The UK's LARGEST inland waterways publication

You, your boat and your fuel

A note on red diesel

 

Red diesel is the duty-reduced fuel sold exclusively for non-road use. Its primary applications are the agriculture and construction sectors but a large quantity is also supplied to the inland waterways market. Sea-going vessels are not obliged to use red diesel and usual burn another class of gas oil (class D), which retains its higher (1000ppm) sulphur content, or entirely different grades of fuel governed by their own specifications.

 

What the changes mean to your boat

 

Sulphur reduction

 

Sulphur occurs naturally in crude oils and unless specifically removed by a dedicated refinery process will be present in fuel sold on the open market. Removing such a significant amount of sulphur from red diesel has two main effects: (a) the natural lubricating properties of a fuel are lost and must be replaced if problems are not to be encountered with fuel pumps or fuel injectors; and (b) the natural biocidal action of a fuel is lost and if problems with ‘bug’ growth are to be avoided then a fuel biocide needs to be added routinely.

 

Increase in the biodiesel content

 

Biodiesel is fuel derived from vegetable oils and is also known by the chemical name fatty acid methyl ester (FAME). Its characteristics are slightly different to that of petroleum diesel and this can have a noticeable effect on the operation of your boat:

 

·         Significant increase in the fuel’s propensity to pick up water – this lowers its calorific value, can cause filter plugging and promote microbial growth (‘bugs’)

·         Decreased fuel stability – the shelf life of FAME-containing fuel is much reduced: fuel ages more quickly resulting in discolouration and gum formation. This could be a problem for seasonally used vehicles.

·         ‘Waxes’ more readily at a higher temperature

·         The potential exists for deposits to form within fuel injectors and on cylinder walls

 

So, what fuel is available and what are you receiving?

 

Red diesel (A2 gas oil) has been compliant with the latest specifications since about November last year.  What is sold as red diesel now, however, could be a blend of various fuels from different sources:

 

·         Some red diesel fuel supply will be manufactured to specification

·         For a variety of reasons some red diesel now in the supply pool is road diesel (EN590) with red dye added. This is good, as you, the boat owner, are getting a higher quality of fuel.  But again, road diesel can contain up to 7% FAME and will contain an average of 5%, so the inherent problems outlined above still exist.

·         Some suppliers maintain that FAME-free gas oil is readily available and that is what they are supplying. These claims have to be taken at face value but we would make the following comments:

o        Obtain a written guarantee of FAME-free fuel from your supplier or have them demonstrate the supply chain to you

o        The total volume of gas oil being used in the UK far outweighs the volume of fuel that those terminals and supply points that claim to be FAME-free are able to supply. Couple this with production limitations on the UK’s refineries and the rapidly rising quantities of imported fuel, which will contain FAME, and the likelihood is that a significant amount red diesel in the pool has FAME in it

o        Due to co-mingling effects within the fuel distribution network, unless you are absolutely certain assume that fuel supplied to you contains FAME

 

How to mitigate the situation

 

Although their priorities are slightly different and they are governed by legal requirements surrounding emissions quality, most tractor manufacturers, for example, now advocate the use of a fuel additive or additives when using red diesel in their equipment. Boat owners should consider a similar practice not least to guard against bug growth and premature fuel ageing. Fuel additives, either discretely or as a single bottle package can:

 

boost cetane number – smoother power delivery, helps with combustion, reduces ‘black smoke’

enhance lubricity – compensates for sulphur removal

preserve a fuel – increase its longevity and improve its oxidation stability, including FAME

prevent water pick-up – inhibits the formation of emulsions and ‘rag’ layers

improve a fuel’s low temperature properties – to meet or exceed fuel specs

kill and control microbial activity – increased risk as FAME increases

remove deposits (service tool) – instant power/torque restoration

prevent deposit formation – enhanced overall fuel quality

 

In addition, good housekeeping around the fuel tank is always a good idea and removing water from the tank regularly, changing fuel filters and increasing fuel turnover are all good practices.

 © Fuel Additive Science Technologies Limited 2011

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