Abstract

The San Luis Basin has been evaluated for its geothermal potential by examining the following attributes: physiography, geology, tectonics and structure, water resources, infrastructure, population and target markets, other geothermal factors, and economic considerations and available incentives. This was accomplished by using a combination of literature reviews and data analyses in conjunction with the interpretation of information obtained from digitized map layers created in ArcGIS^®. The basin has several known hot springs and wells. Some of these are currently being utilized for direct-use applications including aquaculture, spas and pools, and space heating. The basin is characterized by high heat flow and high geothermal gradients. An interpretive geothermal gradient map of Colorado by Berkman and Watterson (2010) shows an average gradient within the basin of approximately 50 degrees Celsius per kilometer (°C km⁻¹) and several higher gradient areas (70–90°C km⁻¹). The most promising areas for electrical power generation (locations with high geothermal gradients) are just south of Poncha Pass at the northern end of the basin and an area northeast of the San Luis Hills. These locations are in the Baca Graben. Temperatures sufficient for power generation (1–1.2 kilometers (km) for the 90 degree Celsius (°C) isotherm and 2–2.5 km for the 180°C isotherm) are in Santa Fe Group sediments. The heterogeneous nature of these sediments may be challenging in terms of finding a large permeable reservoir for power production. In the event that suitable hydrothermal reservoirs are not found, Enhanced Geothermal Systems (EGS), in which permeability is created artificially, may be an alternative in areas with the high geothermal gradients.