Abstract:
Electricity has become the most common form of energy that is used in the daily activities of humans. Most of it, at present, is generated by burning fossil fuels. However, greenhouse gases which cause negative effects on the environment are emitted in the process. To slow down and eventually reduce the greenhouse gases that are generated from electricity generation, alternatives for electricity generation are required. One of the alternatives is geothermal energy. Geothermal energy has consistent availability compared to other forms of renewable energy, however the investment to develop a geothermal power plant is not small. Therefore, it requires careful planning and analysis to minimize the risks. One of the ways to minimize the risks is by doing accurate analyses before the development of the geothermal power plant and this can be accomplished by using good modelling software. The objective of this study is to provide recommendations for a new equation of state (EoS) for mixtures of H₂O and CO₂ to be used with the current geothermal modelling software, TOUGH2. The aim is to increase the accuracy of the EoS by comparing the current methods used in the software with newer equations of state that have been published since the last time the software was updated. To be more specific, the scope of the study is to give suggestions for a new EoS module in TOUGH2, to replace the existing EOS2 module. The EOS2 module is used in modelling geothermal systems containing mixtures of H₂O and CO₂. Findings from the study show that several parts of EOS2 should be updated with the newer equations of state. However, some modules within EOS2 provide better results than the newer alternatives and can be maintained for the time being. The study also highlights the improvement that can be applied to EOS2 module in TOUGH2 in terms of the input variables to simplify the user’s interactions with the software. Alternatives to cut the processing time of the software are suggested in this study.