Economic feasibility and life cycle assessment of off-grid renewable energy-driven liquid hydrogen production systems under various precooling strategies

To address the increasing demand for low-carbon hydrogen and reduce the energy intensity of liquefaction, this study proposes a novel off-gird renewable-powered hydrogen liquefaction system incorporating three different precooling strategies: liquid nitrogen (LN2), liquefied natural gas (LNG), and a combined LNG and LN2. The system integrates photovoltaic panels and wind turbine modeled in TRNSYS with a hydrogen liquefaction process simulated in Aspen HYSYS. A multi-criteria performance evaluation and optimization framework is established based on energy consumption, energy efficiency, exergy efficiency, environmental impact, and economic viability. Results indicate that the LN2 precooling system demonstrates superior energy and economic performance, achieving the lowest specific energy consumption of 6.203 kWh/kg, highest exergy efficiency of 14%, a net present value of $102.51 million, and a shortest payback period of 3.91 years. In contrast, the combined LNG and LN2 precooling strategy provides the greatest environmental benefit, reducing annual CO2 emissions by up to 15,986 tons. These findings demonstrate that integrating cryogenic energy from LNG and LN2 with renewable electricity enhances liquefaction efficiency, improves economic feasibility, and enables emission mitigation. This work offers a robust foundation for developing next-generation hydrogen supply chains powered by clean energy sources.