long term, the contribution of N 2 O to GHE will increase and become more
important than CO 2 due to its higher GWP. A positive news is that during last
20 years the overall amount of energy for producing biomass has significantly
decreased with the implementation of more effective farming techniques (reduction
of the use of fertilizers and pesticides, of the energy used in seeding, growing, and
harvesting) and biomass processing [12].
As a third key point, we have to consider, as already discussed, that the combustion rate of biofuels is much higher than the fixation rate of CO 2 into biomass
and this will make that yearly there will not be a closed cycle between the emitted
CO 2 and the fixed CO 2 , unless unlimited surface areas are considered for the
production of biomass. The claimed “zero emission” is a wish, not a reality, at least
for now. Moreover, the economics of producing bioethanol from waste biomass are
negative even if oil is quoted at 100
+ US$/barrel: fossil fuels are very cheap [13].
Still a lot of work has to be done for making biofuels environmentally and
economically convenient with respect to fossil fuels. The IEA organization has
published a “technology roadmap” on transport and biofuels [14] according to
which second-generation biofuels will rise their share after 2020 and play a key role
toward 2050 reaching 27% of the total fuels used in transport [15].
Recent studies confirm that it is possible that biofuels will reduce the GHG
emission with respect to fossil-C, but this cannot be a general assumption, instead it
demands very special conditions. In any case, the question of “payback time”
remains an open question [16].
Table 4.2 shows the trend of biofuel use in the world since 2004 until 2030.
There is clearly a continuous growth, according to the IEA studies [17].
Today, Brazil is the country that most uses biofuels (bioethanol): it is expected
roughly double its consumption. Major increments are foreseen for OECD countries, EU, and developing countries and which biomass will expand more will
depend on a number of factors and there is not a unified view as for today. Most
likely, bioethanol will remain the major player among biofuels, considered that it
can be produced from practically any cellulosic biomass (grown and residual).
The expanded use of waste/residual biomass will greatly improve the emission
mitigation power of biofuels. In fact, such biomass fraction ends on as CO 2 upon
burning or decomposition in soil.
Its conversion into biofuel will allow avoiding the additional burning of other
C-based materials and most of the energy stored in it can be advantageously used.
The increased contribution of biofuels will change significantly the energy mix
in future years, as shown in Table 4.3.
As Table 4.3 shows, oil consumption will be almost halved with respect to
today, while gas and coal will decrease by 10–15%. Biofuels will more than double
their contribution. Perennial sources (solar, wind, hydro, and geothermal) will be
discussed in Chap. 5.
Such trend will impact positively the emission of CO 2 that will be reduced by
some 10 Gt/y with respect to today [15].
54
4 Reduction of the CO 2 Production
important than CO 2 due to its higher GWP. A positive news is that during last
20 years the overall amount of energy for producing biomass has significantly
decreased with the implementation of more effective farming techniques (reduction
of the use of fertilizers and pesticides, of the energy used in seeding, growing, and
harvesting) and biomass processing [12].
As a third key point, we have to consider, as already discussed, that the combustion rate of biofuels is much higher than the fixation rate of CO 2 into biomass
and this will make that yearly there will not be a closed cycle between the emitted
CO 2 and the fixed CO 2 , unless unlimited surface areas are considered for the
production of biomass. The claimed “zero emission” is a wish, not a reality, at least
for now. Moreover, the economics of producing bioethanol from waste biomass are
negative even if oil is quoted at 100
+ US$/barrel: fossil fuels are very cheap [13].
Still a lot of work has to be done for making biofuels environmentally and
economically convenient with respect to fossil fuels. The IEA organization has
published a “technology roadmap” on transport and biofuels [14] according to
which second-generation biofuels will rise their share after 2020 and play a key role
toward 2050 reaching 27% of the total fuels used in transport [15].
Recent studies confirm that it is possible that biofuels will reduce the GHG
emission with respect to fossil-C, but this cannot be a general assumption, instead it
demands very special conditions. In any case, the question of “payback time”
remains an open question [16].
Table 4.2 shows the trend of biofuel use in the world since 2004 until 2030.
There is clearly a continuous growth, according to the IEA studies [17].
Today, Brazil is the country that most uses biofuels (bioethanol): it is expected
roughly double its consumption. Major increments are foreseen for OECD countries, EU, and developing countries and which biomass will expand more will
depend on a number of factors and there is not a unified view as for today. Most
likely, bioethanol will remain the major player among biofuels, considered that it
can be produced from practically any cellulosic biomass (grown and residual).
The expanded use of waste/residual biomass will greatly improve the emission
mitigation power of biofuels. In fact, such biomass fraction ends on as CO 2 upon
burning or decomposition in soil.
Its conversion into biofuel will allow avoiding the additional burning of other
C-based materials and most of the energy stored in it can be advantageously used.
The increased contribution of biofuels will change significantly the energy mix
in future years, as shown in Table 4.3.
As Table 4.3 shows, oil consumption will be almost halved with respect to
today, while gas and coal will decrease by 10–15%. Biofuels will more than double
their contribution. Perennial sources (solar, wind, hydro, and geothermal) will be
discussed in Chap. 5.
Such trend will impact positively the emission of CO 2 that will be reduced by
some 10 Gt/y with respect to today [15].
54
4 Reduction of the CO 2 Production