Examining the Alternatives: Biofuels as a Decarbonisation Startegy
Biofuels are fuels manufactured from biobased feedstocks (biomass) over a short timeframe. As plants grow, they sequester carbon dioxide from the atmosphere, which then makes up the resulting product. When this is burned, the cycle completes itself, making biofuels a low carbon alternative to fossil fuels.
Biofuels offer the widest scale decarbonization impact, at the fastest pace of any decarbonization strategy in the maritime sector (short of stopping global trade all together). Further, biofuels can offer air quality improvements, with lower particulate matter and hydrocarbon emissions than diesel. The reason biofuels can offer imminent wide scale decarbonization, is the compatibility with current equipment and infrastructure, and comparable cost to current fuels. As with any fuel, there are pros and cons. This article will explore in greater detail the advantages and challenges to deploying biofuels, different types of biofuels and the position of biofuels within the global energy mix.
Advantages
Biofuels, such as biodiesel, are ready to deploy in a range of existing equipment in the maritime sector. CSL shipping demonstrated a year-long trial of biodiesel in place of marine gas oil (MGO) on 8 of their bulk carriers, with no impact on operations, other than much reduced CO2 emissions [1]. Many trucks and port based mobile equipment are already compatible with 100% biodiesel, leading to a 74% reduction in greenhouse gas (GHG) emissions [2], and almost all are compatible with a 20% blend (B20) under warranty.
This cross compatibility of biofuels with existing equipment is unparallelled, and the reason behind the potential scale of impact. Even with the most ambitious electrification (or other) plan, diesel powered equipment will still be operating in ports for years to come, as fleets cannot be replaced overnight. Synthetic diesel (made from CO2 and renewable electricity) also has cross-compatibility; however, as of 2024, is prohibitively expensive [7].
Electric (or other low carbon) alternatives exist for mobile equipment, light transport and many industrial processes, however in shipping, energy density of the fuel is vital. Both space and weight come at a premium on board large ships, and if made battery electric, a large amount of cargo would be displaced to accommodate the required batteries. The energy density of hydrogen is also lower than hydrocarbon fuels, therefore shipping (alongside aviation) requires energy dense fuels. Biofuels can offer a suitable alternative with much reduced emissions.
Challenges
Some equipment manufacturers do not certify their equipment to run on B100, leading to hesitancy amongst operators. Furthermore, some equipment has been known to struggle with the performance of pure B100 over winter conditions. For equipment in this category, either using a biofuel blend (or a ‘flow improver’) during the winter months could be the solution, similar to how petrochemical fuel blends change with seasonal temperatures.
In general, Biofuels are slightly more expensive than their fossil fuel counterparts, yet governmental incentives are making them more affordable. For example, California has especially high financial rewards, which attracts most of the national supply [8]. Biodiesel is consequently being transported over vast distances in tankers, further increasing the carbon footprint of the biodiesel from well-to-tank. Biodiesel made from soybeans grown in the Midwest would be best used on the Great Lakes because the reduced transportation would emit much less carbon than sending those fuels for use in California. This is why a consistent Federal plan for biodiesel use would lower the emissions from producing and transporting the fuels.