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What is bio diesel?

It is a vegetable oil-based fuel that can run in an unmodified engine - be it a car, bus, truck or boat!

Usually made from non-edible vegetable oil it can even be made from recycled fryer oil. The substance can be merged with regular diesel or it can run 1S00% on its own. The future is bio diesel!

It's also one of the most thoroughly tested alternative fuels on the market. Tests have proven that although it performs in a similar fashion to petroleum diesel, bio diesel is far better for the environment.

Bio Diesel is a renewable alternative fuel created from vegetable oils, animal fats, and greases through a chemical process. The chemical process involves reaction of natural oils with an alcohol, and then refining the mixture to create molecules which can be easily burned in a diesel engine. Bio Diesel fuel can be used in any diesel engine in pure form or blended with petroleum diesel at any level. Even a blend of 20% bio and 80% petroleum diesel will significantly reduce carcinogenic emissions and gases that may contribute to global warming. Glycerin is the byproduct of the bio diesel production process, and can be used in personal care products or a variety of chemical applications.

The Department of Environmental Engineering is pursuing research in the field of bio diesel for the past few years. The aim of this research initiative is to try and meet, if not surpass the initiative of the Government of Pakistan to blend at least 10% of bio diesel with mineral diesel fuel in the transportation sector.




How is Bio Diesel made?

Bio Diesel is made through a chemical process called transesterification whereby the glycerin is separated from the fat or vegetable oil. The process leaves behind two products -- methyl esters (the chemical name for bio diesel) and glycerin (a valuable byproduct usually sold to be used in soaps and other products).

Raw Materials:

The main raw materials used for producing bio diesel are vegetable oils and animal fats.  Traditionally, edible oil was being used resulting in price hikes of essential food commodities.  Now, the impetus is towards the harnessing of plants that can yield non-edible vegetable oil for bio diesel production.  The additional benefits of such plants are that they can be reared on marginal land (this is very beneficial for a country such as Pakistan, which has about 65% of its landmass barren and uncultivated due to salinity and other harsh conditions).  The main plants that can be grown on such rough soil include jatropha curcas, castor bean, pongamia pinnata and others (including halophytes).


           Jatropha Plant                                           Castor Plant



             Pongame Plant                                      Jatropha seeds



                Castor Seeds                                      Pongame Seeds


(Conversion of Castor oil into bio diesel in our departmental laboratory)

Conversion of Eruca Sativa L. oil into Bio diesel at our departmental laboratory)

Main features of Jatropha Curcas and Castor bean plants are;

  • Non-edible oil can be extracted.
  • They can grow in waste lands and can consume less water.
  • In cultivation, seed collection, oil extraction and bio diesel production large scale employment can be generated.





The byproducts during bio diesel production i.e. Glycerin and seed cake (Oil extracted from them) can be used in soap, pharmaceutical and fertilizer industries

The cost of 1000 Jatropha saplings (for one acre land) in Pakistan is around Rs.5000/- (Five Thousand Rupees).  One job is created for each acre of Jatropha plantation.  The maximum yield of Jatropha is around 1892 Litres/hectare and for Castor bean is around 1413 litres/hectare.  The field can be cultivated with Jatropha or castor plants on marginal land, because Pakistan is having 100 Million acres of barren land.  The approximate Jatropha oil yield is 12 tons of seeds/hectare/year (35% oil/seed, can be extracted) and Ricinus communis (castor bean) oil yield is around 8 tons of seeds/hectare/year (35% oil/seed).   The Jatropha cultivation has the potential to generate an income of Rs.25000/-(Twenty Five Thousand Rupees) per hectare per month.  Pongamia pinnata can also be grown on marginal land having good oil yield and the climatic conditions of Pakistan are favorable to them.

Due to the global importance of replacing non-renewable and mineral sources of energy with natural renewable counterparts, it is necessary to develop a focused program for harnessing renewable energy in developing countries like Pakistan.  At present the crude oil price in the world is around US$ 120/Barrel.  One renewable and pollution free energy source is bio diesel fuel produced from vegetable oils, which are non-edible like Jatropha (Jamal Gota), Pongame (Sukh Chain) and Castor (Arhand).  The Government of Pakistan announced that 10% blending with bio diesel should start from 2015.

The potential of bio diesel production can be made economical by growing Algae (Kai) in marginal land, in saline water or in the waste water ponds.  The amount of land requirement for growing algae is also minimal as compared to other oil yielding crops.  There are a number of species of Algae identified, which are suitable to our climatic conditions of Pakistan.  Algae having good oil yield can be grown and harvested very quickly.  In addition, algae can produce up to 50 times more oil than ordinary oilseeds. Oil content (% of dry weight) varies between 15% to 70% for algal biomass being cultivated on wastewater streams near power stations.

The cultivation of Algae is expected to bring double benefit to the environment in the sense that Algae can be used to extract nutrients from waste water, which it converts to fats for bio diesel production and Algae extracts pollution from the atmosphere.  Many species of Algae can grow in saline water; this means that algae technology will not put additional demand on fresh water supplies needed for domestic, industrial and agricultural use.

Algal bio diesel resource requirement is land, water and CO2; this can support bio diesel production and CO2 savings. Thus the scientists believe that the “Algae absorbs pollution & gives us oil “for bio diesel production and during bio diesel production glycerin is obtained as by valuable by-product, whose market price is Rs. 170/liter.  Algae farms could also be constructed to use waste water as a food source for algae production.  By using waste water as a nutrient source, these farms essentially also provide a means of recycling nutrients from fertilizer to food to waste and back to fertilizer.  The castor oil yield is 1413 liters/hectare; while the oil yield from Algae is 10000 liters/hectare.  The advantages of Algal growth are:

  • Oil yield is higher (Bio diesel raw material).
  • Can be grown in saline and waste water ponds.
  • Can be used as biomass, burned to produce heat and energy.
  • Alga culture grown material can transformed into methane.
  • Biological hydrogen production by algae is also possible for use in fuel cells.

The advantages directly related to Pakistan’s economy may be;

  • Pollution free greener Pakistan.
  • Employment for farmers/ labors.
  • Reduction in fossil fuel import, saving foreign exchange.
  • Boosts to our petroleum companies.

Algae can create 5,000-20,000 gallons of oil per acre per year, far in excess of palm oil which yields a paltry 635 gallons despite being one of the best crops presently for bio diesel production.  But being edible Palm oil cannot be used as a raw material for bio diesel considering the fact that its production can easily encroach upon fertile farm land (it cannot be grown on marginal land). Algae can also be economically converted into solid fuels, methane gas, or bio-ethanol. It can also be used to generate electricity which in turn can be used to obtain hydrogen fuel to power hydrogen fuel cells.  Another advantage is that algae can even be fed on liquid human sewage and on streams polluted by fertilizer run off reducing pollution.


Transestrification produces methyl esters of fatty acids that are bio diesel, and glycerol.  The reaction occurs stepwise: triglycerides are first converted to diglycerides, then to monoglycerides and finally to glycerol.


Transesterification is catalyzed by acids, alkalis and lipase enzymes. Alkali-catalyzed transesterification is about 4000 times faster than the acid catalyzed reaction.  Consequently, alkalis such as sodium and potassium hydroxide are commonly used as commercial catalysts at a concentration of about 1% by weight of oil.  Alkoxides such as sodium methoxide are even better catalysts than sodium hydroxide and are being increasingly used. Use of lipases offers important advantages, but is not currently feasible because of the relatively high cost of the catalyst. Alkali catalyzed transesterification is carried out at approximately 60 °C under atmospheric pressure, as methanol boils off at 65 °C at atmospheric pressure. Under these conditions, reaction takes about 90 min to complete. A higher temperature can be used in combination with higher pressure, but this is expensive. Methanol and oil do not mix; hence the reaction mixture contains two liquid phases. Other alcohols can be used, but methanol is the least expensive. To prevent yield loss due to saponification reactions (i.e. soap formation), the oil and alcohol must be dry and the oil should have a minimum of free fatty acids. Bio diesel is recovered by repeated washing with water to remove glycerol and methanol.

Contact Us:

Department of Environmental Engineering,
NED University of Engineering & Technology,
Main University Road, Karachi-75270 Pakistan

Contact No: (92-21)99261261-8, Ext. (2211)