Optimizing the Design of Combined Alkaline and Proton Exchange Membrane Electrolyzers to Fully Utilize Fluctuating Renewable Energy

By integrating the economic advantages of alkaline (ALK) water electrolysis with the rapid response capabilities of proton exchange membrane (PEM) electrolysis, there is potential to mitigate power fluctuations and fully utilize renewable energy. However, the optimal design for combining these electrolyzers remains unclear. This paper develops an integrated planning and operation model for ALK and PEM electrolyzers, considering dynamic operational details (i.e., start-up, shutdown, and ramping) and various operating states including idle, underload, variable, and overload states. The problem is to determine the optimal combination of ALK and PEM modules in the combined electrolyzers, which is solved by a commercial solver. The numerical results are conducted based on a photovoltaic site with a 113 MW solar power output. Two typical scenarios, namely peak noon and fluctuating, are selected to analyze the operational details of the combined electrolyzers. It is demonstrated that the combined electrolyzers effectively mitigate wide-range fluctuations and enhance economic efficiency compared to standalone ALK or PEM electrolyzers.