USING CO2 SEQUESTRATION OR ENHANCED OIL AND GAS RECOVERY TO ENHANCE GEOTHERMAL RESOURCES

Injection of carbon dioxide, CO₂, into hydrocarbon reservoirs has been widely employed to enhance oil and gas recovery. Similarly, geologic CO₂ sequestration in deep, saline aquifers relies on injection of supercritical CO₂ into naturally porous, permeable geologic formations below low-permeability cap rocks. During either process, the injected CO₂ is geothermally heated. A fraction of this heated CO₂ can be brought back to the surface for electricity production and subsequent reinjection into the subsurface along with the main CO₂ injection stream. Besides improving electricity production efficiencies, compared to water, all else being equal, this approach results in a geothermal power plant with a negative carbon footprint. The higher efficiencies may also allow more widespread deployment of geothermal power plants that could include regions with moderate to low geothermal temperatures and heat flow rates. The generated electricity would help offset high carbon capture and storage costs and provide electricity for CO₂ compression and subsurface injection equipment. Additional electricity could be sold. The technology required for such a scheme is currently largely available, thereby facilitating rapid implementation. Finally, unlike commonly discussed enhanced geothermal systems (EGS), the CO₂ plume geothermal (CPG) concept presented here does not rely on hydrofracturing low-permeability rock and is thus greatly reducing seismic risks. This should in turn reduce socio-political resistance to geothermal power plant implementation.