5.2.1.1 Anaerobic Digestion of Biomass
The carbohydrates in the biomass using anaerobic digestion (AD) can be
transformed into biogas which constitutes methane (60%) and CO 2 (40%). The
AD technology, although known for many years, in recent times gained more
attention. The home based AD has become more popular in developed and developing countries. In India, AD of biowastes has gained traction in different sectors
namely as home based AD, community based AD, and large scale AD depending on
the quantity and quality of waste generated in the region (Breitenmoser et al. 2019).
Although AD generates energy out of biomass, this technology also generates
digestate to be used as bio-fertilizers or soil enhancer. However, if the AD is to be
completely operated throughout the sector from home to large scale units, it needs to
accommodate more innovative ways such as co-digestion with other wastes, design
and development of suitable reactor for individual sector, synergy between public,
private, and industrial sectors (Bhatia et al. 2018).
5.2.1.2 Bioalcohol Production from Biomass
Among the different sectors of energy consumption worldwide, the major share
(28%) goes to transportation sector which contributes to global warming. It is
predicted that the global mobility will increase triple fold in the 2030; use of
petroleum products will also likely to increase (Balan 2014; Fatih Demirbas et al.
2011). Many countries started producing biofuels from lignocellulosic biomass.
Among the biomass, lignocellulosic biomass (LCB) is the most preferred option
for generation of bioalcohol. The LCB contains 40–50% cellulose, 30–40% hemicellulose, and 20–30% lignin. Cellulose and hemicellulose are polysaccharides
which mainly contain Beta 1, 4 linkages. Lignin the abundant aromatic polymer
finely laced between cellulose and hemicellulose hindering many pretreatments and
prevent accessible of hydrolytic enzymes (Manisha 2017). General bioalcohol
production methods first remove lignin and depolymerize cellulose and hemicellulose into glucose and xylose units. After enzymatic hydrolysis, microorganisms
convert the carbohydrates into bioalcohol. Lignin although not valorized is mostly
burnt to generate electricity. However enormous value added products can also be
generated from lignin (Narron et al. 2016).
5.2.1.3 Biodiesel Production from Biomass
Although bioalcohols were significantly produced, recently biodiesel production
from biomass is gaining attention. Europe is the forerunner in biodiesel production
worldwide. Biodiesel are lipids from oleaginous microorganisms. In nature, certain
bacteria, fungi, yeast, and algae are capable of accumulating lipids in their biomass
more than 70% of their dry weight under high carbon and low nitrogen conditions
(Bhatia et al. 2018; Intasit et al. 2020). These lipids are similar to any vegetable oils
in terms of their biodiesel properties. Use of microorganisms for lipid production
although known for more than 100 years, due to its high cost they were not
commercialized. Recently they are gaining momentum as the use of renewable
biomass is available as a cheap source for biofuels. Biodiesel from oleaginous
microorganisms has many advantages over plant oils, as they do not require huge
90
M. I. Kumar et al.
The carbohydrates in the biomass using anaerobic digestion (AD) can be
transformed into biogas which constitutes methane (60%) and CO 2 (40%). The
AD technology, although known for many years, in recent times gained more
attention. The home based AD has become more popular in developed and developing countries. In India, AD of biowastes has gained traction in different sectors
namely as home based AD, community based AD, and large scale AD depending on
the quantity and quality of waste generated in the region (Breitenmoser et al. 2019).
Although AD generates energy out of biomass, this technology also generates
digestate to be used as bio-fertilizers or soil enhancer. However, if the AD is to be
completely operated throughout the sector from home to large scale units, it needs to
accommodate more innovative ways such as co-digestion with other wastes, design
and development of suitable reactor for individual sector, synergy between public,
private, and industrial sectors (Bhatia et al. 2018).
5.2.1.2 Bioalcohol Production from Biomass
Among the different sectors of energy consumption worldwide, the major share
(28%) goes to transportation sector which contributes to global warming. It is
predicted that the global mobility will increase triple fold in the 2030; use of
petroleum products will also likely to increase (Balan 2014; Fatih Demirbas et al.
2011). Many countries started producing biofuels from lignocellulosic biomass.
Among the biomass, lignocellulosic biomass (LCB) is the most preferred option
for generation of bioalcohol. The LCB contains 40–50% cellulose, 30–40% hemicellulose, and 20–30% lignin. Cellulose and hemicellulose are polysaccharides
which mainly contain Beta 1, 4 linkages. Lignin the abundant aromatic polymer
finely laced between cellulose and hemicellulose hindering many pretreatments and
prevent accessible of hydrolytic enzymes (Manisha 2017). General bioalcohol
production methods first remove lignin and depolymerize cellulose and hemicellulose into glucose and xylose units. After enzymatic hydrolysis, microorganisms
convert the carbohydrates into bioalcohol. Lignin although not valorized is mostly
burnt to generate electricity. However enormous value added products can also be
generated from lignin (Narron et al. 2016).
5.2.1.3 Biodiesel Production from Biomass
Although bioalcohols were significantly produced, recently biodiesel production
from biomass is gaining attention. Europe is the forerunner in biodiesel production
worldwide. Biodiesel are lipids from oleaginous microorganisms. In nature, certain
bacteria, fungi, yeast, and algae are capable of accumulating lipids in their biomass
more than 70% of their dry weight under high carbon and low nitrogen conditions
(Bhatia et al. 2018; Intasit et al. 2020). These lipids are similar to any vegetable oils
in terms of their biodiesel properties. Use of microorganisms for lipid production
although known for more than 100 years, due to its high cost they were not
commercialized. Recently they are gaining momentum as the use of renewable
biomass is available as a cheap source for biofuels. Biodiesel from oleaginous
microorganisms has many advantages over plant oils, as they do not require huge
90
M. I. Kumar et al.