Page 277 - Biosystems Engineering

Biodiesel and Ethanol in Engines 255

period of 3 years (Article 21 Finance Law 2001). The U.S. Senate
Finance Committee approved an excise tax exemption for biodiesel in
2003. Moreover, the legislation provides a 1-cent reduction in the die-
sel fuel excise tax for each percentage of biodiesel blended with petro-
leum diesel up to 20 percent. However, the tax exemption will one
day come to an end, and other steps will be needed to continue to
promote the social inclusion and the economic attraction of biodiesel.
This could be facilitated by the selection of low-cost raw materials,
such as nonedible oils, used in frying oil or animal fat, and use of a
lower-cost transesterification process.
The literature 1,6,18 already shows that many researchers have
worked on nonedible vegetable oils such as Jatropha, mahua, karanja,
neem, and so on and edible vegetable oils such as rapeseed, sun-
flower, soybean palm, and others separately to study the performance
and emission characteristics of these oils in a diesel engine.
Among several indigenous plant species—Jatropha, karanja, and
putranjiva—are plants that bear seeds of nonedible oils and are going
to be of interest all over the world. These plants can be cultivated eas-
ily in barren soils of stony, sandy, and clayish soil textures with less
maintenance and low moisture content. These plants are medium-
sized and are found abundantly in the Northern Hemisphere. Million
tons of seeds of Jatropha, karanja, and putranjiva go to waste annu-
ally, which can be useful to reduce the fuel crisis. Also, growing these
plants can provide employment, improve the environment, and
enhance the quality of rural life.
Biodiesels consist of methyl esters of fatty acids that are produced
by catalytic transesterification of triglycerides of vegetable oils with
alcohol. In this process, triglyceride molecules are successively con-
verted into di- and monoglycerides and finally into fatty acid alkyl
esters and glycerol. These monoesters are known as biodiesels.
18
OCOR K1 OH + RCOOMe
OCOR MeOH OCOR Fatty acid methyl ester
OCOR K1 OCOR
Triglyceride Diglyceride (Fame)
(TG) (DG)
OH K2 OH
OCOR MeOH OH + RCOOMe
OCOR K2 OCOR
DG Monoglyceride (Fame)
(MG)
OH K3 OH RCOOMe
OH MeOH OH + (Fame)
OCOR K3 OH
MG Glycerol
The alcohols commonly used are methanol and ethanol. Several
parameters, such as type of catalyst (alkaline, acid, or enzyme), oil/
alcohol ratio, temperature, reaction time, and purity of the reactants