HMRC internal manual

Biofuels and Fuel Substitutes Assurance

Structure of the Industry: Production methods



is a chemical process, which utilises an alcohol inreaction with vegetable oil, the reaction of which is accelerated using a catalyst, e.g.caustic soda or an acid. This produces both biodiesel (fatty acid methyl ester or‘FAME’) and crude glycerol.

Filtration and blending predominately involves the use of waste or UCO but can also use new or SVO – rapeseed oil is particularly suitable for conversion. Oil is filtered using a succession of graduated filters to remove impurities and in some cases to “segregate” larger fat molecules from smaller fat molecules. The resulting clean and/or thinned vegetable oil may be used to produce biodiesel.

NB. Whatever method of production is used it is the responsibility of the producer to have the finished fuel tested. If the finished fuel meets the fiscal specification it is entitled to the currently published biodiesel duty rate.


Bioblend may only be produced in a tax warehouse. This is because it is defined in law as the blending of biodiesel with non-duty paid heavy mineral oil to produce a fuel which may be used in place of diesel. Bioblend is produced by adding a small proportion of biodiesel (usually 5%) to diesel (95%). Bioblend may be produced using different proportions. The current European standard for diesel (EN 590) allows for a maximum of 5%biodiesel. However, there are no restrictions set by HMRC and there are no restrictions on mixing duty paid fuels.


Bioethanol is a liquid consisting of ethanol (ethyl alcohol) which has been produced from biomass. In effect the production of bioethanol is no different from the production of other alcohols and involves the processing, fermentation and distillation of intermediate products derived from raw materials, which may be defined or classified as biomass. The resultant alcohol must be denatured for use in the manufacture of bioethanol. HMRC have produced an agreed formulation for the denaturant to be used in the production of bioethanol. Although bioethanol is capable of being used as a fuel, because of its effect on petrol engines if used on its own, it is most commonly used to produce bioethanol blend.

Bioethanol blend

Bioethanol blend may only be produced in a tax warehouse. This is because it involves the blending of bioethanol with non-duty paid light mineral oil to produce a fuel which may be used in place of petrol as a road fuel.

An alternative means of producing bioethanol blend involves the use of EthylTertiary Butyl Ether (ETBE). ETBE is produced by mixing ethanol and iso-butylene and reacting them with heat over a catalyst. ETBE can then be blended with petrol or burnt in an engine for use as a road fuel. From 1st of January 2005, the blend of ETBE and petrol may be treated as bioethanol blend under section 6AE of the Hydrocarbon Oil Duties Act. To benefit from any published reduced rate of excise duty and to qualify as biofuel, ETBE must have been sourced from biomass.