What Drives Marine Biofuel Uptake? An Agent-Based Analysis of Policy and Infrastructure Interactions in Singapore

Biofuel is the main drop-in low-carbon marine fuel available today, yet it made up only about 2.4% of bunker sales in Singapore in 2025. This paper assesses how market-based measures, infrastructure changes and supply-side adjustments affect biofuel uptake in Singapore's bunkering market. We develop an agent-based model in which vessels, bunker barges and terminals trade conventional low-sulphur fuel oil, a B24 blend and B100 through utility-driven deals. The model is calibrated on 2024 monthly sales data of the Maritime and Port Authority of Singapore (MPA) and validated out-of-sample on 2025, reproducing annual LSFO and B24 sales within 5% and 3%. Market-based measures are the only levers that raise biofuel uptake on their own, as doubling the carbon price raises the bio-containing share 3.5 times, and a small change in vessels' emission-penalty weight moves it significantly. Infrastructure changes have no effect at baseline prices but raise B100 sales by more than 70% once a carbon price exists. Supply cuts of up to 90% leave uptake unchanged, because bunker barges and terminals hold large spare capacity. Price signals should therefore come first, as access measures only work once a price signal exists. The framework extends to other ports and fuels.