In recent times, a rapid increase in the use of compression ignition (CI) engines in the transport sector has been observed. This is predominantly due to the superior thermal efficiency and brake specific fuel consumption that can be achieved when using CI engines. In addition, the continually increasing global oil prices and the introduction of strict vehicular emission requirements have resulted in an increased demand for alternative fuels. The use of Biodiesel, Fischer-Tropsch (F-T) diesel and Dimethyl ether (DME) as alternative fuels to petroleum diesel in Australia has been investigated in detail in this thesis. Accurate and well justified recommendations with regards to the feasibility of each fuel have been presented.
Biodiesel was found to be an attractive fuel as it can be produced solely from renewable feedstocks, contains no sulphur or aromatics and its use results in substantial reductions of many of the key vehicular emissions. The implementation of B100 biodiesel was found to be a non-feasible option for Australia in the short term. This is chiefly due to B100’s inferior performance characteristics, the constraints its use may cause on agricultural activities, as well as the increase in NOx emissions and operational complications associated with its use. On the contrary, it was determined that the use of a B20 biodiesel blend is a feasible option in
the short term. This is largely due to the emission reductions that can be achieved when using this blend, its cost competitiveness, as well as the compatibility of this blend with current refuelling infrastructure and engine fuel delivery systems.
In the short term, the use of F-T diesel was determined to be a feasible alternative to petroleum diesel in Australia. F-T diesel provides marginally superior engine performance, a considerable reduction in all of the considered vehicular emissions and also contains no sulphur or aromatics. As well as this, F-T diesel can be used in any unmodified CI engine, can be produced at a lower cost than petroleum diesel and is compatible with the current petroleum distribution and refuelling infrastructure that exists within Australia. The full scale implementation of F-T diesel also assists in providing Australia with energy security; due to Australia’s extensive coal and natural gas resources.
In the long term, it was determined that DME is the most suitable alternative fuel for CI engines in Australia. This is primarily due to the superior engine performance and emission reductions that can be achieved when using DME. The full scale implementation of DME also holds the potential to offer Australia with a higher degree of fuel security, once again, due to Australia’s extensive natural gas and coal reserves. In the short-term, the large capital investment required to modify refuelling infrastructure and engine fuel systems are hindering the full-scale implementation of DME. The development of a gaseous transportation fuel such as DME, also holds the potential to aid in the full-scale transition to hydrogen, which is considered by many as the ultimate ‘end game’ transportation fuel in the future.