Geothermal brines with high CO2-contents require special treatments during the production of geothermal energy. Released into the atmosphere, the high emissions can cause a worse environmental damage for geothermal energy than for energy derived by the usage of fossil fuels (Aksoy et al. 2015). Besides the environmental impact, the CO2 also negatively affects the performance of the condenser and the turbogenerator (Simsek et al. 2005). For a proper handling of the gases the thermodynamic properties must be determined. A relevant factor in this regard is the solubility of the CO2 in the liquid phase. The solubility of the gas phase thereby mainly depends on the pressure and temperature conditions, but also on the dissolved ions within the brine, and the composition of the vapor phase. Given this information, it is possible to determine the position in a geothermal well where the CO2 degasses from the liquid solution, the so-called bubble point. On the contrary for prevention of greenhouse gas emissions, an estimation of required power plant operation can be achieved.