A Refinery Perspective on Decarbonizing with Marine Biofuels

This work seeks to understand what biofuel production pathways a refinery might prefer to produce very-low sulfur fuel oil (VLSFO) for marine applications. A comprehensive refinery optimization model was developed using AspenTech’s PIMS linear programming software. The model was configured to allow (1) direct blending of soy biodiesel, renewable diesel, Fisher-Tropsch diesel, and several pyrolysis oils and (2) indirect blending of all pyrolysis oils via co-processing in a fluidized catalytic cracker (FCC) and diesel hydrotreater into the marine fuel pool. Results showed preferred pathways to bio-VLSFO production included co-processing low-quality pyrolysis oil in an FCC to blend the resulting biogenic LCO, directly blending soy biodiesel, and directly blending small quantities of pyrolysis oil. Bio-VLSFO production costs were compared with those of fossil-VLSFO subject to different marine fuel demands, benchmark crude oil prices, and biogenic fractions in the finished product. Given benchmark crude oil prices over 60 $/Bbl, bio-VLSFO production appeared to be significantly cheaper than fossil-VLSFO. Corresponding marginal abatement costs of CO₂ mostly ranging from -300 to 350 $/ton-CO₂ were also determined using a simplified but novel approach to allow comparison with other decarbonization strategies. This work indicates that low-sulfur contents in biofuels, relatively relaxed specifications for marine fuels, and current difficulties in meeting VLSFO specifications with crude oils can combine to make bio-VLSFO production cost-effective. Moreover, marine fuels appear to be a good entry point for refiners to start decarbonizing with biofuel pathways that could eventually be extended to other product pools.