Enhanced geothermal systems for clean firm energy generation

Geothermal energy provides clean, steady and renewable electricity and heat, but the use of geothermal energy has conventionally been constrained to locations with adequate subsurface heat and fluid flow. Enhanced geothermal systems (EGS) enable geothermal energy usage in unconventional areas by enhancing the subsurface permeability and increasing fluid flow, which is then extracted as a carrier of the thermal energy. In this Review, we discuss the development of EGS and its role in providing energy. Some EGS are operating commercially in Europe and provide heat and/or electricity, but technical issues and concerns over induced seismicity have historically hindered the broader expansion of EGS. Adaptation of…