Preliminary Investigation of a Bio-Based Low Sulfur Heavy Fuel Oil

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.