Webinar – CO2 in Geothermal Power Plants – capturing, compression, injection – Jan 15, 2021

Since the World Bank published the ESMAP Technical Report 009/16 on greenhouse gas emissions from geothermal plants in 2016, we reported,  CO2 emissions in geothermal power generation are under debate (ESMAP 2016). Non condensable gases (NCG) are naturally present in many geothermal high-temperature reservoirs and fluids. The most dominant gas is carbon dioxide (CO2). Operators use different strategies to handle NCG emissions, depending on the amount of CO₂, the brine conditions and the power plant process.

In most of the cases NCGs are vented to the atmosphere via cooling towers or air cooled condensers. A number of plants capture CO₂ in order to utilize it for food or agricultural industry or sell it as industry gas. Additionally, the generation of biomass via algae farming is scientifically investigated. The dissolution of CO₂ in brine before reinjection is already practiced on a small scale in turkey.

All the strategies described above are limited by the amount of CO₂ that can be handled, the infrastructure, the market situation to trade CO₂ or the auxiliary demand for capturing and transformation. The study presented in the next Focus in Geothermal is investigating the advantages and disadvantages of generating supercritical CO₂ for re-injection. Therefore, the main power plant processes were analyzed to derive reasonable and transferable conditions.  Based on well data and simplified reservoir conditions re-injection pressures ware calculated for brine and CO₂. Based on pressure data thermodynamic calculation were carried out in order to reduce the auxiliary demand of electricity for capturing and compression of CO₂.

The study shows that re-injection of supercritical CO₂ may be an economic and feasible way for reducing the CO₂emissions of geothermal power plants when the structural geology and the reservoir conditions are suitable for storage.

Dr. Hartwig Schröder from Enex Power will present the study in the upcoming Focus on Geothermal Webinar on January 15, 2020 at 14.00 (CEST). You can register free of charge at www.igc.events/en/webinar.