"As the maritime industry decarbonizes, FAME-based biofuels are crucial. However, adopting new fuels involves more than just replacing the old ones. As demand for marine biofuels grows, shipowners face new challenges in storage, handling and compatibility.  Our Adaptive Fuel Line is designed to adapt to these changes, with modular components and real-time automation – and Alfa Laval is there at every step, from drydocking upgrades to onboard support for crews." - Remco de Witte

At Alfa Laval, we are working closely with shipowners, operators and industry stakeholders to ensure this transition is both safe and sustainable. Let's take a closer look at how marine fuel handling is evolving, why it matters and how our Adaptive Fuel Line is supporting the transition.

From fossil fuels to biodiesel (FAME)

Historically, marine fuel oil has been exclusively fossil-based. Biofuels were off the table for regular use in diesel-powered ships, largely due to classification requirements and fuel standard limitations. That changed in 2024 with the revision of the ISO 8217 fuel standard. This allows the inclusion of FAME as a certified blending component in marine gasoil or residual fuels – eliminating the need for special exemptions to run trials or operate on blends. (Note that methanol or ammonia fuel systems require a complete reconfiguration of the equipment onboard and these are not covered under ISO 8217.)

Now, operators can legally order marine fuel blends with biofuel percentages ranging from 7% to 100%. Only sustainably produced biofuels should be used onboard – when purchasing biofuels, these fuels should meet the strict sustainability criteria backed by a “proof of sustainability” certificate that confirms their environmental origin and full lifecycle carbon footprint. Such documentation is critical for operators across all ship types to meet CII and FuelEU Maritime targets and satisfy ESG-conscious cargo owners.

Blending and storage challenges

One of the first misconceptions around biofuels is blending. Although technically possible onboard, it is strongly discouraged. Fuel should be pre-blended by certified suppliers to avoid inconsistencies that can lead to sludge formation, instability or even spontaneous separation in the tanks. Fuel systems are not chemical laboratories. Best practice is to draw down bunker tanks as much as possible before introducing a new fuel type, ideally emptying, cleaning and inspecting tanks before bunkering biofuels.

FAME-based biofuels differ fundamentally from fossil fuels: they degrade over time. Derived from organic feedstocks such as waste oils or used cooking oil, FAME is more susceptible to oxidation (in air) and biodegradation (especially with water exposure). If stored too long – typically beyond three to six months – biofuel can break down, forming gums, sediments and microbial contamination that compromise filters, separators and injectors.

Moisture and cold-flow behaviour pose the greatest storage challenges. FAME attracts water, encouraging microbial growth that accelerates fuel degradation and can corrode tanks. In cold conditions, particularly in double-bottom tanks exposed to seawater, FAME can crystallize into wax at temperatures as high as 10°C, potentially solidifying the entire batch and requiring costly manual removal.

Managing temperature is critical but tricky: while heating prevents wax formation, it also speeds up oxidation and degrades fuel quality. Operators must balance these risks carefully. Clogged filters, pump failures and unplanned downtime are real threats as biofuels are adopted, so proper housekeeping is essential.

How our Adaptive Fuel Line addresses these issues

The Adaptive Fuel Line is designed specifically to manage these kinds of trade-offs and variables, offering modular components that work together to handle fuel conditioning, temperature regulation, water removal and contamination control. Real-time monitoring and automation ensure the system can adapt quickly to different fuel qualities and types.

Key components include:

• Fuel Conditioning Modules (FCM): These regulate temperature and viscosity to ensure the fuel entering the engine meets precise specifications, regardless of blend ratio or fuel type.
• ALCAP™ separators: Used to remove water and impurities from the fuel before it reaches the engine (especially critical for biofuels as already stated).
• Automation and real-time control: Advanced sensors and control algorithms adjust treatment parameters on the fly based on real-time fuel conditions. This ensures stable performance and equipment protection, even when switching between fuel types.
• Engine management integration: The system communicates with the vessel’s engine management to optimize combustion and ensure compatibility during fuel transitions.

Rather than designing for a single fuel specification, the Adaptive Fuel Line supports multi-fuel operations. Biofuels are retrofit-compatible in that they can be used in existing installations with only minor modifications. Whether you're switching between different blends or running on full biofuel for part of a voyage, the system ensures stable supply and optimal engine conditions throughout.

Who manages this onboard?

Managing biofuel isn't just a technical problem, it is an operational challenge. Vessel crews must be trained to understand the properties of the fuel they are handling. They need to monitor for oxidation, know how to identify early signs of degradation and take proactive steps to prevent cold-flow issues or contamination.

This is where Alfa Laval’s service and support offering comes in. We work with crews and fleet managers to interpret data from onboard systems, provide recommendations and troubleshoot problems in real time. Sometimes the issue is fuel-specific; other times it may be a configuration or tank management challenge. In many cases, especially during planned dry dockings, operators can take advantage of Alfa Laval’s drydocking services to upgrade or adapt existing equipment for better biofuel compatibility. Our role is to help operators build operational confidence as they navigate unfamiliar fuel territory.

Evolving with the market

The marine fuel landscape is unlikely to stabilize anytime soon. As second-generation biofuels and other synthetic or waste-derived options enter the market, fuel properties will vary even more. That is why the Adaptive Fuel Line is not a one-time product – it is a long-term platform for fuel flexibility designed to be updated as and when required – software, sensors and even mechanical elements can be adapted as the industry evolves. Moreover, Alfa Laval’s insight into these emerging fuels extends beyond ship systems – we also provide equipment for use in land-based fuel processing applications, including biofuel refineries, giving us an unprecedented view of the full fuel lifecycle and future trends.

Biofuels are a fundamental shift

Marine biofuels are already in use, offering a tangible path to decarbonization without requiring new engines. But they must be handled with care, supported by proper systems and backed by expert guidance.

For shipowners and operators, the key question is not whether to adapt but how – and how soon. At Alfa Laval, we’re not only providing the equipment to make this transition possible – we are also sharing our expertise at every step. So, if you are planning to integrate biofuels in your fleet, or if you are simply unsure where to start, don't hesitate to reach out.