Until very recently, geothermal energy for commercial use has only been feasible in places where that heat naturally reaches the surface of the Earth, such as geysers and hot springs. For example, Iceland gets a quarter of its energy from geothermal energy. But Iceland is a geological anomaly. Globally, geothermal energy accounts for just 0.5% of renewable energy. But now, the application of fracking technology borrowed from the oil and gas sector could totally revolutionize geothermal energy availability, and possibly even bring it to your own backyard.