Bunkering fuel: A path toward sustainability

Bunkering is the process of supplying fuel to ships. It involves the transfer of fuel from storage tanks, on land or on board specialised vessels, into a ship’s fuel tanks. Bunkering fuel, or marine fuel, has historically been heavy fuel oil, a low-cost but highly polluting option. However, as environmental regulations tighten around the globe, there is an ongoing shift towards cleaner alternatives such as liquefied natural gas (LNG), biofuels and other low-carbon solutions.

Bunkering involves several steps to ensure safety, efficiency and compliance with environmental standards. It starts with the preparation of the ship and fuel transfer systems, followed by the actual fuelling process from a storage facility or a bunkering vessel to the ship. Once the transfer is completed, the fuel tanks are sealed, and the necessary documentation is signed off. Close attention to safety and regulatory compliance is essential throughout this process to prevent spills.

Carbon-neutral fuels do not add to the net amount of carbon dioxide in the atmosphere during their life cycle. They work by either producing zero carbon emissions during combustion or by offsetting emissions through carbon capture and storage (CCS) technologies. Such fuels are central to achieving the global maritime industry’s goal of net-zero emissions by 2050.

With the phasing out of traditional fossil fuels, alternative fuels for existing diesel engines are becoming much more prevalent. The maritime sector is exploring green fuels such as LNG, biofuels, ammonia and hydrogen. These fuels promise significant reductions in GHG emissions, although they are still in varying stages of development and adoption.

When produced using renewable energy, ammonia becomes a zero-carbon fuel. However, it still presents challenges in terms of toxicity and storage. Although ammonia bunkering is in its early stages, it is being explored for use in ships equipped with ammonia-compatible engines. Ammonia bunkering requires specialised infrastructure and stringent safety protocols.

Derived from organic materials, biofuels such as biodiesel are considered a more sustainable alternative than traditional bunkering options. Biofuels made from crops absorb CO₂ during their growth, balancing out the emissions produced when they are burned. They can be used in conventional engines with minimal modifications, making them an attractive, economical option for retrofitting existing fleets.

Hydrogen is produced from many sources. The industry uses colours to differentiate the various types. Grey hydrogen is the most common form and is generated from natural gas or methane. Blue, or low-carbon, hydrogen is produced from fossil fuels with carbon capture. Green hydrogen is generated from renewable energy sources such as hydropower, wind and solar power, resulting in zero emissions when used as fuel.

Natural gas is the cleanest fossil fuel and an important “bridging fuel” in the transition to low-carbon energy. Liquefied natural gas (LNG) is predominantly methane with a mixture of ethane that has been cooled down to a liquid form for ease and safety of storage and transport. It has gained momentum due to its price competitiveness, abundant supply and lower emissions compared to traditional fuels.

Global LNG bunkering increased by 62 per cent in 2023 compared to 2022. The transfer of LNG traditionally required jetties and quays, but there has been a dramatic scaling up of ship-to-ship bunkering in recent years. LNG bunkering vessels are equipped with advanced systems to handle the extremely low temperatures of the fuel and ensure safer transfer operations. These transport tanks are built with internal and external compartments with a vacuum system between them to reduce the amount of heat transfer.

Companies are increasingly investing in LNG bunkering infrastructure to meet the rising demand for cleaner shipping fuels. One such company is Norwegian ECOnnect Energy which has developed an innovative LNG transfer system consisting of a floating platform. This makes it possible to offload, reload and bunker LNG at locations that were previously deemed unfeasible.

As the maritime industry strives to meet international emissions reduction targets, the adoption of alternative fuels is accelerating. LNG bunkering vessels are becoming a common sight in major ports, and technology to retrofit diesel engines to run on cleaner fuels is being developed at a rapid pace. A combination of these green fuels and innovative technologies is essential for cutting emissions in shipping and beyond.