The Potential Impacts of Co-produced Geothermal Waters

1. The Potential Impacts of Co-produced Geothermal Waters • KEY POINTS • The amount of geothermal energy contained in oil and gas producing sedimentary basins is orders of magnitude greater than the energy requirements of the U.S., but it is largely untapped. • Previous estimates of the accessible stratabound geothermal resource were based on only one or two aquifers within a basin and resulted in a gross underestimate . For example, the accessible resource in ND and SD was estimated to be 2,050 EJ. Analysis of all potential aquifers in South Dakota and North Dakota indicates that the total accessible resource base in the two basins is approximately 33,700 EJ. • Advances in Organic Rankine cycle (ORC) technology makes temperatures as low as 90 ºC cost-competitive power production, and use of existing infrastructure eliminates drilling and well completion costs. • Large basins such as the Williston Basin, Denver Basin, Powder River Basin, Anadarko Basin, and the US Gulf Coast region contain more than a dozen potential geothermal aquifers having temperatures greater than 100 °C. • Approximately half of global anthropogenic CO2 derives from coal-fired power plants. School of Engineering and Mines Will Gosnold1, Zhengwen Zeng1, Mike Mann2, Hossein Salehfar3 1 Geology and Geological Engineering, 81 Cornell, Mail Stop 8358, willgosnold@mail.und.edu, (701-777-2631); zeng@und.edu, (701-777-3027) 2 Chemical Engineering, 241 Centennial Drive, Mail Stop 7101, mikemann@mail.und.edu, (701-777-3852) 3 Electrical Engineering, 243 Centennial Drive, Mail Stop 7165,hosseinsalehfar@mail.und.edu, (701-777-4432) “The potential power production in the mid-continent using oil field waste waters with ORC technology is estimated to be at least 5.9 GW and could be as high as 21.9 GW,” (McKenna et al., 2005; MIT - 2007). The Madison Fm in western North Dakota contains 1,476 EJ of thermal energy. Colors are temperature, contours are depth (m). EGS is an acronym for Enhanced Geothermal Systems The table below was derived from Appendix A.2.2 of the MIT Report “Future of Geothermal Energy, 2007.” The two temperature maps above relate to Enhanced Geothermal Systems and were developed as part of a series of maps by the SMU Geothermal Laboratory for the Department of Energy. The implications for utilization of EGS were summarized as follows in the MIT Report. “If we limit our calculation of stored thermal energy in place to a depth of 10 km beneath the land area of the United States, then the amount of thermal energy in the crust is so large (about 14 million quads) that we can view it as sustainable. Even if we were to use it to provide all the primary energy consumed in the United States, we still would be depleting only a tiny fraction of it.” "The Future of Geothermal Energy," MIT Report, January 22, 2007. • POTENTIAL IMPACTS • Development of currently produced oil field geothermal waters in 31 oil and gas producing states could provide all power necessary to produce the oil fields and as much as 6.8 percent of the current electric power consumption in those states. • Development of sedimentary basins specifically for geothermal water production using abandoned or capped wells in oil and gas fields could establish an extensive geothermal power infrastructure and provide a sustainable and secure domestic energy resource. • Large-scale development of binary power plants using geothermal resources could replace coal-fired power plants and bring about a significant reduction in anthropogenic greenhouse gas production.