Using Geologically Sequestered CO2 to Generate and Store Geothermal Electricity: CO2 Plume Geothermal (CPG)

Abstract

CO2 Plume Geothermal (CPG) is a carbon neutral renewable electricity generation technology where geologic CO2 is circulated to the surface to directly generate power and then is reinjected into the deep subsurface. In contrast to traditional water geothermal power generation with an Organic Rankine Cycle (ORC), CPG has fewer system inefficiencies and benefits from the lower viscosity of subsurface CO2 which allows power generation at shallower depths, lower temperatures, and lower reservoir transmissivities. In this paper, we modify our existing geothermal electricity models by: 1) replacing TOUGH2 reservoir simulations with analytic solutions for a 5-spot reservoir impedance, and 2) including heat loss to the surrounding rock using a semi-analytical heat transfer solution. We report the results of 3050 simulations in a single plot, showing the power generation of both direct CPG systems and indirect water geothermal systems for depths between 1 and 7 km and reservoir transmissivities between 102 and 105 mD-m (10^-13 and 10^-10 m^3).