Optimizing the operational strategy of a solardriven reactor for thermochemical hydrogen production

Abstract

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%.