Advances in Electrochemical Compression of Hydrogen

This paper evaluates the potential for electrochemical hydrogen compression systems (EHCs) regarding their engineering performance, manufacturability, and capital costs. EHCs could enhance or replace mechanical hydrogen compressors. The physical embodiment of EHCs is similar to that of low temperature (LT) proton exchange membrane (PEM) fuel cell systems (FCSs). They also share common operating principles with LT PEM FCS and with PEM electrolysis systems. Design for Manufacturing and Assembly (DFMA™) analysis is applied to EHCs to identify manufactured designs, manufacturing methods, projected capital costs under mass-production, and cost drivers for both the EHC stack and the balance of plant (BOP). DFMA™ analysis reveals that EHC stack costs are expected to be roughly equal to EHC BOP costs, under a variety of scenarios. (Total EHC system costs are the sum of stack and BOP costs.) Within the BOP, the primary cost driver is the electrical power supply. Within the stack, the primary cost drivers include the membrane electrode assembly (MEA), the stamped bipolar plates, and the expanded titanium (Ti) cell supports, particularly at lower hydrogen outlet pressures. As outlet pressure rises, capital costs escalate nonlinearly for several reasons. Higher pressure EHCs experience higher mechanical loads, which necessitate using a greater number of smaller diameter cells and a greater tie rod mass. Higher pressure EHCs also exhibit a higher degree of back-diffusion, which necessitates using more cells per system.