Optimizing the operational strategy of a solar-driven reactor for thermochemical hydrogen production

In this paper the operational strategy of a pilot plant for regenerative hydrogen production based on two-step thermochemical redox cycles is investigated with focus on optimal operational parameters for highest solar-to-fuel efficiency. The current plant consists of a solar driven large-scale 250 kW thermochemical inert gas reactor using ceria as reactive material for water splitting and an efficient fluid heat recovery system. Here we analyse the most important process conditions, which are operating temperatures, mass flow rates and duration times for both steps in the cycle. A highly accurate and detailed simulation model combined with well-suited optimization routines reveals new insights in most efficient operational strategies. Within the optimization material and technical limits of the used components are considered, thereby yielding reliable practical results. Optimal operational parameters are found by using a temperature swing strategy with corresponding solar-to-fuel plant efficiency determined by up to 1.1%. (C) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This paper investigates the operational strategy of a pilot plant for regenerative hydrogen production based on two-step thermochemical redox cycles, with a focus on optimizing operational parameters for the highest solar-to-fuel efficiency. Using a highly accurate simulation model and well-suited optimization routines, new insights into the most efficient operational strategies are revealed. The study considers the material and technical limits of the used components, yielding reliable practical results. Optimal operational parameters are found using a temperature swing strategy, resulting in a solar-to-fuel plant efficiency of up to 1.1%.