Abstract
The Earth beneath our feet holds an almost comically simple solution to our energy problems. Drill down a few kilometers anywhere on the planet and you’ll find temperatures hot enough to boil water.
Run that water through a turbine, generate electricity, reinject the cooled water into the ground, repeat. No fuel needed. No emissions. Just heat from the planet’s molten core, which will remain hot for billions of years – long after anyone stops caring about quarterly earnings reports.
This isn’t some exotic technology. Humans have been harnessing geothermal energy for millennia. The ancient Romans built elaborate bath complexes over hot springs. In the 14th century, residents of Chaudes-Aigues in France piped geothermal water through the world’s first district heating system. The Maori of New Zealand cooked food in geothermal steam pits for centuries before European contact.
In 1904, an Italian prince named Piero Ginori Conti successfully powered five light bulbs with geothermal power in Larderello, Italy – the first time geothermal energy had been converted to electrical power anywhere on Earth.
That should have been the beginning of a revolution. Instead, geothermal power has spent the past century as energy’s perennial also-ran. Modern deployment creeps forward slowly, highly concentrated in a handful of countries blessed with obvious volcanic geology. Kenya and Iceland lead the list of countries where geothermal plays an outsized role, by virtue of being located on tectonic plate boundaries where the Earth’s heat rises closest to the surface. The list traditionally also includes El Salvador, New Zealand and Nicaragua, all in locales with similar geological features.
Meanwhile, 80 percent of geothermal energy consumed globally goes to heating and cooling, 20 percent to electricity generation. While the two technologies have fundamental differences, there’s a clear link – even if just in people’s imagination. The pools of Iceland’s Blue Lagoon are perhaps the most famous example of the broader benefits of geothermal power. Indeed, the pools of the outdoor spa operational throughout Iceland’s dark, cold winters are filled with the pristine-clean waste water of one of HS Orka’s power plants. These brine pools now attract so many paying tourists that they account for a sizable portion of the energy company’s revenues.
By now we know that geothermal’s potential extends well beyond happenstance based on winning the geological lottery – spectacular where you can find it, useless everywhere else. Recent drilling innovations, particularly those borrowed and adapted from the oil and gas industry, are making it increasingly viable to tap geothermal resources in ordinary geology beneath ordinary places. Not just in volcanic hotspots, but places where people live and work. Under Iowa. Under Germany. Perhaps under most of the planet’s surface.