Assessment of Key Research Findings for the Use of CO2 as a Working Fluid For Geothermal Energy Production

Abstract

The geothermal community has produced a significant body of research exploring the use of CO2 as a heat exchanging fluid for high temperature fractured hard rock systems and low temperature porous sedimentary systems. In this paper, we review some 100 publications to evaluate the state of readiness of this novel technology for the production of geothermal energy. Specifically we discuss key findings related to 1. Net efficiency gained during the transition for water dominated to CO2 dominated systems, the geochemical reactivity of the reservoir and the wellbore environment, as well as the differences between low temperature sedimentary and high temperature – engineered geothermal systems. 2. The ability to directly use produced CO2 in turbines 3. The ability to store CO2 in sedimentary or fractured geothermal reservoirs This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.