utility drills just 600 or 700 feet — shallow enough to be affordable — and pipes water through the ground. Because soil maintains a fairly constant temperature year-round at that depth, the water stays warm in winter and cool in summer. Heat pumps in individual homes extract warmth from that water in cold months, then reverse the process in summer, using the ground as a natural thermal battery. This approach doesn't require drilling miles deep or waiting for breakthrough technology. It's available now.

Geothermal can also complement wind and solar. When renewable energy is abundant, facilities use it to heat water and pump it underground. When the wind stops and clouds roll in, that stored heat comes back up to generate electricity. The ground becomes a battery.

What's Actually Stopping It

Geology matters. The temperature gradient — how fast heat increases with depth — varies by location. Rock may be hot enough for drilling two miles down in one place, but just one mile in another. Water loss during drilling is another problem in dry regions. And certain rock types can infuse water with minerals that corrode equipment.

None of these are showstoppers. They're engineering challenges with known solutions. The real barrier is attention. Europe has focused on solar and wind for good reason, but geothermal's constant output and small footprint make it a natural complement. And as Mindeková points out, the transition offers something often overlooked: workers from the oil and gas industry can transfer their drilling expertise directly into geothermal development. It's not a story of disruption but of redeployment.

The heat is there. The technology exists. What's needed now is the will to dig.