Ethyl Alcohol has often been touted as the bio-fuel that can challenge the fossil fuels in future. This assumption has driven many countries like Brazil, USA, and others including India to go for use of blends of petrol and ethanol in varying proportions hoping to reduce their dependence on imported crude oil progressively. It is amazing how in Brazil, more than 50% of the automobiles are run on 100% ethanol while rest use flex fuels containing up to 25% ethanol blended with petrol. While in USA corn is the source from which alcohol is produced by saccharification and yeast fermentation, in Brazil sugarcane provides the carbon source for alcohol fermentation. There are many issues which confront the world when considering large scale switch over to ethanol and there does not appear to be any consensus on them with divergent views being being expressed by the scientific as well as the policy makers.
Probably one of the critical issues is the desirability of diverting food materials like corn, sugarcane and others for non-food uses with its attendant consequences. A wide variety of carbon sources can be used with appropriate technology to derive alcohol. These include besides corn and sugarcane other feed-stocks like bagasse, sugar beet, sorghum, switch grass, barley, hemp, kenaf,potatoes, cassava, sunflower, fruits, molasses, many food grains, straw, cotton etc. Recent spurt in food grain prices, in sympathy with crude oil prices has been attributed to greater demand for alcohol for blelding with gasoline resulting in 15-20% more production in USA alone diverting increased corn into this stream. Many oppose use of food materials like corn for alcohol production because it is blamed for harming the environment, prompting food riots in many parts of the world and wasting public money on thoughtless subsidies which otherwise could have been better utilized to evolve truly renewable energy systems through research and development. Massive subsidies at the crop level first to corn growing companies and then to petrol companies for blending alcohol later only can sustain alcohol as a bio-fuel. If these subsidies are stopped ethanol as a bio-fuel may not be a viable proposition in many countries.
Use of non-food resources like cellulosic wastes such as grasses, bagasse, straws etc is another approach being considered for ethanol production though commercialization of the technology may take some time. The advent of ambient condition processing technology may yet make the technology energy efficient compared to the conventional elevated temperature saccharification-fermentation technology. Some experts feel that bio-fuels from agriculture wastes are more energy efficient and have a smaller impact on environment pollution and food prices. The allegation that 10% addition of alcohol reduces mileage and consequently such an approach will call for import of 11% more crude oil needs to be looked into. While hydrated alcohol can run a car engine designed for 100% alcohol fuel, flex fuels call for using only anhydrous alcohol with less than 1% water in cars that run on such blends with possibly increased VOC emissions. It is irrefutable that ethanol consumption will be 51% more than gasoline to get the same mileage since energy per unit is 34% lower in ethanol.
Some proponents feel that instead of bio-conversion, a more economic and environment friendly approach will be direct burning which yields more net energy than the bio route. Even with corn, pyrolysis of whole plant is considered more desirable than using only the kernel. Corn growing and processing into ethanol is alleged to be consuming 29% more energy than what it can yield as a a bio-fuel while others require up to 57% more fossil fuels with negative net energy yield. It is difficult to find where the truth lies in this on going debate regarding bio-fuels and their role as effective alternative to fossil fuels.
Bio-diesel mostly based on soybean is another area beset with problems of clarity. If edible oils like Palm oil, Soybean oil and others are diverted for non-food uses, it can have disastrous consequences on the availability and prices of these scarce food source, especially in the third world countries. Besides the large quantity of glycerol generated as a by-product will have to find economic use. Recent reports regarding the development of a technology to convert glycerol to ethanol using anaerobic fermentation with a special strain of E.coli may provide a solution to this problem if and when it is commercialized. Current production of about 250 million gallons of bio-diesel has generated 25 gallons of glycerol and the figure is likely to go up to 100 million gallons when the bio-diesel production is slated to cross the one billion gallon mark soon. Bio-diesel proponents claim that it reduces pollution by 41% as compared to fossil fuels.
The dilemma facing the world is how the emerging fossil fuel crisis can be averted by finding alternate environmentally viable options without losing further time. While food crops must be spared from their use as a renewable energy source through the alcohol route, a world-wide action program needs to be launched to increase the efficiency of many of the currently known alternatives like solar, wind, wave, geothermal and other energy systems and look out for other new economically and environmentally viable technologies for providing clean energy to meet the aspirations of future generations.