Page 117 - Advances in Eco-Fuels for a Sustainable Environment

90 Advances in Eco-Fuels for a Sustainable Environment

biofuel feedstock mainly comprised of microalgae as a feedstock [5]. The fourth-
generation biofuels are produced from captured environmental carbon by utilizing
advanced technologies such as petroleum hydroprocessing, advanced biochemistry
geosynthesis,orlowpressureandlowtemperatureelectrochemicalprocesses.Environ-
mental CO 2 ,H 2 O, and heat energy are the feedstocks of fourth-generation biofuels [6].
When we consider the scenario of growing crops for fuel, the problem would be that the
crops will undoubtedly take up the land that is used for growing food.
These feedstocks of crop origin formed the first-generation biofuel feedstocks.
With the increase in population all over the world and the already existing problem
of shortage of food, the reliability of ecofuel production from growing crops or plant
sources could be a massive blow for the existence of the human race in the future.
Another factor in ecofuel production from growing crops is the amount of land needed
to supply fuel demands; it depends on the type of biomass used and the fuel output
obtained. Moreover, all the feedstocks used for the production of ecofuel cannot grow
in all the regions of the world. Some grow well in some locations but not in others.
Apart from this, biologic feedstocks require a huge amount of water for production
and processing as well. The supply of clean and fresh water would be a question with
the increase in world population. Even without the ecofuels, the world is experiencing
water shortage [7]. The drawbacks of first-generation biofuels were overcome by
second-generation biofuels [8].
Nonedible plant oil, which is a second-generation biofuel feedstock, can be culti-
vated in barren land or unused land whereas edible oil plants require arable land [9].
The production of ecofuels from wastes would be ideal if sustainable conversion is
achieved, but the feedstocks such as WCO, soapstock, and grease contain high
amounts of free fatty acids. The presence of free fatty acids makes the production
of ecofuel such as biodiesel more complicated because it undergoes saponification
during the production. Even though there are sufficient feedstocks available for the
production of ecofuels, it would be wise to select the feedstock in such a way that
it doesn’t affect the survival of the human race.
Third-generation feedstocks such as microalgae are said to be one of the promising
feedstocks. Moreover, microalgae can also be cultivated in wastewater, which in turn
lowers the freshwater utilization for ecofuel production. Not all the species of micro-
algae may form a good feedstock with high oil yield but genetically engineered micro-
algae with enhanced lipid production can be an ideal feedstock. However, excellent
and economic culturing and harvesting technologies are also required for the cheaper
production of ecofuel from microalgae [10]. In production of ecofuels from waste, the
problem of free fatty acids can be overcome by using efficient biocatalysts with higher
reproducibility and reusability. Indeed, more research is needed in the sustainable con-
version of ideal feedstocks to ecofuel.

4.2 Feedstocks for ecofuel production

The ecofuels have many advantages when compared to other nonrenewable resources
such as petrol, diesel, etc. The main barrier that obstructs its commercialization is the
cost of its production. The cost of ecofuel such as biodiesel depends on the feedstock.