Geothermal Resource Assessment of South Dakota

Abstract

Seven geothermal aquifers in South Dakota contain an accessible resource base of about 11,207.93 x 10/18 J. The resource estimate was obtained by first using heat flow, thermal conductivity, temperature gradient, and stratigraphic data to estimate aquifer temperatures. The heat content of each aquifer was determined from the product of the volumetric heat capacity, aquifer volume, and temperature difference between the aquifer and the mean annual temperature for a 14 x 14 grid of 240 km2 cells. Geothermal fluid temperatures range from about 120 degrees C in the Deadwood Formation in the Williston Bain to about 30 degrees C for the Newcastle Sandstone in south central South Dakota. The area containing the resource lies largely wet of the Missouri River. About 10,000 km2 of the resource area is characterized by anomalously high heat flow values greater than 100 mW m-2.