Stability Improvement of Biooil-Bunker-Blends

The transition towards lower-carbon shipping requires fuels that can be introduced into existing ships and fuel systems while new zero-carbon options scale up. One promising route is to blend biooils from renewable and waste-derived sources into conventional bunker fuels. However, differences in fuel chemistry can lead to phase separation, solid precipitation and sludge formation, limiting the amount of biooil that can be safely used. The ongoing STAB3 project is investigating what controls this compatibility, as a basis for improving blend stability.

The project combines detailed characterisation of selected fuels with improved methods for assessing blend stability over time. The work examines how properties such as acidity, composition, viscosity and interactions between fuel components influence miscibility, phase behaviour and sludge formation. Unstable phases are being separated and characterised to clarify their origin, while flow, mixing and droplet behaviour are being studied to determine how the blends behave as multiphase systems. Based on these insights, commercial dispersants and small amounts of co-solvents are being evaluated as potential routes to improve stability and enable higher biooil content.

STAB3 aims to develop improved tools and best-practice recommendations for evaluating biooil-bunker compatibility and for designing more stable blends. As the project progresses, promising formulations will also be assessed from environmental and life-cycle perspectives, including the potential for accidental release into the marine environment.

The project is led by DTU Offshore in collaboration with DFDS and EO. The aim is to generate results that support further fuel development and testing, and to identify practical pathways for increasing the use of lower-carbon bio-based components in shipping fuels without compromising fuel handling and operational reliability.