Sustainable removal of non-condensable gases from geothermal waters

Geothermal energy is becoming an attractive option for supplying the world with clean and sustainable energy. One of the highlighted issues in utilising the energy from geothermal systems is removal of non-condensable gases (NCGs) from geothermal waters. This paper discusses and reviews existing technologies for removing NCG with emphasis on their energy requirements further the possibility is investigated of using two-phase ejectors (also known as eductors) to remove NCGs from geothermal waters. Energy analysis of isothermal and adiabatic vacuum processes for removing non-condensable gases by an ideal vacuum machine are presented and later compared with the measured performance and with the energy consumption of commercial vacuum pumps and eductors. Advantages of removal of NCG using a passive method employing eductors and the prospect of improving the efficiency of these devices are also presented. Based on the experimental data, it is shown that eductors offer a sustainable alternative for NCGs removal from geothermal waters.