Creating renewable hydrogen & powering multiple generations with an integrative solar and renewable hydrogen systems: A case study of China

This study proposes and evaluates a solar-assisted biogas polygeneration plant that simultaneously supplies electricity, district heating, chilled water, and compressed hydrogen for building clusters. Unlike previous multigeneration concepts based on gas–steam Brayton–Rankine cycles and hydrogen liquefaction, the proposed system integrates an anaerobic digester treating food waste, a parabolic-trough solar field with two-tank molten-salt thermal energy storage, a biogas-fired organic Rankine cycle (ORC) for power generation, a proton-exchange-membrane (PEM) water electrolysis unit for on-site hydrogen production, and a single-effect LiBr–H₂O absorption chiller for cooling. A steady-state thermodynamic model is developed and assessed using energy and exergy balances, parametric sensitivity analysis, and combined techno-economic and life-cycle carbon evaluation. At the nominal design point, the ORC achieves an energy efficiency on the order of 18–22 %, while the overall polygeneration plant attains a total energy efficiency above 40 % and an exergy efficiency close to 50 %, owing to extensive recovery of low-grade heat in district heating and absorption cooling. Relative to a conventional supply configuration with separate gas boiler, vapor-compression chiller, and grid electricity, the proposed system reduces specific CO₂ emissions by roughly 30–40 % and primary energy consumption by 25–35 %. Levelized cost of electricity and hydrogen fall within ranges compatible with emerging distributed energy markets, with the levelized cost of hydrogen declining significantly when the plant is operated in a hydrogen-oriented mode during high solar availability. Sensitivity results highlight the critical influence of solar multiple, storage capacity, and biogas yield on both exergy performance and economic indicators. Overall, the analysis demonstrates that coupling anaerobic digestion, solar thermal collection, ORC power generation, and PEM-based hydrogen production in a single distributed platform offers a technically feasible pathway to low-carbon, multi-service energy supply for urban communities. • Solar–biogas polygeneration supplies power, heat, cooling, and hydrogen. • Integrated ORC, AD, TES, PEM, and absorption cooling boosts overall efficiency. • System cuts CO₂ emissions by 30–40 % vs. conventional energy supply. • LCOE and LCOH fall within viable ranges for distributed urban markets. • Solar multiple, storage, and biogas yield strongly shape system performance.