Performance assessment of a geothermal- and LNG-driven zero-carbon multi-generation system for production of potable water, green hydrogen, and utilities

Abstract

Given the limited availability of fossil fuel resources, humanity must explore alternative energy solutions. Geothermal energy stands out as a promising, clean, and reliable option. This study proposes a novel configuration of an eco-efficient, geothermal energy-based multi-generation system capable of producing power, hydrogen, oxygen, potable water, as well as hot and chilled water. The system integrates a combined flash-binary geothermal subsystem, a water electrolysis, a multi-effect desalination unit, and an LNG regasification unit. The design and simulation of the system were conducted using Aspen HYSYS software, yielding outputs of 520.8 kg/h of green hydrogen, 770,968.4 kg/h of chilled water, 511,867 kg/h of hot water, 8,581 kW of power, 4,133.4 kg/h of oxygen, 19,630.27 kg/h of potable water, and 216000 kg/h of natural gas. The proposed system underwent thermoeconomic, thermodynamic, and environmental analyses. The energetic and exergetic efficiencies of the system were determined as 34.87 % and 70.9 %, respectively, while the TUCP and LCOE were determined to be 5.816 $/GJ and 0.2564 $/kWh, respectively. Environmental analyses demonstrated the system’s capability to save approximately 13.729 Mm³/year of fuel and reduce CO₂ emissions by 58,280 t/year, underscoring its significant environmental benefits. Additionally, a parametric study was conducted to evaluate the system’s performance metrics based on key decision variables. The findings demonstrate that augmenting the geofluid flow rate and temperature, LNG flow pressure, turbine T-102 outlet pressure, and turbine T-101 inlet temperature enhances net power output, while also improving the system’s economic and environmental performance.