evergreen plants of cedar, cypress, hemlock, pine, reed, and cedar, and these are fastgrowing trees and possess low densities. Hardwood trees include acacia, alder,
aspen, beech, cottonwood, eucalyptus, poplar, oak, and willow and are mainly
found in the northern hemisphere. The hardwoods and softwoods differ in physical
and chemical composition (Romani et al. 2011). The woody biomass consists of
cellulose microfibrils reinforced together with hemicellulose and lignin (Alvira et al.
2010). These complex structures are usually formed by tracheids and vessels (plant
parts responsible for translocation and transportation of water in plants) in the middle
covered by layers of complex microfibrils around them. These structural
complexities provide toughness to wood and require different pretreatment methods
before its conversion to bioethanol (Zhu et al. 2010).
7.2.2.2 Non-woody Biomass for Bioethanol Production
Non-woody biomass usually comprises of agricultural residues, aquatic plants,
native energy crops, and municipal waste. Apart from huge availability,
non-woody biomass is relatively easy, cheap, and less energy intensive in conversion to bioethanol as compared to woody biomass. The detailed account of
non-woody biomass is given below.
7.2.2.2.1 Agricultural Residues for Bioethanol Production
After harvesting of the agricultural crops such as corn, wheat, rice, sugarcane,
cassava, and palm oil, there are huge amount of residues generated such as straws,
stover, bagasse, and empty fruit brunches which can contribute to the world biomass
and potential feedstock for bioethanol production.
7.2.2.2.1.1 Cereal Straws for Bioethanol Production
The dry stalks which remain after harvesting of cereal grains such as rice, wheat,
barley, oat, corn, and sorghum are called as cereal straws. It consists of 33–47%
cellulose along with 20–30% hemicelluloses and can be considered as an important
substrate for bioethanol generation. The harvesting of wheat from 1 hectare of field
usually generates 1–3 tons of straw and the annual world rice straw production is
around 731 million ton/year, and as wheat and rice are stapled food for several
countries, there is huge availability of wheat/rice straw for bioethanol production
(Saini et al. 2015). Annual cereal straw production collectively from Europe, the
USA, India, and China is 1580.2 million ton/year (Tye et al. 2016).
7.2.2.2.1.2 Corn Stover for Bioethanol Production
The residues generated after harvesting of corn from corn plants are collectively
called as corn stover. The corn stover mainly constitutes cobs, husks, leaves, and
stalks and produced at a rate of around 4 ton/ acre of harvested land (Kim and Dale
2004). Corn stover is mainly produced in North and South American nations.
However, it plays a crucial role in restocking organic matter in soil, but with
sustainable management and safeguards, a suitable amount of corn stover can lead
to production of 80 million gallons of bioethanol (Liew et al. 2014).
7 Bioethanol Production: Generation-Based Comparative Status Measurements
163
aspen, beech, cottonwood, eucalyptus, poplar, oak, and willow and are mainly
found in the northern hemisphere. The hardwoods and softwoods differ in physical
and chemical composition (Romani et al. 2011). The woody biomass consists of
cellulose microfibrils reinforced together with hemicellulose and lignin (Alvira et al.
2010). These complex structures are usually formed by tracheids and vessels (plant
parts responsible for translocation and transportation of water in plants) in the middle
covered by layers of complex microfibrils around them. These structural
complexities provide toughness to wood and require different pretreatment methods
before its conversion to bioethanol (Zhu et al. 2010).
7.2.2.2 Non-woody Biomass for Bioethanol Production
Non-woody biomass usually comprises of agricultural residues, aquatic plants,
native energy crops, and municipal waste. Apart from huge availability,
non-woody biomass is relatively easy, cheap, and less energy intensive in conversion to bioethanol as compared to woody biomass. The detailed account of
non-woody biomass is given below.
7.2.2.2.1 Agricultural Residues for Bioethanol Production
After harvesting of the agricultural crops such as corn, wheat, rice, sugarcane,
cassava, and palm oil, there are huge amount of residues generated such as straws,
stover, bagasse, and empty fruit brunches which can contribute to the world biomass
and potential feedstock for bioethanol production.
7.2.2.2.1.1 Cereal Straws for Bioethanol Production
The dry stalks which remain after harvesting of cereal grains such as rice, wheat,
barley, oat, corn, and sorghum are called as cereal straws. It consists of 33–47%
cellulose along with 20–30% hemicelluloses and can be considered as an important
substrate for bioethanol generation. The harvesting of wheat from 1 hectare of field
usually generates 1–3 tons of straw and the annual world rice straw production is
around 731 million ton/year, and as wheat and rice are stapled food for several
countries, there is huge availability of wheat/rice straw for bioethanol production
(Saini et al. 2015). Annual cereal straw production collectively from Europe, the
USA, India, and China is 1580.2 million ton/year (Tye et al. 2016).
7.2.2.2.1.2 Corn Stover for Bioethanol Production
The residues generated after harvesting of corn from corn plants are collectively
called as corn stover. The corn stover mainly constitutes cobs, husks, leaves, and
stalks and produced at a rate of around 4 ton/ acre of harvested land (Kim and Dale
2004). Corn stover is mainly produced in North and South American nations.
However, it plays a crucial role in restocking organic matter in soil, but with
sustainable management and safeguards, a suitable amount of corn stover can lead
to production of 80 million gallons of bioethanol (Liew et al. 2014).
7 Bioethanol Production: Generation-Based Comparative Status Measurements
163