CO2-Plume Geothermal (CPG) in Austria? Tackling the CCS dilemma

Austria is committed to becoming climate net-neutral by 2040, no later than 2050. Reducing the country’s hard-to-abate Carbon Dioxide (CO2) emissions will require substantial deployments of CO2 Capture Utilization and Sequestration (CCUS) to reach this challenging goal. Due to legal regulation and missing public acceptance across Europe, CO2 sequestration sites for CCUS hubs are typically being developed offshore. This is especially challenging for inland countries, such as Austria, where domestic CO2 sequestration is currently not in development and export of CO2 can only take off once CO2 transport infrastructure is completed. At the same time, geothermal energy production is seen as a key technology to provide green base-load energy to decarbonize the heating sector in cities with huge district heating networks. Utilizing CO2 as the subsurface energy extraction working fluid in future geothermal projects, called CO2-Plume Geothermal (CPG), can contribute to both storing hard-to-abate CO2 emissions until proper transport infrastructures across Europe have been developed and complementing the development of geothermal energy production. In this work, we assess the Austrian potential for using CO2 as the geothermal working fluid in depleted hydrocarbon fields. We screened 59 hydrocarbon reservoirs in Austria to assess their CCS and CPG suitability. Furthermore, we distinguish between hydrocarbon fields, suitable for heat and/or electricity production, and compute the levelized cost of energy (LCOE) production as well as the potential net energy produced by CPG. While Austria’s CO2 sequestration capacities in depleted hydrocarbon reservoirs are small, compared to saline formations in offshore Europe, developing national onshore CO2 storage sites can bridge crucial periods until the CO2 can be shipped offshore, promoting the country’s climate goals. We believe that adding CPG to CCS, resulting in CCUS, increases the acceptance of CCS in general and in particular in onshore countries. Additionally, cooling the CO2 due to energy extraction, i.e. reducing the reservoir temperature, increases the reservoir’s CO2 sequestration/storage capacity and is expected to decrease CO2 injection risks by controlling/reducing the pore-fluid pressure in the CCS/CPG reservoir.