Biodiesel in Gas Oil

Background

New European Directives for Renewable Energy and Fuel Quality will require changes to the
composition of gas oil in January 2011. Gas oil intended for use in non-road mobile
machinery [tractors, etc.] will have to have a sulphur content of 10ppm or less and contain
up to 7% by volume of biodiesel [Fatty Acid Methyl Ester {FAME}]. These changes are
reflected in a revised edition of the British Standard for gas oil [BS 2869:2010] and fuel to the
new specification will become available in late 2010. The existence of a new grade of gas oil
with a significant biodiesel content creates increased possibilities of cross-contamination,
wrong product delivery or delivered product not declared as containing biodiesel [a
requirement of the revised British Standard].

Because of limitations in the production and supply structure, only one type of gas oil
may be widely available and this will inevitably be the non-road mobile machinery
[NRMM] grade with a significant biodiesel content.

Potential problems

There is considerable experience with automotive diesel containing biodiesel and some
published advice on handling this is available from the Department for Transport and major
oil companies; much of this information has some relevance to gas oil containing biodiesel
used in other applications, but is not sufficiently specific to these. Biodiesel is a powerful
solvent, with good detergency properties, it is an effective paint stripper and will take up
water from the surroundings; problems that may arise, caused by the presence of biodiesel
in gas oil, can include: ICOM Energy Association – Biodiesel in Gas Oil Statement August 2010

• Material incompatibility - many common rubbers, plastics and surface coatings will
degrade from contact with biodiesel
• Residual deposit flushing, causing clogged filters, etc.
• Water uptake, with enhanced potential for mould growth, producing solid matter and
acids
• Fuel stability - biodiesel can degrade over time by oxidation and hydrolysis
• Cold flow, waxing and precipitation problems
• Burner and component tolerance of biodiesel and/or its degradation products 

Preparation

An initial check on tank condition and suitability for biodiesel-containing fuel should be
carried out, this should include the material(s) of construction, age, condition and
appearance, damaged areas, surface coating{s}, etc and any obvious deficiencies should be
remedied. The tank should be cleaned effectively internally and water & solid deposits or
mould growth removed as efficiently as possible [this may require a specialised tank
cleaning service]. The materials used for pipes, tubes, seals, etc. should be investigated for
biodiesel compatibility and, if necessary, replaced with a suitable biodiesel-resistant
alternative; the security of joints in the system should also be examined, ensuring that
biodiesel-compatible sealing materials and compounds have been used. Check the material
& condition of all filters and replace if necessary [this will be an ongoing requirement as
biodiesel-containing fuel is introduced to the system]. Ensure that pump seals are made from
biodiesel-resistant material [preferably a fluoroelastomer].

Housekeeping

The routine checks and actions set out in the Oil Care Campaign booklet, “Get to know your
oil tank” will be required more frequently for biodiesel-containing fuel due to its strong
detergency, solvent and hygroscopic properties compared with those of purely hydrocarbon
fuels. Tanks should be frequently examined for signs of degradation in structure, material or
coatings and for any other apparent weaknesses. Regular checks with prompt and
appropriate removal and remedial action, must be undertaken for any water, dirt, mould
growth, etc. present in the tank. Filters should be examined and, if necessary, changed,
especially following the first deliveries of biodiesel-containing fuel. Pipework, seals, pumps
and other components must be checked frequently for signs of actual, or potential, oil leaks
and remedial work undertaken immediately. Burner components should be examined
regularly for signs of degradation or deposit formation and remedial action initiated, if
necessary.

Additional Information:

Equipment manufacturers should ensure that their service engineers and agents are made
aware of the forthcoming changes in order to assess any likely issues and make any
necessary updates to their systems prior to class D gas oil with a percentage of biodiesel
being introduced.

10/2010