Electro‑hydrogen sizing and operation optimization for a hydrogen production station based on solid oxide electrolysis cells considering stack degradation

Solid oxide electrolysis cells (SOECs) are increasingly being deployed as the core units in hydrogen production stations owing to their high energy-conversion efficiency and reversible operation. However, existing studies tend to overlook SOEC degradation, leading to cost overruns, capacity oversizing, and suboptimal economic performance. To address this, this study proposes a comprehensive methodology for capacity sizing and operational optimization of SOEC-based hydrogen production stations that considers stack degradation. A hydrogen production station centered on a 20 kW-class SOEC system is modeled and supplemented by wind turbines (WTs) and photovoltaic (PV) panels, lithium-ion batteries (LIBs), and a hydrogen storage tank (HST). For the SOEC system, an assessment model of the degradation rate is developed, and a cumulative degradation factor is proposed to accurately calculate the actual hydrogen production rate. Moreover, by merging a rule-based energy allocation strategy with the NSGA-II algorithm, the system sizing is optimized to achieve a loss of hydrogen supply probability (LHSP) of 0. The optimized configuration comprises 639 PV panels, 52 WTs, 13 LIB sets, and a 299 kg-capacity HST, with a levelized cost of hydrogen (LCOH) of $11.19·kg−1. Furthermore, an operational cost function for the SOEC system is developed based on technical criteria for lump degradation resistance, and an economic optimization strategy is then designed to minimize daily operating costs. Furthermore, a comparative analysis is conducted of the strategy's advantages and the effects of feed-in penalty prices. The results show that the daily operating cost with the proposed strategy is $9.6648, a 49.42% reduction compared with $19.1091 by the rule-based strategy. Meanwhile, as the penalty price increases, both the SOEC system and BESS operation costs, the SOCHST and SOCBESS increase, while the feed-in power decreases.