Geothermal Alternate Energy: Expanding the Options

Immense amounts of energy can be obtained from the hot dry rock (HDR) of the earth, as an extension/expansion of the hydrothermal resources. The extraction of usable energy from a HDR reservoir made by hydraulically fracturing the hot, but essentially dry rock between two deep drill holes has been successfully demonstrated at Fenton Hill, New Mexico, by the Los Alamos National Laboratory. Depending on the location and depth of future HDR reservoirs, the extracted heat may be either high grade (for generation of electricity), or low grade (for direct‐use space heating, food processing, etc.). The circulating hot water can also be used to augment energy production from other energy systems, such as boiler feedwater preheat, process heat for synfuel production, or stimulating bacteria growth in cold climates (for instance, more rapid digestion in sewage treatment plants or landfill dumps). When the HDR technology of drilling and fracturing in crystalline rock is coupled with solar energy production, excess summertime heat from solar collection facilities can be transferred and stored in manmade underground reservoirs for wintertime withdrawal and utilization. The same technology can provide huge, but easily accessible, heat sinks for reject industrial heat, creating many options for industry, municipalities, and district heating organizations to integrate energy demands with heat disposal requirements.