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    By Ashwani Kumar | July 22nd 2012 06:47 AM | 1 comment | Print | E-mail | Track Comments
    About Ashwani

    Professor Emeritus ,Former Head of the Department of Botany, and Director Life Sciences, University of Rajasthan, Jaipur. 302004, India At present...

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     "Bioethanol, Biobutanol, Biodiesel, Vegetable oils, Biomethanol, Pyrolysis oils, Biogas, Biohydrogen. Biodiesel: Technically, Mono-alkyl esters of long chain fatty acids derived from renewable lipid feedstock such as vegetable oils and animal fats for use in Compression Ignition engines”. 
    The definition eliminates pure vegetable oils. Depending on the feed stock it may be referred as : – Soybean methyl ester - SME or SOME – Rape methyl ester - RME – Fatty acid methyl ester - FAME (a collective term including both of the above). – Vegetable oil methyl ester - VOME yielding plants provide bio-diesel. 

     Present status and future prospects: a) Wood, wood chips agriculture waste to Briquetting, Gasifier, Vacuum pyrolysis or Bio-gas, heat and electricity generation. b) Oil to trans-esterification to obtain Fatty acid methyl ester (FAME) e.g. Rape seed methyl ester ( RME). c) Liquid hydrocarbons to hydro-cracking – cracking of tri-terpenoid chain and adding of hydrogen using zeolite catalyst in bio-refinery.

    Next generation biofuels: • Lignocellulosic biofuels made from the lignin and cellulose in the cell walls of plants. • The feedstocks for these biofuels – trees, grasses, or leftover plant materials – have several potential advantages. • Require less intensive agriculture and may be grown on “marginal” land, reducing competition for resources. • Could be made from agricultural or forestry residues such as rice husks and corn stover. • 2007 UN report estimated – Biofuels commercialized by 2015 – Competitive with petroleum-based fuels by 2025-2030. 

     Second and third generation biofuels: altering host material and /or developing new enzyme systems. a. Metabolic engineering for entire product b. Industrial application of biofuel inclusive of related bio products of commercial value from fourth generation products. Direct conversion in to biofuel. 

     Objectives of study: a) First generation biofuels: Developing first generation biofuel crops to be grown in semi arid regions on wasteland. b) Lactiferous crops: Euphorbiaceae, Asclepiadaceae, Compositae, family members containing latex as biofuel crops. Strategy to develop their agro-technology. Biomass conversion studies in collaboration with IIP, Dehradun. c) Collection and evaluation of high yielding Jatropha curcas from different locations in Rajasthan – Germ plasm collection, evaluation in collaboration at TERI, New Delhi, raising stock material in nursery from elite samples. d) Agronomical and multilocational trial of selected genotypes. e) To standardize nursery techniques for large scale planting material in vivo and in vitro. f) To demonstrate the agro-forestry practices for cultivation of Jatropha curcas in wastelands and to standardization of the growth parameters for improvements. g) To generate information on economics of production costs for different regions. h) To evaluate quality and quantity of liquid fuels under actual field conditions of large scale cultivation. i) To standardize growth cycle and productivity in terms of total production vs biofuel production. j) Improving the plant productivity using various physical, physiological, biochemical parameters including nutritional and hormonal applications. k) To generate scientific and technological information for large scale applications. l) To establish pilot plant for extraction of biodiesel. m) Village level plantation in 40 villages in Alwar district n) Education on use of biofuels and establishment of mini bio-diesel plants on site in Alwar district. 

     METHODOLOGY:

    a) Growth of cultivation of Biofuel plants Certain potential plants were selected and attempts were made to develop agro-technology for their large scale cultivation (Kumar 1984; Kumar et al. 1995; Kumar 1998; Kumar l996; Kumar 1994; Roy and Kumar 1998a)n (Kumar 1995; Kumar 2000). A 50 ha bio-energy plantation demonstration project center has been established on the campus of the University of Rajasthan to conduct the experiments on large scale cultivation of selected plants with the objective of developing optimal conditions for their growth and productivity, besides conserving the biodiversity.

     Next generation bio-fuels shall involve technical components : (a) Biological sciences: Plant biotechnology, Cellular and molecular biology, microbial /industrial biotechnology. (b) Chemical technology sciences: catalysis, reaction engineering and separations. b) Bioethanol production:  The acid pre-treatment of lignocellulosic biomass for biofuel ethanol production not only enables the release of monosaccharides, but also generates several types of compounds, which are inhibitory to yeast.  Furans, like 5-hydroxymethylfurfural (HMF) and furfural, are known to inhibit yeast growth and viability and to reduce ethanol productivity.  Thus, faster conversion rates of HMF and furfural are desirable.  Yeast strains are naturally able to slowly reduce HMF and furfural to less toxic compounds, however the rate of inhibitor conversion and cofactor utilization are strain dependent (NADPH-dependent).  Dehydrogenase responsible for HMF conversion in S. cerevisiae Development of biofuel resources: 

    Work done and review:  During last 30 years we have carried out significant investigations on biofuels which are summarized here in brief only. Some of the important findings of the research work carried out by contemporary researchers and future projects are also reviewed. This paper presents original results as well as review of research work being carried out in the field. The selection of biofuel material is of utmost importance. Initial studies of Calvin (1974) concentrated on laticiferous plants.  During my visit to his lab in University of  California (Berkley Campus)  Nobel Laureate  Professor Melvin Calvin  in 1980  suggested  me  to try the laticiferous plants in Rajasthan, whose climate is broadly similar to Arizona desert in several respects. We commenced work on laticifers in 1980 itself and  Department of Non-conventional energy sources (DNES) subsequently  Ministry of Non-Conventional Energy Sources granted   research projects to us to carry out researches on biofuels in 5 ha area to begin with which was raised to 50 ha energy demonstration project center (EPDPC). Euphorbia lathyris and Euphorbia anitsyphilitica, Pedilanthus tithymaloides, Calotropis procera, Euphorbia royleana, and Euphorbia caducifolia were investigated in detail. During this period (1970-1990) active research was carried out in in India, USA, Australia and Japan (Kumar, 1984, 2001, 2008 and 2011). Out of 600 plants screened around 12 plants were selected for intensive studies. 
    Two plants viz Calotropis procera, Euphorbia antisyphilitica were selected for detailed investigations and Department of Biotechnology,  with its director  Director Dr Renu Swarup,  Govt of India supported all India level project on bio-fuels under chairmanship of Professor A.K. Sharma of University of Kokatta and  (2002-2007) in which a dozen research Institute and Universities of India were involved. 
     Calotropis procera grows wild while Euphorbia antisyphilitica has been introduced from Mexico. We conducted  detailed studies  on the growth and cultivation and improvement of hydrocarbon contents of Calotropis procera and Euphorbia antisyphilitica. 12 accessions of Calotropis procera were analysed and their growth parameters studied at the Energy Plantation Demonstration Centre, University of Rajasthan, Jaipur under Department of Biotechnology project Agrotechnology for their improved growth and hydrocarbon yield potential has been documented by Department of Biotechnology in their report (Kumar 2007) .
     Hydrocarbons from plants Some of the laticiferous plants identified by Bhatia et al. (1983) were investigated in detail at Jaipur (Kumar 2001b; Kumar 2000; Kumar 1995; Kumar et al. 1995).The work done included i) Hydrocarbon yielding plants, ii) high molecular weight hydrocarbon yielding plants, iii) non edible oil yielding plants (I) Hydrocarbon yielding plants included : 1. Euphorbia lathyris Linn., 2. Euphorbia tirucalli. Linn., 3. Euphorbia antisyphilitica, Zucc.,4. Euphorbia caducifolia Haines., 5.Euphorbia neriifolia Linn, 6. Pedilanthus tithymalides Linn, 7.Calotropis procera (Ait.)R.Br.,8.Calotropis gigantea(Linn) R.Br. II) High Molecular Weight Hydrocarbon Yielding Plants : Parthenium argentatum Linn. III) Non edible oil yielding plants 1. Jatropha curcas. 2. Simmondsia chinenesis Considerable work has ben carried out on these plants (Kumar and Roy 1996; Roy and Kumar 1990; Roy and Kumar 1998b; Kumar 1994; Kumar 1995). Investigations on several plant species have been carried out at our center including Euphorbia lathyris (Garg and Kumar 1989a; Garg and Kumar 1989b; Garg and Kumar 1990b; Garg and Kumar 1987a; Garg and Kumar 1989c; Garg and Kumar 1987c; Garg and Kumar 1987c) Euphorbia tirucalli, Euphorbia antisyphilitica (Johari et al. 1990; Johari et al. 1991) Pedilanthus tithymaloides(Rani and Kumar 1994; Rani et al. 1991; Rani and Kumar 1994 ) ; Calotropis procera (Rani et al. 1990); Euphorbia neeriiifolia and E. caducifolia (Kumar 1994; Kumar 1990); Jatropha curcas (Roy 1996; Roy and Kumar 1990)and Simmondsia chinensis. The results have been published from time to time ( Kumar, 2001) 

     Next generation biofuels can reduce negative impacts.  The first to arrive will be lignocellulosic biofuels made from the lignin and cellulose in the cell walls of plants.  The feedstocks for these biofuels – trees, grasses, or leftover plant materials – have several potential advantages.  They require less intensive agriculture and may be grown on “marginal” land, reducing competition for resources.  Lignocellulosic biofuels could be made from agricultural or forestry residues such as rice husks and corn stover.  A 2007 UN report estimated that these biofuels would be  commercialised by 2015 and become competitive with petroleum-based fuels in the next 10-15 years. Possible alternatives: Oil yielding crops: Europe has concentrated oil yielding crops like raps ( Brassica rapa ) in Gerrmany, and soybean oil is used in USA for biofuel. Author himself witnessed buses in campus of University of Illinois, Urbana Chamapaign Campus, USA 
     There are three alternatives for mature biomass Bioethanol from corn Fig. 13. Soyabean cultivation in USA in a private farm, a bus being run on soybean diesel, Biofuel have closed cycle and dont add carbon to atmosphere and a petrol pump selling bio-diesel based on raps oil in Germany. Corn Ethanol at Petrol pumps  E 85 in USA is sold commercially. 

        Future of bioenergy: In a number of scenarios of the global food and agriculture system in 2030, we examine to what extent increases in livestock and crop productivity, and changes in human diets, may expand the bioenergy potential. The results from the scenarios indicate that if the recent projections of global agriculture made by the FAO come true, the prospects for bioenergy plantations will be less favorable. In our scenario depicting the FAO projections, it is estimated that total agricultural land area globally will expand from current 5.1 billion ha to approximately 5.4 billion ha in 2030, leaving little room for a major expansion of bioenergy plantations(Wirsenius 2003). Lignocellulosic biofuels: Currently, cellulosic biofuels and algal biodiesels are prominent biological approaches to sequester and convert CO2. Ethanol and biodiesel are predominantly produced from corn kernels, sugarcane or soybean oil create food vs fuel competition and destabilize land use pattern for agriculture. In order to avoid this another biofuel feedstock, lignocelluloses—the most abundant biological material on earth is being explored. Lignocelluloses is everywhere—wheat straw, corn husks, prairie grass, discarded rice hulls or trees. The race is on to optimize the technology that can produce bio-fuels from lignocelluloses sources more efficiently—and biotech companies are in the running. There is campaign, which advocates that 25% of US energy come from arable land by 2025. The EU had called for a threefold increase in bio-fuel use by 2010, to 5.75% of transportation fuel. Whereas starch is soft, lignocelluloses, the main component of the plant cell wall, has evolved to resist degradation. It consists of mostly hemicelluloses and cellulose—glucose chains stacked into crystalline fibrils, largely impenetrable to water or enzymes. Lignin, a more complex macromolecule, makes up much of the rest. Wood, one potential source of lignocelluloses, for example, typically consists of 40–50% cellulose, 25% hemicelluloses and 25–30% lignins; the rest is made up of cell wall proteins and pectins. One approach to extract fuel from lignocelluloses borrows technology from the coal and oil industry to convert plant material into ‘syngas,’ mainly carbon monoxide and hydrogen. Syngas is then converted into ethanol or biodiesel by the Fischer-Tropsch process, invented in Germany in the early 1900s, usually using iron or cobalt catalysts. Another approach, popular in the United States, relies on enzymes and fermentation to produce cellulosic ethanol. Fig.16 Composition of Cell Wall Why is cellulose so difficult to turn into fermentable sugars? • Starch is a storage polysaccharide designed by nature as a food reservoir • Cellulose is part of a lignocellulosic composite designed by nature to resist degradation Synthetic biology for biofuels  Synthetic biology has rapidly grown out of genetic engineering into a new science with new risks.  Genetic engineers merely modify existing organisms by splicing a few genes from one organism into another.  Synthetic biologists have far greater ambitions. They aim to design entirely new life forms with pre-selected functions, like the microbes which will digest trees and grasses and ferment them into biofuels, or the algae which will harvest solar energy to produce oil. Synthetic biology.  Still others aim to construct synthetic life forms entirely from scratch using DNA synthesisers, “the biological equivalent of word processors”.  The world’s first self-replicating synthetic genome, announced by the J. Craig Venter Institute on 20 May 2010, was constructed in this way.  Venter described it as “the first self-replicating species we’ve had on the planet whose parent is a computer.”  Source: Nicholas Wade, ‘Researchers Say They Created a “Synthetic Cell”’ The New York Times (New York, 20 May 2010) accessed 5 August 2011. Recombinant DNA technology is being employed for modification of plant cell wall components to increase biofuel yields. The model describes the outline of recombinant expression of cell wall-targeted enzymes or proteins in transgenic plants. Fig.17. Modification of plant cell wall components to increase biofuel yields. The model describes the outline of recombinant expression of cell wall-targeted enzymes or proteins in transgenic plants. Fig.18. The interest of the end users is increasing globally in use of biofuels. Metabolic engineering Recent advances in synthetic biology and metabolic engineering suggest that, rather than limiting ourselves to fuel molecules provided by nature, we should engineer microorganisms to produce new fossil-fuel replacements (Keasling 2008). Such products, which might include short-chain, branched-chain and cyclic alcohols, as well as alkanes, alkenes, esters and aromatics. To produce longer-chain alcohols and alkanes, it should be possible to tap into the fatty acid pools of nearly any organism. Sequential reduction, decarboxylation or decarbonylation followed by reduction of fatty acids to alcohols and alkanes could yield valuable fuel candidates. It is also possible to esterify fatty acids with alcohols from any number of sources to produce candidate biodiesels. Isoprenoid biosynthesis offers an even richer source of next-generation biofuels. With the ability to produce branched-chain and cyclic alkanes, alkenes and alcohols of different sizes with diverse structural and chemical properties, this pathway could produce fuels or precursors to gasoline, diesel and jet fuel additives or substitutes. Efficient production of isoprenoid precursors has been engineered in E. coli and Saccharomyces cerevisiae, and many different isoprenoids have been produced using these engineered hosts. (Atsumi et al. 2008) Biofuels produced from Algae and Cyanobacteria :  Further down the pipeline are biofuels produced from photosynthetic algae and cyanobacteria.  This involves growing, harvesting, and then heating or chemically treating algae to recover the oil inside their cells.  Algae that continuously secrete oil through their cell walls are in development. 4. DISCUSSION: Biomass resources are potentially the worlds largest renewable energy source – at an annual terrestrial biomass yield of 220 billion oven dry tonnes. Biomass conversion to fuel and chemicals is once again becoming an important alternative to replace oil and coal. Biodiesel from the rape seed oil methylester (RME) produced by farmer cooperatives is about 2000 t RME per year. A large facility of 15000 t RME per year is located at the oil mill at Bruck/Leitha in Austria. RME is excellent substitute for diesel. Already, European countries, mainly France, Italy, Germany and Austria are leading in biodiesel production, nearing 500,000 tons in 1997 out of which 250,000 was produced in France. (Staff 1998) The production capacity of biodiesel in Germany was fully utilized in1997, the sold quantity amounting to roughly 100,000 t. World production of biofuel was about 68 billion L in 2007. The primary feedstocks of bioethanol are sugarcane and corn. Bioethanol is a gasoline additive/substitute. Bioethanol is by far the most widely used biofuel for transportation worldwide. About 60% of global bioethanol production comes from sugarcane and 40% from other crops. Biodiesel refers to a diesel-equivalent mono alkyl ester based oxygenated fuel. Where we stand today: • First generation biofuels – bioethanol from cereal • Crops and biodiesel from oilseeds – increase greenhouse gas emissions. - Land use change - deforestation for plantations. • These biofuels - fertilizer-intensive - Drives soil erosion and eutrophication of aquatic ecosystems • They compete for agricultural land - Pressure on food availability. • Challenges in Ensuring - poor retain access to land and receive a fair share of the benefits from biofuels  Several candidate species for future biofuel production show the traits of invasive species.  Brazilian sugarcane-to-ethanol producer Cosan announces a $12 billion joint venture with joint venture withOil giant Royal Dutch Shell.  Synthetic microorganisms released into the environment, accidentally or intentionally, could share genes with other microorganisms through horizontal gene transfer or evolve beyond their functionality.  Production of advanced biofuels.  Shell will contribute to the venture its equity interests in two advanced biofuel developers: Codexis and Iogen, in which the oil giant has 14.7% and 50% stakes, respectively.  Codexis, based in Redwood City, California, is developing enzyme products to use as biocatalysts to convert biomass into fuels.  Ottawa, Ontario, Canada–based Iogen is developinga cellulosic biomass-to-ethanol conversion process that combines thermal, chemical and biochemical techniques “One hypothetical, worst-case scenario is a newly engineered type of high-yielding blue-green algae cultivated for biofuel production unintentionally leaking from outdoor ponds and out-competing native algal growth. A durable synthetic biology-derived organism might then spread to natural waterways, where it may thrive, displace other species, and rob the ecosystem of vital nutrients, with negative consequences for the environment”. Hydrocarbons from plants Some of the laticiferous plants identified by Bhatia et al. (1983) were investigated in detail at Jaipur (for review see (Kumar 1995; Kumar 2000; Kumar 2001a) . Certain potential plants were selected and attempts were made to develop proper agro- technology for their large scale cultivation. Initially work was initiated at 5 ha and subsequently extended to the 50 ha EPDPC. Growing Interest By End Users • Pratt&Whitney Canada: investigating biofuels from algae and Jatropha. • Boeing: algae will be 1º feedstock for aviation biofuels within 10-15 years. • Air France-KLM: agreement with Algae-Link to procure algae oil to be blended with conventional jet fuel. • JetBlue, Airbus, Honeywell and the International Aero Engines partnership: replace up to 30 percent of jet fuel with biofuels produced from algae and other non-food vegetable oils. • Air New Zealand: test Jatropha as a fuel Targets now promoted by the US Department of Energy (DOE) call for 30% of today’s fuel use to be supplanted by 2030 with ethanol— 60-billion gallons of it each year. Triglycerides from oil seed crops can’t come close to meeting U S diesel demand (60 billion gal/yr) as agricultural productivity can’t be diverted from the food supply. Under that scenario, much of the fuel is slated to come from lignocelluloses, which the DOE expects will become cheaper to make as the technology improves. Researchers at the US National Renewable Energy Lab (NREL, Golden, Colorado) estimate the capital cost of a cellulosic biomass–converting facility which would yield 50-million gallons of ethanol per year, at $215 million—about three- to fourfold more expensive than a corn grain ethanol plant with the same yield. According to the US Renewable Fuels Association, a trade association for the US ethanol industry, annual production totaled 3.9-billion gallons last year, up 15% from 2004. But estimates indicate that new plants to produce another 1.9-billion gallons a year are under construction and will come online by 2007. However at present, less than 1% of the United States’ fuel stations sell ethanol. Targets now promoted by the US Department of Energy (DOE) call for 30% of today’s fuel use to be supplanted by 2030 with ethanol—60-billion gallons of it each year. Despite the fact that biomass represents about one third of the energy consumption in developing countries, it is not taken very well into account in energy studies. A set of factors explain the slow growth on the biomass utilization . They include: 1. High costs of production 2. Limited potential for production 3. Lack of sufficient data on energy transformations coefficients. 4. Low energy efficiency 5. Health hazard in producing and using biomass. In the large scale use of biomass for energy risks are insecurity in raw material supply and prices, doubts about adequate quality assurance and hesitance for a wider acceptance by the diesel engine manufacturers, missing marketing strategies for targeting biodiesel differential advantages into specific market niches and last not least missing legal frame conditions similar to the clean air act in the USA. 5. ACKNOWLEDGEMENTS The constant encouragement of Professor Dr. K-H. Neumann is gratefully acknowledged. His frequent visits witnessed the development of the wasteland into greenland. The support from Professor Dr. Sven Schubert Institut fur Pflanzenernaehrung der Justus Liebig Universitat Giessen, Germany and research grant by Alexander von Humboldt Foundation is gratefully. 6. REFERENCES: • Alexandratos, N. World agriculture: towards 2010: an FAO study, Food&Agriculture Org.; 1995. • Atsumi, S., Hanai, T. and Liao, J. C. 'Non-fermentative pathways for synthesis of branched-chain higher alcohols as biofuels', Nature, 2008; 451: 86-89. • Bhatia, V. K., Srivastava, G. S., Garg, V. K., Gupta, Y. K., Rawat, S. S. and Singh, J. 'Study of laticiferous (latex-bearing) plants as potential petro-crops', Fuel, 1983; 62: 953-955. • Calvin, M. 'Petroleum Plantations for Fuel and Materials', Bioscience, 1979; 29: 533-38. • Garg, J. and Kumar, A. 'Studies on biomass production and improvement in biocrude content', in Workshop on Petrocrops, New Delhi, 1986; 69-81. • Garg, J. and Kumar, A. Effect of growth regulators on the growth, chlorophyll development and productivity of Euphorbia lathyris L., a hydrocarbon yielding plant. In:Progress in Photosynthesis Research. , The Netherlands + Martinus Nijhoff Publishers; 1987a. • Garg, J. and Kumar, A. 'Effect of growth regulators on the growth, chlorophyll development and productivity of Euphorbia lathyris L.A hydrocarbon yielding plant. 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Eds.)', Elsevier Applied Science, London, 1990a; I: 1.527-1.531. • Garg, J. and Kumar, A. 'Improving the growth and hydrocarbon yield of Euphorbia lathyris L. in semi-arid regions of Rajasthan. In: Biomass for Energy and Industry, Eds. Grassi, G., Gosse, G. and Santos, G. (London + Elsevier Applied Science)', 1990b: 1.527-1.531. • Johari, S. and Kumar, A. 'Effect of N, P and K on growth and biocrude yield of Euphorbia antisyphilitica', Ann. Arid Zone, 1992; 31: 313-314. • Johari, S. and Kumar, A. ' Influence of growth regulators on biomas and hydrocarbon yield from Euphorbia antisyphilitica (Zucc)', J. Phytol Res., 1994; 7: 65-68. • Johari, S., Roy, S. and Kumar, A. 'Influence of edaphic and nutritional factors on growth and hydrocarbon yield of Euphorbia antisyphilitica Zucc. In: Biomass for Energy and Industry. Eds. Grassi, G., Gosse, G. and Santos, G. (London + Elsevier Applied Science)', 1, 1990: .522-1.526. • Johari, S., Roy, S. and Kumar, A. 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In: Bioenergy 84 Vol.4, Bioenergy in developing countries. , London + Elsevier Applied Science Publishers; 1984. • Kumar, A. Prospects of raising latex bearing plants in semi-arid and arid regions of Rajasthan. In: Biomass for Energy and Industry (Eds G. Grassi, G. Gosse and G. dos Santos) London; 1990. • Kumar, A. 'Laticifers as potential bioremedients for wasteland restoration', J. Environment&Pollution 1994; 1: 101-104. • Kumar, A. 'Cultivation of hydrocarbon yielding plants in Rajasthan as an alternative energy source', J. Environment&Pollution, 1995; 2: 67-70. • Kumar, A. Biomass energy crops of semi arid regions of India and their energy potential. In: Biomass for Energy and Industry, C A R M E N, Germany; 1998. • Kumar, A. Hydrocarbon yielding plants and future prospects of biotechnological approach. In : Recent Advances in Biotechnology, New Delhi + Panima Publisher; 2000. • Kumar, A. 'Bioengineering of crops for biofuels and bioenergy. 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'Effect of organic manures on growth and hydrocarbon yield of Euphorbia lathyris L. J.' Environment & Pollution, 1995; 2: 207-210. • Kumar, A., Johari, S. and Roy, S. 'Production and improvement of bioenergy sources.' J. Indian. Bot. Soc., 1995; 74A: 233-234. • Kumar, A. and Roy, S. 'Biomass resources of semi arid regions: Production and improvement of wood energy source. In: Biomass for energy and environment (P. Chartier, G.L.Ferrero, U.M. Henius, S.Hultberg, J. Sachau, M.Wiinblad, eds.) ', Elsevier Science, U.K, 1996: 721-724. • Rani, A. and Kumar, A. 'Effect of edaphic factors on the growth and physiology of Pedilanthus tithymaloides Var. Green', Journal of Environment and Pollution, 1994; 2: 5-8. • Rani, A. and Kumar, A. 'Micropropagation of Pedilanthus tithymaloides var. Green, a hydrocarbon yielding plant. ' J. of Phytol. Res, 1994 7: 107-110. • Rani, A., Roy, S. and Kumar, A. Eds. Grassi, G., Gosse, G. and Santos, G. Influence of morphological and environmental factors on growth and hydrocarbon yield in Calotropis procera. In: Biomass for Energy and Industry. , London + Elsevier Applied Science; 1990. • Rani, A., Roy, S. and Kumar, A. (Eds.H.L. Sharma and R.N. Sharma)Effect of salinity stress or growth and hydrocarbon yield of Pedilanthus tithymaloides variety Green (Linn.) Point. In: Proc. Bio-Energy for Humid and Semi-humid Regions New Delhi; 1991. • Roy, S. Growth and productivity of non conventional energy sources: J.curcas In: Biomass for energy and environment. (P. Chartier, G.L.Ferrero, U.M. Henius, S.Hultberg, J. Sachau, M.Wiinblad, eds.), Elsevier Science, U. K; 1996. • Roy, S. and Kumar, A. ' Prospects of wood energy production in semi-arid and arid regions of Rajasthan. In: Proc. Biomass for Energy and Industry. (G. Grassi, G. Gosse and G. das Santos, eds.)', Elsevier Applied Science, 1990; London: 2.1153-2.1156. • Roy, S. and Kumar, A. 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    Comments

    the article at the link below is a must read before any serious discussion on ethanol

    http://www.stgeorgeutah.com/news/archive/2012/05/04/op-ed-counterpoint-t...