Fuel Cells as Power Option for Mobility: Progress and Prospects
With the direct electrochemical conversion of chemical energy to electrical energy, fuel cells represent a promising solution for electrical mobility. In contrast to the internal combustion engine with a generator, the PEM fuel cell is more compact at a comparable specific power. The PEM fuel cell is a mature technology today, whereby cost, lifetime, and reliability are three main criteria for commercial success and acceptance on the market, wherein a fuel cell system must be better than a conventional system.
The catalyst and the membrane determine the cost of a PEM system at cell level. At system level, the auxiliary equipment cost accounts for the largest share, whereas the stack accounts for about 40 % of the total system cost. The auxiliary equipment is also the “Achilles’ heel” in terms of reliability. Problems with fans, compressors, and leakages are the most frequent causes for a shutdown of the system. The core component, the stack, usually works reliably over the required operating hours and is truly maintenance-free.
The technology targets for the PEM fuel cell for 2020 and the long-term targets, both set in 2009 by the “Fuel Cell Technologies Office” of the “US Department of Energy”, were already achieved in 2015 and surpassed in some cases, such as the power density of the fuel cell stack and system or the required operating time. The commercial breakthrough, however, requires a well-performing overall system with a corresponding hydrogen infrastructure. Such system is already being tested in the context of urban mobility. Bauhaus Luftfahrt re-evaluates in the field of climate impact of aviation the long-term technology potentials at all levels of integration, ranging from stack efficiency to the techno-economic potential of the overall system.
- Specific power and power density: State of the art (2018) of the technology of PEM fuel cell stacks in different power classes compared to the technology targets of the “US Department of Energy”
- Fulfilling technology targets: Multi-criteria representation of the 2015 state of PEM fuel cells (best values) against the Department of Energy 2020 targets and long-term ambitions