7.2.1.1.1 Corn for Bioethanol Production
Commercially, corn is extensively used as feedstock for bioethanol production, and
its application has increased rapidly. The USA is the leading corn producer with
annual production of 116.32 billion gallons and utilizes 28% of it, i.e., 42.4 billion
gallons for ethanol generation (AFDC 2016). In year 2014, the USA alone generated
around 14.3 billion gallons of bioethanol from corn (RFA 2015). The corn yield is
also very high in Asia followed by Europe and South America (Kim and Dale 2004).
The factors affecting the corn-based ethanol yield are corn variety, quality of corn
used, kernel composition, presence or absence of mycotoxins, and hardness of
endosperms. The ethanol yield ranges from 3 to 23% with more yield from free
sugar-rich kernels (Singh 2012).
7.2.1.1.2 Grains for Bioethanol Production
The climatic condition of an area also limits the application of different crops for
bioethanol production. The climatic condition of Canada limits corn growth and
favors wheat; therefore, it is most readily used crop for grain-based bioethanol
production. The other crops used for bioethanol production were triticale, barley,
and oat (Saunders et al. 2011). McLeod et al. (2010) tested the suitability of grains
(i.e., 31 lines and cultivars of wheat, triticale, barley, and oats) as feedstock for
production of ethanol in Western Canada. Starch, pentoses, and β-glucan yield from
different cultivars were determined to estimate ethanol yields. It was observed that
the ethanol yield was maximum for wheat followed by triticale, barley, and oat.
Muktham et al. (2016) suggested that wheat can be used to replace barley for
bioethanol production. Belboom et al. (2015) also suggested that wheat-based
ethanol can generate 42.5–61.2% less GHG emissions as compared when the same
amount of gasoline is used.
7.2.1.1.3 Tubers and Roots for Bioethanol Production
Different tubers and roots, i.e., sweet potatoes, potatoes, Jerusalem artichoke, and
cassava, have high concentrations of stored starch. This high starch storage potential
makes it as suitable raw materials for 1G bioethanol (Hoover 2001). There are
several advantages using tubers and roots for ethanol production such as:
(i) Economic harvesting.
(ii) On-farm processing.
(iii) Availability of cost-effective ethanol conversion techniques.
(iv) Can be grown in different soil types, even in low fertile soil thus leaving fertile
one for other crops (Thatoi et al. 2016).
(v) Can be grown in a variety of climates (tropical, subtropical, semi-arid
conditions).
(vi) Annual nature of most tubers and root crops makes it a suitable feedstock for
bioethanol (Ray and Swain 2011).
The annual production of cassava ranks sixth after rice, wheat, corn, potatoes, and
barley in the developing countries. Its ability to grow in low fertile soil, in all types of
climatic condition, all year around, and high starch yield per hectare (~36.3 tons)
160
B. Kumar et al.
Commercially, corn is extensively used as feedstock for bioethanol production, and
its application has increased rapidly. The USA is the leading corn producer with
annual production of 116.32 billion gallons and utilizes 28% of it, i.e., 42.4 billion
gallons for ethanol generation (AFDC 2016). In year 2014, the USA alone generated
around 14.3 billion gallons of bioethanol from corn (RFA 2015). The corn yield is
also very high in Asia followed by Europe and South America (Kim and Dale 2004).
The factors affecting the corn-based ethanol yield are corn variety, quality of corn
used, kernel composition, presence or absence of mycotoxins, and hardness of
endosperms. The ethanol yield ranges from 3 to 23% with more yield from free
sugar-rich kernels (Singh 2012).
7.2.1.1.2 Grains for Bioethanol Production
The climatic condition of an area also limits the application of different crops for
bioethanol production. The climatic condition of Canada limits corn growth and
favors wheat; therefore, it is most readily used crop for grain-based bioethanol
production. The other crops used for bioethanol production were triticale, barley,
and oat (Saunders et al. 2011). McLeod et al. (2010) tested the suitability of grains
(i.e., 31 lines and cultivars of wheat, triticale, barley, and oats) as feedstock for
production of ethanol in Western Canada. Starch, pentoses, and β-glucan yield from
different cultivars were determined to estimate ethanol yields. It was observed that
the ethanol yield was maximum for wheat followed by triticale, barley, and oat.
Muktham et al. (2016) suggested that wheat can be used to replace barley for
bioethanol production. Belboom et al. (2015) also suggested that wheat-based
ethanol can generate 42.5–61.2% less GHG emissions as compared when the same
amount of gasoline is used.
7.2.1.1.3 Tubers and Roots for Bioethanol Production
Different tubers and roots, i.e., sweet potatoes, potatoes, Jerusalem artichoke, and
cassava, have high concentrations of stored starch. This high starch storage potential
makes it as suitable raw materials for 1G bioethanol (Hoover 2001). There are
several advantages using tubers and roots for ethanol production such as:
(i) Economic harvesting.
(ii) On-farm processing.
(iii) Availability of cost-effective ethanol conversion techniques.
(iv) Can be grown in different soil types, even in low fertile soil thus leaving fertile
one for other crops (Thatoi et al. 2016).
(v) Can be grown in a variety of climates (tropical, subtropical, semi-arid
conditions).
(vi) Annual nature of most tubers and root crops makes it a suitable feedstock for
bioethanol (Ray and Swain 2011).
The annual production of cassava ranks sixth after rice, wheat, corn, potatoes, and
barley in the developing countries. Its ability to grow in low fertile soil, in all types of
climatic condition, all year around, and high starch yield per hectare (~36.3 tons)
160
B. Kumar et al.