Description:
At the request of the United States Department of
Energy, the author was asked by the Geothermal
Energy Association (Washington, D.C.) to prepare a
white paper on the subject (in connection with a new
national assessment of geothermal resources). This
paper offers a possible scheme in which geothermal
resources are classified into seven categories based
on temperature: non-electrical grade (<100°C), verylow
temperature (100°C to <150°C), low temperature
(150°C to 190°C), moderate temperature (190°C to
<230°C), high temperature (230°C to <300°C), ultrahigh
temperature (>300°C), and steam fields
(approximately 240°C with steam as the only mobile
phase). In the first four classes, liquid water is the
mobile phase in the reservoir; in the “high” and
“ultra-high” temperature reservoirs, the mobile fluid
phase is either liquid or a liquid-vapor mixture.
