Evaluation of the Effect of Low-Carbon Fuel Blends’ Properties in a Light-Duty CI Engine

De-fossilization is an increasingly important trend in the energy sector. In the transport sector the de-fossilization efforts have been centered in promoting the electrification of vehicles, nonetheless other pathways, like the use of carbon neutral or carbon-offsetting fuels under current vehicle fleets, are also worth considering. Low-carbon fuels (LCF) can be synthetized from sources that can take advantage of the carbon already present in the atmosphere (either by technologies like direct carbon capture or biological processes like photosynthesis in biofuels) and use energy from renewable sources for the necessary industrial processes. Although, LCFs can be compared to fossil fuels as energy sources for internal combustion engines, their composition is not the same and their properties can modify the engine combustion and emissions. This work evaluates the use of several diesel-like LCFs in a light duty compression ignition engine and correlates the fuel consumption, NOx, soot and CO₂ emissions to the fuel properties. Results indicate that the combined effect of a low density, low aromatic proportion, high energy density and high cetane number Fischer-Tropsch/FAME fuel blend can maintain the fuel consumption and soot emissions close to results with diesel at most engine conditions and reduce NOx emissions 0.5 - 2.5g/kWh. It was also observed that fuels with higher proportions of OMEx (with lower energy density and increased oxygen proportion) can reduce the soot emissions for the same level of NOx emissions with a fuel consumption penalty. Tank-to-wheel CO₂ emissions show little variation between fuels, while the well-to-wheel emissions are proportional to the renewable content.