(Invited) Key Barriers to Commercial Deployment of Next Generation Proton Exchange Membrane Electrolyzers
Authors: Ayers Katherine E 
Published: February 2020

Hydrogen is gaining increased international attention based on the imminent roll out of fuel cell vehicles, as well as the growing need for energy storage to manage high levels of renewable and inherently intermittent energy sources on the electrical grid. Hydrogen from electrolysis based on proton exchange membrane (PEM) technology in particular is of interest due to the lack of carbon footprint, scalability, ability to ramp from near zero output to 100% rated capacity or greater, and the lack of corrosive electrolyte. While electrolysis and fuel cells are not typically as efficient on an electrical round trip basis vs. many battery systems, hydrogen is highly deployable, providing flexibility to optimize the grid system. Hydrogen can be used to crosslink different infrastructures such as the electrical grid, the transportation grid, and chemical processing. For example, hydrogen produced using excess renewable energy can either be fed back to the electrical grid via fuel cells, used to fuel hydrogen-powered vehicles, or used to upgrade conversion of biogas to methane.
PEM electrolysis has the technical maturity and reliability to serve these applications, but is still handicapped by legacy materials and manufacturing processes vs. the next generation technology advancements that have been made in fuel cells. Feasibility of translating many of the elements of current fuel cell technology to electrolyzer systems has been demonstrated, but the specific requirements of electrolysis cells provide additional technical gaps which prevent materials developed for fuel cells to drop seamlessly into electrolysis processes. Some customization and optimization of materials and processes are needed to enable implementation in electrolysis cells. There are also areas of development needed including understanding the impact of process scale up on resulting material properties, translation from machined proof of concept prototypes to parts fabricated by high speed manufacturing methods, and integration of research efforts on different components into a cohesive cell design. In addition, scale to larger cell sizes brings new fundamental questions and materials and design challenges.
These issues are often masked by the typical metrics and models currently in use for electrolysis, such as the DOE H2A model. The H2A model is a very detailed tool which provides relative comparisons between technologies based on constant assumptions, but does not reflect present commercial production, partially because this information is typically considered proprietary by companies. The H2A model is instead based on technology which has been demonstrated at a high enough technical fidelity to prove feasibility of commercialization within 5 years. It does not take into account the often challenging scale up and manufacturing development, or the investment required for the remaining hurdles to commercialization. It also assumes production of 500 units/year at 1500 kg/day hydrogen output per unit, or almost 2000 MW of annual capacity. No commercial company has reached even 5% of this total annual hydrogen output in sales, and thus large extrapolations are being made at both a manufacturing readiness level and volume production level in the model.
Electrolysis also does not currently have the same well-defined material targets and metrics as fuel cells, such as hydrogen and oxygen crossover, platinum group metal loading, electrocatalyst support stability, and bipolar plate resistivity and corrosion resistance. These quantitative metrics would help to highlight specific progress being made in these areas vs. the overall system metrics which dampen the impact of a single component. Balance of plant is also an important contributor to cost, efficiency, and reliability which is not typically addressed in detail in government technology roadmaps.
This talk will present the limitations in commercial PEM electrolysis which drive cost and efficiency, the large potential for improvements in these areas for electrolyzers, and remaining technical challenges that need to be addressed to provide a full solution. Specific barriers which remain in translating the output of successful research programs to commercialization will also be addressed, including manufacturing and integration challenges. Finally, comparison between approaches in the United States and Europe in supporting technology development will be presented.