Castor and jatropha oils: production strategies – A review

Abstract

The Brazilian bioenergy matrix is based on four platforms: ethanol, energy forests, residues and co-products and biodiesel. The food-energy dichotomy in the use of edible oils is one factor which has stimulated the search for non-edible oleaginous energy crops, such as many native palms. By the year 2000 Brazil had an annual deficit of 80 thousand tons of castor oil, making necessary to import oil from China and India. After a strong debate the National Program on Biodiesel Production (NPBP) was launched by December 2004. After an initial excessive enthusiasm, small producers being focused in the program, a more mature and realistic planning is undertaken. Production in semi arid lands is being stimulated, mainly castor (Ricinus communis) and Jatropha (Jatropha curcas). Apart from belonging to the same botanical family (Euphorbiaceae), both plants are well resistant to poor soils. Castor plant is well adapted to practically the whole country, except for some extreme areas (too low water availability or too much rain). Castor keeps being an alternative for the semi arid region but much more technology is requested to make it largely exploited. Following the petroleum crisis of 1980’s an ambitious research program on Jatropha curcas was initiated, later on discontinued and presently retaken by Embrapa and some Universities. Progress is slower than in the case of Ricinus communis. The first agronomical observations confirmed low productivity, problems with pests and diseases, high harvesting costs etc. Some strategic factors should be considered for the production of castor and Jatropha oils: 1. Production of raw materials; 2. Production of oils; 3. Detoxification and value aggregation to the extraction cakes and residues. Regarding raw material production, it is necessary a strong, long term research program on genetic breeding (short cycle varieties, with high productivity and allowing a sole harvesting), soil fertility, pest control, domestication and mechanization. Just to mention Embrapa, in 2007 a new cultivar (BRS Energia) was launched, characterized by low height and single crop per year, thus facilitating mechanized harvesting. In 2009, a new cultivar is expected to be launched, with high tolerance to gray mould, castor principal disease. Concerning oil quality, no significant difference is observed among cultivars, but for biodiesel purposes genetic material with lower ricinoleic acid content is welcomed. The oil production of both species results in nitrogen rich cakes. However, since the cakes contain toxic components making difficult or impeding its production in large scale, total elimination or inactivation of toxic compounds is mandatory before the cakes can be considered useful as animal feed, fertilizer, in waste water pretreatment or any other application. Physical chemical and/or bio detoxification methods are being carried on.