INTERVIEW: VPS on Quality Issues to Look For When Buying Biofuels

Steve Bee is group commercial and business development director at global testing firm VPS. Image Credit: VPS

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• Six key quality issues to monitor
• Tests designed for 100% biofuels not always suitable for blends
• New VPS biofuels service to be announced later this week
• 0.5% of samples VPS received last month were biofuels

As the shipping industry rapidly increases biofuel blend purchases to cut GHG emissions, buyers should be aware of a new set of quality pitfalls to avoid, according to testing firm VPS.

The Port of Rotterdam saw a total of about 329,000 mt of biofuel blend sales in the first half of 2022, while Singapore has seen about 70,000 mt in the whole year to date. These numbers are likely to grow sharply next year as biofuel blends approach the mainstream of bunker sales worldwide.

But buyers taking on these less familiar blends should be aware of what they're getting into, Steve Bee, group commercial and business development director at global testing firm VPS, said in an interview with Ship & Bunker this week.

"Everyone calls it a drop-in fuel, and that's exactly what it is; you can basically put it into existing engine technology without real issue in terms of burning it," Bee said.

"But you've got to understand that the overall fuel management operations from the point of it coming over the ship's rail, where it's stored and how its handled, temperatures et cetera and how you move it around -- that's the difficult part.

"Once it gets to the engine, it's fine."

Qualities to Watch Out For

Bee listed six particular qualities to keep an eye on when taking on biofuel blends.

The list is as follows:

• Renewable content
• Stability issues
• Energy content
• Cold flow properties
• Corrosivity
• Microbiological activity

"The ISO 8217 tests are always a great place to start, in terms of the applicability of that particular fuel as a marine fuel," he said.

"However, on top of that, you've obviously got other considerations."

Renewable Content

"Accurately measuring the renewable content of the fuel is going to be critical, because that's going to be used to calculate and verify the reduction of CO2 emissions," Bee said.

"What we've seen is that the current FAME method isn't actually that accurate in terms of reproducibility, precision and accuracy, so VPS made validated modifications to the method to improve the accuracy.

"What we've been able to do is to improve the test method in order to ensure that we're getting a more precise reading at that particular infrared wavelength," he said.

Stability Issues

"Also important with biofuels is the stability," Bee said.

"As we saw with VLSFO, you have a certain shelf life, which is far less than the standard traditional hydrocarbon fuels that we used prior to VLSFO.

"With biofuels probably the best analogy to make is milk and butter; if you don't refrigerate them, they tend to become rancid.

"We're employing a test called the Rancimat method to measure oxidation stability.

"But we've got another couple of tests that we look at in terms of bio-oxidation stability: iodine value, a measure of the unsaturated material within biofuels, and looking at linolenic acid, as another measure of stability.

"A lot of these tests are designed to look at the pure biofuel, let's say 100% FAME, coming under the EN 14214 FAME standard.

"However, once you start blending these disparate materials into either a VLSFO or a diesel MGO, a lot of the test methods aren't directly applicable to blends.

"So we have modifications of certain tests, that will give you information about blended material, but the first line in the sand is really to do as many of these ISO 14214 tests as you can on the bio part of that material as a pre-test."

Energy Content

"Knowing the energy content is obviously key, as you want to know how much bang you're getting for your buck," Bee said.

"Normally this is done through ISO 8217 as a calculation; however, with biofuels, that's not applicable.

"So what you have to do is a physical test known as a bomb calorimetry test.

"It's an ASTM  test, under the ASTM D240 standard, and that measures the gross calorific value.

Cold Flow

"Cold flow properties are a key issue," he said.

"With a blended bio-MGO, you'd be looking at cloud points, and if you're looking at a darker blend material -- with VLSFO or HSFO -- you'd be looking at the wax appearance with temperature testing.

"This is just a measure of the potential for paraffin wax to precipitate out from the raw material."

Corrosivity

"In terms of corrosivity, we've obviously got the acid number, which is a standard test," Bee said.

"But then biomaterial can attack certain surfaces like copper or steel, so there's a copper corrosion test, and a steel corrosion test, which can be applied to the biomaterial itself."

Microbiological Activity

"Esters by their very nature absorb water and when you have warm fuel being stored at elevated temperatures, you will get microbial growth at the fuel/water interface.

"These bugs can get to a certain level where they'll start corroding tank walls, pipework et cetera, and they can form sludges as the bugs die off.

"So measuring bacteria, yeast and fungi within the fuel is a key issue."

Other Pitfalls

Beyond the main list of quality problems, Bee outlined two more potential areas of concern with biofuel blends.

The first was issues arising from the higher flashpoint of these blends.

"FAME has a high flashpoint, and in combination with a high oxygen content this increases fuel consumption, but also potentially NOx formation," he said.

"This can lead to quicker accumulation of unspent biofuel, and may lead to soot in the lubrication oil and NOx in the exhaust system."

The second was glycerides.

"Another thing to be aware of is the presence of glycerides," he said.

"Glycerol is used as a fundamental building-block in the production of FAME; you use glycerol with an alcohol, normally methanol, to produce fatty acid methyl esters.

"This reaction can actually go one way or the other depending on conditions like temperature.

"If you find that you have higher glyceride content in your final product, then these components can cause problems like sticking to metallic surfaces, and negatively affect the vessel's operation.

"We've had to develop gas chromatography methods to measure these components within a blended fuel."

The Trappings of FAME

It's notable in discussions around biofuels that buyers are now actively paying large sums to add FAME to their bunkers, where previously it was treated as a contaminant to be avoided where possible.

Earlier sets of ISO specifications had a de minimis FAME content requirement, meaning its presence in the fuel should be negligible for the fuel to be found on-specification.

But as Bee explained, this was at a time when FAME content in road diesel was for the first time up to 7%, and the concern was that it would end up in the marine fuel supply chain by accident with ship operators unprepared with how to handle it. With buyers now deliberately taking it on for its GHG-saving properties, they will familiarise themselves with its idiosyncrasies and learn how to avoid problems.

"I don't think the issues have actually changed," he said.

"If you know it's there and you know what to expect, you can mitigate a lot of the risks that are associated with that particular type of material."

New VPS Biofuels Service

VPS is now launching a new service to help its customers work with the new biofuel blends, Bee said.

"Before VLSFO came along, we put together an additional protection service to help give our customers a greater level of protection in terms of damage prevention," he said.

"That was basically your ISO 8217 tests with some additional tests like lubricity or GCMS.

"And now we've done a similar thing for biofuels, an additional protection service called APS Bio.

"This covers 100% FAME fuels, blends with MGO and blends with VLSFO or HSFO.

"We'll be launching that by the end of this week."

Biofuels' Growing Bunker Market Share

While biofuel blends currently take up a small section of the market -- the 70,000 mt of biofuels sold in Singapore so far this year was about 0.2% of the conventional fuels total sold there in January to September -- the share is growing.

Biofuel blends took up about 0.5% of the samples received by VPS in September, Bee said. but that percentage has roughly doubled in the past three or four months.

Quality problems in the samples seen so far have been thin on the ground. But it will take more than 15 minutes of FAME for issues to emerge; the market should be prepared for these problems to arise as biofuel blends start to be handled in a more conventional way after the current trial periods have ended, Bee said.

"I have not encountered any real problems with biofuels at all so far," he said.

"But what I would say is that at the moment you're talking about biofuels which are taken as relatively small stems and then used very quickly; they're not on board the ship for a long period of time.

"Things like oxidation, stability, microbial growth and corrosivity may not have had the time to have an impact.

"As this material gets stored on our ships for longer, then obviously these problems will become more of an issue."