1.1 Biomass currently supplies about one third of the developing countries energy varying from about 90% in countries like Uganda, Rawanda and Tanzania, to 45 percent in India, 30 percent in China and Brazil and 10-15 percent in Mexico and South Africa mostly in traditional highly inefficient ways. Traditional uses of biomass in developing countries represents the bulk of energy; (900 to 1000 Mtoe, (38.42 EJ). The crucial questions are whether the two billion or more people who are now dependent on biomass for energy will increase. The fact that 90 percent of the worlds population will reside in developing countries by about 2050 suggests that biomass shall remain an important source of energy in future also. Biomass indeed a "renewable" resource as long as agriculture does not deplete soil fertility and forestry obeys some "sustainability rules" dating back to 18th century when the German forester von Carlowitz coined the notion of "sustainable forestry" ("nachhaltige forstwirtschnaft). Biomass utilization could thus contribute to a "closed cycle". It is apparent that significant increase of the biomass harvest of developing countries should not be considered a sustainable option for alleviating other environmental problems as for example resource scarcity or global warming. Thus if biomass utilization should play a major role in environmental policy its efficiency has to be increased. The biomass harvested should be used as effectively as possible in order to contribute to as such as possible to the substitution of environmentally detrimental materials and fuels. Besides this the availability of the land for raising the biomass is another important factor. If the biomass has to be grown on the aerable land then the competition and costs of food vs fuel production shall be grossly unbalanced India with its vast expanse of wasteland unsuitable for agricultural production (nearly 180 million ha) could be considered for economically viable production of biofuels. 1.2 As the number of people continues to rise, the demands for the natural resources of the earth will also rise. Therefore, the strain on world resources continues to grow. One of the principal natural resources besides food are the energy resources. Almost 95% of the energy is directly or indirectly derived from plants and stored under the earth in the from of coal, petroleum & natural gas. 1.3 Even by liberal estimates these fossilized fuel resources are not going to last longer (1). Calotropis procera is a potential energy resource, containing latex, an emulsion of oil and water. The oil fraction looks, feels and acts like crude oil (1). The latex is converted into petroleum like substances by using hydro-cracking in presence of zeolite catalysts (1). By some of the estimates majority of the compound in latex consists of terpenoids and sugars. 1.4 Some of the options available for producing liquid fuel from biomass, is the direct extraction of low molecular, non-polar constituents from plants. (2), (3) & (4). The material termed biocrude, is a complex mixture of liquids, triglycerides, waxes, terpenoids, phytosterols and other modified isoprenoid compound that can be catalytically upgraded and used as liquid fuels and chemical feed stocks. The object of the present investigation was to examine effect of height and weight of the plant for their hydrocarbon yield and productivity under semi-arid condition or Rajasthan. Calotropis procera is most potential plant of semi-arid region yielding biocrude. 2. Materials and Methods - 2.1 During the present investigation Calotropis procera (Ait) R. Br. of family Asclepiadaceae was screened for the organic extractables using hexane extraction procedure. The plant material was collected from Rajasthan Univ. Campus, Jaipur. 2.2 The plant is one of the most abundantly available plants in the semi-arid and arid conditions of the country. It is an important member of traditional herbal medicine in every home of India. Traditionally the leaves of aak are warmed and tied around any body organ in pain. It practically useful in backache and in joint pains, warm leaves also relieve from stomachache if tied around. Inhalation of burnt leaf cures headache. The traditional folk healers use the milky latex of aak for several ailments. Leaf latex if applied on fresh cut, stops bleeding immediately. Recent investigations have been found that the alkaloids calotropin, calotaxein and uskerin is stimulant to heart. Flowers and roots are used in Ayurvedic medicine. Plant is anthelmintic, the ashes act as an expectorant. the leaves are applied hot to the abdomen to cure the pain inside. flower is tonic, antisialagogue, appetizer., and cures stomachache piles and asthma. Flowers are believed to have detergent properties so they are given in cholera. The fresh roots are used as a toothbrush and are considered by pathans to cure toothache. Aak is an alternative, tonic and diaphoretic, in large dose emetic. Root bark useful for treating chronic cases of dyspepsia, flatulence, constipation, loss of appetite, indigestion and mucus in stools. Leaves are used against guinea worms. Flowers useful in asthma. Seed oil is geriatric and tonic. Green copra is given in asthma. Plant used in spleen complaints, rheumatism, epilepsy, hemiplegia, sores, small pox and protracted labor. Properties and uses of Aak are the same as of C. gigantea The plant is used as source of fuel as direct burning the dried plant material. However present paper suggests its use as a bio-energy source. 2.3 Though distributed allover India it is grows in milder climatic conditions in south and north east and west. In Rajasthan it grows wild in the Udaipur division. Aak is purgative, anthelmintic alexipharmic; cures leprosy, unclers, leucoderma, tumors, piles, diseases of spleen, liver and abdomen. Juice is anthelmintic and laxative; cures piles and kapha. Dried and powdered plant is taken with milk acts as a good tonic. Action is similar to Digitalis on the heart. Root bark and juice have emetic, diaphoretic, alternative and purgative properties. It is used in dysentery and as a substitute for Ipecauantha. It is regarded as a great remedy in syphilitic afflictions and is called "Vegetable mercury". In intermittent fevers it is used as antiperiodic and diaphoretic. It cures asthma and syphlis. In form of paste applied to elephantiasis. Tincture of leaves is use in intermittent fevers. Latex is bitter, healing, oleagenous and irritant, used in combination with Euphrobia neerifolia as purgative. Flowers are sweet, bitter, digestive, tonic, stomachic, anthelmintic, analgesic, astringent; cure inflamations, tumours, kapha and are good in ascites. 2.4 The Calotropis procera was collected from different districts of Rajasthan falling under various agroclimatic conditions and initial investigations on the anatomy, growth and productivity were carried out on naturally occurring plants from the Jaipur districts. Samples from different places are under detailed investigation at IIP Dehradun. Here the preliminary results are presented. 2.5 The plants were cut from the above ground and their fresh weight was determined. The plants were dried in shade for three days or more separately according to their height and fresh weight, till their dry weight become constant. The dried plant material was finally powdered. Ten g. of the powdered plant material was packed in thimbles made from whatman filter paper No. 1. The extraction was done using hexane solvent systems in soxhlet apparatus. Initial extraction was done in hexane for 18h. in a soxhlet apparatus at 40-450C. The hexane extractables were collected after 18h and excess of solvent was removed by distillation at 450C. The fractions were transferred to the previously weighed vials and were finally dried at 400C for 24h. or till the weights became constant for determination of bio-crude. 3. Results and discussions : 3.1 Calotropis procera has greater biocrude contents as compared to C. gigantea. Results are presented in Table-1. 3.2 The percent dry weight ranged from 12.05 to 23.45 percent. Maximum total extractable was recorded from the plant having 122 cm. height and fresh weight was 2.4 kg. Maximum percent biocrude of stem was 12.67%. 3.3 Maximum bio-crude obtained from stem was followed by leaves and flowers (Fig. 1). Thus the relative distribution of latex was dependent on plant parts utilised. 3.4 The world derives a fifth of its energy from renewable resources - 13-14 percent from biomass and 6 percent from hydro. In the case of biomass this represents about 25 mboe/day (55EJ/year). In developing countries it is the most important source of energy (35 percent of total ) for the three quarters of the worlds population which lives in them. In some developing countries biomass provides 90 percent or more of total energy. First efforts to cultivate hydrocarbon producing plants for fuel production were made by Italians in Ethiopia had limited success. Presently the largest fuel program is in Brazil where government currently spends a considerable amount on subsidizing the production of alcohol, mostly from biomass of sugarcane. Production was estimated to increase so much that around 11 to 14 million cars will use alcohol (with gasoline) by the year 2000 (5). Recently about 30 thousand tones of rape biofuel yearly is produced at the industrial chemical factories in Poland (6). The important sources investigated during last years from 1993 to 1996 included rapeseed oil, rape methylester, bioethanol from potatoes, sugar beet and wheat. Agricultural/forestry residues : Straw, wood residues cut grasses from landscape cultivation. 3.5 The liquid bioenergy carrier (RME) rapeseed oil fatty acid methylester) is obtained from rapeseed. The advantage of liquid energy sources are best utilized as fuel for motor vehicles. RME can be used in conventional diesel engines in cars as substitute for diesel fuel (7). The 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, mission marketing strategies for targeting. Biodiesel differential advantages into specific market niches and last not least missing legal frame conditions similar to clean air act in the USA. The present article shall present systematic development in the area of production of biodiesel and future prospects. 3.6 However in Indian scene the hoice of plant has to be limited to those plants which do not compete with the aerable land requirement and Calotropis procera is one such plant which can grow in wasteland. India has a land mass of approximately 329 million ha. Approximately 175 million of land is degraded land with productivity below its potential. 3.7 The present investigations suggest the optimal yield conditions. Detailed investigations are in progress under field conditions in vivo and in vitro and results shall be presented in subsequent papers. Acknowledgement : A financial support received from Department of Biotechnology, Govt. of India, is gratefully acknowledged. REFERENCES (1) Calvin, M. 1984. Renewable fuels for the future, J. Appl. Biochem. 6: 3-18. (2) Calvin, M. 1979. Petroleum plantations for fuel and materials. Bioscience. 29 : 533-537. (3) Garg, J. and A. Kumar. 1986. Studies on biomass production and improvement in biocrude content. Proc. Workshop on petrocrops. New Delhi. pp. 69-81. (4) Kumar, A., S. Johari and S. Roy. 1995. Production and Improvement of Bio-energy sources. J. Indian. Bot. Soc. 74A : 233-244. (5) Hall, D.O., and P.J. De Groot. 1986. Plant photosynthesis for fuels and chemicals, Vol. 1. In: Proc. of the International Congress on Renewable Energy Sources (Terol Sed) CSZC Serrano Madrid, Spain. pp. 2-13. (6) Grazybek, A., M. Rogulska and A. Roszkovski. 1996. Rope biofuel production in Poland overview of actual situation and perspectives : Chartier et al. 9Eds.). Biomass for Energy and Environment. Permagon Elsevier Science. Oxford pp. 343-348. (7) Kaltschmitt, M. G.A. Reinhardt and T.N. Stelzer. 1996. LCA of biofuels under different environmental aspects. In : Chartier et. al. (Eds.) Biomass for Energy and Environment, Permagon. Elsevier Science. Oxford. pp. 369-386.