Bioconversion of Food Waste into Ethanol:
A Review
Nituparna Dey and Ashok N. Bhaskarwar
Abstract
The development of sustainable sources of energy brings
forth the idea of exploration of different renewable
sources for the production of biofuels. Globally, the
contribution of the biofuel industry in reducing fossilfuel dependency, mainly in the transportation sector, is
rising. With the development of alternative sources of
energy, biofuels like ethanol and butanol are becoming
progressively comparable to the petrochemical-derived
fossil fuels in terms of their technical and environmental
performance. First-(1G) and second-generation (2G)
biofuels are derived from food-competent substrates and
non-food-competent substrates, respectively. This chapter
demonstrates the feedstocks available from different food
wastes for biologically-derived ethanol and how they help
in ensuring sustainability. Biochemically, ethanol is
produced from microbial-fermentation reactions. This
article brings out an in-depth comparison of thermochemical and biochemical routes for ethanol production. It
aims to provide a basis and understanding of the plausible
shift toward the development of microbially-derived
fuels. There are, however, many technological challenges
for the commercial production of biofuels. Different
pretreatment techniques adopted for structural modification of biomass have been discussed. Also, different
fermentation strategies based on the degree of integration
of intermediate steps involved have been described. The
selection of the pretreatment techniques, fermentation
strategies, and other intermediary steps in the biological
process synchronously determine the overall economic
competitiveness and the level of technological readiness
of the process. The technology-readiness levels (TRL) of
1G and 2G bioethanol-production technologies are at
commercialization and pilot-plant demonstration stages,
respectively.
Keywords
Bioethanol Á Lignocellulosic-based biomass Á
Pectin-based biomass Á Pretreatment techniques Á
Microbial fermentation Á Ethanol recovery
1 Introduction
The global-energy dependency is the key concern of the
twenty-first century. 90% of the world’s energy requirement
is met through fossil-fuel consumption (coal, petroleum, and
natural gas) (Sivakumar et al. 2010; Singh et al. 2016; Dale
2008). The conventional energy sources (coal, petroleum,
and natural gas) have limited reserves and their utilization
has adverse effects on the environment, which include
greenhouse-gas emissions like that of carbon monoxide,
NO x , SO x , and drastic changes in climatic conditions (Stephen and Periyasamy 2018). Petroleum oil contributes to
40% of our energy demands. There is, therefore, a surge in
the price of petroleum oil and soon we would reach the
tipping point, the peak-oil point. The peak-oil point is considered to be a theoretical stage where the exploration of
newer oil fields will not suffice to compensate for the
depletion of the existing oil reservoirs. It is predicted
vaguely when the peak-oil point will occur, but the consumption trends depict that the oil reserves would be
depleted soon. Besides, of the existing oil reserves, some are
located in the areas of political agitation which make them
inaccessible, and thus the fluctuations in the oil supply and
price are well expected (Sivakumar et al. 2010). The
fossil-fuel dependency along with an increase in pollution
levels worldwide creates the need for the development of
renewable fuels.
N. Dey Á A. N. Bhaskarwar (&)
Department of Chemical Engineering, Indian Institute
of Technology Delhi, Hauz Khas, New Delhi, 110016, India
e-mail: ashoknbhaskarwar@yahoo.co.in
N. Dey
e-mail: nituparna.dey@gmail.com
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
Inamuddin and A. Khan (eds.), Sustainable Bioconversion of Waste to Value Added Products, Advances in Science,
Technology & Innovation, https://doi.org/10.1007/978-3-030-61837-7_3
45
A Review
Nituparna Dey and Ashok N. Bhaskarwar
Abstract
The development of sustainable sources of energy brings
forth the idea of exploration of different renewable
sources for the production of biofuels. Globally, the
contribution of the biofuel industry in reducing fossilfuel dependency, mainly in the transportation sector, is
rising. With the development of alternative sources of
energy, biofuels like ethanol and butanol are becoming
progressively comparable to the petrochemical-derived
fossil fuels in terms of their technical and environmental
performance. First-(1G) and second-generation (2G)
biofuels are derived from food-competent substrates and
non-food-competent substrates, respectively. This chapter
demonstrates the feedstocks available from different food
wastes for biologically-derived ethanol and how they help
in ensuring sustainability. Biochemically, ethanol is
produced from microbial-fermentation reactions. This
article brings out an in-depth comparison of thermochemical and biochemical routes for ethanol production. It
aims to provide a basis and understanding of the plausible
shift toward the development of microbially-derived
fuels. There are, however, many technological challenges
for the commercial production of biofuels. Different
pretreatment techniques adopted for structural modification of biomass have been discussed. Also, different
fermentation strategies based on the degree of integration
of intermediate steps involved have been described. The
selection of the pretreatment techniques, fermentation
strategies, and other intermediary steps in the biological
process synchronously determine the overall economic
competitiveness and the level of technological readiness
of the process. The technology-readiness levels (TRL) of
1G and 2G bioethanol-production technologies are at
commercialization and pilot-plant demonstration stages,
respectively.
Keywords
Bioethanol Á Lignocellulosic-based biomass Á
Pectin-based biomass Á Pretreatment techniques Á
Microbial fermentation Á Ethanol recovery
1 Introduction
The global-energy dependency is the key concern of the
twenty-first century. 90% of the world’s energy requirement
is met through fossil-fuel consumption (coal, petroleum, and
natural gas) (Sivakumar et al. 2010; Singh et al. 2016; Dale
2008). The conventional energy sources (coal, petroleum,
and natural gas) have limited reserves and their utilization
has adverse effects on the environment, which include
greenhouse-gas emissions like that of carbon monoxide,
NO x , SO x , and drastic changes in climatic conditions (Stephen and Periyasamy 2018). Petroleum oil contributes to
40% of our energy demands. There is, therefore, a surge in
the price of petroleum oil and soon we would reach the
tipping point, the peak-oil point. The peak-oil point is considered to be a theoretical stage where the exploration of
newer oil fields will not suffice to compensate for the
depletion of the existing oil reservoirs. It is predicted
vaguely when the peak-oil point will occur, but the consumption trends depict that the oil reserves would be
depleted soon. Besides, of the existing oil reserves, some are
located in the areas of political agitation which make them
inaccessible, and thus the fluctuations in the oil supply and
price are well expected (Sivakumar et al. 2010). The
fossil-fuel dependency along with an increase in pollution
levels worldwide creates the need for the development of
renewable fuels.
N. Dey Á A. N. Bhaskarwar (&)
Department of Chemical Engineering, Indian Institute
of Technology Delhi, Hauz Khas, New Delhi, 110016, India
e-mail: ashoknbhaskarwar@yahoo.co.in
N. Dey
e-mail: nituparna.dey@gmail.com
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
Inamuddin and A. Khan (eds.), Sustainable Bioconversion of Waste to Value Added Products, Advances in Science,
Technology & Innovation, https://doi.org/10.1007/978-3-030-61837-7_3
45