Quality and Storage Properties of Upgraded Fast Pyrolysis Bio-Oil for Marine Transport

In-depth data on the long-term storage quality of upgraded fast pyrolysis bio-oil, SDPO (stabilized and deoxygenated FPBO), was produced, reflecting its usability as marine fuel. Stability of the SDPO (∼5 wt % oxygen) was good based on a long-term storage stability study and new accelerated aging method. The fuel properties of SDPO and its 30% blends with marine fuels remained stable over a storage period of one year. Some fuel properties of the analyzed SDPO batch require consideration to meet the specifications for marine distillate fuel, notably, density, viscosity, cetane number, flash point, acid number, water content, carbon residue, and ash content. By removal of light components, the flash point of SDPO could be improved. Development needs for the analyses were identified. An accelerated aging test for SDPO was developed in the project. The oxidation stability and lubricity methods should be developed and validated for the SDPOs. There are not yet standards or internationally approved methods for chlorine and sulfur analyses either for FPBO or for SDPO. On the other hand, there is not yet a limit for chlorine in the content of marine fuels in ISO 8217:2017. The boiling point range of SDPO is much wider than that of marine fuels. Methodology is needed to ensure that the SDPO batch used does not have a tendency to form precipitate in blending with marine fuels, and blending protocols are needed for large batches of SDPO. It was also observed that SDPO production is not yet standardized and may lead to variations within different batches. Attention is needed also on aspects that were not covered, such as decomposition products, corrosivity, and additives. Noted is also that SDPO could be more appropriate for marine distillate fuels, since high temperatures are needed to lower the viscosity of the residual fuels to the appropriate range for use in marine diesel engines.