A liquid biofuel which is obtained from animal fats or vegetable oils and alcohol by chemical processes and can be used as alone, in diesel engine or by blending with the diesel oil. ASTM International (originally known as the American Society for Testing and Materials) defines biodiesel as a mixture of long-chain monoalkylic esters from fatty acids obtained from renewable resources, to be used in diesel engines. The crops which are useful for the production of biodiesel are Sunflower, Soyabean, Jatropha, Taramira, Safflower, Mustard, Peanut, Cottonseed, Sesame, Rice bran, Linseed, Castor and Canola. Biodiesel is produced by transesterification reaction from vegetable oils or animal fats and an alcohol. Transesterification is a chemical reaction which converts an ester (animal fat or vegetable oil) into mixture of esters of the fatty acids which makes up the oil (or fat). Then Biodiesel is obtained after the purification of the mixture of fatty acid methyl esters (FAME).
There are following advantages of biodiesel as we compare it diesel fuel.
• It is low toxic as compared to the diesel fuel.
• Due to reduced emission of carcinogenic substances, it has lower health hazards.
• As a lubricant, it has excellent properties.
• During its production, used cooking oil, residues from meat processing can be used as raw material.
• It can be used in conventional diesel engine without modifications.
Most of the technologically advanced countries believe on the importance of fossil fuel, however, they are successfully using energy sources which are renewable for their energy needs. Pakistan is using hydropower technology for energy needs which is successful and renewable. For many researchers, biogas is gaining interest because fuel produced from it is similar to the fuel extracted from crude oil. But the great hurdle is high cost and non-continuous supply of vegetable oil. Generally, for biodiesel production, vegetable oil is reacted with methanol or ehanol. Methanol is cheaper than ethanol, so widely methanol is used. Methanol is obtained from coal and in Pakistan there are 180 billion tons reserves of coal. On the other hand, 76 sugar mills are present in the country with a capacity 300,000 tons for crushing the cane per day, and the main by-product for ethanol production is cane molasses. So, excess of ethanol is present for biodiesel production.
For biodiesel production, caustic soda is generally used as a catalyst, whereas for present country need, production of caustic soda is enough. Sodium chloride is used as a raw material for caustic soda production. Due to huge reserves of sodium chloride, production of caustic soda can be increased. India is very successful in the production of biodiesel from seeds of jatropha plant. While in Pakistan, Jatropha can be cultivated in saline soil with less water and high temperature. Jatropha plant can produce about two tons of biodiesel fuel per year per hectare. If Pakistan uses all uncultivated land for biodiesel production, then 56 million tons of biodiesel per year can be produce, while our present need for fuel diesel is 8.5 million tons. To increase the production of edible oil Government of Pakistan is very serious and established the department of Pakistan Oilseed Development Board.
It was resulted from the economic analysis for indigenous oil that the factor which may increase the price of biodiesel is virgin vegetable oil. In the past decade, India was successful in decreasing the cost of biodiesel fuel by growing jatropha plant. Other countries also tried the same and achieved some success. However, Pakistan remains behind the scene in biodiesel production. The total energy demand of the Pakistan is 32 MTOE (million tons of oil equivalent), while the energy supply is about 63 MOTE. But most of it is imported, so country is deficient in energy.
On the other hand the energy consumption is increasing at rate of 5 per cent per annum. It is necessary that there should be continuous and cheap supply of the energy for sustainable economic growth. At present, the role of sustainable sources of energy is less and more efforts are required to make it significant in country energy supply mix. It is resulted from the study which is described in paper that if indigenous vegetation that can produce in edible oil is grown on barren areas of the country then cost of feedstock can be reduced and biodiesel can become the solution of poor energy economy.
In addition to this, by developing ponds on some marginal land algal growth can be increased which may increase the biodiesel production. To improve the socio-economic condition of the country there is need of hour to develop biodiesel industries. The government of Pakistan created the Alternative Energy Development Board (AEDB) with this mission. One of the scopes of work includes the employment of 10 per cent biodiesel in diesel fuel market by the year 2025. If this target is achieved then the country may save US$ 1 billion per year by decreasing imports of fossil fuels.