countries are majorly dependent on wheat and sorghum, respectively, for bioethanol
production. Maize accounts for 67% of bioethanol production; however, in terms of
biomass production, sugarcane is the leading contributor, as it requires the least
amount of water as compared to other food crops (Gerbens-Leenes et al. 2012; Rulli
et al. 2016). In the last two decades due to food feed competition and land-water
utilization concern, lignocellulosic biomass has gained much interest and undergone
several technological advancements. This can be supported by the fact that by 2016,
around 67 commercial 2G bioethanol production facilities have been established
around the world, among these about one third generate ethanol in tons
(US Department of Energy, 2016). In the case of 2G bioethanol production, the
USA is the leading 2G bioethanol producer with around 35% of the installed
capacity. Currently, India is also moving toward commercialization of 2G ethanol
generation based on techniques developed by DBT-ICT Centre for Energy
Biosciences and commercialization led by Hindustan Petroleum and Bharat Petroleum (DBT 2017). For the first time in the context of Indian history, application of
bioethanol as aircraft fuel was successfully demonstrated in India when a SpiceJet
plane (72-seater aircraft) successfully completed its run from Dehradun to Delhi
(TCI 2018). The processing cost involving pretreatment of the 2G feedstock due to
its recalcitrance behavior and enzymes cost is a limiting factor for commercialization
of 2G generation bioethanol (Behera and Ray 2015). National Renewable Energy
Laboratory, USA, has demonstrated the application of low-cost hydrolyzing
enzymes developed by private laboratories “Novozymes and Genencor,” to make
the overall ethanol production process cost-efficient (NREL 2010). Several ongoing
researches for search of cost-efficient pretreatment strategies are under process as
evident from the research article on biomass pretreatment. However, the literature
survey demonstrates the fact that the economic feasibility of a pretreatment strategy
is substrate dependent; therefore there is a need to understand the effect of different
pretreatments on different feedstocks and develop a universal pretreatment strategy.
Commercial production of the algal bioethanol is still in the laboratory or pilot scale
due to several limitations of which one being the cost of the reactors to provide the
controlled environment for enhanced and rapid bioethanol yield. The demand of
bioethanol all over the world will keep on increasing and therefore create
opportunities for algae and nonfood-based feedstocks for generation of ethanol.
7.5
Limitations and Future Prospects
The advantages and disadvantages of different ethanol generations have been
tabulated in Table 7.5. The 1G bioethanol production is the most evolved technique
covering most of the bioethanol yield. However, the major limitations associated
with this generation are the food vs fuel conflict, which has forced the scientific
community to focus toward the 2G feedstock. The shift from 1G to 2G is evident
from the growing number of publications in the area of 2G biofuel accompanied by
decrease in research publications in the area of first generation. However, it may be
also because of the reason that the first-generation feedstock-based bioethanol
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B. Kumar et al.
production. Maize accounts for 67% of bioethanol production; however, in terms of
biomass production, sugarcane is the leading contributor, as it requires the least
amount of water as compared to other food crops (Gerbens-Leenes et al. 2012; Rulli
et al. 2016). In the last two decades due to food feed competition and land-water
utilization concern, lignocellulosic biomass has gained much interest and undergone
several technological advancements. This can be supported by the fact that by 2016,
around 67 commercial 2G bioethanol production facilities have been established
around the world, among these about one third generate ethanol in tons
(US Department of Energy, 2016). In the case of 2G bioethanol production, the
USA is the leading 2G bioethanol producer with around 35% of the installed
capacity. Currently, India is also moving toward commercialization of 2G ethanol
generation based on techniques developed by DBT-ICT Centre for Energy
Biosciences and commercialization led by Hindustan Petroleum and Bharat Petroleum (DBT 2017). For the first time in the context of Indian history, application of
bioethanol as aircraft fuel was successfully demonstrated in India when a SpiceJet
plane (72-seater aircraft) successfully completed its run from Dehradun to Delhi
(TCI 2018). The processing cost involving pretreatment of the 2G feedstock due to
its recalcitrance behavior and enzymes cost is a limiting factor for commercialization
of 2G generation bioethanol (Behera and Ray 2015). National Renewable Energy
Laboratory, USA, has demonstrated the application of low-cost hydrolyzing
enzymes developed by private laboratories “Novozymes and Genencor,” to make
the overall ethanol production process cost-efficient (NREL 2010). Several ongoing
researches for search of cost-efficient pretreatment strategies are under process as
evident from the research article on biomass pretreatment. However, the literature
survey demonstrates the fact that the economic feasibility of a pretreatment strategy
is substrate dependent; therefore there is a need to understand the effect of different
pretreatments on different feedstocks and develop a universal pretreatment strategy.
Commercial production of the algal bioethanol is still in the laboratory or pilot scale
due to several limitations of which one being the cost of the reactors to provide the
controlled environment for enhanced and rapid bioethanol yield. The demand of
bioethanol all over the world will keep on increasing and therefore create
opportunities for algae and nonfood-based feedstocks for generation of ethanol.
7.5
Limitations and Future Prospects
The advantages and disadvantages of different ethanol generations have been
tabulated in Table 7.5. The 1G bioethanol production is the most evolved technique
covering most of the bioethanol yield. However, the major limitations associated
with this generation are the food vs fuel conflict, which has forced the scientific
community to focus toward the 2G feedstock. The shift from 1G to 2G is evident
from the growing number of publications in the area of 2G biofuel accompanied by
decrease in research publications in the area of first generation. However, it may be
also because of the reason that the first-generation feedstock-based bioethanol
188
B. Kumar et al.