Bio-diesel is a fuel with attributes showing  remarkable similarities to ordinary diesel but it is made out of renewable plant oils or animal fats. The oils used tend in the main to be rapeseed oil, sunflower oil, palm oil or soya bean oil.

To obtain a fuel of high quality the oils need to undergo a chemical reaction with methanol resulting in a methyl ester. An example of this is rape-methyl-ester (RME). Bio-diesel is non-toxic, contains low levels of sulphur and aromatics and is bio-degradable.

The combustion properties of diesel and bio-diesel are so similar that normal diesel engines can operate on bio-diesel with only minor technical changes.

No technical changes are required to engines if up to 5% bio-diesel is added to normal diesel. With a mixture greater than 5% the risk exists that the rubber used for gaskets and fuel hoses may deteriorate.

It is perhaps worthwhile mentioning that bio-diesel sold at petrol stations contains less than 5% plant/animal oil and in fact consists of mineral oil for 95%.

The following attributes  are of relevance:

	Petrol (EN228)	Diesel (EN590)	Bio-diesel
Specific gravity	720-775 kg/m3	820-845 kg/m3	875 kg/ m3
Sulphur content (2005)	Max. 50ppm	Max. 50ppm	Circa 20 times lower than traditional diesel
Sulphur content (2009)	Max. 10ppm	Max 10ppm
Aromatic compounds	Max 35%	n.a.
Octane number*	Min.95	n.a.
Cetane number*	n.a.	Min. 49	48
Freeze resistance	n.a.	At least -20°C	-12°C
Heating power	32,025 kJ/liter	35,700 kJ/liter	32,500 kJ/liter

The difference in heating power between normal diesel and bio-diesel leads to a reduction in engine power. By treating bio-diesel with Dipetane this reduction does not take place (>35,700kj/liter).

The addition of Dipetane to bio-diesel naturally also ensures reduced fuel consumption as found with normal diesel.