Any vegetable oil like Soya oil as also oils used for frying can go to make biodiesel. In diesel engines, one can either use biodiesel fully replacing diesel or combination of diesel and biodiesel in any proportion. The fuel tank can be filled with just diesel, just biodiesel or diesel-biodiesel at any ratio.
Why Biodiesel?
Demand for fuels like diesel or petroleum is so overwhelming that most of the countries have to import them. On the other hand, biodiesel can easily be manufactured indigenously. Thus precious dollars which would otherwise have gone to a foreign country can be saved and dependence on them for fuels reduced. While biodiesel manufacturing would create job within the country, reduction of import would strengthen the balance of trade. Isn't that great? Apart from these economic considerations, the other weighing factor is that the oil is not going to last forever. Oil is non-renewable and also a pollutant. Biodiesel is ever renewable and without any toxic effects. As it is made from vegetable oil, it is no pollutant of air. We all know how rampant use of carbon fossil fuels is contributing to global warming and climatic change. The air is foul with carbon emissions. With biodiesel which is almost free from carbon, emissions warming the globe are almost gone and we can take a deep breath in a cleaner air. The wear and tear of automobile engines is far less when diesel is replaced by biodiesel. Even a small addition of biodiesel to the diesel increases the lubrication which means longer engine life. Less noise and less smoke- that's what clinches the deal for biodiesel. Anyone who has abhorred the belching smoke and the engine noise of a diesel run automobile would heartily welcome the soothing biodiesel.
Minuses
Biodiesel is also not without its disadvantages. In spite of steadily rising availability, biodiesel is still to be available readily across the country. The consumption for biodiesel is increasing by leaps and bounds (gone up 5 times in 5 years between 2001 and 2006) and the indigenous production can hardly keep pace with this growth in consumption. Using biodiesel in fuel tanks hitherto using diesel clogs the fuel filter by peeling off the accumulated diesel on the tank wall. This may be a problem for the fuel injectors. Biodiesel is more gelling than diesel and at a temperature below 32 degrees Fahrenheit may get a little sticky. The problem can be overcome by keeping the proportion of biodiesel to 20% and mixing the fuel with 80% diesel. This combination is most widely used having a gel point of 15 degrees Fahrenheit. In extreme cold climates, additives like kerosene in the diesel-biodiesel mixture can further bring down the gel point. While biodiesel poses no problems for new cars, rubbers used in fuel lines of old cars may get eroded with use of biodiesel. The NOx emissions from biodiesel cause smog but reductions of greenhouse gases far outweigh this small disadvantage.
