and heterogeneous polymer comprising trans-coniferyl, trans-sinapyl and
trans-coumaryl alcohols. It forms a complex matrix arranged covalently linked to
side groups of other diverse hemicelluloses and covers the cellulose microfibril. It
occupies 2–40% of the plant cell wall in which C–C and C–O–C provide stability by
protecting them from microbial attack (Mooney et al. 1998).
7.4 The Concept of Biorefinery
Biorefinery is classified into three different generations based on the use of different
feedstock and the products (Azad et al. 2015). The raw materials used for firstgeneration biorefinery are corn, barley, sunflower, etc. Bio-based ethanol, diesel,
biogas, methanol and vegetable oils come under this generation (Cherubini 2010).
Due to the presence of high oil and sugar content, the bioconversion into biofuel is
easy with this generation. Based on the previous reports of life cycle assessment
analysis by Reinhardt et al. (2007) and Gasol et al. (2007), a remarkable decrease in
the (GHG) emission has been observed as the consumption of bioethanol and
biodiesel has efficiently replaced gasoline and diesel obtained from fossil resources.
Apart from various benefits, this generation have a drawback of facing difficulties in
feed and food industries as they use food resources and agricultural land (Cherubini
2010; Dutta et al. 2014).
In contrast to this, the second-generation biorefinery uses leftover residues from
the food crops and cereals which are known as lignocellulosic plant biomass such as
husks, bagasse, straws, animal fat and municipal solid wastes which can be used for
biofuel production along with other value-added products (Azad et al. 2015; Geddes
et al. 2011; Zanuso et al. 2017). Based on various literature of life cycle assessment
analysis, it was concluded that the second generation is more advantageous than the
first as it is more eco-friendly, economic and more socially feasible as compared to
food-based resources and requirement of agricultural land (Dutta et al. 2014).
Whereas, in third generation of biorefinery, aquatic biomass, e.g. algae, rice in
proteins, oil and carbohydrates has been used for biofuel production (Martín and
Grossmann 2012). Aquatic biomass consists of three groups: microalgae,
cyanobacteria, and macroalgae. Although it is not a seasonal feedstock, with high
oil productivity and high tolerance rate, its processing cost is very high due to the
high cultivation cost and energy input which eventually affects the economic
viability of the process (Cervantes-Cisneros et al. 2017). Among all the three
generations, the second generation has been considered more efficient, because the
whole process can be considered economic from the use of waste products as
resources till the production of value-added end-products.
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trans-coumaryl alcohols. It forms a complex matrix arranged covalently linked to
side groups of other diverse hemicelluloses and covers the cellulose microfibril. It
occupies 2–40% of the plant cell wall in which C–C and C–O–C provide stability by
protecting them from microbial attack (Mooney et al. 1998).
7.4 The Concept of Biorefinery
Biorefinery is classified into three different generations based on the use of different
feedstock and the products (Azad et al. 2015). The raw materials used for firstgeneration biorefinery are corn, barley, sunflower, etc. Bio-based ethanol, diesel,
biogas, methanol and vegetable oils come under this generation (Cherubini 2010).
Due to the presence of high oil and sugar content, the bioconversion into biofuel is
easy with this generation. Based on the previous reports of life cycle assessment
analysis by Reinhardt et al. (2007) and Gasol et al. (2007), a remarkable decrease in
the (GHG) emission has been observed as the consumption of bioethanol and
biodiesel has efficiently replaced gasoline and diesel obtained from fossil resources.
Apart from various benefits, this generation have a drawback of facing difficulties in
feed and food industries as they use food resources and agricultural land (Cherubini
2010; Dutta et al. 2014).
In contrast to this, the second-generation biorefinery uses leftover residues from
the food crops and cereals which are known as lignocellulosic plant biomass such as
husks, bagasse, straws, animal fat and municipal solid wastes which can be used for
biofuel production along with other value-added products (Azad et al. 2015; Geddes
et al. 2011; Zanuso et al. 2017). Based on various literature of life cycle assessment
analysis, it was concluded that the second generation is more advantageous than the
first as it is more eco-friendly, economic and more socially feasible as compared to
food-based resources and requirement of agricultural land (Dutta et al. 2014).
Whereas, in third generation of biorefinery, aquatic biomass, e.g. algae, rice in
proteins, oil and carbohydrates has been used for biofuel production (Martín and
Grossmann 2012). Aquatic biomass consists of three groups: microalgae,
cyanobacteria, and macroalgae. Although it is not a seasonal feedstock, with high
oil productivity and high tolerance rate, its processing cost is very high due to the
high cultivation cost and energy input which eventually affects the economic
viability of the process (Cervantes-Cisneros et al. 2017). Among all the three
generations, the second generation has been considered more efficient, because the
whole process can be considered economic from the use of waste products as
resources till the production of value-added end-products.
7 Xylanases: A Helping Module for the Enzyme Biorefinery Platform
165