ABSTRACT
Geothermal fluid-a hot, sometimes salty, mineral-rich liquid and/or vapouris the carrier medium that brings geothermal energy up through wells from the subsurface to the surface. This hot water and/or steam is withdrawn from a deep underground reservoir and isolated during production, flowing up wells and converting into electricity at a geothermal power plant. Once used, the water and condensed steam is injected back into the geothermal reservoir to be reheated. It is separated from groundwater by thickly encased pipes, making the facility virtually free of water pollution. A resource that uses an existing accumulation of hot water or steam is known as a ‘hydrothermal’ resource. While several other types of geothermal resources exist, all producing geothermal plants in the United States use hydrothermal resources. Characteristics of the geothermal fluid, including temperature, chemistry, and non-condensable gas content (NCG), can influence power plant design.
