Engine Impacts and Opportunities of Various Fuels, Including GTL and FAME: Toward Specific Engine Calibration?

World wide, energy policy makers are increasingly keen to move away from petroleum based fuels to more diverse and renewable sources of energy for reasons of environmental protection, energy security and continued economic development. A well-known example is Gas-To-Liquid (GTL) diesel fuel which is derived from natural gas and thus provides a diversification away from crude oil, which is the feedstock for 97% of the world transport fuels. Towards the same goal, Fatty Acid Methyl Esters (FAME), from vegetable oils, recycled oils, or animal fat, are being used with increasing frequency as blends with diesel fuel, even at a concentration of 30% in some captive fleets (B30). In this paper, the impacts on engine pollutant emissions and performance are evaluated. The chemical properties of these diesel fuels can offer several benefits in terms of more favourable NOx/PM trade-offs (GTL and B30), lower CO₂ emissions, and higher performance (GTL), but a specific engine calibration for each of these fuels is needed to fully take advantage of these benefits. This raises an important issue, namely, what the effect would be on the engine emissions and performance with such calibrations when switching back to regular diesel fuels. It is, however, shown that some of these benefits may already be achieved by engine control solutions while keeping the initial engine calibration based on regular diesel fuel.