A didactic platform dedicated to the characterization and modeling of a PEM electrolyzer under current ripple constraints
Authors: Guilbert Damien , Mantilla Villalobos María Alejandra , Rey Juan M. 
Published: October 2024

Hydrogen is considered a key energy vector to decarbonize transportation and industry sectors, both responsible of global average temperature increase due to the intensive use of fossil fuels. Currently, most of hydrogen is generated by employing thermochemical processes (e.g. coal gasification, natural gas conversion) that may be coupled with carbon capture, utilization, and storage (CCUS) solutions. However, despite generated hydrogen is low-cost, low-carbon hydrogen objective has not been yet met. Over the last few years, many governments and environmental agencies in countries like Colombia and France have adopted a strategy dedicated to the production and the use of low-carbon hydrogen through water electrolysis process fed by renewable energy sources (e.g. wind, solar, hydro, geothermal) to meet the growing hydrogen demand. Water electrolysis process consists of splitting pure water thanks to electricity into pure hydrogen and oxygen. This process is carried out by electrolyzers operating in different ways according to the type of electrolyte material employed and the ionic species they transport. The coupling between intermittent renewable energy sources and electrolyzers involves the use of power converters such as AC-DC converters and/or DC-DC converters. Both power converters by their operation generate low and high-frequency current ripple (from a hundred to a ten thousand of Hertz). Current ripple generated by power electronics have been a major concern for fuel cells and more recently on electrolyzers for increasing understanding of cell and stack degradation processes. Long-term effects of current ripple generated by power electronics on electrolyzers performance constitute now a key issue. For this reason, the outcomes of these investigations will allow guiding to an optimal design of power converters from the current ripple point of view. To raise students’ awareness of these issues, a didactic platform relying on a proton exchange membrane (PEM) electrolyzer system has been exploited. The electrolyzer system is fed directly by the power grid through two power converters (i.e. a single-phase full-wave bridge rectifier and a step-down DC-DC converter). Both power converters create current ripple whose electrolyzer is subjected. The students can analyse the direct impact of current ripple on the electrolyzer voltage response and realize the likely degradation over a long period of operation. In the paper, the didactic platform including the PEM electrolyzer system is presented and some experimental outcomes. Then, an equivalent circuit model (ECM) is proposed to simulate the real voltage behavior under current ripple constraints. The parameters of the model can be assessed by using a set of experimental data. This ECM is useful for investigating the effects of current ripple on electrolyzer stack performance. The conclusions of these investigations must be considered to design in a suitable way power converters for this application.