(Invited) High Power Water Electrolysis As a New Paradigm for Operation of PEM Electrolyzer

Abstract

Recent proliferation of environmentally conscious applications that acquire energy from renewable sources brings with them an interesting challenge of grid integration. Due to their unpredictability and intermittent nature renewable energy sources require substantial overcapacity to guarantee certain levels of energy production to satisfy targeted demand at any given time. This creates opportunities to capture output of that excess capacity during periods of high production/low demand, when the grid cannot accept such excesses. Such situations create opportunities to obtain electrical power at very low cost. One use of such inexpensive energy could be the electrolytic production of hydrogen for the purpose of energy storage (to be used in fuel cells at a later time), as chemical feedstock, or fuel (to supplement natural gas). Source of H2 is also necessary for deployment of fuel cells vehicles, and PEM electrolysis is one of the most promising environmentally clean sources. If done using renewable electricity it would also help meet energy independence goals for countries presently importing fossil fuels. A PEM water electrolyzer essentially works like a fuel cell in reverse. While some aspects and challenges of its operation are common / similar to fuel cells, some are different. In general it could be said that thanks to the somewhat higher kinetics of oxygen evolution as opposed to oxygen reduction the performance of electrolyzers has to date slightly exceed the performance of related fuel cells, but the difference is not dramatic. We intend to shatter this common perception and present some preliminary data showing operation of electrolyzer at previously unheard of power levels. This new level of performance was made possible by adapting techniques, procedures, and processes 3M already developed for making and testing fuel cells to electrolyzers. Our 3M proprietary NSTF catalyst was found to be an extremely good fit to water electrolysis (carbonless, durable, low mass transport losses, high conductivity, good heat dissipation, strongly hydrophilic – weakness in fuel cells, but strength in electrolysis). Recent advancements in fuel cell PEM membranes were equally as adaptable to water electrolysis and as important as the catalyst to enable such high power operation. What's perhaps of even more interest is that while the new high power operation mode is enabled, at the same time the efficiency of hydrogen production at low power levels, should one choose to run the electrolyzer that way, is not negatively affected. The presentation will cover progress achieved to date on the development of tools for characterization of PEM electrolyzers and performance. One of the highlights will be a description of >10 A/cm2 electrolyzer cell operation using propriety 3M MEAs with very low PGM loading (much less than present commercial electrolyzer MEAs). The associated challenges (durability, etc.), being a good fit to the intermittent nature of renewable energy sources, and potentially changing the basis of competition will be discussed. Figure 1