Life-cycle analysis of emissions from fuel ethanol and blends in Australian heavy and light vehicles

Because carbon dioxide emissions from the combustion of a renewable fuel are not anthropogenic greenhouse gases, there are significant greenhouse gas benefits in using ethanol that is derived from sugar or wheat, especially from waste feedstock. However, if the ethanol is used as an additive (as in diesohol or petrohol) then some of these greenhouse gas benefits are lost because ethanol is less efficient as a fuel. The vapour pressure of petrohol is higher than that of either petrol or ethanol, so that it is unclear whether there are, or are not, air quality benefits associated with the use of ethanol. A measurement program that surveys a significant proportion of E10 alternative fuel vehicles should be undertaken, along with a parallel program to test the emission variations that result from the changes in the petrol. The performance of overseas models in relation to the Australian situation is unknown, and a combined modelling and measurement program is needed to determine its validity.