Geologic Assessment of Four Greenfield Sites for Solar-Geothermal Hybrid Power Plants

Abstract

Power generation from low to medium temperature geothermal resources, including conventional hydrothermal systems and oil & gas producing reservoirs with elevated temperatures, can help stabilize the electric grid with increasing power contributions from variable renewable resources. But the generation of power from the low to medium temperature geothermal resources are costly because of poor thermal efficiencies. To overcome this technoeconomic barrier, these sub-par geothermal resources can be hybridized with other sources of thermal energy such as concentrating solar and natural gas and make them more competitive and attractive for power generation. In addition, hybridization can expand the potential geothermal resource areas to several other regions in the US. In this work, we selected four low to medium temperature geothermal resources in Idaho, California, New Mexico, and Mississippi and investigated hybridization of these resources with different potential for concentrating solar heating for competitive power generation. Two of the sites, Grand View in Idaho and McGregor Range in New Mexico are conventional low-temperature hydrothermal resource areas with low and high concentrating solar heating potential, respectively. The other two sites, Elk Hills in California and Cranfield in Mississippi, are currently and previously oil and gas producing reservoir systems of elevated temperatures with high and low concentrating solar heating potential, respectively. This paper presents the geology, hydrology, and thermal characteristics of these selected sites and summarizes the modeling results of hybridized power generation with concentrating solar heating technology.