Consolidating emission indices of a diesel engine powered by carbon nanoparticle-doped diesel/biodiesel emulsion fuels using life cycle assessment framework

This study was aimed at consolidating emission indices of a diesel engine powered by carbon nanoparticles (CNP)-doped diesel/biodiesel emulsion fuels using a life cycle assessment (LCA) framework. The effects of fuel chemistry and engine load on the consolidated LCA-based environmental indicators of the engine (i.e., human health, ecosystem quality, climate change, and resource consumption damage categories) were investigated. Mineral diesel was reconstituted by adding 5 wt% biodiesel, 3 wt% water, and various concentrations of the waste-derived aqueous CNP ranging from 38 to 150 μM. Three CNP-free baseline fuels were also used as control. The engine was loaded in the range of 25–100% and at a fixed speed of 1000 rpm. In general, electricity use in the CNP manufacturing process increased all the investigated damage categories for the fuel blends dosed with the nanoadditive. Nevertheless, the lowest weighted environmental impacts per GJ shaft work were also obtained for the CNP-doped emulsified fuels. More specifically, dosing diesel/biodiesel emulsion fuel with 38 and 150 µM CNP favorably mitigated all the LCA-based environmental indicators considered herein through declining brake specific fuel consumption, boosting brake power, as well as abating lower brake specific nitrogen oxides and brake specific carbon dioxide. The weighted environmental impacts showed that diesel/biodiesel emulsion fuels doped with 150 and 38 µM nanoadditive were the most appealing fuel blends at low and full load operations, respectively. The eco-friendliest blend was diesel/biodiesel emulsion doped with 38 µM nanoadditive with an overall score of 61.3 mPts/GJ shaft work.