| Abstrakt: |
Renewable energy is an energy source that is naturally inexhaustible and continuously replenished. One of renewable energy sources is geothermal energy. As a country located in the ring of fire, Indonesia has abundant geothermal energy potential of 29 GW, which accounts up to 40% of world's geothermal potential. Geothermal energy can help Indonesia to reach national target to reach 23% energy mix from renewable energy by 2025. However, geothermal energy potential utilization in Indonesia is still limited, with only 2130.7 MW installed electric capacity as of 2021. Furthermore, hydrogen energy is a new energy source which is a potential future main energy source. Hydrogen can be produced via electrolysis by splitting water molecule into hydrogen and oxygen using electrical energy. If the electrical energy is generated from renewable energy sources, the produced hydrogen is called as "green hydrogen". Ulubelu geothermal power plant discharges 772.2 kg/s of separated brine with 175°C temperature and 9 bar pressure, thus has the potential waste energy to be utilized. From those conditions, an innovation is proposed to utilize the separated brine at Ulubelu geothermal power plant for green hydrogen production using an integrated bottoming binary cycle using and electrolysis unit system. The bottoming binary unit uses Organic Rankine Cycle (ORC), which is analyzed using energy analysis using n-pentane, n-butane, and isopentane working fluids. Meanwhile, the electrolysis unit is analyzed using electrochemistry analysis. The result shows that the bottoming ORC is able to generate the highest specific power output of 149.6 kW/kg.s using n-pentane as the working fluid with 26.2% thermal efficiency and net power output of 45,498 kW. The electrical energy produced by the bottoming ORC is used to power an alkaline electrolyzer to produce 20.53 tonne/day of green hydrogen and 162.96 tonne/day of oxygen. Furthermore, the electrolyzer requires 229.35 tonne/day of steam condensate as the water supply. [ABSTRACT FROM AUTHOR] |
