Environmental Engineering Reference
In-Depth Information
friendly, but under cost-intensive higher temperature and pressure (Al-Zuhair 2007; Demirbas
2008; Andrade et al. 2011). BIOX is a new method that “converts both triglycerides and free fatty
acids in a two step, single phase, continuous process at atmospheric pressures and near-ambient
temperatures, all in less than 90 minutes” (http://www.bioxcorp.com/). This process can use grain,
cooking grease, and animal fats as feedstocks.
3.5.2 m
aJor
B
iodiESEl
c
ropS
3.5.2.1 soybean
Soybean is a biodiesel plant that has garnered a lot of interest. It is thought to have originated
from China and is cultivated worldwide. It is a bushy, green legume with seeds typically consisting
of approximately 20% oil and is the world's main supply of vegetable oil. The oil has five fatty
acids that make up its composition: palmitic, stearic, oleic, linoleic, and linolenic. There are many
uses of soybean in areas such as livestock/poultry feed, plastics, paints, cosmetics, pharmaceuti-
cals, and diesel fuel. In general, soybean is planted in spring/early summer and harvested in fall.
Tropical areas allow for soybean growth year round. Lately, genetic improvement of this crop has
been focused on several traits such as yield, pest resistance, and seed oil composition (Lee et al.
2007), but emphasis is geared more toward modifying oil content (fatty acid composition). There are
numerous genetic maps of soybean that help in identifying potential target genes to modify, such as
those affecting growth/flowering (
E1-5
), leaf form (
lf1, Lf2, Ln, Lo, Lnr, lw1, lw2, lb1 lb2
), disease
(
Hb, Hm, hs1-hs 3, CP4, Als1
), sterility (
st1-st8, ms1, ms6, fs1, fs2, msp
), and fatty acid composition
(
fap2, Fas, St1, St2, Ol, fan1-fan3
). Currently, soybean is transformed through
Agrobacterium
or
particle bombardment using one of three typical explants: cotyledonary node, embryonic axis, or
somatic embryos (Lee et al. 2007).
Agrobacterium
relies on a biological method of transformation,
whereas particle bombardment uses physical induction (Finer and Larkin 2008). One advantage
of using soybean is its ability to grow without the addition of nitrogen as fertilizer. Yields in the
United States for soybean are 2668 kg/ha, with an overall net negative energy return when produc-
ing biodiesel (Pimentel and Patzek 2005) with costs of $0.70/L ($2.64/gal) (Demirbas 2009). One
of the main disadvantages to using soybean oil is that it is a major food crop in the United States,
with similar problems to that of incorporating corn for bioethanol.
3.5.2.2 Jatropha
Jatropha is an important nonfood crop adapted to environments of tropical and subtropical cli-
mates, semi-arid, and marginal lands. Jatropha can grow in various soils, but it is sensitive to frost
and waterlogging (Achten and Mathijs 2007). Other attractive features of jatropha include drought
hardiness, rapid growth, easy propagation, low cost of seeds, and small gestation period (Sujatha
et al. 2008). Jatropha oil is odor and colorless, with its seed oil content variously reported to be
between 30% and 50%. The main disadvantage of using jatropha oil for biodiesel is its high viscos-
ity (Pramanik 2003). The high viscocity of jatropha oil reduces the efficiency of fuel injectors in
the diesel engines (Demirbas 2008). Reducing the viscosity was done through dilution with diesel
blends, with 70-80% diesel showing the greatest improvement (Pramanik 2003). In addition to
being cultivated for its oil content, jatropha plants are being used in water and wind erosion control
as a living fence to protect food crops and to make soap (Achten and Mathijs 2007; FAO 2010).
Citing Bayer Crop Science AG as source, CSA News (2008) reported that Jatropha may provide up
to 2270 L/ha oil and boasted that Jatropha oil is a high octane oil/Octane 60 oil (CSA News 2008).
Because of this, jatropha is one of the very efficient biofuels and can be used with slight modifica-
tions to the diesel engine. Also, this oil is environmentally clean (Bayer Crop Science AG 2008).
Overall, jatropha is expected to have a positive effect on land currently thought to be wasteland.
Because jatropha harvesting is currently not mechanized, manual labor will be needed, potentially
increasing the number of jobs available in rural environments (FAO 2010).
