What is the Geothermal Energy Resource?
Geothermal energy is the flow of heat from the earth, coming from natural cooling and natural radioactive decay within the core. This heat flux results in significant temperatures at depths commonly reached by deeper geothermal and oil and gas wells. In areas with appropriate geology, heat traps are formed and there are hotter spots much nearer to the surface. Tapping this energy source requires drilling to reach appropriate temperatures, fractures within the earth to allow flow of a fluid such as water, and circulation of that working fluid to capture the heat energy. That heat can then be used for electricity generation, for direct heating, for driving indirect heating and cooling cycles, and for driving fuels production cycles. Geothermal resources can be categorized as: • Hydrothermal: either hot water under pressure or as steam, that is currently being used commercially to power upwards of 2800 MWe of electricity generation capacity within the U.S. and about 8000 MWe of generation
