Development and modeling of an ORC-based poly-generation system for hydrogen and freshwater production from wind turbine waste heat

Due to the global demand for clean energy and freshwater, research has focused on integrated systems for hydrogen and water production from waste heat. Renewable energies will play a major role in the prospect of supplying human energy over the coming decades, and wind energy, as one of the largest of these resources, is important and studied. Large wind turbines generate significant waste heat in their devices when energy is extracted from the wind. This study proposes an integrated poly-generation system that harnesses waste heat from a 7.58 MW wind turbine via an Organic Rankine Cycle (ORC) to drive seawater reverse osmosis (SWRO) with an energy-recovery pressure exchanger (PEX) and an alkaline water electrolyzer (AEL) for simultaneous production of potable water and hydrogen. Energy and exergy analysis were conducted for the combined system, and four candidate organic working fluids were screened. Multi-objective exergy optimization identified R1234yf as the optimal ORC fluid, delivering the lowest total exergy destruction among the fluids examined. For the considered operating point (7.58 MW turbine, average wind speed of 10 m/s), the ORC recovers approximately 147.5 kW of waste heat. Under the exergy-optimal configuration, this combination can produce about 37.42 m³ /day of freshwater and 27.20 kg/day of hydrogen, with an overall system exergy efficiency of 12.59%, and ORC exergy efficiency of 24.83%. Exergy destruction is dominated by the ORC evaporator and condenser; moreover, the SWRO unit exhibits an exergy destruction roughly 1.5 times greater than that of the AEL. The results highlight key components for targeted thermodynamic improvements and demonstrate the thermodynamic feasibility of wind-turbine waste-heat recovery for off-grid freshwater and hydrogen co-production.