Maximizing the potential of biodiesel through nanoparticle assistance: A review of key factors affecting performance and emissions

With recent focus on reduced global footprint and depletion of fossil fuel sources, it becomes imperative to look for renewable sources of energy. Biodiesel presents a sustainable alternative due to its renewable nature and has 7.4 % lesser global warming potential than diesel. However, the yield of biodiesel is low, resulting in increased cost. Waste oils and algae have been used as an alternate to reduce the cost and increase the yield of biodiesel. Several nanocatalysts such as titanium dioxide, zinc oxide, and graphene oxide have been used to increase the biodiesel yield to more than 95 %. This review focuses on different kinds of feedstock used for biodiesel production and the role of different nanoparticles in improving the yield of biodiesel. Biodiesel has high fuel consumption, low thermal efficiency, and produces low power due to its high viscosity. Nanoparticles enhance the combustion and ignition characteristics of biodiesel in compression ignition engines, producing more power along with reduced fuel consumption and improved thermal efficiency. Studies have reported that addition of 90 ppm of CeO2 and carbon nanotubes to waste cooking oil biodiesel increased the brake power by 7.4 % and reduced the fuel consumption by 4.5 % compared to B20. Similarly, reduced graphene oxide reduced the fuel consumption of corn biodiesel by 16.3 % and improved the thermal efficiency by 18 % with respect to B100. Nanoparticles also help in the reduction of CO, HC, and smoke emissions. For example, addition of 90 ppm of CeO2 and carbon nanotubes reduced the NOx, HC, CO and smoke emissions of waste cooking oil biodiesel by 19 %, 17 %, 39 % and 25 %, respectively. In addition, adding reduced graphene oxide led to 18 %, 16 %, 15 % and 18 % reductions in NOx, HC, CO and smoke emissions, respectively, for corn biodiesel. Performance and emission characteristics of different biodiesel blends have been compared with diesel, and the effect of nanoparticles on these characteristics have been analyzed.