Page 223 - Advances in Eco-Fuels for a Sustainable Environment

Advances in bio-oil extraction from 7

nonedible oil seeds and algal
biomass

G. Baskar, G. Kalavathy, R. Aiswarya, I. Abarnaebenezer Selvakumari
Department of Biotechnology, St. Joseph’s College of Engineering, Chennai, India

7.1 Introduction

In recent years, the exhaustion of fossil fuels has alarmed society and encouraged
environmental experts to focus on alternative energy. In addition to the depletion
of fossil fuels, their combustion emits most greenhouse gases that cause environmen-
tal damage. The world majorly depends on this nonrenewable source [1]. The variable
and increasing prices of petroleum products, depleting fossil fuels, and their harmful
impacts on the environment accentuate the significance of developing a renewable
and environmentally friendly alternative. To minimize the emission of greenhouse
gases in the environment, various policies have been proposed to reduce the depen-
dency on fossil fuels. As a result, at present a pollution-free and renewable substitute
for diesel fuel has gained importance around the world; this subsitute is found to have
many advantages over traditional fuels.
Biofuels have been noticed prominently owing to their sustainability and opera-
tional efficiency in minimizing the environmental impact [1]. This led to the estab-
lishment of potential liquid and gaseous biofuels in the transportation sector,
showing a rapid global rate [2]. The biofuel has a low emission of harmful gases to
the environment, a higher flash point, more combustion efficiency, and an almost
sulfur-free and nonaromatic fuel. It is also biodegradable and is derived from renew-
able sources such as domestic feed stock, nonedible seeds, and micro and macro algae.
Chemically, biodiesel is the mixture of fatty acid alkyl esters (FAAEs), most often
methyl or ethyl esters (FAMEs and FAEEs, respectively) obtained by the alcoholysis
of triacylglycerols (TAGs) from vegetable oil, animal fats, and algal oil. In the revers-
ible and consecutive alcoholysis reaction, one mole of acylglycerols reacts with one
mole of alcohol and one mole of ester is formed at every step in the absence or pres-
ence of a catalyst. Alcoholysis of bio-oil can be chemically or enzymatically cata-
lyzed. Chemical catalysts (base and acid) of alcoholysis can be homogeneous or
heterogeneous, while the enzymes used as a catalyst are lipases. Noncatalytic
alcoholysis reactions occur at high temperatures and pressures; that doesnt have
any practical implication [1]. The biodiesel could be used as pure fuel or as a blend
with petrodiesel, which is stable in all ratios. Biodiesel production is expected to

Advances in Eco-Fuels for a Sustainable Environment. https://doi.org/10.1016/B978-0-08-102728-8.00007-3
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