Page 575 - Refining Biomass Residues for Sustainable Energy and Bioproducts

Life cycle assessment, technical and economical analyses of jatropha biodiesel 525

24.2.1 Jatropha plant

Jatropha curcas is a shrub native to Brazil but has adapted very well in Africa
(Mali, Senegal, Cˆ ote d’Ivoire, etc.) (Maes et al., 2009). The plant can reach 10 m
with a lifespan of up to 50 years. It can start producing after 5 years (Maes et al.,
2009). Each plant gives fruits containing between 30% and 40% of oil (Achten
et al., 2013). Among the plants used today for the production of biodiesel, Jatropha
has the advantage of being able to grow on lands that are unsuitable for conven-
tional agriculture. This avoids the difficulty of competition with food (Achten et al.,
2008).

24.2.2 Jatropha oil

Jatropha oil is obtained through two extraction methods used today, namely,
mechanical and chemical (Achten et al., 2008, 2013). Mechanical extraction is
carried out from manual presses or motorized screw presses for larger productions
with the efficiency between 75% and 85% (Achten et al., 2008, 2013). The main
method of chemical extraction is the extraction with a solvent, usually n-hexane
(95% of the oil is obtained) (Achten et al., 2008, 2013). With the chemical extrac-
tion a better yield and less impurities are obtained, compared to the mechanical
extraction (Achten et al., 2008, 2013). However, chemical extraction is only
profitable for large productions and may have greater environmental impacts
(Adriaans, 2006). Extraction of the oil generates coproducts such as cakes
(Adriaans, 2006). The amount of oil remaining in the cake depends on the extrac-
tion method (more oil in the cake for mechanical extraction than for chemical
extraction) (IFAD-FAO, 2010).

24.2.3 Jatropha biodiesel

Jatropha oil is a promising renewable raw material for biodiesel production
(Table 24.1). High efficiency and relatively inexpensive methods for oil biodiesel
conversion have already been developed (Henning, 2009). The oil can be chemi-
cally modified into biodiesel through several methods of which transesterification is
mostly used (Islam et al., 2011). Transesterification is a chemical reaction between
the oil and an alcohol (methanol or ethanol) to produce a methyl ester or an ethyl
ester of Jatropha oil (Jatropha biodiesel) and glycerol as a coproduct (Behera et al.,
2010).

24.2.4 Use of Jatropha oil and biodiesel
The Jatropha oil and biodiesel can be used in diesel engine in order to generate
electricity for instance (Chapuis, 2014).
Jatropha oil can be used directly in some diesel engines (Contran, 2013).
However, its use in conventional diesel engines is generally difficult because of its
high viscosity that can clog the various filters, make it difficult to start, and cause