Investigation on SOE performance under elevated pressure with AC:DC operation

By 2030, solid oxide electrolyzers (SOEs) are expected to be a key electrolysis technology, due to their high electrical efficiency, low material costs, and dual functionality as fuel cells. The main challenges for SOEs are limited stack lifetime (e.g., 20,000 hours) and cell size (e.g., 100 cm2). A new operational method for SOE, named 'AC:DC', patented by DynElectro in 2019, has shown promise in addressing the key challenges. This method involves overlaying an alternating current (AC) on a direct current (DC), allowing intermittent operation in fuel cell mode. Tests on SOEs indicated that AC:DC can enhance lifespan by removing temperature variations and improving impurity resilience through electrochemical oxidation/reduction processes.
Capital expenses (CAPEX) for balance-of-plant equipment such as heat exchangers, pipes and compressors can be reduced by 50% when increasing the operation pressure from ambient pressure to 5 bar for SOE. Additionally, high pressure operation enables increased hydrogen production capacity for SOE.
In present study, the MESH project aims at building a setup and conducting SOE cell testing under elevated pressure (up to 5 bar) with AC:DC operation. The preliminary experimental investigations are presented. Furthermore, the dynamic SOE operations during the testing are discussed from system point of view.