We proposed an additional unit of the geothermal power plant to harness the vacant excess steam emitted to the atmosphere in the electricity generation cycle of the Kamojang geothermal power plant, owing to high potential of thermal energy due to the vapor-domination of the steam discharged from the geothermal well. Based on the validated model calculation, the optimization of the system was carried out through the selection of variations of the gas removal system (GRS) of the non-condensable gasses (NCGs). Five GRS schemes were carried out in this study: a one-stage steam ejector, a two-stages steam ejector, a one-stage liquid ring vacuum pump (LRVP), a two-stage LRVP, and a hybrid system (ejector plus LRVP). The proposed scheme shows that one-stage LRVP system achieved the best model for the GRS in the proposed plant, generated an electric power of 15.94 MW, representing a 7.6% increase to the current 200 MW installed capacity, with a house load energy consumption of 755.18 kW.