Holistic energy flow analysis of a solar driven thermo-chemical reactor set-up for sustainable hydrogen production

In this contribution, a holistic energy flow analysis of a solar driven pilot plant for green hydrogen production using two-step thermochemical cerium-based redox cycles is carried out. The plant consists of a heliostat field, a large-scale inert gas reactor, an efficient fluid heat recovery system and an electrical vaporizer for steam generation. The system behaviour is physically described, and energy flows are quantified using a complex simulation model considering material and geometric properties of the complete system design. The system energy flow and corresponding impact on plant efficiency is thoroughly analysed with emphasis on plant design, operational strategy, and influence of the crucial control parameters. Influences of a heat recovery system and the size of various types of heat losses are investigated, potential efficiency improvements are revealed and useful possibilities for plant design and material modifications are discussed. The transient system behaviour is investigated by varying temperatures and mass flow rates in a broad practicable range to gain more insight in efficient reactor design and plant control. Two temperature swing strategies are investigated in more detail, which are by far more efficient than any near-isothermal or isothermal strategy for this application