Notes on Biodiesel, Bioethanol and BioGas
There are two main types of biofuel - biodiesel and bioethanol.
There are other types too, but they are relatively 'niche products - for example, biogas.
Biodiesel
- Generally used as an additive (up to five per cent) in fossil diesel. High quality biodiesel (note: there is an EU quality standard - EN14214) can be used in blends of up to five per cent in any diesel vehicle, with no adverse impacts. It can be used in higher blends and even neat, but this would currently invalidate many vehicle warranties and can require special modifications to engine components. Fuel standards could allow more than five per cent in the future: this is something the EU is looking into.
- Generally produced from 'oily' crops like rapeseed, sunflower, palm etc, or from recovered used cooking oil. Because these oils are more viscous than fossil diesel, they need some processing (known as 'esterification') to make them less likely to gum up fuel pumps etc.
- Usually two to three times more expensive to produce than fossil diesel but the differential fluctuates widely (current high oil prices mean wholesale (ie pre-tax) diesel is now approaching 30p per litre, biodiesel around 45p per litre). The exception is biodiesel from recovered cooking oil, which is cheap, but often of low quality.
- Currently produced in low volumes by a cottage industry in the UK, mostly from used cooking oil, and imported from, for example, Germany. But a number of new plants are getting off the ground (eg the Argent plant in Motherwell, which is producing 50 million litres a year).
- Available as a per cent blend at about 100 filling stations in the UK, including a number of Tesco stores in SE England.
Bioethanol
- Generally used as an additive (up to five per cent) in petrol. As with biodiesel, it can be used at higher blends (eg in Brazil virtually all cars run on 30 per cent or higher blends), but not without some (relatively cheap) vehicle modifications. Ford and others are already producing 'E85 flex-fuel vehicles' which can run on any petrol containing anything from zero to 85 per cent ethanol.
- Generally produced from starchy crops like wheat, sugarbeet, sugar cane etc. As with potable alcohol, it can be made from virtually any organic substance (grass, wood, green bits of municipal solid waste), but the technologies for doing so are not proven at commercial scale.
- More expensive to produce than petrol, especially from crops like wheat, but countries like Brazil can produce it very efficiently from sugar cane (prices as low as 7p per litre before import tariffs, which are currently around 20p per litre).
- Produced in huge volumes by Brazil and the US. Roughly three per cent of all US gasoline sales were bioethanol in 2005. But not produced at all in the UK (although some companies, including British Sugar, have announced plans to do so).
- Starting to be used in UK petrol. In March 2006, bioethanol sales amounted to some 8 million litres (about 0.4 per cent of total UK petrol sales).
Biogas
- Just like compressed natural gas (CNG), except that it is generally produced by collecting the methane which is naturally emitted from landfill sites or other forms of rotting vegetation.
- Only suitable for use in CNG-powered vehicles (of which there are only 500 or so in the UK).
