5 Conclusions
According to available scientific literature and company initiatives, it is clear that
the bioethanol production from microalgae should focus on not only the increase of
the carbohydrate content but also the higher productivity of biomass. Technical and
economic evaluations are necessary to verify the gains and losses of energy
involved in the production of ethanol from microbiological biomass. The relevance
of genetically engineered microorganisms with traditional processes must also be
discussed, as it is well known that enzymes and yeasts can efficiently produce
bioethanol with high productivity. The main technological bottlenecks of hydrolysis and fermentation seem to be being solved by several researches in this area,
even helped by the production of the second-generation ethanol. Finally, more
studies are necessary, particularly for better understanding of carbohydrate accumulation (hydrolysis and fermentation), as well as metabolic pathway of dark and
photofermentation, which appears indeed as a highly promising technological
application in the future.
References
Behrens, P. W., Bingham, S. E., Hoeksema, S. D., Cohoon, D. L., & Cox, J. C. (1989). Studies on
the incorporation of CO 2 into starch by Chlorella vulgaris. Journal of Applied Phycology, 1,
123–130.
Brennan, l, & Owende, P. (2010). Biofuels from microalgae—A review of technologies for
production, processing, and extractions of biofuels and co-products. Renewable and
Sustainable Energy Reviews, 14, 557–577.
Chen, C. Y., Zhao, X. Q., Yen, H. W., Ho, S. H., Cheng, C. L., Lee, D. J., et al. (2013).
Microalgae-based carbohydrates for biofuel production. Biochemical Engineering Journal, 78,
1–10.
Costa, R. L., Oliveira, T. V., Ferreira, J. S., Cardoso, V. L., & Batista, F. R. (2015). Prospective
technology on bioethanol production from photofermentation. Bioresource Technology, 181,
330–337.
de Farias Silva, C. E., & Bertucco, A. (2016). Bioethanol from microalgae and cyanobacteria: A
review and technological outlook. Process Biochemistry, 51(11), 1833–1842.
Doucha, J., & Lívanský, K. (2009). Outdoor open thin-layer microalgal photobioreactor: potential
productivity. Journal of Applied Phycology, 21, 111–117.
Dragone, G., Fernandes, B. D., Abreu, A. P., Vicente, A. A., & Teixeira, J. A. (2011). Nutrient
limitation as a strategy for increasing starch accumulation in microalgae. Applied Energy, 88
(10), 3331–3335.
Gupta, A., & Verma, J. P. (2015). Sustainable bio-ethanol production from agro-residues: A
review. Renewable and Sustainable Energy Reviews, 41, 550–567.
Hirano, A., Ueda, R., Hirayama, S., & Ogushi, Y. (1997). CO2 fixation and ethanol production
with microalgal photosynthesis and intracellular anaerobic fermentation. Energy, 22, 137–142.
Ho, S. H., Huang, S. W., Chen, C. Y., Hasunuma, T., Kondo, A., & Chang, J. S. (2013).
Bioethanol production using carbohydrate-rich microalgae biomass as feedstock. Bioresource
Technology, 135, 191–198.
Kim, H. M., Oh, C. H., & Bae, H. J. (2017). Comparison of red microalgae (Porphyridium
cruentum) culture conditions for bioethanol production. Bioresource Technology, 233, 44–50.
11 Biofuels from Microalgae: Bioethanol
245
According to available scientific literature and company initiatives, it is clear that
the bioethanol production from microalgae should focus on not only the increase of
the carbohydrate content but also the higher productivity of biomass. Technical and
economic evaluations are necessary to verify the gains and losses of energy
involved in the production of ethanol from microbiological biomass. The relevance
of genetically engineered microorganisms with traditional processes must also be
discussed, as it is well known that enzymes and yeasts can efficiently produce
bioethanol with high productivity. The main technological bottlenecks of hydrolysis and fermentation seem to be being solved by several researches in this area,
even helped by the production of the second-generation ethanol. Finally, more
studies are necessary, particularly for better understanding of carbohydrate accumulation (hydrolysis and fermentation), as well as metabolic pathway of dark and
photofermentation, which appears indeed as a highly promising technological
application in the future.
References
Behrens, P. W., Bingham, S. E., Hoeksema, S. D., Cohoon, D. L., & Cox, J. C. (1989). Studies on
the incorporation of CO 2 into starch by Chlorella vulgaris. Journal of Applied Phycology, 1,
123–130.
Brennan, l, & Owende, P. (2010). Biofuels from microalgae—A review of technologies for
production, processing, and extractions of biofuels and co-products. Renewable and
Sustainable Energy Reviews, 14, 557–577.
Chen, C. Y., Zhao, X. Q., Yen, H. W., Ho, S. H., Cheng, C. L., Lee, D. J., et al. (2013).
Microalgae-based carbohydrates for biofuel production. Biochemical Engineering Journal, 78,
1–10.
Costa, R. L., Oliveira, T. V., Ferreira, J. S., Cardoso, V. L., & Batista, F. R. (2015). Prospective
technology on bioethanol production from photofermentation. Bioresource Technology, 181,
330–337.
de Farias Silva, C. E., & Bertucco, A. (2016). Bioethanol from microalgae and cyanobacteria: A
review and technological outlook. Process Biochemistry, 51(11), 1833–1842.
Doucha, J., & Lívanský, K. (2009). Outdoor open thin-layer microalgal photobioreactor: potential
productivity. Journal of Applied Phycology, 21, 111–117.
Dragone, G., Fernandes, B. D., Abreu, A. P., Vicente, A. A., & Teixeira, J. A. (2011). Nutrient
limitation as a strategy for increasing starch accumulation in microalgae. Applied Energy, 88
(10), 3331–3335.
Gupta, A., & Verma, J. P. (2015). Sustainable bio-ethanol production from agro-residues: A
review. Renewable and Sustainable Energy Reviews, 41, 550–567.
Hirano, A., Ueda, R., Hirayama, S., & Ogushi, Y. (1997). CO2 fixation and ethanol production
with microalgal photosynthesis and intracellular anaerobic fermentation. Energy, 22, 137–142.
Ho, S. H., Huang, S. W., Chen, C. Y., Hasunuma, T., Kondo, A., & Chang, J. S. (2013).
Bioethanol production using carbohydrate-rich microalgae biomass as feedstock. Bioresource
Technology, 135, 191–198.
Kim, H. M., Oh, C. H., & Bae, H. J. (2017). Comparison of red microalgae (Porphyridium
cruentum) culture conditions for bioethanol production. Bioresource Technology, 233, 44–50.
11 Biofuels from Microalgae: Bioethanol
245