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29 October 2019

Gas Oil, FAME content and the RTFO - our advice to consumers

The article provides information about recent changes to the Renewable Transport Fuel Obligation (RTFO) and the consequential impact on levels of bio components within liquid fuels. It also includes guidance for good housekeeping with regards to the storage of fuel.

The Renewable Transport Fuel Obligation (RTFO)

The Renewable Transport Fuel Obligation (RTFO) is one of the Government's main policies for reducing greenhouse gas emissions from fuel supplied for use in: (i) road vehicles, and (ii) non-road mobile machinery (including tractors). The Obligation came into effect in 2008, and specified that a percentage of the fuel used in these applications must come from sustainable and renewable resources.

From 1st January 2019 the overall percentage of these fuels that must be derived from renewable sources increased to 8.50%. It will now continue to increase, up to 12.40% overall by 2032.

The responsibility to meet these targets lies with the suppliers, although how they go about meeting the obligation is up to them. Until this point, suppliers have been meeting the targets in three main ways: paying a fixed sum for each litre of fuel sold in order to 'buy-out' of their obligation; introducing ethanol within blends of unleaded petrol; and adding Fatty Acid Methyl Ester (FAME) to gas oil and road diesel. FAME is the generic name given to recycled cooking oils, tallow (animal fats), plant oils and other renewables which have been converted to long chain molecules suitable for use as biodiesel – a diesel replacement fuel.

British Fuel Standards and FAME

The sale and provision of liquid fuels in the UK is governed by British Standards, which define a range of physical properties that fuel must meet, with maximum and/or minimum limits across a range of parameters.

One of these parameters for both Ultra-Low Sulphur Gas Oil and for Road Diesel is the level of FAME permitted, expressed as a maximum %. In 2004, the British Standard for Road Diesel (BS EN590) changed to permit FAME content up to 5%, before increasing in 2009 to the current level of 7%.

FAME has therefore been present in road diesel since 2004, in varying quantities up to these maximum levels.

However, while the specification for Gas Oil (BS EN2869) has also permitted the inclusion of FAME since 2006, in practice ULS Gas Oil has rarely contained FAME in levels above 0.5% - 1%. But, in the face of more challenging RTFO obligations, suppliers are now beginning to add FAME to their Ultra Low Sulphur Gas Oil blends, up to the levels permitted by the BS standards.

Potential issues

While the fuel supplied by these suppliers meets British Standards, the increase in FAME content up to the levels permitted could cause issues for end users who are unprepared, and unaware of the potential impact of improper oil storage.

Unlike diesel or gas oil, FAME is hygroscopic which means it attracts and holds onto water. FAME is also a powerful solvent, with good detergency properties – and can effectively act like a ‘paint stripper’. As a result, and the experience within the automotive sector and oil industry regarding the use of FAME in diesel, the following issues could occur:

• Material incompatibility (many common rubbers, plastics and surface coatings can degrade from contact with fuels containing FAME).
• Residual deposits causing clogged filters.
• Water uptake - with enhanced potential for mould, bacteria and algae growth.
• Decreased fuel stability / decreased fuel shelf life. Discolouration, gum formation and separation of crude-derived and biodiesel elements may occur.
• Reduced cold-weather performance. The frequency of waxing issues may increase

Our advice

Our advice to all gas oil and diesel consumers, along with that of the UK and Ireland Fuel Distributors Association (UKIFDA, our trade body), is as follows:

• Carry out regular tank checks, to check the general condition of the tank, and the appearance of any damage or irregularities. At Watson Fuels, our drivers carry out tank inspections before each delivery. And, should you be in need of a new fuel tank, please contact your local depot or fuel account manager, who can talk you through the range of static and transportable fuel tanks that we recommend.
• Limit the storage time of gas oil, and keep tanks topped up to reduce air flow, which can attract moisture.
• If you notice any water, dirt, mould or growth in the tank or fuel, seek specialist help. Watson Fuels can advise on appropriate specialists to provide remedial action.
• Check your tank immediately after each delivery and check and examine filters, pipework and seals on a regular basis. Replace filters after every two-to-three deliveries.

UKIFDA also advise that “one of the biggest steps users can take is to ensure all fuel is bought from a reputable distributor, ideally from a member of UKIFDA”. Watson Fuels are proud members of UKIFDA. As a result, you can be sure that all fuels provided by Watson Fuels will always be sourced from the highest quality UK-based suppliers, and will always meet British Standards

If you have a concern regarding your storage tank, or wish to discuss the above further, please contact your local depot or fuel account manager in the first instance


UKIFDA (2019) Being Prepared for FAME
Department for Transport (2019) RTFO Guidance Part One: Process Guidance 2019