Jatropha—considered as the best source of biofuel among the various plant based fuel resources, is a drought-resistant, hardy bush of two-three metres that is notable for its ability to grow in poor soils and with rainfall as low as 250 millimetres per year. A low-input crop, the plant has been in use for many centuries across Latin America, Africa and Asia as a natural hedge and for medicinal uses. The plant originates from Central America and is widely cultivated in almost all tropical and subtropical climates. Due to its ability to grow on marginal land, Jatropha does not compete with food crops for land, making it a superior choice to the first-generation biofuels that are largely criticized for contributing to the increase in food prices. Odeveza aims to grow Jatropha only on land which is not ideally suited for food crop production and which has not previously been populated.

Jatropha oil is an environmentally safe, cost effective renewable source of non conven-tional energy and a promising substitute for diesel, kerosene and other fuel oils.

High density plantations of the species can be an ideal way of sequestering maximum solar energy over a short gestation period as Jatropha is fast growing and can be grown successfully on all kinds of barren and unproductive wastelands. Also it does not compete with food crops for land area, on the contrary, the rich organic manure obtained from Jatropha enrich the soils for increased food production.

Botanical Properties of Jatropha

Jatropha is a small tree or shrub with a smooth, gray bark that exudes a whitish coloured, watery latex when cut. Normally, it grows between three and five meters in height but can attain height of up to eight or ten meters under favourable conditions.

Leaves

The plant produces single hollow leaves with three or five angles. The leaves spread along the stem. The top and bottom of the leaf surface is green; however, the bottom surface is typically a paler in colour. The leaf is wife with a heart or an oval shape, generally 5-15 cms long. The leaf is hollow, with stripes, and pointed at the end with a spiral phyllotaxis. The leaf bones just like fingers with five to seven main leafs bones.

Flowers

The petiole length ranges from six to 23 mms. The inflorescence is formed in the leaf axil. Flowers are formed terminally, individually, with female flowers usually slightly larger in size. In conditions where continuous growth occurs—such as in Mozambique—an unbalance of pistillate or staminate flower production results in a higher number of female flowers. Flowers on the Jatropha tree are compound flowers, greenish yellow in colour, with single sex organ and one house. The females flowers outnumber the male flowers by three to five times.

Fruits

The Jatropha tree produces as many as three crops in a year in Mozambique. The main determinants of the number of crops are adequate soil moisture and sufficiently high temperatures. Each inflorescence yields a bunch of approximately 10 or more ovoid fruits. A three, bi-valved cocci is formed after the seeds mature and the fleshy exocarp dries.

Chemical Properties of Jatropha

Analysis of Jatropha seed indicates the following chemical composition:

The oil content is 35 to 40% of seed weight and 50 to 60% of the kernel. The oil contains 21% saturated fatty acids and 79% unsaturated fatty acids. The seeds contain some poisonous chemical with purgative properties rendering Jatropha oil unfit for human consumption. Crude Jatropha Oil (CJO) can be processed to produce a high-quality biodiesel that can be used in a standard diesel car.

Given the high cetane number (51.0 compared to 47.8 for diesel) and energy content (calorific value of 39.7 compared to 42.0 for diesel), CJO can be directly used in a diesel engine with some minimal modifications. Once mixed with methanol to produce biodiesel, CJO shows a significant improvement in its physical qualities.

Cultivation and Care

Jatropha can grow almost anywhere, including wastelands and gravelly, sandy and saline soils. The plant can thrive on the poorest stony soil and grow in the crevices of rocks. It is a tropical species and grows well in subtropical conditions. The tree only requires a minimal amount of water and can withstand long period of drought by shedding its leaves—reducing transpiration loss.

Rainfall

Jatropha need a mere 250 mm of rain a year—though annual rainfall of at least 900 mm can significantly reduce irrigation costs—and requires watering only during its first two years, mostly in the closing days of the dry season. The need for pesticides and other polluting substances is minimized due to the pesticidal and fungicidal properties of the plant.

Temperature

The tree can tolerate a wide range of temperatures, though it cannot grow in frost. The ideal mean annual temperature for the plant range from 11.0 to 28.5^oC. For good germination of seeds, hot and humid weather is preferred.

Soil

For Jatropha, it is crucial to have well-drained soils, ideally with a higher content of sand than is adequate for other agricultural operations. Highly fertile black cotton soils, which hold water and alkaline soils are less than ideal for Jatropha. Once the roots penetrate deeper, Jatropha can also tolerate acidic or salty soils. The pH of soil is an important consideration for the survival of the plant and should ideally be 5.5 to 6.5.

Hydrology

The Jatropha tree is deciduous, losing its leaves in the winter months and during the periods of drought, thereby reducing transpiration appreciably. Though there is relatively little information available about the hydrology of the plant, there is nothing to indicate that the plant should use any more water than bushy hillside vegetation, and could potentially use significantly less than, for example, sugarcane or an area of bush encroachment. In fact, the most authoritative study done on the hydrology of the plant to date—Jatropha curcas in South Africa: An Assessment of its Water Use and Bio-Physical Potential points to a possible increase in streamflow due to planting of Jatropha.

Propagation

Jatropha is usually propagated on mass scale both by seed as well as stem cuttings. For commercial cultivation normally it is propagated by seeds. Well-developed seeds are selected for sowing.

Harvesting and Processing

Jatropha is expected to produce commercial seed yields within 12 to 18 months of planting and to reach maturity in four to five years. The useful economic life of the plant is typically 30 to 50 years.

After the initial harvesting —12 to 18 months from planting— the plant produces two harvests per year. Once ripe, the fruit is collected—either manually or through a semi-automatic process similar to the one used for olive picking—and the seeds are separated from the fruit. The seeds are then crushed to extract vegetable oil, with oil content of approximately 35-40%. The vegetable oil is converted to biodiesel through a transesterification process.