The integrative use of binary cycle technology to improve thermal efficiency and efficiency in geothermal power plants: A case study of Ulumbu geothermal power plant in Indonesia

This study aims to enhance geothermal power plant efficiency by integrating Organic Rankine Cycle (ORC) technology at the Ulumbu Geothermal Power Plant in Indonesia. It focuses on utilizing steam from existing backpressure turbines, incorporating vapor pressure data and non-condensable gas (NCG) quantities to optimize the ORC system. The vapor pressure data helped determine the working fluid evaporation temperature in the evaporator, aiming to maximize total output power from both the steam and ORC turbines. NCGs were managed by improving the evaporator design to facilitate discharge and enhance system efficiency. Two binary cycle models were evaluated, with Model 2 using R1233zd(E) as the working fluid emerged as optimal. This model increased thermal efficiency by 8.039% and generated an additional 2.006 kWe. The study included a prefinancial analysis and a greenhouse gas (GHG) emission study, providing a comprehensive feasibility and environmental impact assessment. The results demonstrated ORC technology's potential to significantly boost power output and efficiency in geothermal power plants, supporting Indonesia's renewable energy and sustainability goals. This research provided a detailed framework for future implementations, maximizing geothermal resource utilization.