A comprehensive thermo-enviro-economic assessments of a novel geothermal-based multigeneration process: Integrating power generation, hydrogen production, CO2 capture, and absorption cooling

Abstract

This research presents a multigeneration technique that harnesses geothermal energy and recovers waste heat from carbon dioxide separation employing MEA solvent. The process produces many outputs, such as collected carbon dioxide, heating, electricity, and cooling. This innovative method facilitates the processing of industrial flue gas to generate useful goods while utilizing renewable energy sources. The system incorporates a PEM electrolyzer, a geothermal power plant, a carbon dioxide capture unit, and an absorption chiller. The geothermal power plant comprises single flash and organic Rankine cycle components, which improve the power plant's efficiency. The absorption chiller cycle is thermally linked with the carbon dioxide capture unit, generating chilled and hot water. The influence of critical factors, including geothermal fluid flash pressure and hydrogen production rate, on further operational variables is examined. The findings indicate that augmenting hydrogen generation in this arrangement results in a reduction of energy and exergy efficiencies. The exergy analysis shows that the system is completely irreversible. The tower stripper in the carbon dioxide capture unit was found to be the place where the exergy degradation was the highest. An environmental assessment indicates that net carbon dioxide emissions are 725 kg/h, with a carbon dioxide footprint of 0.027 ton/MWh. The findings indicate that the energy, exergy, and electrical efficiencies of the novel process are 16.68 %, 59.19 %, and 13.49 %, respectively at base condition. The final optimum solution by TOPSIS with PESA-II multi objective optimization shows, 73.001 % exergy efficiency and 0.022 tons of CO₂ emissions per MWh for first scenario and TPUC of 9.043 $/GJ and an exergy efficiency of 73.431 % for second scenario.