Optimal Design of Modular Production System for Renewable Methanol under an Uncertain Energy Supply

Modular production systems (MPS) for renewable methanol offer a multifaceted solution by consuming renewable energy, utilizing carbon dioxide, and enabling medium- and long-term energy storage through methanol production. However, the inherent fluctuation and uncertainty of renewable energy present significant challenges for system design and operation. Therefore, based on a comprehensive consideration of the fluctuations and uncertainties of renewable energy output, an optimization design model of MPS for renewable methanol is developed, targeting the minimization of total annual costs. The work incorporates customized efficient solution strategies, including stochastic scenario generation method, linearized relaxation, and solution algorithms. Through a practical case study, the implementation process of the proposed model and method is demonstrated, yielding the optimal capacity configuration and production scheduling plan of MPS for renewable methanol under uncertainty. By comparing the results with those obtained under deterministic single scenario conditions, this study elucidates the impact of renewable energy uncertainty on the design capacity, design redundancy, and economic viability of MPS. Additionally, the operational characteristics of MPS for renewable energy under uncertainty are explored. The findings indicate that the characteristics of renewable energy output are key factors affecting the design and operation of MPS for renewable methanol. Specifically, the capacities of electrolyzers, hydrogen tanks, and the MPS are correlated to power characteristic parameters, while the capacity of the battery is associated with power density characteristic parameters. Accounting for uncertainty during the system design phase can significantly enhance system capacity and operational flexibility, while significantly improving equipment utilization and the utilization rate of renewable energy. These results will provide necessary references for the design and operation of renewable chemical production.