Biological Fuel Generation
2.3. Biological Fuel Generation
It has been a great achievement for India to retain the world’s third largest producer of ethanol via fermentative procedures next to USA and Brazil. India validly runs more than 125 distilleries across the country with an installed capacity of approximately 750 million litres per annum. However, the average yield of ethanol per MT of molasses ranges between 225-235 L depending on the content of residual cane sugar present in molasses. The major portion of ethanol is used up in various industrial
applications, a reasonable proportion in making alcoholic beverages, and a certain quantum is utilized in the production of so called ‘power gasoline’ as an automobile fuel energy. Industrial usage of ethanol
encompasses a variety of products, such as : PVC, polyethylene (PE), synthetic rubber, solvents, phar- maceuticals, preservatives, and organic chemicals.
In a host of ‘developing countries’ e.g., Indian sub-continent, South-East Asia, African conti- nent etc., the most judicious and practicable utility as ‘diesel fuel’ is gaining wide recognition and tremendous popularity over the usual petroleum variants. Therefore, most approximately in these speci-
fied countries, the strategic conversion of ‘biomass’ into ethanol (C 2 H 5 OH) and methane (CH 4 ) prob- ably do not muster enough primary interest rather than to device and develop newer methods for the production of possible diesel fuel substitutes via intensive research and dogged determination, for instance : alkanes, butanol and vegetable oils. Besides, one may also exploit certain available biomass
sources solely for ‘diesel fuel generation’, such as : woody biomass yielding turpentine, extraction of oilseeds producing fuels, selected aquatic biomass (viz., water hyacinth), and specific oil producing
microorganisms (viz., Botryococcus). In fact, some of the vegetable oils do have the potential for being utilized as perspective (substitute) fuel in ‘tractors’ that run on diesel only. Thus, the dual advantage of fast-growing, high yielding vegetable oils for use both as a ‘food’ and a ‘diesel fuel’ may turn out to be
a certainly more attractive, feasible, and viable option that needs to be implemented rapidly. Fig. 6.2 illustrates the various aspects of ‘biomass fermentative procedures’ thereby yielding
much desired and valuable by products, namely : fuel oil, CO 2 , and sugarcane bagasse.
ADVENT Raw
Residues material
substrates (wood, straw, etc.)
vegetable
and waste
substrate
materials OF
BIOTECHNOLOGY Procedural
Physical
Biochemical stage
anaerobic aerobic
Product Sugar
oils and
Procedural Fermen-
stage tation
fermentation
synthesis Refining
Product Ethanol
and carbo-
of oleic
fats
acids
Application Chemical
raw material
Fuel
Heat recovery
Fig. 6.2. Sequential Conversion of Biomass into Value-added Products, Energy,
and Industrial Feed Stocks.
[Adopted From : Kleinhanss W : Natural Resources and Develop., 33 : 106-127 (1991)]
PHARMACEUTICAL BIOTECHNOLOGY
Growing Fuel : Biomass refers to solar energy stored in organic matter. The natural growth of plants and trees in the universe makes use of the phenomenon of photosynthesis thereby help in the conversion of energy from the sun in the form of CO 2 into carbohydrates e.g., cellulose, starches, and sugars. In fact, the carbohydrates represent the organic chemical entities which exclusively make up the ‘biomass’. Eventually, when plants meet their fatal end, the very phenomenon of ‘decay’ invariably
gives rise to the ‘energy’ stored in carbohydrates and discharges CO 2 back into the atmosphere. Hence, biomass designates a ‘renewable source of energy’ by virtue of the fact that the growth of newer plants and trees replenishes the prevalent supply of carbohydrates.
Several millions of years, natural processes occurring in the earth meticulously transformed organic matter into present day’s reserve of fossil fuels, otherwise termed as non-renewable sources of energy, which essentially comprise of natural gas, crude oil, and coal deposits ; and these three components are being consumed regularly as on date across the globe with a ray of apprehension that they may not get exhausted one day leaving the world’s consumers in peril and distress.
Interestingly, the actual usage of ‘biomass’ for energy exploitation fails to enhance CO 2 emis- sions overwhelmingly ; and, therefore, does not contribute significantly towards the possible risk of ‘global climatic alteration’. Contrarily, the legitimate consumption of biomass in this universe by mankind to generate energy is invariably regarded as a measure to dispose of nature’s waste materials, perhaps as a scavenger, which may otherwise would create serious environmental risks.
In the very beginning of this new millenium (i.e., 2001) United States only utilized biomass sources upto 3% of all energy consumed ; supplied more than 50% of all renewable energy utilized ; represented nearly 10% of all electric generating capacity from renewable sources. However, in a glo- bal scenario biomass catered for more than six folds the combined energy provided by geothermal, solar, and wind energy sources. In true sense, globally biomass rightly and urgently meets almost 14% of the world’s energy requirements efficaciously in the service of the mankind.
It is, however, pertinent to state here that the ‘biomass energy’ presently refers to making exclu- sively ‘fuel’, for instance : renewable diesel from plants, and ethanol ; but may also encompass inciner- ating plant materials and waste products viz., skilfully tapping natural gas from garbage dumps, rice husk, and sawdust. Some newer emerging techniques include :
• Gasifying plant material to make fuel for electric plants • Energy crops and fast growping trees for use in converted coal-power plants. • Utilization of bacteria and algae for extracting hydrogen from waste disposal matter.