Essentially, all biofuels are produced from solar energy captured by the photosynthetic activity of plants. During the day, as sunlight falls on leaves, plants absorb CO₂ (carbon dioxide) from the atmosphere and use both to grow, creating bio mass, flowers, fruits and seeds, with seeds of some species being oil bearing. As a by product of photosynthesis, the trees and plants release oxygen into the atmosphere, thereby refreshing it.

Broadly, there are two groups of biofuels – petrol additives and diesel additives.

Petrol additives are basically ethanol (ethyl alcohol) which is produced by the digestion of plant sugars, and cellulose. Ethanol is the alcohol that we drink – whiskey, vodka, rum, etc are all ethanol made by fermentation of plant sugars. So sugarcane, wheat, barley, malt, potatoes, corn and various other plant products containing sugar can be fermented to yield ethanol. The resulting alcohol is distilled, purified and then blended into petrol in the desired ratio.

Another way of producing ethanol is to take bio mass – basically the plant itself, its stem and leaves, and digest it with special enzymes that convert it into alcohol. Again the resultant alcohol rich fluid has to be refined, purified and the ethanol extracted.

Diesel additives are basically vegetable (and animal) fats that have been refined in a special process called transesterification in which the long hydrocarbon chains are broken down to a smaller size similar to that of diesel. This refined oil is called biodiesel or B100, denoting 100% pure biodiesel. Chemically known as FAME (fatty acid methyl ester) it is a drop in replacement for mineral diesel meaning that it requires no modification to existing engines for its use.

There are three major sources of bio diesel – edible oil from seeds of plants, edible oil from seeds of trees, inedible oil from seeds of trees. The production process for all of them is the same. The plant or tree is cultivated to maturity then the oil seeds are harvested. The seeds are then crushed in an oil mill to extract the crude vegetable oil. Sometimes a process of solvent extraction is also used to dissolve out all the oil in the seed. This crude oil is then refined via transesterification to get B100. This is then blended into normal diesel in the desired ratio.