Geothermal resources are reservoirs of hot water that exist at varying temperatures and depths below
the Earth's surface. Deep wells can be drilled into underground reservoirs to tap steam and very
hot water that can be brought to the surface for use in a variety of applications, including electricity
generation, direct use, and heating and cooling.
Converting Geothermal Energy into Electricity
Heat emanating from the Earth’s interior and crust generates magma (molten rock).
Because magma is less dense than surrounding rock, it rises but generally does not reach
the surface, heating the water contained in rock pores and fractures. Wells are drilled
into this natural collection of hot water or steam, called a geothermal reservoir, in order
to bring it to the surface and use it for electricity production. The three basic types of
geothermal electrical generation facilities are binary, dry steam (referred to as steam),
and flash steam (referred to as flash). Electricity production from each type depends
on reservoir temperatures and pressures, and each type produces somewhat different
environmental impacts. In addition, the choice of using water or air cooling technology
in the power plants has economic and environmental trade-offs.
Geothermal energy is a vast underutilized heat and power resource,
Geothermal Energy is:
*Renewable *Produces electricity consistently, running 24 hours per day / 7 days per week,
regardless of weather conditions. EGS can supply baseload energy with limited to no
intermittency, eliminating the need for energy storage technologies *Domestic—U.S. geothermal resources can be harnessed for power production without
importing fuel. *Small Footprint—Geothermal power plants are compact; using less land coal, wind or
solar *Geothermal is “CLEAN”. Geothermal emits little to no greenhouse gases. Most
other geothermal power plants use a closed-loop binary cycle power plant and have no
greenhouse gas emissions other than water vapor that may be used for cooling. *EGS has the potential to be an important contributor to the U.S. energy portfolio as a source of clean, renewable energy.
