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In earlier work we have shown that engine operation with oxygenated fuels (e.g., biodiesel) reduces the particulate matter (PM) emissions and extends the engine tolerance to exhaust gas recirculation (EGR) before it reaches smoke limited conditions. The same result has also been reported when high cetane number fuels such as gas-to-liquid (GTL) are used. A likely mechanism for engine-out particulate growth is the reintroduction of particle nuclei into the cylinder through EGR. These recirculated PM particles serve as sites for further condensation and accumulation promoting larger and greater number of particles. In order to further our understanding of EGR influence on total PM production, a diesel particulate filter (DPF) was integrated into the EGR loop. A PM reduction of approximately 50% (soot) was achieved with diesel fuel through filtered EGR, whilst still maintaining a significant NOX reduction.

A comparison is being undertaken of the performance of five identical vehicles, using alternative fuels, by the Public Works Department of Victoria. The comparison is being made in normal vehicle duty in service, over 60,000 km, and by laboratory testing. Problems encountered in vehicle conversion to alternative fuels, and in installing instrumentation, and in normal operation are described. Laboratory test results of vehicle efficiency and emissions are presented and compared. The fuels considered are petrol, diesel fuel, Liquified Petroleum Gas (LPG), and Compressed Natural Gas (CNG). An Electric powered vehicle is proposed for this trial and is described. Initial conclusions indicate favourable cost reduction in using LPG or diesel fuel compared with Petrol and CNG.