Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming

by Paul Hawken

One of these new approaches is enhanced geothermal systems (EGS), which typically targets deep underground cavities and creates hydrothermal pools where they do not currently exist. EGS uses engineering to make use of areas that contain ample heat but little or no water, adding it in rather than relying on nature’s supply. By injecting high-pressure water into the earth, EGS techniques fracture and break up hot rock, making it more permeable and accessible. Once the rock is porous, water can be pumped in via one borehole, heated underground, then returned to the surface via another. After using it for electricity production, injection wells pump spent water back down into the reservoir. Or, in the case of Iceland’s Blue Lagoon geothermal spa, the Svartsengi power plant’s wastewater becomes bathwater for residents and tourists alike. With recirculation, the cycle repeats.