make it suitable for bioethanol feedstock (Behera and Ray 2015). Potato is a seasonal
crop grown primarily in a temperate climate with abundant availability in northern
hemisphere region. Potato is ranked as fourth important crop around the world.
China is the leading producer of potatoes (20%); Russia and India follow the list with
12% and 8%, respectively (Thatoi et al. 2016). Sweet potato is an annual crop grown
in tropical and subtropical regions. China is the leading producer of sweet potatoes
(80%) followed by Uganda and Nigeria (3%) (Duvernay et al. 2013). Sweet potato is
ranked seventh as favorite food crop grown around the world. Different varieties of
sweet potatoes are grown such as white, orange, and purple. The white variety of
sweet potato containing high starch is less sweet, so it is less preferred as food
source, thus making it an appropriate substrate for production of bioethanol (Thatoi
et al. 2016). Sweet potatoes are even manipulated for its high starch content and low
liquefaction temperature, thus making it more adaptive for ethanol production.
Sweet potatoes K 9807.1 has 4500–6500 L ethanol yield per hectare which is 1.6
times higher than corn (Lareo et al. 2013).
7.2.1.2 Sugar-Containing Feedstock for Bioethanol Production
The sugar-based bioethanol is produced by sugar-based feedstocks, i.e., sugarcane,
beet sugar, sweet sorghum, fruits, and energy crops. Brazil, Germany, France, and
India are the leading producers of sugar-rich feedstock. The sugarcane (C4 grass) has
high solar radiation to biomass conversion capability with per hectare yield of 62–74
tons (Sindhu et al. 2016). Brazil is the leading producer of sugarcane-based
bioethanol (79% from sugarcane) and replaced almost 42 % of its gasoline need
with sugarcane-based bioethanol. In 2015–2016, Brazilian produced 8 billion
gallons bioethanol and used mostly to meet its domestic needs by blending with
gasoline from 18 to 27.5% (SugarCane.org 2019). Another C4 plant i.e. sweet
sorghum, has high yield (54–111 tons/ha), high carbon assimilation efficiency
(50 g/m
2 /day), accumulation of extractable sugar in high concentration in their
stalks, have high water use efficieny, can be grown in tropical as well as temperate
climate and can be grown from seed (added advantage over sugarcane) (Laopaiboon
et al. 2007). Ekefre et al. (2017) evaluated three different cultivars of sweet sorghum
as ethanol feedstock. Different parameters such as diameter, density, and height of
stalk along with overall biomass and juice yield were compared for enhanced ethanol
yield. The cultivar Theis resulted in maximum ethanol yield of 7619 L/ha followed
by M81 E (6106 L/ha) and Dale (5077 L/ha) (Ekefre et al. 2017). Sugar beet is used
for bioethanol production extensively in France and introduced in India and in trail
stages in tropical countries (Marx et al. 2012). Sugar beet has a high yield of 54–111
tons/ha with low requirement of rainfall (Vohra et al. 2014). Several researches are
ongoing for application of sugar beet and sugar beet processing waste for ethanol
generation and found that sugar beet can be an economical option (Dziugan et al.
2013).
The fruits which are usually discarded due to its physical appearance and low
quality can be used as feedstocks for production of ethanol as these fruits are rich in
soluble sugar and do not require any complex pretreatment before fermentation by
yeast (Chandrasekaran and Bahkali 2013; Chniti et al. 2014). Fruit juice or fruit
processing industries or waste from pineapple and grape pomace can be a feasible
7 Bioethanol Production: Generation-Based Comparative Status Measurements
161
crop grown primarily in a temperate climate with abundant availability in northern
hemisphere region. Potato is ranked as fourth important crop around the world.
China is the leading producer of potatoes (20%); Russia and India follow the list with
12% and 8%, respectively (Thatoi et al. 2016). Sweet potato is an annual crop grown
in tropical and subtropical regions. China is the leading producer of sweet potatoes
(80%) followed by Uganda and Nigeria (3%) (Duvernay et al. 2013). Sweet potato is
ranked seventh as favorite food crop grown around the world. Different varieties of
sweet potatoes are grown such as white, orange, and purple. The white variety of
sweet potato containing high starch is less sweet, so it is less preferred as food
source, thus making it an appropriate substrate for production of bioethanol (Thatoi
et al. 2016). Sweet potatoes are even manipulated for its high starch content and low
liquefaction temperature, thus making it more adaptive for ethanol production.
Sweet potatoes K 9807.1 has 4500–6500 L ethanol yield per hectare which is 1.6
times higher than corn (Lareo et al. 2013).
7.2.1.2 Sugar-Containing Feedstock for Bioethanol Production
The sugar-based bioethanol is produced by sugar-based feedstocks, i.e., sugarcane,
beet sugar, sweet sorghum, fruits, and energy crops. Brazil, Germany, France, and
India are the leading producers of sugar-rich feedstock. The sugarcane (C4 grass) has
high solar radiation to biomass conversion capability with per hectare yield of 62–74
tons (Sindhu et al. 2016). Brazil is the leading producer of sugarcane-based
bioethanol (79% from sugarcane) and replaced almost 42 % of its gasoline need
with sugarcane-based bioethanol. In 2015–2016, Brazilian produced 8 billion
gallons bioethanol and used mostly to meet its domestic needs by blending with
gasoline from 18 to 27.5% (SugarCane.org 2019). Another C4 plant i.e. sweet
sorghum, has high yield (54–111 tons/ha), high carbon assimilation efficiency
(50 g/m
2 /day), accumulation of extractable sugar in high concentration in their
stalks, have high water use efficieny, can be grown in tropical as well as temperate
climate and can be grown from seed (added advantage over sugarcane) (Laopaiboon
et al. 2007). Ekefre et al. (2017) evaluated three different cultivars of sweet sorghum
as ethanol feedstock. Different parameters such as diameter, density, and height of
stalk along with overall biomass and juice yield were compared for enhanced ethanol
yield. The cultivar Theis resulted in maximum ethanol yield of 7619 L/ha followed
by M81 E (6106 L/ha) and Dale (5077 L/ha) (Ekefre et al. 2017). Sugar beet is used
for bioethanol production extensively in France and introduced in India and in trail
stages in tropical countries (Marx et al. 2012). Sugar beet has a high yield of 54–111
tons/ha with low requirement of rainfall (Vohra et al. 2014). Several researches are
ongoing for application of sugar beet and sugar beet processing waste for ethanol
generation and found that sugar beet can be an economical option (Dziugan et al.
2013).
The fruits which are usually discarded due to its physical appearance and low
quality can be used as feedstocks for production of ethanol as these fruits are rich in
soluble sugar and do not require any complex pretreatment before fermentation by
yeast (Chandrasekaran and Bahkali 2013; Chniti et al. 2014). Fruit juice or fruit
processing industries or waste from pineapple and grape pomace can be a feasible
7 Bioethanol Production: Generation-Based Comparative Status Measurements
161