Exploiting geothermal power is easy in volcanic regions like Iceland, where geology brings heat from the Earth’s core close to the surface. In other places, however, accessing this source of renewable energy requires enhanced geothermal systems (EGS). 

These systems use a network of channels created by hydraulic fracturing. Water pumped down one borehole extracts heat from rocks a kilometre or more underground as it travels through those channels and then brings it to the surface via a second…