All about biodiesel

Regular diesel now features an element of biodiesel, but is there the opportunity for the industry to go one – or many – steps further? Toby Clark finds out

Regular diesel fuel (DERV, to the EN590 standard) now consists of a ‘B7’ blend of 93% fossil diesel and 7% FAME biodiesel produced from waste products. It’s certainly a step toward carbon emissions reduction – but what about 100% biodiesel, known as B100?

Refrigeration manufacturer Thermo King, for instance, says that “B100 offers a 60% reduction in greenhouse gas emissions and up to 80% lower level of fine particles”. At Solutrans, the firm announced that a wide range of its units would soon be able to run on B100 biodiesel – that is, 100% FAME produced from waste products and complying with the EN14214 standard. The manufacturer had already validated HVO biodiesel (EN15940) in all its units in 2021.

Once certified, the units will meet the NRMM (Non-Road Mobile Machinery) V requirements, and Thermo King says that vehicles running exclusively on B100 are eligible for France’s Crit’Air 1 vignette, allowing them to drive in its urban low-emission zones.

If Thermo King can do it, what about vehicle manufacturers? It turns out that some OEMs can supply B100-compliant vehicles, albeit at a cost and with some operational limitations. So, in theory, everybody could reap the low-carbon benefits of B100.

Argent Energy is a supplier of biodiesel made from waste fats and oils, and its corporate affairs director, Dickon Posnett, is on the board of the Renewable Transport Fuels Association (RTFA). However, he does not suggest that B100 is a solution for everybody.

“If the authorities incentivise the use of B100, it excludes so many operators – and if you have an effective incentive mechanism and it works, there isn’t enough biodiesel in Europe to do it, especially waste-based biodiesel,” he says. At the moment there is no direct fiscal incentive for operators to use biodiesel, but Posnett offers hope. “Through the RTFA, we are having conversations with Treasury about a possible incentive mechanism for ‘high blends’ [such as] B15, B20, B30.”

Surely even B20 or B30 (ie, 20% or 30% FAME blends) is far below what could be achieved with all-biodiesel running? “It does sound low,” admits Posnett. “But it’s still tripling or quadrupling the amount of bio and, therefore, the carbon savings. It’s not ‘B100 or nothing’ – that's the point.”


“What we mean by high blends is above the current limit of 7% but, realistically, we talk about above 10% because we’d like to get B10 as the standard instead of B7,” he says, adding that some OEMs need to do the testing and certification that shows their power units work with B10. “The B10 standard exists [EN16734], so it’s a case of the UK implementing it and telling retail outlets they’ve got to start offering B10. But, if you look at the process that the E10 [petrol with 10% bioethanol] introduction involved, it’s not simple. There are logistics and practical problems, with maybe a number of smaller fuelling stations not having two diesel tanks and pumps.”

Posnett points out the need for a ‘protection grade’ fuel, which could be B7, to suit existing vehicles. “I think the DfT found it really hard to introduce E10, but B10 is effectively a 40% uplift in the amount of bio going into the vehicle fleet, so it makes an awful lot of sense.”

High blends could be introduced into truck and coach fleets more easily: “Deliver B20 or B30 direct to companies that have back-to-base refuelling,” advises the Argent Energy man. “You might want to clean the tank out first, but it's effectively a drop-in replacement.”

One of the main issues with pure biodiesel is that its CFPP (cold filter plugging point) is higher than for regular DERV, making its flow worse at low temperatures. This generally requires fuel tank heating, perhaps with a separate tank of EN590 for the engine to start on (and sometimes to shut down on). Retrofit solutions, such as the Vector System from US-based Optimus Technologies, work this way. “If you’ve got one diesel fuel tank in your yard, you need a second, heated, tank and a pump to dispense it,” says Posnett.


Scania is offering B100-compatible vehicles, but its technical notes point out that “biodiesel has a negative effect on fuel filters as they become blocked. This concerns the prefilter before the feed pump in particular. In order to counteract blockage, coarse-meshed filters which are more resistant to blockage are used”.

Another objection to biodiesel is its aggressive effect on seals, but most modern vehicles are already prepared for this: Scania, for example, says that “seals that are resistant to biodiesel were introduced in November 2012”. Biodiesel absorbs water more readily than EN590, which causes problems in some applications. Scania recommends that “vehicles with downtimes for more than two months are not approved for biodiesel”.

B100 undoubtedly has a lower energy content than DERV: Volvo says that the deficit is around 8% and warns that “performance and driveability might be reduced and fuel consumption might increase”. Other minor issues include the need for correct labelling of EN590 and EN14214 tanks.

Oil change intervals are always a concern with biodiesel, too. Scania’s technical note on B100 states: “Biodiesel has a negative effect on the oil and causes it to oxidise.” It adds: “The boiling point of FAME EN14214 is higher than for diesel, which means that the fuel does not evaporate if it gets into the oil sump. To avoid the risk of running on thin oil, the oil changes must be carried out more frequently.”

“What we’ve always recommended is to abide by those schedules, but keep an open mind and keep doing research,” says Posnett. “Every time we’ve found that, the operators soon get confidence in it.” In fact, it seems that many fleets revert to the conventional oil-change schedules.

But be aware: if you convert an older vehicle that has been running on normal diesel, the surfactant properties of B100 can shift old residues in the tank and pipes, which then go on to clog up filters and other components. However, Posnett says there are examples of fleets that have been more reliable when running on B100, because of problems that arise with blending. “You don’t necessarily know what your diesel’s like – and blending these two different components introduces unknowns,” he reasons. “We test all the way along and all our fuel is distilled. We know it’s a very high-grade fuel, even compared to any sort of refinery diesel.”

As an example of how B100 can work, Posnett cites one fleet of Scania buses. “The ones running on B100 had not missed a beat and were more reliable than the ones running on B7.”

One of the reasons, he thinks, was the quality of the fuel storage. “The fuel tank [had] a good heating system, which was reliable and had a good desiccation filter. So the air in the tank is always kept dry – [because] water can affect biodiesel to a larger extent than diesel. We make sure it’s kept dry, then it works really well.”


EN590 Retail diesel or B7 — conventional ultra low sulphur diesel plus up to 7% FAME/biodiesel

EN16734 B10 – conventional diesel plus up to 10% FAME/biodiesel

EN16709 B20/30 – conventional diesel plus up to 20%/30% FAME/biodiesel

EN14214 B100 – 100% FAME/biodiesel

EN15940 Paraffinic diesel including


Related content