Carbon emission from bio-fuels:

Carbon emission from bio-fuels:

Bio-fuels are the fuels of solid, liquid or gaseous in nature, which has been derived from bio-mass – recently living organisms or their metabolic byproducts. Thus, it could be oils from plants, manure from cows, wood from trees etc. For example, bio-gas (i.e., gas produced by the biological breakdown of organic matter in the absence of oxygen); bio-ethanol; bio-diesel; straight vegetable oil etc., are the bio-fuels. It is a renewable energy source, mostly have agricultural based, unlike other natural resources such as petroleum, coal and nuclear fuels.

It has been seen that certain social and environmental benefits bio-fuels has as compare to use of fossil fuels, such as reduction of greenhouse gas emission, increased national energy security, increased rural earnings and development and above all, reduction of use of fossil fuel.

Bio-fuels and other forms of renewable energy are thought to be ‘carbon neutral’ or ‘carbon negative’. Carbon neutral or carbon negative is the difference of quantum of carbon produced and emitted to the atmosphere when these are used as fuels and the quantum of carbon absorbed in the process of their growth. If both are same, is called carbon neutral or if quantum of carbon absorbed through photo-synthesis is more than the emission is called carbon negative. Both the cases are advantageous towards environment point of view and reduction of global warming.

Strictly speaking, bio-fuels are neither carbon neutral nor carbon negative. This is because extra energy is required to grow crops and process them into fuel. This extra energy releases extra carbon to atmosphere as emission. For example, plants require fertilizer to grow, requires energy for transportation and processing; this extra energy releases carbon to the atmosphere as emission. Therefore, this emission aspect is to be debated, whether we are really gaining in respect of carbon emission, by using bio-fuel. However, the arable lands can be better utilized if people shift towards bio-fuels; so the rural earnings. The poorly irrigated land mass also can be taken up for cultivation.

Ethanol as fuel:

Ethanol as fuel:

Ethanol or alcohol can be used as fuel very effectively, as a bio-fuel alternative to gasoline. 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. 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.

Current interest in ethanol mainly lies in ‘bio-ethanol’ that is produced from agricultural based starch or sugar. Basically, carbon-based feedstocks are used for bio-ethanol production. Agricultural feedstocks are considered renewable. Feedstock such as sugar cane, bagasse, miscanthus, sugar beet, sorghum, grain sorghum, switch-grass, barley, hemp, kenaf, potatoes, sweet potatoes, cassava, sunflower, fruit, molasses, corn, stover, grain, wheat, straw, cotton and other biomass can be used for production of bio-ethanol.

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.

There has been considerable debate about actual usefulness of bio-fuel like bio-ethanol. 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.