A U.S. startup says it has developed an enhanced geothermal system (EGS) that engineers say can tap into heat from the Earth’s interior without any associated risks of triggering earthquakes or polluting underground aquifers. While typical EGS processes require developers to pump liquids into deep wells at high pressure, a process that has on occasion trigged small earthquakes, GTHerm has developed an approach that doesn’t require fracturing or water cooling. Instead, the process includes installation of a solid-state heat exchanger, or “heat nest,” at the bottom of the well that can more efficiently draw heat from surrounding rock with the help of a highly conductive grout encasing the heat exchanger. Fluid is sent down the well in a closed loop that carries the heat back to the surface, where it creates steam that drives electricity-generating turbines. “We’re basically a heat pump on steroids,” said Michael Parrella, CEO and founder of the Connecticut-based company. The company, which is now testing the commercial feasibility of the technology, hopes to have demonstration plants in place as early as 2012.