Critical materials in PEMFC systems and a LCA analysis for the potential reduction of environmental impacts with EoL strategies

Abstract

Commonly used materials constituting the core components of polymer electrolyte membrane fuel cells (PEMFCs), including the balance-of-plant, were classified according to the EU criticality methodology with an additional assessment of hazardousness and price. A life-cycle assessment (LCA) of the materials potentially present in PEMFC systems was performed for 1 g of each material. To demonstrate the importance of appropriate actions at the end of life (EoL) for critical materials, a LCA study of the whole life cycle for a 1-kW PEMFC system and 20,000 operating hours was performed. In addition to the manufacturing phase, four different scenarios of hydrogen production were analyzed. In the EoL phase, recycling was used as a primary strategy, with energy extraction and landfill as the second and third. The environmental impacts for 1 g of material show that platinum group metals and precious metals have by far the largest environmental impact; therefore, it is necessary to pay special attention to these materials in the EoL phase. The LCA results for the 1-kW PEMFC system show that in the manufacturing phase the major environmental impacts come from the fuel cell stack, where the majority of the critical materials are used. Analysis shows that only 0.75 g of platinum in the manufacturing phase contributes, on average, 60% of the total environmental impacts of the manufacturing phase. In the operating phase, environmentally sounder scenarios are the hydrogen production with water electrolysis using hydroelectricity and natural gas reforming. These two scenarios have lower absolute values for the environmental impact indicators, on average, compared with the manufacturing phase of the 1-kW PEMFC system. With proper recycling strategies in the EoL phase for each material, and by paying a lot of attention to the critical materials, the environmental impacts could be reduced, on average, by 37.3% for the manufacturing phase and 23.7% for the entire life cycle of the 1-kW PEMFC system.