Outlook for Geothermal Energy
. The resource base (estimated total amount of energy) of geothermal energy is larger than the resource bases of coal, petroleum , natural gas , and uranium (uranium is used in the production of nuclear energy ) combined. The discovery and development of additional geothermal reservoirs depends on several factors. These factors include the depth, heat, and water content of a particular reservoir, as well as the permeability (property of having fractures that allow liquids to flow through) of the rock in the reservoir. The depth and heat of a geothermal reservoir cannot be changed, but the amount of water in the reservoir and the permeability of the rock can be increased. Private and government research projects underway in the United States, in Japan, and in Europe are focused on finding ways to increase the permeability and amount of water in certain types of hot rock (so that water can circulate more freely throughout the rock and become better heated). Engineers are increasing the a