Techno-economic analysis of an integrated desalination-renewable-hydrogen system for zero-emission freshwater and electricity production

• Double pass RO integrated RHS modelled to supply electricity and freshwater. • Integrated system produces electricity at LCOE of $0.165/kWh. • Feed pressure variation in double pass RO resulted in WPC in between $4.34–$6.90/m 3. • WPC has minimal impact on LCOH. • LCOE drops with inflation and rises with discount rate; NPC shows opposite trend. Developing a large-scale renewable hydrogen system intended to supply reliable clean electricity to remote island communities are constrained by limited freshwater availability for system itself: i.e., hydrogen production through electrolysis requires high-quality water. This study, hence, presents a detailed technoeconomic analysis of a double-pass reverse osmosis (DP-RO) arrangement integrated with a renewable hydrogen energy system, with a focus on assessing the impact of freshwater production cost on the hydrogen production cost. This arrangement is designed to supply sustainable freshwater and electricity to a remote island in southeast Australia. The proposed system comprises photovoltaic panels (3964 kW), wind turbines (3000 kW), proton exchange membrane electrolyser (1200 kW) and fuel cell stacks (1900 kW), hydrogen storage tanks (8000 kg), lithium-ion batteries (4725 kWh), and a DP-RO. The DP-RO system was modelled in MATLAB, where the specific energy consumption was determined as 5.96 kWh/m 3 and 1.69 kWh/m 3 for the pump used in 1st pass and in the 2 nd pass of the DP-RO system, respectively. The levelised costs of electricity and hydrogen were found to be 0.165 $/kWh and 40.5 $/kg, respectively. The electrolyser uses 4,148.9 MWh/year of excess electricity and produces 63110 kg of hydrogen annually, requiring 1073 m 3 of freshwater. Sensitivity analysis revealed that variations in feed pressure of the 1st pass and the number of elements per pressure vessel in the DP-RO system can significantly influence the economics of the system. Notably, the water production cost ranged between 4.34 $/m 3 and 6.90 $/m 3 depending on the key parameters defining the system, while this has marginal impact on the levelised cost of hydrogen production. The findings demonstrate the feasibility of integrating a DP-RO system with a renewable hydrogen system to provide a scalable solution for simultaneous freshwater and electricity production in remote and resource-constrained regions.