5 Process Intensification Strategies for Biofuel Production
from Microalgae
Depletion of current fossil fuel reserves and pollution due to emissions from the
usage of these fossil fuels have created a situation where there is a need to focus on
fuels which can be produced in an easy manner and cause lesser emissions on use.
Biofuels like biodiesel, bioethanol, and biogas are the alternatives which can replace
the conventional fossil fuels. These biofuels can be produced from microalgae which
are a rich source of biomass and can be utilized in a sustainable manner as it can be
grown without the competition to food chain and has the energy content higher than
that of the other biomass sources available. Biodiesel is produced via transesterification reaction of oil with a methanol to yield fatty acid methyl esters (FAME).
Bioethanol is mostly produced by anaerobic fermentation of sources which are rich
in sugars and starch using yeast as the microbial culture. Biogas is also obtained via
anaerobic fermentation based on the use of methanogenic culture to utilize the
biodegradable content available in feedstock. Due to high lipid content, microalgae
can be effectively utilized for biodiesel production though their ability to accumulate
starch and cellulose also make them suitable to be used for bioethanol and biogas
production (Gendy and El-Temtamy 2013). Biodiesel is indeed the most common
biofuel produced from microalgae as observed in open literature though some work
has also been carried out to produce bioethanol and biogas from microalgae.
5.1 Biodiesel
Biodiesel is mostly produced from virgin vegetable oils, waste cooking oil, animal
fats, and non-edible oils. The main advantage of biodiesel is that the physical
properties are same as that of diesel obtained from crude oil, and hence, it can be
used directly in diesel engine. The raw material which is selected for the production
contributes a major proportion in the overall production cost as it depends on
different factors like ease of availability, actual cost, and characteristics of oil. Thus,
selection of the material plays a major role in process economics. The reaction
involved in biodiesel production is the reaction of oil (triglycerides) with methanol
in the presence of catalyst, and the product produced is fatty acid methyl ester
(FAME) which is commonly called as the biodiesel.
Biodiesel can be produced by catalytic, non-catalytic, and in situ transesterification reactions. Catalytic process involves the use of homogenous, heterogeneous,
and enzymatic catalyst. Non-catalytic process involves the use of methanol at critical
temperature with possible simultaneous extraction and transesterification process. In
situ transesterification is a process similar to the non-catalytic process performed at
higher temperature and pressure and offers advantages as minimal usage of solvents,
easy separation of products, and lesser reaction time. We now present an overview of
important production approaches as catalytic (both homogeneous and heterogeneous) and in-situ transesterification.
4 Process Intensification of Biofuel Production …
67
from Microalgae
Depletion of current fossil fuel reserves and pollution due to emissions from the
usage of these fossil fuels have created a situation where there is a need to focus on
fuels which can be produced in an easy manner and cause lesser emissions on use.
Biofuels like biodiesel, bioethanol, and biogas are the alternatives which can replace
the conventional fossil fuels. These biofuels can be produced from microalgae which
are a rich source of biomass and can be utilized in a sustainable manner as it can be
grown without the competition to food chain and has the energy content higher than
that of the other biomass sources available. Biodiesel is produced via transesterification reaction of oil with a methanol to yield fatty acid methyl esters (FAME).
Bioethanol is mostly produced by anaerobic fermentation of sources which are rich
in sugars and starch using yeast as the microbial culture. Biogas is also obtained via
anaerobic fermentation based on the use of methanogenic culture to utilize the
biodegradable content available in feedstock. Due to high lipid content, microalgae
can be effectively utilized for biodiesel production though their ability to accumulate
starch and cellulose also make them suitable to be used for bioethanol and biogas
production (Gendy and El-Temtamy 2013). Biodiesel is indeed the most common
biofuel produced from microalgae as observed in open literature though some work
has also been carried out to produce bioethanol and biogas from microalgae.
5.1 Biodiesel
Biodiesel is mostly produced from virgin vegetable oils, waste cooking oil, animal
fats, and non-edible oils. The main advantage of biodiesel is that the physical
properties are same as that of diesel obtained from crude oil, and hence, it can be
used directly in diesel engine. The raw material which is selected for the production
contributes a major proportion in the overall production cost as it depends on
different factors like ease of availability, actual cost, and characteristics of oil. Thus,
selection of the material plays a major role in process economics. The reaction
involved in biodiesel production is the reaction of oil (triglycerides) with methanol
in the presence of catalyst, and the product produced is fatty acid methyl ester
(FAME) which is commonly called as the biodiesel.
Biodiesel can be produced by catalytic, non-catalytic, and in situ transesterification reactions. Catalytic process involves the use of homogenous, heterogeneous,
and enzymatic catalyst. Non-catalytic process involves the use of methanol at critical
temperature with possible simultaneous extraction and transesterification process. In
situ transesterification is a process similar to the non-catalytic process performed at
higher temperature and pressure and offers advantages as minimal usage of solvents,
easy separation of products, and lesser reaction time. We now present an overview of
important production approaches as catalytic (both homogeneous and heterogeneous) and in-situ transesterification.
4 Process Intensification of Biofuel Production …
67