Second-generation biofuels are produced from lignocellulosic matter and waste
material of crops, residue obtained from agricultural produce particularly wheat
straws and corn husks. Other waste biomass includes non-edible part of agriculture
residues and by-products of plants. These can be produced by feedstock, can also be
grown on arable land (which is not a general practice) or using agricultural residues.
The conversion technology is also biochemical or thermochemical method of
converting the biomass into biofuel. Other feedstock sources such as forestry
residue, seed crops, waste oils and fats, solid waste etc. can also be used. Common
examples are biodiesel, biohydrogen and biomethanol.
Third-generation biofuels are algal biofuels produced from algae by extraction of
oil. Sources can be marine reserves, seaweeds, cyanobacteria and microorganisms.
Its production cost is low and biofuel is high-yielding as compared to conventional
first-generation biofuels.
Fourth-generation biofuels are biofuels that do not require destruction of biomass
for conversion to biofuel. These types of biofuels are electrofuels and photobiological solar fuels produced by using cheap, inexhaustible resources such as solar
energy (Aro 2016; Chiaramonti 2011; Mbaneme-Smith and Chinn 2015) (Tables 2.1
and 2.2).
2.3 Technology for Production of Biofuels
The extraction of biofuel from marine/agricultural biomass can be done initial drying
step. Biofuel production from wet biomass, i.e. agricultural biomass is done by
hydrothermal treatments, hydrolysis by application on enzymes, and microbial
fermentation to produce different end products such as bioethanol/biohydrogen/
biobutanol. The extraction method from dry biomass, i.e. marine biomass or seaweed, involves different steps such as direct combustion, pyrolysis, gasification and
finally trans-esterification to biodiesel.
2.3.1 Pretreatment
The pretreatment is the foremost essential step in biofuel production. Pretreatment is
done by physical, physicochemical, chemical or biological process. The physical
pretreatment involves milling; chemical pretreatment involves acid or alkali treatment, hot-water treatment, steam treatment, microwave and solvent extraction, and
biological pretreatment involves enzymatic and microbial treatment. Since the
breakdown of lignocellulosic material is not easy, pretreatment is an essential step
to separate cellulose, lignin and hemicelluloses.
2 Application of Microorganisms for Biofuel Production
37
material of crops, residue obtained from agricultural produce particularly wheat
straws and corn husks. Other waste biomass includes non-edible part of agriculture
residues and by-products of plants. These can be produced by feedstock, can also be
grown on arable land (which is not a general practice) or using agricultural residues.
The conversion technology is also biochemical or thermochemical method of
converting the biomass into biofuel. Other feedstock sources such as forestry
residue, seed crops, waste oils and fats, solid waste etc. can also be used. Common
examples are biodiesel, biohydrogen and biomethanol.
Third-generation biofuels are algal biofuels produced from algae by extraction of
oil. Sources can be marine reserves, seaweeds, cyanobacteria and microorganisms.
Its production cost is low and biofuel is high-yielding as compared to conventional
first-generation biofuels.
Fourth-generation biofuels are biofuels that do not require destruction of biomass
for conversion to biofuel. These types of biofuels are electrofuels and photobiological solar fuels produced by using cheap, inexhaustible resources such as solar
energy (Aro 2016; Chiaramonti 2011; Mbaneme-Smith and Chinn 2015) (Tables 2.1
and 2.2).
2.3 Technology for Production of Biofuels
The extraction of biofuel from marine/agricultural biomass can be done initial drying
step. Biofuel production from wet biomass, i.e. agricultural biomass is done by
hydrothermal treatments, hydrolysis by application on enzymes, and microbial
fermentation to produce different end products such as bioethanol/biohydrogen/
biobutanol. The extraction method from dry biomass, i.e. marine biomass or seaweed, involves different steps such as direct combustion, pyrolysis, gasification and
finally trans-esterification to biodiesel.
2.3.1 Pretreatment
The pretreatment is the foremost essential step in biofuel production. Pretreatment is
done by physical, physicochemical, chemical or biological process. The physical
pretreatment involves milling; chemical pretreatment involves acid or alkali treatment, hot-water treatment, steam treatment, microwave and solvent extraction, and
biological pretreatment involves enzymatic and microbial treatment. Since the
breakdown of lignocellulosic material is not easy, pretreatment is an essential step
to separate cellulose, lignin and hemicelluloses.
2 Application of Microorganisms for Biofuel Production
37