Conceptual design and selection of a biodiesel fuel processor for a vehicle fuel cell auxiliary power unit

Within the European project BIOFEAT (biodiesel fuel processor for a fuel cell auxiliary power unit for a vehicle), a complete modular 10 kWe biodiesel fuel processor capable of feeding a PEMFC will be developed, built and tested to generate electricity for a vehicle auxiliary power unit (APU). Tail pipe emissions reduction, increased use of renewable fuels, increase of hydrogen-fuel economy and efficient supply of present and future APU for road vehicles are the main project goals. Biodiesel is the chosen feedstock because it is a completely natural and thus renewable fuel. Three fuel processing options were taken into account at a conceptual design level and compared for hydrogen production: (i) autothermal reformer (ATR) with high and low temperature shift (HTS/LTS) reactors; (ii) autothermal reformer (ATR) with a single medium temperature shift (MTS) reactor; (iii) thermal cracker (TC) with high and low temperature shift (HTS/LTS) reactors. Based on a number of simulations (with the AspenPlus® software), the best operating conditions were determined (steam-to-carbon and O2/C ratios, operating temperatures and pressures) for each process alternative. The selection of the preferential fuel processing option was consequently carried out, based on a number of criteria (efficiency, complexity, compactness, safety, controllability, emissions, etc.); the ATR with both HTS and LTS reactors shows the most promising results, with a net electrical efficiency of 29% (LHV).