Page 32 - Advances in Eco-Fuels for a Sustainable Environment

Introduction to sustainable and alternative ecofuels 9

sustainable feedstocks for alternative aviation fuels because this fuel accounts for
about 30% of their operating costs worldwide [16]. The aviation sector accounts
for about 10% of global liquid fuel consumption and 2% of the world’s total CO 2 emis-
sions [6]. The use of alternative aviation fuels can optimize costs and reduce environ-
mental pollution. Biodiesel can be used by blending up to 20% with fossil fuel in the
modern engine, which can reduce GHG emissions from the transport sector by up to
60% [78].
The recent research aims to assess new, sustainable, and technically viable
advanced aviation biofuels and biodiesels for reducing emissions because renewable
energy resources are largely undeveloped. The commercial applications of these
ecofuels could create a new economic direction by creating new energy markets (such
as aviation biofuel) and trading biodiesels, which can create future energy security by
reducing dependency on fossil fuels. The study on ecofuels is significant because:

The ecofuel industries will get new feedstock information for increasing their production and
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fuel quality.
The transport sector, including the aviation sector, will get more improved ecofuels to meet
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their demands and reduce operating and maintenance costs.
The engine designers will get novel guidelines to develop more efficient engines fueled with
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sustainable ecofuel for proper combustion, including less friction and wear and increased
durability with longer engine life, which will help to customize newly developed ecofuel
applications in transport vehicles.

1.5 Sustainability of ecofuels

Sustainability of ecofuel applications depends on some key parameters such as avail-
ability of feedstocks, oil yield, conversion process, fuel properties, and capability for
emissions reduction. Application of pure ecofuel in an engine requires modification of
the engine combustion system, which may cause some technical problems such as
higher specific fuel consumption, higher NO x emission, lower thermal efficiency,
and heavy gum and wax formation [79, 80]. However, it can be used for blending with
fossil fuel up to 20% without any modification of the combustion system [81].Asan
oxygenated fuel (general formula –CHO–), ecofuels have excellent capability for
emissions reductions compared to fossil fuel (–CH–). This self-oxygenation in the
ecofuels enhances combustion quality, which promotes complete combustion. The
improvement of the main fuel properties (such as density, viscosity, calorific value)
can also play an important role in complete combustion by overcoming the major
drawbacks. Different combustion strategies such as alteration of fuels, alteration of
combustion processes, and posttreatment of the exhaust gas can be used to reduce
emissions. The alteration of the combustion process (i.e., low-temperature combus-
tion) and posttreatment of the exhaust gas involves a lot of investment and modifica-
tion of engine systems, which is still not economically viable [28].
Nowadays, research on ecofuel aims to achieve the goal of maximum possible
emissions reduction without any modification of the modern engine using the