Biodiesel

Not all vehicles are compatible with Biodiesel.

Vehicle owners should confirm with the manufacturer if their vehicle is suitable for use with Biodiesel.

Biodiesel blended fuels need to be properly refined and produced to meet high quality standards and it is essential that all aspects of legislated national fuel quality standards for diesel and vehicle manufacturer recommendations are maintained at all times and locations.

FCAI's position regarding biodiesel is summarised as follows:

  • Fatty Acid Methyl Esters (FAME) including vegetable derived esters (VDE) are generally acceptable when blended with conventional diesel fuel up to 5% (vol/vol). The FAME(s) on which the biodiesel is based must comply with either EN14214 or ASTM D6751 standards.
  • The diesel to which this FAME biodiesel is blended must conform to EN590.
  • The resultant diesel/biodiesel blend must meet the specifications in the Fuel Quality Standards Act when it is finalised.
  • FCAI members will not warrant damage caused by using biodiesel blends greater than B5, unless such use is sanctioned by a particular manufacturer.
  • FCAI does not generally support use of 100% biodiesel fuel (B100).
  • FCAI does not generally support use of 100% biodiesel fuel (B100).

FCAI members do not support the use of E-Diesel (Diesohol) and will not warrant damage caused by its use.

It should also be remembered that the type of feedstock has a significant influence on the oxidation stability and cold flow properties of the resultant biodiesel. Most feedstock in the US is soybean with a relatively high degree of unsaturation, hence relatively poor oxidative stability but good cold flow properties. In Europe rapeseed is the main source of biodiesel. This has better oxidative stability whilst maintaining good cold flow properties. In many parts of South East Asia, particularly Malaysia, palm oil is used for producing biodiesel. Crude palm oil has a high level of saturation which imparts good oxidative stability but poorer cold flow properties. Biodiesel made from animal fats (tallow), has good oxidative stability but poor cold flow properties.

The FAME components have a negative influence on engine oil properties in the biodiesel blend. Because of the very high boiling points of FAME, there will always be dilution of engine oil due to the presence of esters. The consequences are a decrease of lubricity, reduction of oil service intervals and even drivability problems or engine damage in extreme cases.

EXTRACT FROM THE WORLD WIDE FUEL CHARTER

The recommendations in the World Wide Fuel Charter (WWFC) are particularly relevant in Australia where diesel engine technology comes entirely from overseas sources. The following is an extract from the WWFC:

Fatty Acid Methyl Esters (FAME), frequently termed biodiesel, increasingly are being used to extend or replace diesel fuel. Such use has been driven largely by efforts in many nations to exploit agricultural produce and/or to reduce dependency on petroleum-based products.

Several different oils may be used to make biodiesel, for example, rapeseed, sunflower, palm, soy, cooking oils, animal fats and others. These oils must be reacted with an alcohol to form ester compounds before they can be used as biodiesel fuel. Unprocessed vegetable oils, animal fats and non-esterified fatty acids are not acceptable as transportation fuels due to their very low cetane, inappropriate cold flow properties, high injector fouling tendency and high kinematic viscosity level. Historically, methanol has been the alcohol most used to esterify the fatty acids, and the resultant product is called fatty acid methyl ester (FAME). Research is underway to enable the use of ethanol as the reactant alcohol, in which case the product is called fatty acid ethyl ester (FAEE).

The European standards organisation, CEN, has published an automotive FAME standard (EN 14214) that establishes specifications for biodiesel use as either: (i) a final fuel in engines designed or adapted for biodiesel use; or (ii) a blendstock for conventional diesel fuel. Similarly, ASTM International has established specifications for neat biodiesel (ASTM D6751) but only for use as a blending component, not as a final fuel.

Generally, biodiesel is believed to enhance the lubricity of conventional diesel fuel and reduce exhaust gas particulate matter. Also, the production and use of biodiesel fuel is reported to lower carbon emissions on a source to wheel basis, compared to conventional diesel.

At the same time, engine and auto manufacturers have concerns about introducing biodiesel into the marketplace, especially at higher levels. Specifically:

  • Biodiesel may be less stable than conventional diesel fuel, so precautions are needed to avoid problems linked to the presence of oxidation products in the fuel. Some fuel injection equiupment data suggest such problems may be exacerbated when biodiesel is blended iwth ultra-low sulphur diesel fuels.
  • Biodiesel requires special care at low temperatures to avoid an excessive rise in viscosity and loss of fluidity. Additives may be required to alleviate these problems.
  • Being hygroscopic, biodisesl fuels require special handling to prevent high water content and the consequent risk of corrosion and microbial growth.
  • Deposit information in the fuel injection system may be higher with biodiesel blends than with conventional diesel fuel, so detergent additive treatments are advised.
  • Biodiesel may negatively impact natural and nitrile rubber seasl in fuel systems. Also, metals such as brass, bronze, cooper, lead and zinc may oxidize from contact iwht biodiesel, thereby creating sediments. Transitioning from conventional diesel fuel to biodiesel blends may significantly increase tank sediments due to biodiesel's higher polarity, and these sediments may plug fuel filters. Thus, fuel system parts must be specially chosen for their compatibility wiht biodiesel.
  • Net (100%) biodiesel fuel and high concentration biodiesel blends have demonstrated an increase in NOx eshaust emission levels.
  • Biodiesel fuel that comes into contact with the vehicle's shell may be able to dissolve the paint coatings used to protect external surfaces."