Reported sludging incidents rise

John LaRese, marine fuels expert

Following the initial fuel-related challenges post-2020, complexity has increased further as new fuel streams come on line. In the past few months Infineum has seen an upturn in the number of sludging incidents. With over 40 years’ experience at ExxonMobil, John LaRese, has a unique background combining onboard maritime operations and shoreside marine fuel technical expertise. Having worked with Infineum since 2022, providing technical support on marine fuel additives, he is well positioned to share his views on fuel quality trends, their potential impacts and some ideas on sludge prevention and cure.

“When the new fuel regulations came into force in 2020, there was a shift to very low sulphur fuel oil (VLSFO) and an increase in fuel-related issues," John explains. "This was due, firstly, to a need for fuel suppliers to learn how to blend fuels within the new envelope to ensure stability and secondly, for end users to learn how to handle these new types of fuels if stability issues arise. Over time, fuel suppliers identified the optimum composition of fuel blends, and it has been a relatively quiet time in regard to fuel-related issues, with only one or two reported incidents a year. But now things are changing, and we are seeing issues with sediment, compatibility and fuel stability. Fuel incidents being reported to Infineum are rising alarmingly – we have already dealt with three cases in the last month.”

With such a dramatic change, Amy asked John to provide an insight into the likely causes of this increase in onboard sludging. “In my view, what we are seeing now is that new and existing fuel suppliers are pushing the boundaries a little bit and are trying different blend stocks. This is all driven by supply and demand, along with cost in terms of which blend stocks are available and which are cheaper to use – because refiners need to make a profit and end users want value for money. Unfortunately, this can only lead to an uptick in fuel-related issues, where the fuel breaks down, asphaltenes drop out and the vessel experiences sludging."

"Vessel personnel and shoreside management need to take the risk of vessel sludging very seriously.”
John LaRese, marine fuels expert

So how can sludging be prevented? As John continues, prevention requires action from both marine fuel producers and consumers. “Planning and preventative action will be the difference between a well managed and poorly managed event. From a fuel manufacturing perspective, the correct choice of blend components is key to ensuring that the fuel will remain stable and not break down and deposit asphaltenes. Aboard the vessel, the most important factor is to keep the fuel segregated from previous batches of fuel. When dealing with particularly difficult fuels, this may include lowering levels in the settling and service tanks to minimise comingling, which can help manage the transition from one fuel to the next.”

What happens when sludge forms?

When the worst happens and sludge forms, John says, there are immediate and long term impacts on ship performance, and things can quickly deteriorate if the issue is not addressed. “The immediate concern is how to maintain fuel treatment via purifiers and filters – the crew will need to carry out extensive and continuous cleaning and clearing of filters, purifiers, tanks and potentially pipelines. For a vessel at sea, if the fuel cannot be purified it cannot be consumed, which means the propeller stops turning and the lights go out. While in most cases it is not as severe as that, sludging can lead to vessel delays, debunkering and huge costs.”

Sludge can block filters and purifiers, which can prevent the fuel from reaching the engines

John goes on to explain that even on-specification products cannot be used directly in ship engines, which gives marine fuels a unique set of requirements. “Marine fuels need to be purified, filtered and heated before they can be consumed in the diesel engines. The problem we're seeing is that end users are not always able to purify the fuel and it breaks down, separates and plugs up the purifiers. And so what you have is a ship at sea that cannot consume the fuel. But, because the fuel could have been on-specification when taken on board, there is a good chance that any incurred costs would not be recoverable from the fuel supplier.”

“Longer term consequences include sediment buildup in tank bottoms, which requires extensive cleaning and disposal during docking periods,” John confirms. “If the sediment buildup is severe, it can lead to acute issues if it is stirred up during rough weather, which may make it necessary to take the vessel out of service for cleaning before scheduled docking periods.”

What can be done on board?

With the incidents of sludging on the rise, Amy wanted to find out John's thoughts on what ship and shoreside personnel can do to minimise the consequences of sludging. “The stability of a fuel that is on-specification when blended and delivered can be like a time bomb ticking as it slowly breaks down in storage. When vessel personnel are switching over to start consuming a new batch of fuel they should be especially aware of operations and intently monitoring purifier and filter parameters. Vessels should have a plan in place to deal with troubled fuel before there is an issue."

"Shoreside management can look at the potential consequences to their operations and ensure vessel personnel have the tools they need to manage fuel problems including adequate spare parts and fuel additives, whether for preventative treatment or for use during extreme issues.”
John LaRese, marine fuels expert

To make his point for preparation and prevention clear, John uses the analogy of a housefire. “While most homes will never have a fire, homeowners proactively install smoke detectors and fire extinguishers, devise an escape plan and buy adequate insurance - just in case. In my view, the same planning and foresight is needed regarding fuel-related issues on board at sea. To minimise the risk it is important for vessel personnel to buy fuel from a reputable supplier, keep the fuel segregated, closely monitor purifier and filter operations, especially during fuel change over, and operate purifiers in parallel with minimal flow, lowering purifier discharge intervals. It is also vital to have a plan of action if issues arise and to have a stock of additive on board for emergencies.”

How can additives help?

John’s long career, both ship and shoreside, means he has seen a number of unexpected sludge problems that have been successfully addressed by using additives. As he explains to Amy, it is important for others to draw learnings from these experiences.

“What usually happens after the vessel has departed port, is that there is a time delay before they start consuming the new fuel and trouble is identified. If there is no fuel additive on board for emergency use it may be some time before the next port call, when additive can reach the vessel. During this interim period vessel personnel struggle to treat the fuel, which can be overwhelming since they must undertake additional, time-consuming purifier and filter maintenance in addition to their normal daily duties."

"Maintaining a stock of additive on board for use in these situations can make the difference between managing the troubled fuel and the fuel dictating vessel delays.”
John LaRese, marine fuels expert

There are two distinct choices to be made – the first is to initiate preventative procedures, such as using additives or fuel conditioning, and the second is reactive cleanup. In Amy's view, preventative treatment can be a very cost effective approach, since additives are less than $1 per treated tonne, while emergency treatment can require 100 times more additive to be dosed in. Since John has experience of working on shoreside support of emergency sludge treatment, Amy was keen to gain his view on both approaches.

“Fuel issues range from minimal to catastrophic. Maintenance doses of additive will help reduce the consequences of all sludging issues. However, with severe cases, maintenance doses of additive are not sufficient to counteract compatibility issues and maintain the stability of the fuel. In these cases, higher dosage rates have proven to help manage the severely troubled fuel. As well as preventing operational issues, the use of sludge management additives can help avoid debunkering or sludge disposal costs, since the additives ensure the fuel is used to power the vessel rather than being wasted.  This not only saves money, but can also help to reduce the risk of expensive fuel disputes."

Cost reduction is high on vessel operators’ lists of priorities and Amy asked John if in his opinion it is worth the upfront investment in preventative fuel treatment as standard, or whether just treating fuels retrospectively when problems arise is a better option.

“Again it all comes back to cost vs risk. You could choose to dose every single fuel on a preventative basis. Then there would be less sludge, the purifiers would stay in better shape and in terms of maintenance, there is less sludge to clean out of the bottom of storage and settling tanks. But, if there have not been issues with fuel quality, shoreside would question this approach. I think for vessel operators on a regular run where they know the bunkers are less than adequate, it would be cheaper to take the fuel and do a maintenance dose of additives every day or on an every bunker basis to overcome the poor quality fuel. Vessels constantly using the same high quality fuel, could simply stock an additive on board for emergencies. Then if something goes wrong with a blend, or a bad batch of fuel is taken on, emergency additive treatment can be started straight away.”

A lower carbon future

The maritime industry is working hard to cut greenhouse gas emissions in line with the International Maritime Organization’s goal of net zero by 2050. Again a paradigm shift in fuels is expected and as John explains to Amy, he does not see completely smooth sailing ahead.

“In the future, ammonia and hydrogen will be used and I see fewer problems there because the vessels will have been specifically designed to use those fuels. To me, while the technology of the future looks very promising, we've got a long road before we get there. If you think about it, 2050 is right around the corner and you've got to design these massive engines, you've got to build them and make sufficient quantities of the new fuels available globally. In my view, from a vessel owner/operator perspective, there's really no incentive and no push to do it. If owner operators are not going to purchase this new technology, engine builders and shipyards are not going to build it, which means things are unlikely to happen by 2050.”

In the interim, before hydrogen and ammonia are more widely adopted, Amy wanted to know John’s opinion on whether sludge management additives have a role to play in drop-in biofuels, such as cashew nutshell liquid (CNSL), FAME residue and pyrolysis oils.

“I think we're going to run into bumps and hurdles as we start seeing lower carbon fuels come out."
John LaRese, marine fuels expert

"Biofuel is not going to get us to net zero - it is just a temporary fix – and right now it's not cost effective and there is limited availability. I do think things could change – if, for example, governments realise they're not going to reach net zero by 2050, they may put legislation in place to make biofuel a lot more attractive. If biofuels are used at a much higher blend ratios we would have to adapt to the changes, and the demand for additives may increase. But again, going back to the start of the conversation, everything is driven by cost, availability, legislation and incentives. There are a lot of unknowns out there, and I think Infineum will be ready with fuel additive solutions that can match the changing needs of the maritime industry and overcome issues that arise.”

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