biodiesel as compared to other having traditional crops. They are considered as the
third generation of biofuels and best alternative, overcoming the flaws of first and
second generations. Carbon dioxide can be converted into organic compounds more
efficiently by microalgae (while using light energy) with higher photosynthetic
efficiency and higher production of biomass. Microalgae can grow extremely rapidly
with high oil yields, and can also double the biomass within 24 h, thus becoming a
promising source of biodiesel production. Since algae use huge amounts of carbon
dioxide and also biodiesel contains less sulphur when obtained from algae, it reduces
the threat of global warming by reduction of emissions of CO 2 hydrocarbons and
SO 2 . Microalgae also produce an abundance of proteins and carbohydrates that can
result in the formation of valuable co-products like methanol fuel production
(Spolaore et al. 2006).
Microalgae have a unicellular or simple multicellular structure, namely bluegreen (cyanobacteria), green, red, brown algae and diatoms. Prokaryotic microalgae,
i.e. blue-green algae are commonly used for biodiesel production. Although there are
a number of species of microalgae that can accumulate lipid, this must be taken into
consideration that only few species are utilized for biodiesel production. There is
variation in the lipid content in algal cells from 20% to 60% of dry weight biomass,
and can reach approximately 80% in some genera, i.e. Botryococcus, Neochloris
oleabundans, Nannochloropsis and Schizochytrium. Microalgae oils are an abundant source of unsaturated fatty acids, i.e. linolenic acids, linoleic, oleic; palmitoleic
acid, essential amino acids, like valine, leucine, isoleucine, etc. Various species of
microalgae such as C. protothecoides, B. braunii and C. chlorella may produce more
lipids depending on the culture media used, mineral salts (nitrogen, phosphorus,
iron, etc.) and change in temperature (Xu et al. 2006; Wang et al. 2008).
Several steps are required for biodiesel production. Firstly, biomass production is
done through the growth of algal cells and then cells are isolated to the culturing
medium. Isolation is followed by extracting lipids from algal biomass and then fatty
acids are trans-esterified followed by fractioning on chromatographic columns.
Figure 2.1 presents the stages of biodiesel production from microalgae (Chisti
2007; Frac et al. 2010; Anwar et al. 2019).
2.4.1.2 Production of Biomass from Microalgae
Biomass production from algae is influenced by various factors like light (sunlight
would be preferred to reduce the production cost), carbon dioxide, water, mineral
salts (nitrogen, phosphorus, iron, etc.) and temperature (within range of 20–30
C).
Algal biomass has around 50% of carbon in its dry matter as it utilizes atmospheric
carbon dioxide necessary for algal growth.
Various methods can be used for growing algae on large scale such as open ponds
and photobioreactors. The former utilizes sunlight as the immediate source of solar
energy and are cheaper but the yield is lower as compared to photobioreactors.
Photobioreactors are built of translucent materials and have higher harvesting
efficiency as it permits growing of exactly those microalgal species that are required
in order to obtain a greater amount of oil compared to algae culturing in ponds.
2 Application of Microorganisms for Biofuel Production
41
third generation of biofuels and best alternative, overcoming the flaws of first and
second generations. Carbon dioxide can be converted into organic compounds more
efficiently by microalgae (while using light energy) with higher photosynthetic
efficiency and higher production of biomass. Microalgae can grow extremely rapidly
with high oil yields, and can also double the biomass within 24 h, thus becoming a
promising source of biodiesel production. Since algae use huge amounts of carbon
dioxide and also biodiesel contains less sulphur when obtained from algae, it reduces
the threat of global warming by reduction of emissions of CO 2 hydrocarbons and
SO 2 . Microalgae also produce an abundance of proteins and carbohydrates that can
result in the formation of valuable co-products like methanol fuel production
(Spolaore et al. 2006).
Microalgae have a unicellular or simple multicellular structure, namely bluegreen (cyanobacteria), green, red, brown algae and diatoms. Prokaryotic microalgae,
i.e. blue-green algae are commonly used for biodiesel production. Although there are
a number of species of microalgae that can accumulate lipid, this must be taken into
consideration that only few species are utilized for biodiesel production. There is
variation in the lipid content in algal cells from 20% to 60% of dry weight biomass,
and can reach approximately 80% in some genera, i.e. Botryococcus, Neochloris
oleabundans, Nannochloropsis and Schizochytrium. Microalgae oils are an abundant source of unsaturated fatty acids, i.e. linolenic acids, linoleic, oleic; palmitoleic
acid, essential amino acids, like valine, leucine, isoleucine, etc. Various species of
microalgae such as C. protothecoides, B. braunii and C. chlorella may produce more
lipids depending on the culture media used, mineral salts (nitrogen, phosphorus,
iron, etc.) and change in temperature (Xu et al. 2006; Wang et al. 2008).
Several steps are required for biodiesel production. Firstly, biomass production is
done through the growth of algal cells and then cells are isolated to the culturing
medium. Isolation is followed by extracting lipids from algal biomass and then fatty
acids are trans-esterified followed by fractioning on chromatographic columns.
Figure 2.1 presents the stages of biodiesel production from microalgae (Chisti
2007; Frac et al. 2010; Anwar et al. 2019).
2.4.1.2 Production of Biomass from Microalgae
Biomass production from algae is influenced by various factors like light (sunlight
would be preferred to reduce the production cost), carbon dioxide, water, mineral
salts (nitrogen, phosphorus, iron, etc.) and temperature (within range of 20–30
C).
Algal biomass has around 50% of carbon in its dry matter as it utilizes atmospheric
carbon dioxide necessary for algal growth.
Various methods can be used for growing algae on large scale such as open ponds
and photobioreactors. The former utilizes sunlight as the immediate source of solar
energy and are cheaper but the yield is lower as compared to photobioreactors.
Photobioreactors are built of translucent materials and have higher harvesting
efficiency as it permits growing of exactly those microalgal species that are required
in order to obtain a greater amount of oil compared to algae culturing in ponds.
2 Application of Microorganisms for Biofuel Production
41