Geothermal energy, a nearly inexhaustible source of clean energy, has the potential to transform global power generation. While countries like Iceland have successfully tapped into geothermal resources, the challenge lies in accessing the vast amounts of heat stored beneath the Earth’s surface. Currently, only 32 countries operate geothermal power plants, and less than 700 plants worldwide generate around 97 Terawatt hours (TWh) of electricity annually—a fraction of its potential. Experts believe geothermal could contribute up to 1,400 TWh annually by 2050, along with billions of TWh of heat.
Iceland, home to over 200 volcanoes and numerous hot springs, serves as a model, using geothermal energy to heat 85% of homes and generate 25% of the country’s electricity. However, tapping into this clean energy source is not so straightforward elsewhere, where drilling deep enough to reach the high temperatures necessary for power generation remains a major hurdle. While the Earth emits immense energy, its practical extraction is limited by technological and financial barriers.
In places like Iceland, geothermal wells can reach temperatures of up to 350°C (662°F) at depths of 1.5 miles (2.5 km), with some experimental wells in Reykjanes reaching superheated fluids as hot as 600°C (1,112°F). These high temperatures are essential for generating electricity, but drilling to these depths requires costly and complex technology. The challenge intensifies in regions like the UK, where the temperature at 5 km deep is around 140°C (284°F). To generate power, temperatures must exceed 374°C (705°F) to reach a state called supercritical, where water becomes a highly energetic substance capable of generating up to 10 times the energy of conventional geothermal wells.
Traditional drilling methods, even with advanced materials like diamond-tipped bits, struggle to reach these depths due to the extreme pressures and temperatures that cause frequent failures. In 2009, a drilling team in Iceland accidentally tapped into supercritical conditions, encountering highly acidic steam and uncontrollable pressures that led to a two-year hiatus before the well could be sealed.
To overcome these challenges, innovative companies and researchers are developing new drilling technologies. Quaise Energy, a spin-off from MIT, is pioneering millimetre-wave drilling, using high-frequency microwave beams to vaporize rock, allowing for deeper, more efficient drilling. Though still in laboratory testing, the technology could revolutionize geothermal energy extraction, with potential field trials starting in 2025.
Meanwhile, GA Drilling, based in Slovakia, is working on pulse plasma drilling, which disintegrates rock using high-energy electric discharges without melting it. This method reduces the need for frequent equipment replacement, potentially allowing access to geothermal power at depths of 10 km or more. These breakthroughs could unlock geothermal energy for regions once thought unreachable, offering a sustainable and reliable power source to meet global energy demands.
