Towards low-carbon marine fuels: compatibility and stability of bio-oil derivatives

The need for sustainable transition of maritime sector pushes industry towards exploring new possibilities both in fuels and energy efficiency measures. The use of bio-fuels is considered to be one of the most prominent ways to achieve the Interntaional Maritime Organization (IMO) Strategy goals on the reduction of greenhouse gases (GHG) emissions from ships. Among other bio-fuels, bio-oil produced from waste feedstock by means of pyrolysis, despite being studied thoroughly, is not widely used commercially because of its detrimenting qualities. In this study, bio-oil improved by different low-cost measures (drying in the presence of ethyacetate, esterifying with methanol, bio-oil and vacuum residue co-coking) is studied as a potential sustainable component of residual marine fuel. The limiting quality of bio-oil derivatives for marine fuel, as expected, was acidity, which restricted their content to approximately 2, 3 and 7% wt. for unrefined, dried and esterified bio-oil respectively. These components also led to a strong decline in asphaltene stability, with potential total sediment (TSP) results increasing from 0.01 up to 0.25% wt. However, aside from esterified bio-oil, the 0.10% wt. TSP limitation was only broken when exceeding proposed compontent content. ASTM D7061 method was also used to study the asphaltene stability, and solvent replacement from toluene to ethyl acetate was proposed as to produce better correlation of the method with TSP results. Additionally, unrefined and dried bio-oil exhibited comingling issues with base marine fuel. Nevertheless, coker gas oil produced from vacuum residue and bio-oil feedstock showed no issues with dilution, ashaltene stability and acidity. The potential effect of bio-oil derivatives on improving stability of the unstable fuel oil was also studied but proved to be insufficient. © 2026 Elsevier Ltd.