for energy production with zero-CO 2 emission; the must is that we keep a balance
and use wood at the same rate it is produced. Unfortunately, this is not the case as
we harvest wood at a faster rate than trees grow. This is the big problem, which sets
a limit to the use of biomass as energy source. It is useful to recall that the shift from
the use of biomass as energy source to fossil-C, more dense in energy, in late 1700s
was a compulsory step due to the industrial revolution. Biomass cannot satisfy our
society’s energy needs. Moreover, as discussed in Chap. 5, the direct burning of
biomass also causes the emission of particulate and noxious pollutants. So, we have
to find routes that may cause less environmental burden, such as the conversion of
the raw materials into biofuels. Additionally, taking into account the carbon
up-taken from soil, the use of biomass can become a net transfer of CO 2 from
surface soil to the atmosphere, unless clever strategies are implemented. Using
biomass, thus, is not “per se” a way to a zero-emission of CO 2 , and it will reach
such target if we use soil with the right strategy and apply the concept of biorefinery
to the use of biomass. Ethanol and biodiesel can be valid alternatives to fuels
derived from fossil-C supposed that the conflict between food-energy and the use of
soil is solved. Biogas, which is formed by fermentation of fresh organic waste or
fresh non-eatable grown biomass, is composed mainly of methane (60%) and CO 2
(40%), which is an interesting option of using waste or non-eatable biomass.
However, the winning strategy is the use of waste biomass, biomass grown on
marginal soils (such as polluted or arid soils, which are not suited for growing
edible biomass), and the use of non-edible biomass.
11.2.1 Production of Fuels and Chemicals from Aquatic
Biomass
Algal technology is attracting a lot of attention for the ability of algae to fix
inorganic carbon and convert it into several value-added products, including biofuels precursors. Both macro- and microalgae are under analysis for exploitation.
Various strains have a different potential, show a different adaptation to being
grown out of their natural environment, and can be useful to produce high value
products, materials, and fuels for market [7, 8].
Macro- and microalgae are rich in protein, carotenoids, antioxidants, fatty acids,
enzymes, polymers, peptides, toxins, and sterols and other compounds, which can
be used for several purposes (Fig. 11.4).
Microalgae have been identified as a third generation feedstock, and a more
efficient source of biodiesel (estimated production: 50–70 t ha
−1 y
−1 in open ponds
and 150 t ha
−1 y
−1 in photobioreactors) compared to terrestrial energetic oily crops
(*3 t ha
−1 y
−1 for soybeans, *9–15 t ha
−1 y
−1 for corn, and *13 t ha
−1 y
−1 for
switch grass) [9]. Nevertheless, due to their complex composition (Fig. 11.4) the
use of microalgae for making only biodiesel is not economic [10]. However, it is
necessary to apply the concept of biorefinery [7] for a most viable economic use of
algal biomass [11, 12].
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11 Enhancing Nature
and use wood at the same rate it is produced. Unfortunately, this is not the case as
we harvest wood at a faster rate than trees grow. This is the big problem, which sets
a limit to the use of biomass as energy source. It is useful to recall that the shift from
the use of biomass as energy source to fossil-C, more dense in energy, in late 1700s
was a compulsory step due to the industrial revolution. Biomass cannot satisfy our
society’s energy needs. Moreover, as discussed in Chap. 5, the direct burning of
biomass also causes the emission of particulate and noxious pollutants. So, we have
to find routes that may cause less environmental burden, such as the conversion of
the raw materials into biofuels. Additionally, taking into account the carbon
up-taken from soil, the use of biomass can become a net transfer of CO 2 from
surface soil to the atmosphere, unless clever strategies are implemented. Using
biomass, thus, is not “per se” a way to a zero-emission of CO 2 , and it will reach
such target if we use soil with the right strategy and apply the concept of biorefinery
to the use of biomass. Ethanol and biodiesel can be valid alternatives to fuels
derived from fossil-C supposed that the conflict between food-energy and the use of
soil is solved. Biogas, which is formed by fermentation of fresh organic waste or
fresh non-eatable grown biomass, is composed mainly of methane (60%) and CO 2
(40%), which is an interesting option of using waste or non-eatable biomass.
However, the winning strategy is the use of waste biomass, biomass grown on
marginal soils (such as polluted or arid soils, which are not suited for growing
edible biomass), and the use of non-edible biomass.
11.2.1 Production of Fuels and Chemicals from Aquatic
Biomass
Algal technology is attracting a lot of attention for the ability of algae to fix
inorganic carbon and convert it into several value-added products, including biofuels precursors. Both macro- and microalgae are under analysis for exploitation.
Various strains have a different potential, show a different adaptation to being
grown out of their natural environment, and can be useful to produce high value
products, materials, and fuels for market [7, 8].
Macro- and microalgae are rich in protein, carotenoids, antioxidants, fatty acids,
enzymes, polymers, peptides, toxins, and sterols and other compounds, which can
be used for several purposes (Fig. 11.4).
Microalgae have been identified as a third generation feedstock, and a more
efficient source of biodiesel (estimated production: 50–70 t ha
−1 y
−1 in open ponds
and 150 t ha
−1 y
−1 in photobioreactors) compared to terrestrial energetic oily crops
(*3 t ha
−1 y
−1 for soybeans, *9–15 t ha
−1 y
−1 for corn, and *13 t ha
−1 y
−1 for
switch grass) [9]. Nevertheless, due to their complex composition (Fig. 11.4) the
use of microalgae for making only biodiesel is not economic [10]. However, it is
necessary to apply the concept of biorefinery [7] for a most viable economic use of
algal biomass [11, 12].
196
11 Enhancing Nature