CO2 emissions from geothermal power plants: evaluation of technical solutions for CO2 renjection

Geothermal utilization for power production, may result in some greenhouse gas emissions. Non condensable gases (NCG) are naturally present in most of geothermal fluids. The dominant is carbon dioxide (CO 2 ), typically constituting more than 95 percent of the total NCG content. CO 2 emission from geothermal power plants is generally small in comparison to traditional base load thermal energy power generation facilities. However, as the geothermal sector has expanded, a wider range of geothermal resources have been brought into exploitation, including geothermal systems with relatively high CO 2 concentrations in the reservoir fluid. Binary (ORC) geothermal plants can offer an effective solution to avoid emissions of CO 2 in the atmosphere. The CO 2 can be collected under pressure at the outlet of the ORC vaporizer, and then compressed and reinjected together with the liquid in the reinjection well. Subject of the paper is the evaluation of the state of the art solution for CO 2 compression and reinjection in the reservoir, with implications on the equipment employed and environmental benefits.