Technical and Economic Assessment of Excess Power Utilization from Geothermal Power Plants

Abstract

The utilization of geothermal energy in Indonesia continues to grow; however, the installed capacity of geothermal power plants has not yet been fully optimized, particularly during periods of low system load. This study investigates the potential use of excess power from geothermal power plants to produce hydrogen via Alkaline Water Electrolysis (AWE) technology and evaluates its technical and economic feasibility. Simulations using Process Simulator were conducted for three input power scenarios (3.40 MW, 10.19 MW and 15.26 MW) to analyze hydrogen production rates, specific energy consumption, and HHV and LHV efficiencies. The simulation results indicate that the AWE system is capable of producing up to 335.82 kg/h of hydrogen, achieving HHV efficiency of up to 97.8% and LHV efficiency of up to 82.7% at lower power input. However, increasing the input power leads to a decrease in efficiency and an increase in specific energy consumption, reaching 156,244 kJ/kg H₂ at the highest power level. From an economic perspective, the calculated Levelized Cost of Hydrogen (LCOH) ranges between 0.665–0.997 USD/kg H₂, while the Levelized Cost of Electricity (LCOE) generated from reconverting hydrogen to electricity falls within 36–54 USD/MWh, making it highly competitive compared to fossil-based power sources. These findings indicate that using excess geothermal power for hydrogen production is an efficient low-carbon energy storage solution. Furthermore, to optimize thermal integration within geothermal power plants, the Solid Oxide Electrolysis Cell (SOEC) technology should be considered, as it can directly utilize waste heat to enhance energy conversion efficiency. Therefore, integrating AWE or SOEC with geothermal power plants presents a promising strategy to support Indonesia’s clean energy transition.