Environmental Engineering Reference
In-Depth Information
sources of energy to meet the growing demand of expanding population. Based on
the raw materials available in a particular region, different alternative biofuel
production should be encouraged.
2 Alternative Energy
Alternative energy is a broad term which includes all the energy that can replace the
fossil fuels and could be served as a key to mitigating the environmental aspects to
transport. Introduction of alternative fuels together with drastic energy ef
ciency
could be a key to sustainable mobility globally. Biological sources such as plant and
microbes could be potential sources for producing alternate fuels, termed as bio-
fuels, including bioalcohols, biodiesel, algal biofuels, biohydrogen, and microbial
fuel cells (Singhania and Pandey 2012 ).
2.1 Bioalcohols
Bioalcohol includes biologically produced alcohols from lignocellulosic (LC)
biomass, chie
y bioethanol and biobutanol.
Bioethanol from LC biomass is among the most promising alternative energy
sources. Due to abundant availability and ubiquitous nature of LC biomass, bio-
ethanol produced from it offers potential bene
fl
ts in terms of quality and quantity
(Singhania et al. 2013 ). Ethanol has higher octane number than petroleum fuels and
lesser CO 2 emissions which makes it energy-ef
cient fuel. It can be blended up to
15 % in gasoline without needing any change in the engine design. Its application
as alternative transport fuel (as replacement to gasoline) has been well commer-
cialized in Brazil since several decades (although that has been from sugarcane).
Biobutanol could be a direct replacement of gasoline as it can be directly burned in
gasoline engine without any engine modi
cation. It is also claimed that it produces
more energy and is less corrosive and less soluble in water than ethanol. Bio-
technologists are trying to develop the microbial strains which could tolerate higher
concentration of butanol and also give improved productivities using metabolic and
genetic engineering approaches. Efforts are also being made to improve the
extractive methods to remove it from the fermentation medium.
Multifaceted approaches are being adopted for developing economically feasible
biomass conversion technologies. Over the period, the attention has shifted on
biore
nery concept with aim of zero waste generation and value addition, either
using the biochemical (sugar) platform, involving pretreatment, hydrolysis, and
fermentation, or thermochemical platform, involving pyrolysis and or/gasi
cation.
Under biochemical platform, a suitable pretreatment process for the LC biomass is
one of the most essential requirements, which could remove the lignin coating
without removing sugar component from the plant cells, so as to overcome the
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