Life-cycle carbon footprint assessment of a solar-power-to-X system based on concentrating photovoltaic/thermal hydrogen production

Driven by the global energy crisis and carbon neutrality targets, mitigating the impact of renewable energy volatility on the low-carbon transition of power systems has become a critical challenge. This work proposes a novel Power-to-X multi-energy coupling system based on dynamic carbon footprint tracking. Through the integrated design of a concentrating photovoltaic/photothermal, a proton-exchange membrane electrolyzer, and a proton-exchange membrane fuel cell, the system enables synergistic “light-electricity-hydrogen” multi-energy flows. A full life cycle carbon footprint model is employed to systematically and quantitatively assess the environmental performance of different energy conversion pathways. Results show that in the compound parabolic concentrator photovoltaic/thermal integrated mode, the carbon emission per unit of electricity is 0.0181 kg CO2eq, demonstrating high environmental friendliness. In the PV/T-PEMEC mode, the carbon emission per unit of hydrogen is 0.986 kg CO2eq, highlighting the green attributes of hydrogen production. In the PEMFC mode, the carbon emission per unit of electricity is 0.0772 kg CO2eq, with hydrogen production identified as the primary emission source. Compared to typical natural gas power generation systems, the carbon footprint of the entire chain of the proposed system is 0.043 kg CO2eq/kWh, demonstrating a reduction of 89.3 %–91.4 %. Although this study doesn't consider factors such as the collector's dependence on direct radiation or the optical precision of the concentrator, the proposed system demonstrates significant advantages in high-efficiency synergy and low-carbon emissions.