Life-Cycle Assessment of a Composite vs. a Metallic Bipolar Plate for Fuel Cell Applications: More Sustainable while Maintaining Same Performance Standards?

Faced with one of the greatest challenges of humanity – climate change – the European Union has set out a strategy to achieve climate neutrality by 2050 as part of the European Green Deal. Life Cycle Assessment (LCA), which among other aspects identifies climate change effects, is an important tool to assess the environmental characteristic of sustainable technologies or products to fulfill this ambitious target. In this context, research is presented that examines the ecological sustainability impacts of a metallic vs a composite bipolar plate made of innovative graphite-compound based foils. A bipolar plate is a central component of the fuel cell stack to ensure efficiency and durability. For this purpose, a LCA was performed for both bipolar plate materials. This assessment follows the methodology of DIN EN ISO 14040/44 and the EU Product Environmental Footprint framework. Focusing on cradle-to-gate system boundary conditions, the research focuses on the manufacturing processes with the relevant material and energy flows. Dealing with uncertainties in the energy supply chain, a comprehensive sensitivity analysis is conducted defining current and future energy scenarios with various shares of renewable and fossil energy carriers. Furthermore, the impact of different material production locations on the outcome of the LCA is investigated, considering changing geopolitical conditions. To assess also the effect on the complete lifetime of a fuel cell sack, the study is extended to cradle-to-grave system boundary conditions for a C-segment SUV and a HD-truck. Beside the evaluation of the global warming reduction potential, the study deals with the impact of the production processes of both bipolar plates on other impact categories like freshwater eutrophication or acidification. The investigations have shown that the use of foil-based graphite-compound bipolar plates can reduce the global warming potential by up to 68 % compared to conventional steel bipolar plates.