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Particulate emissions, especially ultra-fine particulates, from diesel vehicles constitute the major traffic related environment and health-problem in larger cities today. Particulate filters are a promising solution to this problem. The Danish Road Safety and Transport Agency, in cooperation with the Municipality of Odense, has initiated a large-scale project with the objective to mount filters on some 125 heavy-duty vehicles in daily operation in Odense, to obtain operating experiences and environmental data and to demonstrate the technology.

The aim of the project was to demonstrate and evaluate the feasibility of DME (Dimethyl Ether) fuelled buses, through laboratory and field tests. The performance and emission targets of the HD DME engine has been successfully demonstrated and the bus has been converted to accommodate the DME engine and the fuel tank system. Two DME filling stations have been build. Additives for DME lubrication and odor have been selected. A Life Cycle Analysis (LCA) has been made under International Energy Agency (IEA) auspices by some of the project participants. The project has added valuable information, to the over all development of DME fueled vehicles. The strong arguments for DME as a major future fuel are briefly covered including production costs, emissions and feed stock diversity.

In order to document the level of exhaust emisions from biodiesel fuels compared with conventional diesel fuels, several studies have been conducted throughout the world. The results of these studies are, however, not conclusive, and very few reports exist on the potential health risk caused by exhaust emissions from biofuels. The aim of this investigation is to examine the chemical characteristics of exhaust emissions from Rapeseed oil Methyl Ester (RME) compared with a modern diesel fuel, and to document the potential health risk associated with these fuels.

A naturally aspirated, direct injection diesel engine was modified in order to be run on dimethyl ether (DME), with a conventional pump-line-nozzle system. The effects of various modifications to engine timing and the injection system as well as EGR were experimentally determined. Compared to the original diesel engine, the NOx emissions were reduced by over 70% through the use of suitable timing, lowered injector opening pressure and EGR. Particulate emissions were very low, and represent over a 90% reduction as compared to the original diesel version. The original pump-line-nozzle injection system was found to be not well suited to DME operation, CO and HC emissions were substantially higher due to secondary injections, caused by high pressure oscillations and residual pressure with the DME.