With a power consumption of several kilowatts, large trucks consume as much electric energy as a multi-flat house. To supply HVAC, refrigeration plant, auxiliary heating or the driver's coffee machine the vehicles often let their engines idle on motorway stations or over night. Electric generators based on fuel cell, so called Auxiliary Power Units (APUs) could help saving energy and avoid noise and harmful exhaust fumes.
High-temperature fuel cells with solid electrolyte (Solid Oxide Fuel Cell or SOFC) could be commercially interesting, since they do not need platinum. By means of a reformer interposed between fuel tank and fuel cell, SOFCs can turn usual diesel fuel into electricity. Full-ceramics cell types are already quite mature, but they suffer from a critical drawback - their brittleness prevents their usage vehicles; they simply do not survive vibrations and shocks in their location in the vehicle floor for a very long time.
Metal-based versions as devised by scientists from the Jülich research centre along with Austrian companies AVL List GmbH, Plansee SE and the Vienna technical university perform much better; in addition they offer the perspective to lower production cost. Currently these cells however have another weakness: Already after several hundred hours of operation, their performance is declining significantly. "The reason for the excessive ageing effect lies in the micro structure of the electrodes, which is not yet optimal", says Dr. Martin Bram from the Jülich Institute for Energy and Climate Research. "Other factors are the interplay of the electrode material with impurities of the process gases as well as inter-diffusion and oxidation process at the boundary surfaces."