Geothermal Energy Overview
The earth itself offers large supplies of energy. While fossil fuels such as coal, oil, and gas are extracted from the earth and burned, geothermal energy can often be tapped with minimal environmental impact. Heat eminating from the depths of the earth can drive turbines for electricity production or used for direct building heating; and the moderate temperatures underground can supply geothermal pumps with cool water to circulate throughout buildings in the summer.
Colorado Geothermal Resources
from the Renewable Energy Committee report prepared for the Chairman of the Colorado State Senate Majority Ad Hoc Energy Task Force, and approved by the CRES Board of Directors, October 25, 2001.
Two types of geothermal resources are being tapped commercially: hydrothermal fluid resources and earth energy. Hydrothermal fluid resources (reservoirs of steam or very hot water) are well suited for electricity generation. Earth energy, the heat contained in soil and rocks at shallow depths, is excellent for direct use and geothermal heat pumps. Direct-use applications require moderate temperatures; geothermal heat pumps can operate with low-temperature resources.
Colorado has high-temperature resources that are suitable for electricity generation. Every geothermal site has a unique set of characteristics and operating conditions. For example, the fluid produced from a geothermal well can be steam, brine, or a mixture of the two; and the temperature and pressure of the resource can vary considerably from site to site. Therefore, a plant design must be carefully matched to the type and temperature of a particular resource.
Direct-use resources can be used to provide heat in a variety of applications. The versatility and inexhaustibility of these resources make it attractive for municipalities, as well as individuals and businesses. Geothermal heat pumps are similar to conventional air conditioners and refrigerators. But whereas air conditioners and refrigerators discharge waste heat into the air, geothermal heat pumps discharge waste heat into the ground during hot weather and extract useful heat from the ground during cold weather. They are among the most efficient, and therefore least polluting, heating, cooling, and water-heating systems available.
About Geothermal Energy
US DOE Geothermal Program
Geothermal Heat Center