JATROPHA CURCAS: A POTENTIAL PLANT FOR BIO-FUEL
JATROPHA CURCAS: A POTENTIAL PLANT FOR BIO-FUEL
SHIKHA ROY AND ASHWINI KUMAR
Bio-Technology Lab Department of Botany
University of Rajasthan, Jaipur - 302 004
Energy Plantation Demonstration project and Biotechnology Center.
Email. msku31@yahoo.com
ABSTRACT: Jatropha curcas L. (Euphorbiaceae) popularly called Ratanjot is a small tree bearing oil-seed grown on wastelands or hedges in India and tropical America. It is thought to have originated in either Peru (where the only fossils have been found) or Mexico and has become naturalized throughout semi arid Asia and Africa. The oil can therefore be utilized as energy substitute. In times to come it can be competitive with high price of diesel fuel. A large amount of investigations have been carried out on various aspects in our laboratory. It can regenerate naturally by seeds for instance in the monsoon season in Rajasthan, near Udaipur in the so-called Jatropha belt. In dry areas it can only develop from seeds or from cutting watered regularly but without excess. It can also be propagated in the nursery or in the field from about 60cm long cuttings.
1. INTRODUCTION
1.1 Jatropha curcas Linn is a plant that can tolerate salinity and can grow well in all types of soils. It is well suited for foothills as well. Once established it can grow in adverse conditions. Considering the above facts various experimentations have already been conducted in Jaipur on J. curcas regarding its adaptability, growth and yield [1-5].
1.2 Habit and Habitat:
Jatropha curcas is a shrub or tree that grows to a height of 1.5 to 8m.The growth, height, branching, amount of flowering and fruiting, fruit size and yield are also variable according to races; as well as, to climatic and edaphic conditions, to some extent[6,7].
2. Agrotechnology for Jatropha curcas cultivation
2.1 Propagation : It can be propagated in the nursery or in the field from about 60cm long cutting [6,7]. Seeds can easily be stored in dry conditions and thus maintain high germinative capacities for several years.
The cuttings raised during the winter months of October-February having average low temperature (minimum 7-10ºC and maximum 12-22ºC), showed poor growth and sprouting[6].
2.2. The growth and biomass yield :
Fruiting : GA3 (0.3mM) when sprayed on the flowers, the fruit formation increased. It also increased the average seed weight. However in contrast the number of seed per fruit was reduced [6]
Composition of oil : The analysis of J. curcas oil was carri4ed out from the seed obtained after GA3 spray on flowers and control. From the analysis it is evident that there is a shift of oleic acid to linoleic acid (unsaturated fatty acid) in sprayed flower seeds [6]
3. Productivity of J. curcas in global context :
3.1 production per plant varies between 1.5 to 2.0kg. Seed production is attributed to precipitation that ranges from 0.4 tons per hectare to over 12t/ha/a [8]In Mali : [9]reported productivity of J. curcas hedges in Mali from 0.8 to 1.0kg of seed per meter of fence which is equivalent to 2.5 – 3.5 tons per hectare per yeart. Assuming an extraction rate of 30% and an efficiency of the plant oil cooking stove of 50% the total cooking energy for a person could be covered by 55 liter of curcas oil per year. In Mali this quantity can be produced on an area of about 0.06ha or with a hedges of 175m in length. The oil of Jatropha is currently used in Mali for the manufacturing of soap, for medicinal purposes and experimentally as a substitute for diesel engine fuel [9] The fresh seeds harvested in the first year were an average of 93kg per hectare. The yield obtained from 15 pilot sites established during 1991 all across Nicaragua have been between 15 and 20 kg of fruits from third year, and over 30kg of fruits annually from the sixth year. This resulted in annual seed yield of over 5,000 kg per ha. The highest yield recorded so far have been from a hedgerow 8 yr old and 6m tall which was about 9,000 kg per ha per year [10].
3.2 In India : Extensive survey from Udaipur in Rajasthan indicate an average seed yield of respectively 0.125; 0.25; 0.45 and 0.70 ton per ha in rainfed conditions in 2,4,6 and 8 year plantations and 0.3, 0.6, 0.8 and 1.05 tonnes of seeds per ha in irrigated plantations[11].. Irrigated plants flower twice a year, but with a lesser winter flowering, whereas nonirrigated plants flowered mostly in summer. This is comparable to the yield reported in Mali [9] with 1 kg of seeds per meter of hedges (about 1 tonne of seeds per km) in rainfed conditions.
3.3 Seed and oil yield of Jatropha curcas maximum recorded in Rajasthan are 25/ha/yr and 688kg oil/ha/yr respectively at 75% field capacity irrigation and 1.9t/ha/yr. and 632 kg oil/ha/yr at 40% field capacity (oil extracted chemically)[12]. Moreover under rainfed conditions also seed yield was 1.26t/ha/yr with 404kg oil/ha/yr., demonstrated less water requirement for optimum yield. Seed yields are maximum in sun exposed plants but biomass is least in comparison to shade plants [12]
4. OILCAKE
4.1 A by-product of extraction of J. curcas oil is the oil seed cake. In comparison to the values from other organic sources (cowdung manure, compost, other manure and oil cake) oil seed cake from J. curcas provides essential soil nutrients at comparable levels Oil cakes from Jatropha curcas are useable as feed for livestock due to toxicity. It may therefore be used as source of soil organic matter and soil nitrogen or burning of the seed oil cake as a substitute of wood or charcoal for cooking and heating
4.2 The protein remains in the oilcake may however be detoxified by heating up the latter to 140ºC in a conditioner [13]
5. Jatropha curcas as diesel substitute :
5.1 These are the problems associated with the differences in chemical structure between vegetable oils and diesel oil.
5.2 Comparison and suitability of Jatropha curcas oil over other vegetable oils as diesel substitute.
5.3 Jatropha curcas compares well against other vegetable oils. The fuel properties of J. curcas seed oil have been compared with standard specification of diesel oil. Based on its similarity it has also been used as diesel substitute in engines for jeep, pump, etc.). However as the production costs of the oils is relatively higher it may not be economic at the moment, but necessary in times to come, when natural resources will be depleted to a danger point, this will serve as an alternative source.
5.4 Jatropha compares well against other vegetable oils and more importantly to diesel fuel itself in terms of its fuel rating per kilogram or ha of oil producing. It should be noted that oil of other species of the genus Jatropha exceeds. J. curcas oils energy content and in some cases even exceeds diesel fuel’s rating. This is important when considering the potential of cross breeding for improvement of Jatropha for fuel crop.
5.5 The high viscosity of J. curcas oil contributes to the formation of carbon deposits in the engines, incomplete fuel combustion (particularly under low loads) results in a reduction in the life of an engine. The higher solidifying point of curcas oil limits usage in cooler climates and the higher flash point leads to ignition problems. The carbon residue and sulphur content in curcas oil has resulted in hydrocarbon and carbon monoxide emissions which exceed those of diesel oil under certain conditions but sulphur emissions remain negligible when compared to diesel.
5.6 The easiest method to overcome engine problems with viscosity, sticking or gumming is blending of J. curcas oil with diesel. Generally only 10-20% of crude vegetable oil can be blended with diesel to obtain reasonably results. However, further processing also solves many engine problems. The removal of triglyserides chemically by transesterification lowers the oil’s viscosity [10]
6. Engine tests with Jatropha curcas oil :
6.1 Performance testing using crude curcas and diesel oils in Thailand was conducted using a Kubota four stroke cycle diesel engine (7hp/2,200 rpm with a single horizontal piston, a cylinder volume of 400cc and water cooling system, usually run on LPG). Fuel consumption was almost identical for both fuels and the engine ran smoothly on curcas oil, even during acceleration. Fuel pump overlarger fuel filter. Similarly Yanmar diesel engine .Emissions were measured using both fuel types on a 7hp Kubota diesel engine and an 18-hp Yanmar diesel engine. Little difference in perdcent smoke and carbon monoxide concentrations were found on average. The values were also lower than the accepted values as per the standard specification of the Environment board. The sulphur dioxide concentrations were also not detected in emission from the engines run on curcas oil but 125 ppm sulphur dioxide were found in the exhaust gas of the diesel engine run on diesel oil[14]. Moreover, after 1,000 hours of continuous operation using J. curcas oil, the Kubota diesel engine parts (cylinder, piston, ring, valves, injector, etc.) on inspection were found to have remained in good conditions.
6.2 Another study was conducted in Thailand which assessed the results of road tests using crude curcas oil as fuel in an Isuzu diesel pick-up truck (4 cycle, 1,584 cc, and 94 PS/5, 400rpm). Results from the test with speed up to 100km/hr on the highway determined that at idle the engine exhibited a slight knocking tendency, though odour and carbon monoxide emissions were low and starting performance was strong.
6.3 In tests conducted by in Japan using precombustion type diesel engine fueled by crude curcas oil and diesel blends, it was determined that thermal efficiency and emissions were comparable to engine tests using diesel oil. Problems encountered included filter blockage and carbon deposits (choking) at the injection nozzle and precumbustion chamber.
6.4 Further comparative testing on small farm diesel engines using 100 percent transesterified curcas oil, curcas/diesel oil blends (30:70 and 50:50) and 100 percent No. 2 diesel oil. The curcas/diesel oil blends (30:70 and 50:50) and 100 percent No. 2 diesel oil. The curcas/diesel oil mixture exhibit engine performance which were superior to the curcas oil alone. Performance tests were conducted on Yanmar precombustion type engines (2.9kW/2,400rpm). The blended fuels exhibited consumption rates similar to that of diesel at full load and overload. Results from emission monitoring showed that pure curcas oil and curcas/diesel oil blends produced lower black smoke concentrations than diesel oil alone. Hydrocarbon and carbon monoxide concentrations were highest from the engine running on curcas oil alone although the difference was lessened as the load was increased.
6.5 Generally the 30:70 blend oil performed slightly better (i.e. closer to that of diesel) than the 50:50 blends.
7. Upgradation of Diesel with Jatropha Methyl Ester (JME)
7.1 If 0.45 million metric tonne (MT) of Jatropha Methyl Ester (JME) are sufficient to upgrade 3 million MT of diesel from eastern refineries by 2.5 to 3 Cetan numbers, then only 300,000 hectares of Jatropha curcas would be required, when conservatively assuming that one ha is able to yield 1.5 MT of JME. This area is modest in comparison with the 100 million ha or so estimated to be “wasteland” in India[15].
REFERENCES
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