What is Biodiesel?
Biodiesel is a fuel derived from a process known as transesterification whereby the oils produced by oliferous plants (typically in the UK we are talking about rapeseed or sunflower oil as the major sustainable sources) are combined under the correct conditions with a methoxide catalyst to cause separation of the oil into usable fuel oil and glycerol by-product.
In layman's terms, transesterification can be thought of as the process of converting one ester into another ester. An ester is a chemical combination of fatty acids attached to alcohol. Animal and vegetable fats, oils and biodiesel are examples of esters.
If
both vegetable oil and biodiesel are esters, why is it not practical to use
vegetable oil in a diesel engine instead of going through the process of creating
biodiesel? In other words, why is there a need for transesterification?
The answer lies in the difference in viscosity, that is the thickness or resistance to flow, between the two esters. Vegetable oil has too high a viscosity for diesel engines, designed for fossil diesel, to cope with. This is because the constituent alcohol molecule of the vegetable oil ester, glycerol, is very large. Hence we need to reduce the thickness of the vegetable oil by replacing the glycerol with an alcohol that is smaller in molecular size, methanol, and thus create a different ester.
This is what the process of transesterification allows us to do. By converting the vegetable oil ester into the biodiesel ester, it separates the larger glycerol molecules from the fatty acids within the vegetable oil. The methanol combines with the fatty acids producing smaller methyl esters thus creating the more free flowing biodiesel.
Given that transesterification is the process of converting one ester into another, it has to be noted that the process is reversible. This point is highlighted in the section on How to make Biodiesel.
Benefits of Using Biodiesel
As we all know, the fossil fuels are a finite resource and will soar in price as the world's resources dwindle. Alternatives for road transport are not being given the impetus and investment that they deserve (hydrogen fuel cell technology is a prime example) and this represents a tremendous opportunity for the biodiesel industry to solve several problems with a series of simple strokes.
Firstly, biodiesel is completely sustainable. It is carbon neutral in that it releases the same amount of carbon dioxide into the atmosphere as it took out in the first place during the growth cycle. There are other major benefits in the use of biodiesel.
- 3 tonnes less carbon dioxide are liberated from storage in fossilised hydrocarbons
- 180g less sulphur oxides are produced - virtually zero emissions
- 20kg less nitrous oxides are produced
- 50kg less carbon monoxide is produced
- 40kg less particulates are produced - and biodiesel particulate emissions are NON-carcinogenic
Additionally, biodiesel fuel is 98% biodegradeable within 21 days.
Economically, there are also huge potential long term advantages in terms of producing cash-crops for farmers. Such utilisation of set aside and under-utilised land could increase agricultural sector employment by one person per 20 hectares dedicated to energy crops.
Professionally manufactured biodiesel is monitored by Customs and Excise as well as the Environment Agency. It conforms to DIN 51606 and EN 14214 and so is guaranteed to be effective in any diesel engine without modification.
Summary of the Benefits of Using Biodiesel
- Better lubricity resulting in longer life for diesel engines
- Sustainable production
- Significantly kinder to the environment
- Improved fuel economy - up 8%
- Much lower fuel duty - around 20 pence per litre cheaper than fossil diesel
For More Details on any aspect of Biodiesel
Please complete the following enquiry form and one of our staff we will contact you to answer queries you may have regarding biodiesel.
Ensure that you enter a valid email address and telephone number otherwise we cannot respond to your query. * denotes a required field.
