Synergistic solar energy integration for enhanced biomass chemical looping hydrogen production: Thermodynamics and techno-economic analyses

Abstract

The concept of solar-assisted biomass chemical looping hydrogen (H2) production (BCLHP), wherein solar energy is directly integrated into the thermochemical H2 production process, was proposed. The mechanism behind the increased H2 production due to solar assistance was elucidated. Subsequently, a system design was proposed based on this principle, accompanied by strategies for managing solar energy fluctuations during system operation. Thermodynamics and techno-economic analyses were then conducted. The results indicate that the key principle behind the increased H2 production in solar-assisted BCLHP lies in substituting solar energy for the direct oxidation of the oxygen carrier, enabling full utilization of the oxygen carrier for H2 production without the need to maintain thermal balance. The integrated system based on this principle achieves a high solar-to-H2 exergy efficiency, with a theoretical maximum exceeding 30%, outperforming the exergy efficiencies of photovoltaic (PV) and solar thermal H2 production methods, while increasing the molar ratio of H2 to CO2 from 1.31 to 1.74. The economic viability of solar-assisted BCLHP systems and systems combining PV-based H2 production with BCLHP depends on a comprehensive assessment of local PV panel costs, heliostat costs, H2 selling prices, and solar conditions. This research presents a novel approach to enhance solar-to-H2 efficiency.