ABOUT BIODIESEL

What is it?
Biodiesel or Methyl Ester as it's also known is a clean burning renewable fuel made predominantly from vegetable oils. Its physical and chemical properties are very similar to mineral diesel, so it can be used either as a blend with mineral diesel or in its pure form.

How is it being used?
Pure Biodiesel (referred to as B100) is manufactured to a European Standard EN14214. It is the grade used by commercial vehicle and bus operators across Germany.

A blend of 20% Biodiesel manufactured to the US Standard ASTM D 6751 and mixed with mineral diesel (referred to as B20) is the fuel preferred by American truck and bus operators. The B20 blend currently provides commercial vehicle operators in the US with the optimum cost vs benefit balance.

Biodiesel in a 5% blend with mineral diesel is now allowed within the EN590 mineral diesel specification across Europe and is the grade most readily available in the UK today, particularly in the retail network.

Please note that the benefits, storage and handling considerations and other precautionary measures covered in this guidance note relate to the use of pure Biodiesel (B100). These effects are diluted with the use of blends such as B20. A 5% blend can be handled and used as normal mineral diesel.

Why should I use Biodiesel?

Better ignition and combustion
Biodiesel has better ignition and combustion characteristics (due to a higher Cetane Index), which allows the engine to run more smoothly with less of the "knocking" sounds typical of diesel engines.

Reduces exhaust emissions
Biodiesel substantially reduces exhaust emissions (unburned hydrocarbons, carbon monoxide and particulate matter). It contains naturally occurring oxygen, which enables the fuel to burn more completely and all but eliminate the black smoke normally associated with diesel engines. There may be a slight increase in NOx emissions but this is dependant on the engine type and its operating environment.

Improves lubricity & reduces engine wear
Biodiesel has very good intrinsic lubrication properties. Even blends as low as B1 (1% in ULSD) can improve the lubricity in highly de-sulphurised mineral diesel. In engines approved for operation with B100 Biodiesel, the engine wear is significantly reduced.

Fuel consumption
Although there may be a slight increase in fuel consumption when using B100, the effects are mitigated by the improved ignition and combustion qualities of Biodiesel. B20 on the other hand has no effect on fuel consumption; some operators claiming it actually improves fuel consumption.

Safer, biodegradable and non toxic
Biodiesel has a higher flashpoint than mineral diesel. It is also readily biodegradable and non toxic, which makes it a safer and more environmentally friendly fuel to handle, particularly in sensitive areas.

Sulphur free
Biodiesel is naturally free of sulphur and so produces no sulphur dioxide, considered to be one of the main precursors to acid rain.

Carbon dioxide neutral
Biodiesel is made from renewable resources, which means it reduces the contribution of carbon dioxide (one of the main greenhouse gases) to the atmosphere.

What about quality issues?
Biodiesel, like its mineral diesel counterpart, has certain characteristics that may be affected either during manufacturing, or subsequent storing and handling.

A European Standard: EN14214 has been adopted throughout Europe for the manufacture of Biodiesel to ensure it consistently meets the strict quality parameters established. This is the Standard that all reputable manufacturers and suppliers will meet up to the point of sale.

Like all fuels however, the continuing quality of the Biodiesel is dependant on steps taken to safeguard it during storing and handling, right up to the moment it is combusted in the engine.

Will it invalidate my engine warranty?
All motor vehicle manufacturers have accepted that a 5% biodiesel blend in EN590 may be used in all diesel engines regardless of age or mileage.

In addition, a number of motor vehicle manufacturers such as Mercedes, MAN and DAF Trucks, recognising a growing interest in B20 (20% Biodiesel in mineral diesel) and B100 (pure Biodiesel), have carried out tests to check the suitability of Biodiesel for use in their engines.

Consequently, positions adopted by the vehicle manufacturers vary widely with approvals for Biodiesel ranging from 5% in DERV all the way through to full approval for B100. For a vehicle operator to be certain that a particular vehicle or engine type is suitable for a B20 blend or B100 Biodiesel, the vehicle manufacturer should be consulted directly.

Although a vehicle may be suitable to run on B20 or B100, there are still certain considerations that must be taken into account before using Biodiesel for the first time.

Storing and handling pure (B100) Biodiesel
The same properties which give rise to the benefits of Biodiesel such as biodegradability and cleaner running engines are those which need to be considered for storage and handling.

Cleaning properties
As a mild solvent, Biodiesel has excellent cleaning properties. It will loosen and dissolve any accumulated sediment left by mineral diesel in fuel tanks, fuel lines and fuel systems whether in bulk storage or in the vehicle itself. The extent of sediment build up will depend on the age and condition of the storage tank or vehicle, but fuel filters are likely to clog up with these mineral diesel deposits if the fuel tanks and systems are not cleaned before using Biodiesel.

These same cleaning qualities may affect paintwork and the adhesives fixing graphics or signs to a vehicle or tank, so if Biodiesel is spilled, it must be wiped up immediately.

Compatibility with other materials
In older vehicles, Biodiesel may not be compatible with certain polymers and rubbers found in hoses and gaskets that typically form part of the fuel system. Materials such as Nitrile, Fluorosilicon, Polypropylene, Polyvinyl, Tygon and natural Rubber may soften and degrade. Any sediment formation resulting from the degradation of these materials could lead to blocked filters, damaged fuel pumps and so on.

Biodiesel is however compatible with many seals, gaskets and adhesives in use today. Materials such as Teflon, Nylon 6/6, Viton A401-C, Viton GFLT and Fluorinated Rubber are resistant to the effects of Biodiesel and are standard fittings in many approved vehicles. The vehicle operator should check with the vehicle manufacturer to be certain.

Fuel stability and quality maintenance
As a biodegradable material, Biodiesel will age faster than mineral diesel and so current best practice is not to store it for any longer than 6 months.

Biodiesel is affected by water, oxygen and direct sunlight, so any storage tank previously used for mineral diesel should be cleaned thoroughly to remove any sediment and water. Tanks for Biodiesel storage should be selected to minimise water contamination, air contact and exposure to direct sunlight.

As with mineral diesel, Biodiesel is produced to meet summer or winter specifications. If a summer grade is used incorrectly in the winter months, and the air temperature drops to ~5 deg.C, Biodiesel is likely to become viscous with reduced flow rate qualities. This may cause problems with pumping, cold starting and increased stress in fuel systems and injectors. Consequently, the correct specification of Biodiesel should be used at all times.

Can I use Biodiesel in my vehicle right now?
Providing the following precautionary steps are taken, Biodiesel can be used straight away.

1) Check with the vehicle manufacturer to see if the vehicle or engine type has been approved to run on Biodiesel. Certain manufacturers such as Mercedes, MAN and DAF Trucks have granted full approval for the use of B100 in their vehicles. However, the releases only apply to vehicles of a certain age, engine type or chassis number, so it is important to check carefully.

2) Make sure the vehicle tank is clean and free from loose rust particles, sediment and water. If not, flush and drain the tank with either mineral diesel or Biodiesel. The dirty fuel must be disposed of in accordance with the appropriate regulations.

3) Depending on the age and mileage of the vehicle, and the build up of mineral diesel sediment in the fuel system itself, the frequency of the following fuel filter changes may need to be increased to ensure the fuel system is thoroughly cleaned.

a. After the first full tank of Biodiesel, change the vehicle fuel filter. (Note: For older trucks, it is suggested that a spare fuel filter is kept in the vehicle, as it may need changing anywhere between 100 and 300kms).
b. After the second full tank of Biodiesel, change the fuel filter again.
c. After refuelling for a third time, the fuel filter will need to be changed anywhere between 1,000 and 5,000kms.
d. Thereafter, revert to manufacturers recommended servicing intervals for fuel filter changes.

Please note, every vehicle and its operating conditions will differ, so the above fuel filter change intervals are only given as a guide. There are no standard procedures for this activity, so each truck will need to be monitored individually to ensure fuel filters are changed as appropriate.

4) It is considered to be good practice to keep the vehicle fuel tank topped up, particularly if the vehicle is left standing for any length of time. This will help to prevent the build up of moisture in the tank through condensation. Note…the 6 month limit still applies.

5) As with all other fuels, Biodiesel is manufactured and supplied to a European Standard EN14214. Where a vehicle operator has used Biodiesel incorrectly and the fuel itself is found to be within specification, the operator must retain responsibility for any loss or damage caused to the vehicle.