| Abstract |
A strong reduction in global carbon dioxide (CO2) emissions is necessary to achieve the climate targets set out in the Paris Agreement. Decarbonisation of the energy sector, for example, requires baseload renewable energy sources, while decarbonisation of the cement and other heavy industries requires active capture and permanent (geologic) sequestration of CO2 (e.g. carbon, capture, and storage (CCS)). So far, economic constraints prevent the commercial-scale deployment of the CCS technology. Geothermal energy, as one of the renewable energy sources, can provide significant baseload energy supply but is restricted to regions with high (a) geothermal gradients and (b) rock transmissivities. Often, one of these is not given, limiting economic geothermal energy extraction. The usage of supercritical CO2 as a geothermal working fluid by injecting it and circulating it in a closed system from the reservoir to the Earth’s surface to extract the geothermal energy can open possibilities in regions that are otherwise economically disadvantageous for geothermal energy use. Previous studies have shown that the theoretical efficiency of a geothermal system can be doubled to tripled, compared to conventional geothermal systems, due to the significantly lower kinematic viscosity of supercritical CO2, compared to H2O. This concept is commonly known as CO2-Plume Geothermal (CPG). It uses (eventually) permanently sequestered CO2 from a CCS site to a) improve the business case of CCS systems by generating geothermal power (thermal and/or electric) and b) reduce the reservoir temperature and pressure, which in turn increases the overall CO2 storage capacity and safety. In our numerical feasibility study, we investigate the suitability of the active, commercial-scale, research-oriented Aquistore CCS site in Canada for a CO2-circulation demonstration test. We apply a pioneering workflow, combining (1) a field history-matched, heterogeneous reservoir model with (2) a full-physics fluid flow simulator, (3) a wellbore and (4) a simplified surface facility model (representing surface energy extraction and CO2 reinjection) in an integrated manner. |