Integration of geothermal power plant, water treatment plant, AWE, and PEM electrolyzer for green hydrogen production: A techno-economic study

Abstract

Green hydrogen production plays a crucial role in the global shift toward sustainable energy, offering a clean alternative to fossil fuels. However, large-scale adoption is often limited by high production costs and the intermittent availability of renewable energy sources such as solar and wind. Geothermal energy offers a promising solution by providing a stable and continuous power supply for water electrolysis. This study explores the integration of geothermal power with water treatment and electrolysis systems for green hydrogen production. Cooling tower basin water from a geothermal power plant is treated using an ultrafiltration-reverse osmosis-ion exchange mixed bed system to meet the purity requirements for electrolysis. The treated water achieves a conductivity of 1–2 μS/cm for alkaline water electrolysis (AWE) and 0.05–0.08 μS/cm for proton exchange membrane (PEM) electrolysis. A 10 MW AWE and PEM electrolyzer are modeled to produce 181.03 kg/h and 191.26 kg/h of hydrogen, respectively. The levelized cost of hydrogen is estimated at 6.52 $/kg for AWE and 6.67 $/kg for PEM, with electricity costs contributing over 64% of the total. AWE electrolysis at 10 MW requires 1616 kg/h of feed water, while PEM electrolysis requires 1709 kg/h, both supplied by the water treatment plant. Despite higher capital costs and shorter lifespans of PEM electrolyzers, water treatment costs remain minimal at 0.17% of total production costs. The findings demonstrate geothermal energy as a viable alternative to intermittent renewables for continuous hydrogen production. This study offers a techno-economic evaluation of geothermal-based hydrogen production, supporting its role in the global energy transition.