Jatropha curcas or physic nut is a large multi-purpose oil yielding shrub.

The plants reach a height of three meters within three years. Jatropha does not thrive in wetland conditions. The plants grow luxuriantly even in marginal, stony and sandy tracts. It can be grown in the hedges at a spacing of 15 to 20 cm by 15 to 25 cm in single or double rows for conserving soil.

For commercial plantations, the crop can be grown at an espacement of about 2 meters by 1.5 meter or even 3 meter by 3 meter. A dry climate has been found to greatly improve the oil yields of the seeds. However, three to four irrigations a month during summer will help in improving the growth of the plants. Plants raised from the seeds take 3 to 4 years to yield seeds. However, the stem cuttings with rapid growth will start yielding in less than a year of planting. Seed production varies from 0.4 tonnes initially to 10 tonnes per hectare per year, as the bushes grow larger.

The plants respond well to the addition of small quantities of calcium, magnesium and sulphur, it does well when rich organic nutrition is provided. Mycorrhizal association have been observed, and they are known to aid the plants growth under conditions where phosphorus availability is low.

The extraction process standardised for edible oils can be adopted for extracting Jatropha curcas seed oil also. The filtering mechanisms have been modified, and other parameters for preparing the matured seed for extracting oil have been standardized. A by-product of the bio-diesel production, glycerin can be used for making soaps in the rural cottage industries.

Jatropha absorbs carbon from the atmosphere and helps in preventing soil erosion and desertification. It provides a clean fuel with no emissions, and offers plenty of jobs in the rural areas.

India is home to a billion people, about a sixth of the world human population. The process of economic liberalisation and the 'opening up' set in motion in early 1990s have resulted in India's approximately 300 million strong middle class becoming increasingly exposed to the world market of consumer goods. In fact India, with a GDP of about USD 475 billion, is already the fifth largest economy in the world based on Purchasing Power Parity according to World Bank figures and a major future market. Seventy two percent of India's people live in rural areas and about 70% earn their livelihood from agriculture.
One factor that has decelerated India's rate of economic development is the need to import about 70% of its petroleum demand.

Even with all the progress that it has achieved over the past years there is still the problem of poverty and underdevelopment, with about 35% of the total population still under the poverty line. Declining agricultural productivity, and lack of mobility and proper access for produce of remote areas to major markets have compounded the problem.
Indiscriminate land use over several years has resulted in extensive degradation of agricultural land in the country. Of the estimated 130 million hectares of wasteland in India about 33 million hectares are available for reclamation through tree plantation according to Planning Commission of India figures.

Production of bio-diesel from Jatropha plantations hold potential for at least partly remedying these stated problems. Jatropha curcas plants grow on poor degraded soils and are able to ensure a reasonable production of seeds with very little inputs. It is not grazed by animals and is highly pest and disease resistant. Time taken for nut yield is between 2 and 5 years based on soil and rainfall conditions. Yields vary from 0.5 to 12 t/yr based on soil and rainfall conditions (Makkar and Becker, 1999). An average seed production of about 5 tonnes per hectare can be expected under optimum conditions. The seeds contain 55-60% oil that can be converted into bio-diesel by transesterification. A yield of 0.75 to 2 tonnes of bio-diesel could be expected per hectare per year from the fifth year onwards (Fiodl and Eder, 1997). Jatropha plantations yield over long periods of time.

The parameters of Jatropha bio-diesel presented here are similar to the bio-diesel from rapeseed oil, currently widely used in Europe. Bio-diesel could be used in any automobile brand which has been approved for its use by the manufacturers without any modification to the engine or accessories.

Important advantages of using bio-diesel

• The bio-diesel molecules are simple hydrocarbon chains, containing no sulfur, or aromatic substances associated with fossil fuels.

• They contain higher amount oxygen (up to 10%) that ensures more complete combustion of hydrocarbons .

• Bio-diesel almost completely eliminates lifecycle carbon dioxide emissions. When compared to petro-diesel it reduces emission of particulate matter by 40%, unburned hydrocarbons by 68%, carbon monoxide by 44%, sulphates by 100%, polycyclic aromatic hydrocarbons (PAHs) by 80%, and the carcinogenic nitrated PAHs by 90% on an average. The use of bio-diesel complements the working of the
  catalysator and can help a current EURO-1 motor attain the EURO-111 standards.

Jatropha plantations provide the following benefits in addition

• High cost of production: will eventually solve itself when large-scale production and use starts. Also, the price of petro-diesel does not take into account its actual cost; the US General Accounting office estimated that the true cost for a barrel of crude oil to the US citizen is more than USD 45 (current market price USD 21) when environmental and military costs are included.
  

• Modifications are required to the automobiles for use of bio-fuel: many automobile brands are currently marketed ready for use of bio diesel. More information could be obtained from the manufacturers themselves, a quick reference list.
  

• High CFPP (cold filter plugging point) values and hence solidification and clogging of the system at low temperatures: this problem occurs only in places where the temperature goes down to around 0°C, even here the problem is currently solved by adding additives.