There's a Vast Source of Clean Energy Beneath Our Feet. And a Race To Tap It.

The United States has enough geothermal energy to power the entire country. Some are trying to unlock it by using techniques from the fracking boom. From a report: Traditional geothermal plants, which have existed for decades, work by tapping natural hot water reservoirs underground to power turbines that can generate electricity 24 hours a day. Few sites have the right conditions for this, however, so geothermal only produces 0.4 percent of America's electricity currently. But hot, dry rocks lie below the surface everywhere on the planet. And by using advanced drilling techniques developed by the oil and gas industry, some experts think it's possible to tap that larger store of heat and create geothermal energy almost anywhere. The potential is enormous: The Energy Department estimates there's enough energy in those rocks to power the entire country five times over and has launched a major push to develop technologies to harvest that heat. Dozens of geothermal companies have emerged with ideas. Fervo is using fracking techniques -- similar to those used for oil and gas -- to crack open dry, hot rock and inject water into the fractures, creating artificial geothermal reservoirs. Eavor, a Canadian start-up, is building large underground radiators with drilling methods pioneered in Alberta's oil sands. Others dream of using plasma or energy waves to drill even deeper and tap "superhot" temperatures that could cleanly power thousands of coal-fired power plants by substituting steam for coal. Still, obstacles to geothermal expansion loom. Investors are wary of the cost and risks of novel geothermal projects. Some worry about water use or earthquakes from drilling. Permitting is difficult. And geothermal gets less federal support than other technologies.

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