CO[formula omitted] handling in binary geothermal systems — A modelling approach for different CO[formula omitted] contents, salinity, pressure and temperature conditions

Abstract

The decarbonisation of power and heat production is recently one of the major challenges in the Energy sector. Among other technologies, deep geothermal energy is an interesting option, because source temperature, plant capacity, low environmental footprint and high availability allow the application in district heating grids. The majority of geothermal reservoirs contains a certain amount of non-condensable gases dominated by CO2. With respect to corrosion and precipitation effects as well as environmental friendliness and economic optimisation, the handling of these gases is challenging.In this study three different technical options – a gas bypass system, a certain pressure regime and a secondary gas turbine – are investigated to overcome this challenge. The geothermal plant at Bruchsal/Germany was selected as case example for process simulation and further analyses.The major outcome shows that a gas bypass excluding CO2 from the power plant results to be the best option for the existing plant in terms of avoiding CO2 emissions and reaching highest possible power output. Furthermore, the study results recommend the best CO2 handling solution for different conditions within the simulated range (temperatures from 100 to 160 °C, salinity from 0–200g/L, pressures from 15–135bar, and flow rates until 100kg/s) as an essential contribution to the field.