The challenges of biofuel as tanker cargo

With decarbonisation firmly on the shipping industry’s agenda, biofuels have emerged as a viable alternative to fossil fuels, presenting an opportunity for greenhouse gas (GHG) reductions without the need for immediate infrastructural overhaul. The DNV white paper, Biofuels in Shipping, delves deeply into the technical and operational nuances of biofuel use and transport in the maritime sector. While promising, biofuels as a tanker cargo face unique challenges spanning from corrosiveness to contamination risks, which merit close scrutiny.

Supply and demand

The global production of liquid biofuels, including ethanol, FAME (fatty acid methyl ester), and HVO (hydrotreated vegetable oil), reached approximately 111M tonnes of oil equivalent (Mtoe) in 2023, according to DNV. However, only 0.7 Mtoe, or 0.6% of the total supply, was consumed by the shipping sector during the same period. This stark disparity reflects shipping’s nascent adoption of biofuels compared to other transport modes such as road transportation, which accounted for a dominant 98.9% of liquid biofuel consumption.

Since 2015, biofuel bunkering operations have been recorded at more than 60 ports globally, with an additional 30 ports capable of delivering biofuels. Major hubs like Singapore and Rotterdam played a pivotal role in 2023, accounting for nearly half of all marine biofuel deliveries, with 518,000 tonnes of bio-blended fuels bunkered in Singapore alone.

“Technical hurdles include a susceptibility to microbial growth and the need for extensive tank cleaning”

Vitol was one of the first to deliver biofuels in Singapore through its wholly-owned subsidiaries V-Bunkers and Vitol Bunkers. It was able to offer a range of biofuel blends, from B24, B30 and even up to B100 if customers requested it. However, oil tankers were only permitted a fuel blended with biofuel up to 25% concentration; any greater and IMO regulations stipulate a ‘IMO Type 2 chemical tanker’ ship is required. In 2024, V-Bunkers took delivery of IMO Type-2 bunker barges. This infrastructure formed the foundation for biofuels not only as a bunkering fuel but increasingly, as a cargo commodity.

While exact data on biofuel cargo shipments is unavailable, the paper notes that the transport of biofuels as bulk cargo is expected to increase significantly. Regulatory drivers like the EU Emissions Trading System (ETS), FuelEU Maritime, and the IMO’s mid-term GHG measures will bolster demand for biofuels in maritime transport. Projections suggest that these regulations will make the movement of biofuels as cargo a critical component of decarbonisation strategies, particularly as advanced biofuel production scales up to meet rising demand across sectors.

Biofuel suppliers

The DNV white paper incorporates feedback from eight biofuel suppliers and 12 shipping companies, providing critical insights into the maritime market’s present and future relationship with biofuels.

Biofuel suppliers highlighted the growing demand for biofuels in shipping but noted significant competition with other sectors, particularly road transport and aviation. Aviation was identified as a particularly attractive market due to higher margins and stringent regulatory frameworks, such as the EU’s ReFuelEU Aviation directive, which mandates specific blends of sustainable aviation fuel. Suppliers also pointed to constraints in feedstock availability, particularly advanced biofuels made from non-food and non-feed sources. The logistics of blending and distribution, especially for higher biofuel content blends like B30 or B50, also emerged as a critical bottleneck.

Shipping companies offered a grounded perspective, reflecting on operational challenges and practicalities. Feedback underscored the technical hurdles associated with FAME, such as its susceptibility to microbial growth and the need for extensive tank cleaning prior to use. Compatibility with existing shipboard systems was another concern, with companies stressing the importance of consulting engine manufacturers and conducting extensive pre-tests to avoid issues with fuel injectors and separators.

“Many shipping companies expressed optimism about biofuels”

Interestingly, companies that had trialled HVO reported fewer operational disruptions, citing its superior stability and compatibility with existing systems. However, they acknowledged the higher costs associated with HVO and the potential need for additives to address its lower lubricity. Despite these challenges, many shipping companies expressed optimism about biofuels, recognising their drop-in capability and potential for reducing GHG emissions under regulatory frameworks like IMO’s Carbon Intensity Indicator (CII).

Transport and safety

Biofuels such as FAME and HVO possess properties that make them distinct from traditional marine fuels. These differences bring about logistical challenges in transport. Maintaining the integrity of biofuels during transport often requires significant preparatory work, including meticulous tank cleaning and ensuring compatibility with existing tanker systems.

A key operational hurdle lies in the fact that FAME is highly hygroscopic, meaning it absorbs water during storage and transport. This can lead to microbial growth and fuel degradation, further complicating logistics. In contrast, HVO — produced through hydrotreatment — boasts superior stability but demands equally careful handling to avoid contamination during blending or transfer.

Safety remains a paramount concern in biofuel transport and use. FAME’s higher flashpoint makes it less flammable compared to conventional marine fuels, which is advantageous from a safety perspective. However, its tendency to form acids and polymers during storage can lead to operational risks if not adequately managed.

HVO, while generally safer, can sometimes exhibit flashpoints that approach regulatory thresholds. Maintaining robust monitoring protocols during bunkering and transit can help ensure compliance with SOLAS regulations.

Given the unique properties of biofuels, tanker maintenance routines must be adapted accordingly. Tanks used for FAME transport require rigorous cleaning to remove water and sediment, both of which can exacerbate microbial growth and corrosion. For HVO, while cleaning requirements are less intensive, maintaining low water ingress remains crucial.

Balancing potential and practicalities

Biofuels represent a viable pathway for shipping’s decarbonisation, but their integration as a tanker cargo is fraught with challenges. Addressing the technical and operational considerations outlined by DNV and incorporating lessons learned from industry feedback is essential for realising their potential while mitigating risks.

With ports and tanker infrastructure expanding to accommodate biofuels and regulatory incentives accelerating their uptake, biofuels are poised to play an increasingly vital role in the maritime energy transition. However, realising this potential will require sustained efforts to address logistical, technical, and material challenges, ensuring biofuels can serve as a cornerstone of sustainable shipping.