Search

Recently introduced sulfur caps on marine fuels in so-called sulfur emission control areas (SECAs) are forcing shipping companies to sail on more or less automotive grade diesel in lieu of the considerably less expensive, but sulfur-laden heavy fuel oil (HFO) to which they were accustomed. This development is an opportunity for a bio-based substitute, given that most biomass is sulfur free by default. Moreover, given that biomass is typically solid to start with, cracking it to an HFO grade, which is highly viscous in nature, will involve fewer and/or less harsh process steps than would be the case if an automotive grade fuel were to be targeted. In this study, a renewable low sulfur heavy fuel oil (LSHFO) has been produced by means of subcritical water assisted lignin depolymerization in the presence of a short length surfactant, ethylene glycol monobutyl ether (EGBE). The resulting oil contains a lignin derived content of 75 wt.-%, with the remainder consisting of EGBE and water (reusable). The derived LSHFO has a 20% higher heating value than the lignin feedstock. It is still roughly 20% and 30% lower when compared to the HFO and low sulfur marine gas oil (LSMGO) benchmarks, respectively. The lower heating value can be attributed to the fuel bond oxygen (10%) and water present in the LSHFO. Viscosity and sulfur levels, however, are within the HFO and LSMGO range and target respectively. Future work will examine what impact lignin particle size and surfactant type/concentration will have on the results.Graphical abstract

Although waste animal fats such as chicken fat are promising alternative energy sources, biodiesels produced from these type of feedstocks hardly satisfies the EN14214 biodiesel standards. In this study, biomixtures were prepared by blending cottonseed biodiesel and chicken rendering fat biodiesel which were produced via transesterification method. Biodiesels were blended with each other at 60/40, 50/50 and 30/70 volume ratios to produce CO60CH40, CO50CH50 and CO30CH70 fuels. First, fuel properties of the neat biodiesels and novel biomixtures were measured and compared to European biodiesel standards and diesel. Then, the engine performance, combustion characteristics and exhaust emissions of these novel biomixture fuels were measured in a three-cylinder indirect injection diesel engine under various engine loads and at constant speed of 1500 rpm. The fuel characterisation showed that CO60CH40 and CO50CH50 biomixtures met the European standards. The Brake Specific Energy Consumption (BSEC) and Brake Thermal Efficiency (BTE) of all biomixtures were comparable with CO100, CH100 and diesel at the full engine load. The combustion results revealed that the maximum in-cylinder pressure and energy release values of the CO50CH50 were 4.2% and 4.4% higher than the diesel at full engine load because of optimised fuel properties of biomixture such as molecular structure, viscosity, cetane number and iodine value. CO50CH50 had 2.9% reduced CO 2 and comparable CO emission compared to diesel, which were also 5.6% and 13% lower than cottonseed biodiesel respectively. However, NO emission of CO50CH50 was found 3.8% and 5.8% higher than diesel and cottonseed biodiesel. A 6.5% reduction on NO emission was observed when CO60CH40 biomixture fuel was used instead of diesel. To conclude, this research showed that blending of cottonseed and chicken fat biodiesels is a promising approach to meet the EN14214 standards, improve in-cylinder pressure, optimise energy release and reduce exhaust emissions. Blending of different biodiesels will be tested as a future work.