1 Introduction
Microalgae biomass is an interesting alternative to traditional bioethanol crops
because it does not have the inherent disadvantages of bioethanol of the first or
second generation. The cultivation of microalgae may occur in different culture
media, without necessarily using potable water and can carry wastewater, salt water
(seawater) and brackish water in its composition. Microalgae production does not
compete for freshwater intended for irrigation of plantations or for human and
animal consumption. In addition, microalgae cultivation can occur in small areas
and in non-arable, semiarid, or desert lands, since the main factors that influence the
development of microalgae are the availability of sunlight and water for cultivation
(Brennan and Owende 2010). Thus, the cultivation of microalgae does not directly
compete for arable land for food production nor does it increase the occurrence of
burning and deforestation, the main methods for obtaining new arable land. Another
advantage is that when using carbohydrates produced by certain species of
microalgae, the productivity of bioethanol of the third generation (in liters per
hectare per year) may be some orders of magnitude greater than the productivity of
raw materials used in the production of bioethanol of the first and second generations, according to Table 1.
Historically, microalgal biomass has been largely employed in the production of
several compounds for human consumption and industrial application, including
sterols, amino acids, fatty acids, and carotenoids, despite being considered in the
last few years for biofuel production. The interest in converting microalgae into
biofuels relies on some points: productivities superior to those of conventional
energy crops, after lipid and carbohydrate extraction; potentially possible to recover
high-value coproducts from the debris, such as proteins and pigments; low water
consumption in comparison with the irrigation of energy crops; possibility of
cultivation in non-arable lands, using non-potable water, such as wastewaters and
without the application of pesticides and herbicides; and improvement of air
quality, due to CO 2 fixation for biomass growth.
Table 1 Bioethanol productivity from different feedstocks
Feedstocks
Bioethanol productivity (L/(ha year))
Corn straw
1050–1400
Wheat
2590
Cassava
3310
Sweet sorghum
3050–4070
Maize
3460–4020
Beet
5010–6680
Sugarcane
6190–7500
Panicum virgatum (switchgrass)
10,760
Microalgae
46,760–140,290
Adapted from Mussatto et al. (2010)
230
R. G. Bastos
Microalgae biomass is an interesting alternative to traditional bioethanol crops
because it does not have the inherent disadvantages of bioethanol of the first or
second generation. The cultivation of microalgae may occur in different culture
media, without necessarily using potable water and can carry wastewater, salt water
(seawater) and brackish water in its composition. Microalgae production does not
compete for freshwater intended for irrigation of plantations or for human and
animal consumption. In addition, microalgae cultivation can occur in small areas
and in non-arable, semiarid, or desert lands, since the main factors that influence the
development of microalgae are the availability of sunlight and water for cultivation
(Brennan and Owende 2010). Thus, the cultivation of microalgae does not directly
compete for arable land for food production nor does it increase the occurrence of
burning and deforestation, the main methods for obtaining new arable land. Another
advantage is that when using carbohydrates produced by certain species of
microalgae, the productivity of bioethanol of the third generation (in liters per
hectare per year) may be some orders of magnitude greater than the productivity of
raw materials used in the production of bioethanol of the first and second generations, according to Table 1.
Historically, microalgal biomass has been largely employed in the production of
several compounds for human consumption and industrial application, including
sterols, amino acids, fatty acids, and carotenoids, despite being considered in the
last few years for biofuel production. The interest in converting microalgae into
biofuels relies on some points: productivities superior to those of conventional
energy crops, after lipid and carbohydrate extraction; potentially possible to recover
high-value coproducts from the debris, such as proteins and pigments; low water
consumption in comparison with the irrigation of energy crops; possibility of
cultivation in non-arable lands, using non-potable water, such as wastewaters and
without the application of pesticides and herbicides; and improvement of air
quality, due to CO 2 fixation for biomass growth.
Table 1 Bioethanol productivity from different feedstocks
Feedstocks
Bioethanol productivity (L/(ha year))
Corn straw
1050–1400
Wheat
2590
Cassava
3310
Sweet sorghum
3050–4070
Maize
3460–4020
Beet
5010–6680
Sugarcane
6190–7500
Panicum virgatum (switchgrass)
10,760
Microalgae
46,760–140,290
Adapted from Mussatto et al. (2010)
230
R. G. Bastos