(Singh et al. 2017). These organisms exhibit high photosynthetic efficiencies and
yields up to twice that of terrestrial plants, and remain an attractive target for
improving the sustainability of future bioenergy production (Chisti 2013).
Microalgae are a class of microorganisms that exhibit tremendously large biological diversity and metabolic plasticity (Cho et al. 2017). This terminology
envelops a variety of prokaryotic and eukaryotic organisms. Some species can grow
autotrophically and produce organic molecules while others are heterotrophic in
nature, growing in the dark on complex organic material for energy and carbon
source (Chew et al. 2017).
It is a consensus that the supply of sufficient energy qualities, with a minimum
environmental impact, is among the main challengers of the energy world
(Maroneze et al. 2016). However, the search for fossil energy substitutes that meet
the requirements of energy sustainability in order to develop biofuels is not so
recent. Microalgae are very promising candidates that can fill our energy hunger in
a sustainable and environment-friendly manner. Two centuries ago, Rudolf Diesel,
the inventor of the diesel engine, fueled the idea of the production of diesel from
vegetable oil. This was the basis for using microalgae to generate energy
(Barathiraja et al. 2017). Besides the energy concerns, the advantages in terms of
environmental impact and sustainability have been considered. On the other hand,
they also have the advantage of the parallel production of co-products and have the
potential for the mitigation of pollutants, enabling the establishment of biorefineries
in industrial integrated processes (Moreno-Garcia et al. 2017).
Regardless of the many possibilities of exploitation of energy from microalgae,
today, one of the main interests in developing microalgae-based processes is
because of the ability of these microorganisms to produce and accumulate lipids in
their cells (Pereira et al. 2016). Microalgae oil consists of the neutral lipid triacylglycerol, which includes saturated and unsaturated fatty acids, which are stored
in cytosolic and\or plastidic lipid bodies. The accumulation of such lipid bodies can
be enhanced by abiotic stress, through to the adaptions of their biochemical
metabolic pathways and cellular composition in response to external conditions
including physiological inputs (Savchenko et al. 2017). In this sense, the possibility
of lipids accumulation through the manipulation of environment culture conditions
has a great potential for energy production. Biofuels from microalgae are no longer
focused solely on achieving a high lipid yield and its conversion into biodiesel.
Recent technology developments have been facilitated for the use of all algal
metabolites. In addition, biodiesel, biohydrogen, bioethanol, bioethanol and, more
recently, volatile organic compounds have been the main targets of the current
exploitation of energy from microalgae (Santos et al. 2016; Zhu et al. 2017).
Independent of these potentialities, the single biggest and most critical barrier to
the market deployment of commercially viable algae-based production remains the
high cost of cultivating and harvesting the biomass feedstocks, currently a factor of
10–20, which is too high for commodity fuel production (Laurens et al. 2017).
Furthermore, in light of persisting low fossil fuel prices, the microalgae-based
industry is forced to shift its focus from lower-value commodity biofuels and
2
E. Jacob-Lopes et al.
yields up to twice that of terrestrial plants, and remain an attractive target for
improving the sustainability of future bioenergy production (Chisti 2013).
Microalgae are a class of microorganisms that exhibit tremendously large biological diversity and metabolic plasticity (Cho et al. 2017). This terminology
envelops a variety of prokaryotic and eukaryotic organisms. Some species can grow
autotrophically and produce organic molecules while others are heterotrophic in
nature, growing in the dark on complex organic material for energy and carbon
source (Chew et al. 2017).
It is a consensus that the supply of sufficient energy qualities, with a minimum
environmental impact, is among the main challengers of the energy world
(Maroneze et al. 2016). However, the search for fossil energy substitutes that meet
the requirements of energy sustainability in order to develop biofuels is not so
recent. Microalgae are very promising candidates that can fill our energy hunger in
a sustainable and environment-friendly manner. Two centuries ago, Rudolf Diesel,
the inventor of the diesel engine, fueled the idea of the production of diesel from
vegetable oil. This was the basis for using microalgae to generate energy
(Barathiraja et al. 2017). Besides the energy concerns, the advantages in terms of
environmental impact and sustainability have been considered. On the other hand,
they also have the advantage of the parallel production of co-products and have the
potential for the mitigation of pollutants, enabling the establishment of biorefineries
in industrial integrated processes (Moreno-Garcia et al. 2017).
Regardless of the many possibilities of exploitation of energy from microalgae,
today, one of the main interests in developing microalgae-based processes is
because of the ability of these microorganisms to produce and accumulate lipids in
their cells (Pereira et al. 2016). Microalgae oil consists of the neutral lipid triacylglycerol, which includes saturated and unsaturated fatty acids, which are stored
in cytosolic and\or plastidic lipid bodies. The accumulation of such lipid bodies can
be enhanced by abiotic stress, through to the adaptions of their biochemical
metabolic pathways and cellular composition in response to external conditions
including physiological inputs (Savchenko et al. 2017). In this sense, the possibility
of lipids accumulation through the manipulation of environment culture conditions
has a great potential for energy production. Biofuels from microalgae are no longer
focused solely on achieving a high lipid yield and its conversion into biodiesel.
Recent technology developments have been facilitated for the use of all algal
metabolites. In addition, biodiesel, biohydrogen, bioethanol, bioethanol and, more
recently, volatile organic compounds have been the main targets of the current
exploitation of energy from microalgae (Santos et al. 2016; Zhu et al. 2017).
Independent of these potentialities, the single biggest and most critical barrier to
the market deployment of commercially viable algae-based production remains the
high cost of cultivating and harvesting the biomass feedstocks, currently a factor of
10–20, which is too high for commodity fuel production (Laurens et al. 2017).
Furthermore, in light of persisting low fossil fuel prices, the microalgae-based
industry is forced to shift its focus from lower-value commodity biofuels and
2
E. Jacob-Lopes et al.