Posted by: PARTHA DAS SHARMA | August 30, 2008

Bio-Ethanol is a renewable fuel to be blended with gasoline

Bio-Ethanol is a renewable fuel to be blended with gasoline and discussion on second-generation bio-fuels:

A. Ethanol or alcohol can be used as fuel very effectively, as a bio-fuel alternative to gasoline and can give less local pollution. In many of the countries it is used in running vehicles. As it is easier to manufacture and process, it is steadily becoming a promising alternative to gasoline almost throughout the world. It is mainly processed from sugar cane – a very common agricultural produce.

B. Anhydrous ethanol, i.e., ethanol having less than 1% of water, can be blended very effectively with gasoline in varying proportion. 10% ethanol blended gasoline is common in most of the countries for running motor vehicles.

C. Current interest in ethanol mainly lies in ‘bio-ethanol’ that is produced from agricultural based starch or sugar. Bio-ethanol is mainly produced by the process of sugar fermentation. Corn, sweet sorghum, sugar beet, sugarcane and cassava are among the several alternative sources of plant materials from which bioethanol is produced today.

D. Ethanol or ethyl alcohol is a clear colourless liquid, biodegradable, low in toxicity and causes very little environmental pollution when burnt. Ethanol is a high octane fuel and has replaced lead as an octane enhancer in petrol. With an octane rating of 129, compared to about 91 for fossil-petrol, engines fired on ethanol can run at a much higher compression ratio without the octane-boosting additives.

E. Bioethanol-blended fuel burns more completely because the ethanol molecule contains oxygen … the result, carbon-dioxide and carbon-monoxide emissions can be reduced by nearly 90% as compared to engines run exclusively on fossil-fuels. Vehicle engines require no modifications to run on 10 % blends of bio-ethanol nor are vehicle warranties affected either. Flexible fuel vehicles can run on 85% ethanol and 15% petrol blends.

F. The basic steps for large scale production of bio-ethanol are: (a) microbial (yeast), i.e., fermentation of sugars; (b) distillation; (c) dehydration and (d) denaturing.

G. As discussed, ethanol can be used as alternatives or complements to petrol (gasoline) and can give less local pollution. If the raw source is petroleum then they are not renewable. Fortunately, ethanol can be produced organically; e.g. from sugar cane etc., and then they can contribute in reducing climate change. Producing these alcohols organically can also bring economic benefits to rural developments by way of benefiting farmers.

H. There has been considerable debate about actual usefulness of bio-fuel like bio-ethanol. Bio-ethanol and other bio-fuels are coming under increased criticism for diverting food resources and driving up food prices across the world. Replacing fossil fuels by bio-ethanol take large area of arable land mass, which would have been cultivated for food crops. Moreover, the energy and pollution balance of the whole cycle of ethanol production is also not known.

I. Although, production and use of bio-ethanol provides opportunities and risks and is subject to a lot of debate and reports; I see bio-ethanol as a major step towards meeting increasing needs with limited resources – if done the right way. In my opinion, since plants take CO2 out of the air and burning them releases CO2 that is taken out of the air by the next crop of fuel plants, bio-fuels are CO2 neutral. It is just recycling of CO2. Certainly there would be some competition for farmland between food crops and fuel crops, but genetic engineering could develop plants which would thrive on marginal land, where food crops would not grow well. Moreover, energy security issues of the poor, oil importing nations are taken care of well.

J. At present, bio-ethanol is only made from sugars derived from corncobs, sugar beets, grain and sugarcane, with the help of baker’s yeast. A great number of by-products result from the cultivation of these crops, such as straw and corn husks. It would be a major step forward if this leftover material, which also largely consists of sugar, could be used for the production of bio-ethanol. This would allow agricultural land to be used more efficiently and at the same time prevent competition with food supplies.

K. However, under the above controversies for use of bio-ethanol, second-generation bio-fuels are gaining credibility as a solution. Scientists have been working to produce bio-ethanol and other bio-fuels from sources such as agri-wastes, waste paper, brewing byproducts, leftover agriculture products, including straw, corncobs and husks; and many of the cases they have been successful. Technology can also be used to turn more traditional energy crops such as switchgrass into fuel as well. The key to the above second-generation bio-fuel process is a bacterium that grows on a marsh grass. The bacterium,S. degradans’, contains an enzyme that is capable of breaking down tough plant materials into sugar, which can then be converted into ethanol. Scientists were able to create the enzyme in their own lab. This enzyme can break down the cellulosic material into bio-ready fuels in a single step, while requiring fewer caustic chemicals than comparable methods.

L. Bio-fuel / biodiesel from algae are emerging as very important renewable energy source. It has tremendous potential for next-generation green energy as ‘Algae Biodiesel’.


  1. I think corn ethanol gives ethanol a bad name. I would like to see more people looking into the above mentioned ethanol from waste.

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