Greener for Life

The raw material, vegetable oil, can be produced from many different plant sources around the world and it is possible to use any of these vegetable oils, both freshly expelled or extracted and as recycled used cooking oil, for the manufacture of biodiesel.

Within the UK the main source of new oil is from Oil Seed Rape, the plant which we are all familiar with, seen as bright yellow fields every spring. It is possible to use Sunflower as well but the Rape plant is the best suited for the UK climate.

When harvested Rape will produce around 3.5 tonnes of seed per hectare. It has a natural oil content of between 40 – 45% and it is possible to expel most of this with a simple pressing or chemical process.

Pressed Oil Seed Rape Cake

Once pressed the resulting rape seed meal will still have an oil content of 14% but more importantly, it has a protein level of around 33% which make it a valuable animal feed for the UK livestock farmer.

Animals need protein within their diets to produce either milk or meat. By using home grown rape seed protein farmers are able to reduce some of the reliance on imported proteins such as soya. The soya has to be shipped around the world from countries such as Brazil or Argentina . By reducing some of this requirement it will obviously help to lesson our impact on the environment, on deforestation and ultimately, on climate change.

Vegetable Oil from Rape Seed

Pure pressed Rape Oil is a very pure product. It has had no chemicals used in its extraction, pressure being the only process. It is therefore a very important oil for cooking within the UK. If grown, pressed and used locally, the Rape oil will be beneficial to the environment by reducing fuel and transport costs.

At the end of the cooking oil’s life it is possible to collect and recycle it, put it through the biodiesel process and turn it in to road fuel.

Biodiesel from Rape Oil

It is not possible to use pure vegetable oil for conventional diesel engines without some technical modifications. Pure vegetable oil is also ineligible for any duty dispensation where as biodiesel is eligible and therefore offers a financial incentive to be used.

By using a chemical process known as Transesterification, it is possible to change the structure of the vegetable oil to make it suitable for use in conventional diesel engines giving advantages over conventional fossil derived diesel. All Biodiesel produced has to meet a European standard of quality (EN 14214) to ensure its performance and safety.

Biodiesel has been used as road fuel in cars, buses and trucks as well as for boats, tractors and even trains for several years. Long term experience has been gained with using this fuel and some trucks have reached a total of more than 2 million kilometres running on100% pure biodiesel.

Until now Biodiesel has mainly been used in other European countries which have had political support but a change in European law is forcing all countries to encourage its use and the UK is well placed to establish Biodiesel as a main line fuel.

Transesterification

The Transesterification is done using the classical alkali-process. Potassium Hydroxide and Methanol are added to the pure rape oil in a reactor chamber. Glycerine is produced as a by-product which precipitates and is then separated off. This can be used for the production of Biogas or it can be refined for use in the pharmaceutical industry.

The raw biodiesel is then put through a cleaning process to recover the potassium hydroxide for reuse and to remove soaps which would cause a coking residue if not removed. Antioxidants and any winter use additives are then added, the resulting product being Biodiesel to the EU standard EN 14214 and is ready for use as fuel.

Biodiesel performance and safety

Biodiesel has very good ignition behaviour which means that it will give a harmonic combustion process and good engine operation. Because the biodiesel molecule size is similar to the conventional cetane diesel molecule size, it is considered as the best self igniting fuel available at the moment. The energy content of Biodiesel is slightly lower than conventional diesel and experience shows that up to 5% more fuel is used under heavy load conditions.

Biodiesel has an oxygen content of 11% which means it gives lower soot production and a more complete combustion than conventional diesel.

Biodiesel has good lubricating features which will result in lower wear and tear in the engine and has low coking potential ensuring the engines long term efficient operation.

Environmental benefits of Biodiesel

When the Biodiesel fuel is used, it only releases the carbon dioxide (CO2) that it stored during its growth, back into the atmosphere. By substituting conventional diesel a saving of approximately 2.2kg CO2 equivalent per litre is made. For this reason Biodiesel is considered CO2 neutral.

Biodiesel replaces approximately 1.2kg of mineral oil per kg of substituted fossil diesel fuel.

The world resources of mineral oils are fast depleting as the world population grows and lifestyles improve. Fuel security and availability may become a feature with the changing world politics.
The ability to reduce our dependence on these oil reserves obviously makes sense and will allow the UK a level of fuel security into the future.

Other benefits of Biodiesel are reduced emissions of nitrous oxide (N2O) and no sulphur emissions.

Reduced emissions of particles and Benzol along with a major reduction in Hydrogen carbons, proven to be associated with cancers.

Biodiesel has a fast biological decomposition rate which means that it does no harm to water and wildlife.

It is not classed as a hazardous material unlike fossil diesel which has huge pollution potential, Biodiesel therefore is a safe, efficient and environmentally sound fuel to store and use.