(Plenary) Challenges in Going from Laboratory to Megawatt Scale PEM Electrolysis

Abstract

Renewable hydrogen is becoming an increasingly important component of the transition away from fossil fuel use and towards reduction in carbon dioxide production. Hydrogen is the intermediary between primary energy sources and end products in many chemical processes such as ammonia generation, refining, and biogas processing, and is currently mainly produced by reforming of natural gas. Hydrogen from electrolysis can both make a strong environmental impact on these industries and also improve utilization of intermittent renewable energy sources such as wind and solar by leveraging otherwise stranded resources. Hydrogen can also enable improved integration of the electrical grid with the transportation sector and industrial processes, by serving as a storage medium until needed (Figure 1). Because of hydrogen's end use flexibility, electrolysis is a key component of Europe's strategy for energy storage and management of these renewable energy sources on the electrical grid. Proton exchange membrane (PEM) electrolysis is especially well suited to energy capture because of the dynamic range and ability to quickly ramp up and down from near zero output to full capacity. PEM electrolysis was largely developed in the 70’s by GE for life support applications where reliability and reproducibility were key. As the technology was translated to commercial markets it started to compete with the incumbent alkaline water electrolysis on cost, safety (no mixing of O2 and H2), ease of maintenance (no caustic) and operational flexibility (differential pressure operation, idling). While the resulting commercial success of PEM electrolysis suggests that the current state of the technology is sufficiently mature, the truth is that while PEM electrolyzers have demonstrated > 50,000 hrs lifetimes and > 99% reliability in the field, the technology and manufacturing techniques have not changed significantly from those early days. In traditional industrial applications the customer rarely cares about efficiency as much as reliability. At the same time, the robustness and manufacturability of the technology (cell, stack and system engineering), have allowed the systems to be scaled from laboratory scale (0.01kg/day) to megawatt scale (100kg/day) with no loss in performance or reliability. To date the research community has mostly focused on advancing PEM fuel cell technology, producing staggering PGM reduction, improvement in efficiency and translation to high throughput manufacturing. Thus electrolysis technology development has lagged behind PEM fuel cells, providing significant opportunities for continued improvements. Thinner membranes, reduced PGM usage, and improved manufacturing techniques have all demonstrated viability for electrolysis, and have the potential to make higher cost and performance impact. As the application areas for PEM electrolysis start to shift from traditional markets to fueling and renewable energy capture, efficiency, capital cost and ethical resource use become significant factors. Thus advancing the state of the art, translating laboratory advances to commercial PEM stacks and then manufacturing them at scale, while maintaining reliability becomes paramount. Questions that arise are: How do you test reliability, without testing for 50,000 hrs? How do you pick research “winners” at the rotating disk electrode (RDE) level and develop them to large scale PEM membrane electrode assemblies (MEAs). Where is the gap in research at the laboratory scale based on commercial failures? This talk will discuss the challenges in continued scale up, translating laboratory scale findings to commercial systems as well as some of recent advancements and impact on cost. Figure 1