Environmental Engineering Reference
In-Depth Information
Table 2.4
Various feed
stocks used for ethanol
formation and their relative
production value. (Luque
et al.
2010
)
Soure used
Ethanol obtained (I/ton)
Sugar cane
70
Sugar beet
110
Sweet potato
125
Potato
110
Cassava
180
Maize
360
Rice
430
Barley
225
Wheat
340
tion of various feedstocks is required as they hold big share in bioethanol costs
(Dien et al.
2003
).
i.
Feedstocks of bioethanol manufacture
There are many types of feedstock for the production of bioethanol, some of
which are shown in Table
2.4
.
The bioethanol feedstock can be mostly classified into three kinds: sucrose, starch
and lignocellulosic biomass. These are discussed below:
a.
Sucrose containing feedstock
This includes sugar cane, sugar beet, sweet sorghum etc. but bioethanol is chiefly
formed from sugar beet and sugar cane (Dhavala et al.
2006
). About 2/3 sucrose
is made from sugar cane while 1/3 from sugar beet. Brazil is the chief manufac-
turer of sugar cane having worldwide manufacture of about 27 % (Kim and Dale
2004
). Bioethanol formation by sugar cane is very cost-effective especially in
Brazil; since Brazil lowered the sugar cane prices in order to support the bioetha-
nol industry. This significantly dropped the price of the feedstock and generated
a petition for the maintained worth of bioethanol (Cardona and Sanchez
2007
).
In European countries, sugar beet molasses is the best used feedstock. The ben-
efits of using sugar beet include: minimum rotation of crop production, greater
harvest, and great resistance towards climatic variations, less water and fertilizer
necessity. Sugar beet requires 35-40 % less amount of water and fertilizer as
compared to sugar cane (Dhavala et al.
2006
; Luque et al.
2010
).
b.
Starch containing feedstock:
Starch is a biopolymer. In order to obtain bioethanol from this feed stock it is nec-
essary to break it down, which can then further be transformed into bio ethanol
by yeasts. This process is mostly followed for bioethanol production in Europe
and North America (Luque et al.
2010
). Wheat and corn are largely engaged for
these procedures (Balat et al.
2008
). USA owns a large corn bioethanol industry
producing over 15 billion tons per year. The single factor increasing the cost
of the manufacture of bioethanol from corn is the rate of the corn itself. Corn
prices vary from 1 year to another. The price previously ranged between 1.94
and 3.24 $ per bushel (De Oliveira et al.
2005
). The value of corn now is four
