Sustainable marine fuels are finally gaining more traction as governments and private companies around the world look to decarbonise the shipping industry. This hard-to-abate industry contributes approximately three percent of the world’s greenhouse gas emissions at present, and as trade and passenger transport continue to increase, this figure could grow exponentially if nothing is done to decarbonise the sector. Meanwhile, the World Shipping Council (WSC) says better regulations are needed to ensure investments in green fuel are put to good use.
In the U.S., the Department of Energy (DOE) Bioenergy Technologies Office (BETO) is working towards the development of low- and net-zero-carbon sustainable marine fuels (SMFs) to decarbonise the shipping sector. While there is potential for smaller boats to be powered by lithium batteries or hydrogen fuel cells, larger vessels that travel longer distances will require a different approach. BETO is currently investing in research into the production of innovative green fuels that could help replace fossil fuels in powering maritime activities.
Over 90 percent of the goods transported around the world are carried on cargo ships, which rely on heavy fuel oil (HFO) for their power. This fuel comes from petroleum refining activities, which emit huge levels of greenhouse gases (GHGs) into the atmosphere. In contrast, SMFs are produced using materials and methods that help reduce GHGs. They can be made using feedstocks, such as forestry and agricultural waste, non-food energy crops, waste oils, fats, and greases, landfill gas and other waste products.
There are two main approaches to the development of SMFs, the production of fuels that can be used in existing or modified vessels and the manufacturing of fuels that can be used in new, specially made ships. Low-emissions drop-in fuels can be used in existing ship engines without the need for modification, making them suitable for the immediate decarbonisation of the sector. These include renewable diesel, biodiesel, hydrotreated vegetable oil, bio-oil, and bio-crude. Meanwhile, emerging marine fuels with zero or near-zero GHG emissions are being developed to be used in new or modified ship engines, meaning they are suitable for mid- and long-term decarbonisation efforts. These include bio-methanol, lignin-alcohol mixes, and bio-based natural gas.
One of the biggest limitations to emerging marine fuels is the time required to roll these out at the commercial level. It can take several years to develop new ship technology and manufacture a fleet of new vessels, meaning that these fuels cannot be used in the short term to decarbonise marine activities.
Many major companies are now investing in the development and production of SMFs to support the decarbonisation of activities, as governments push companies to support a green transition. Oil and gas giant Chevron hopes to increase its production of renewable diesel to 100,000 bpd by 2030. In 2022, Chevron Renewable Energy Group entered a strategic agreement with Bunker Holding Group, the world’s largest supplier and trader of marine fuels, to develop the U.S. and EU marine markets for sustainable bio-based diesel. The partnership is currently running trials with B20 and B30 SMF across both regions.