Low-Carbon Shipping Fuels
Low-carbon fuels for long-haul trucking, ocean shipping, and aviation are being developed to replace traditional fossil fuels. There are a few main varieties of low-carbon shipping fuels, as discussed in this article.
The most prominent types of low-carbon shipping fuels are biofuels, especially cellulosic biofuels. Hydrogen, ammonia, and methanol potentially have a lower carbon footprint than biofuels, and could be especially useful for ocean shipping. Other categories of low-carbon shipping fuels include liquified natural gas, and synthetic and bio-liquified natural gas (LNG, SNG, and bio-LNG).
Sustainable Aviation Fuels (SAF) are made from biomass – examples include dedicated energy crops, corn grain, oil seeds, algae, other fats, oils, and greases, other waste streams, agricultural residues, and forestry residues. SAF are sourced from the same 2nd and 3rd-generation biomass sources that biofuels for other shipping modes are predominantly sourced from.
Low-carbon shipping and aviation fuels are necessary because these transportation modes (except for, perhaps, long-haul trucking) will be difficult to decarbonize through electrification. Long-haul trucking is a transportation mode in which biofuels, hydrogen, and electrification are all competing technologies in the sector, with no clear winner.
It is commonly believed that hydrogen and hydrogen-derived fuels (ammonia, methanol, and SNG) are going to be prominent low-carbon fuels for ocean shipping in the future, as the world strives toward goals for net zero emissions. Electrification is likely not going to be a good fit for most ocean shipping (outside of smaller ships, such as ferries) due to the large cargo space required for an adequate volume of high-capacity batteries. So far, LNG has emerged as the current predominant option for low-carbon ocean shipping. Hydrogen-derived fuels would provide a lower-carbon fuel alternative to LNG.
Biofuels used for long-haul trucks and other shipping modes, as well as SAF, are often blended with petroleum-based fuels to create a lower-carbon fuel blend. Theoretically and in a best-case scenario, decarbonization for shipping transportation fuels could best be solved through electrification and green hydrogen-derived fuels. However, cargo space for sufficient batteries is an issue for shipping electrification, and cost is an issue for both of these low-carbon solutions for shipping.