Page 103 - vol5_n2

233 IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 2
E. M. R. FAIRBAIRN | T. P. DE PAULA | G. C. CORDEIRO | B. B. AMERICANO | R. D. TOLEDO FILHO
thermoelectric generation, where the energy generated is suffi-
cient to ensure the self-sufficiency of sugar cane mills and still gen-
erate surpluses. The CO2 emissions from biomass burning does
not contribute to the intensification of greenhouse effect, since the
carbon from sugar cane already existed in the atmosphere and
was absorbed during the vegetal growth.
The main product of bagasse burning is the SCBA. The mass of
ash generated corresponds to about 2.5% of the bagasse burned,
or 0.6% of the mass of sugar cane harvested.
5. Considerations on the methodology
for CDM implementation
In accordance with the UNFCCC guidelines, a CDM project must
follow a specific methodology for the activity developed. For the
case of this study, the methodology applied is the ACM 0005,
entitled Approved and Consolidated Baseline Methodology for In-
creasing the Blend in Cement Production [16], which defines all
the prerequisites, constraints, and equations needed for legitimate
determination of emission reductions.
The ACM 0005 methodology is applicable to any project that in-
creases the share of additives in cement, i.e. reduce the share of
clinker. In addition, there are prerequisites such as that there is no
shortage of additive used, there is no suitable alternative destina-
tion for the additive and cement production is geared only to the
internal market.
Considering national production of SCBA (2.556 Mt) and cement
(46 Mt) in the year 2007, and assuming a replacement of up to
50% permitted by Brazilian standard [17], it is concluded that the
amount of additive produced is enough to supply 37% of national
production of cement during the project implementation with re-
placement fraction of 15%, with no shortage of ash.
Currently, the most common destination of the ash produced is the
use as soil fertilizer, although its fertilizers properties are not relevant
and its degradation is very slow, so that this practice aims at the sim-
ple disposition of ash. Searches for new destinations that add value
to the ash, as an additive in cement production, are preferable alter-
natives, and therefore, more suitable than the common practice [6].
According to the SNIC [3], the cement production geared to expor-
tation in 2007 corresponded to 2.7% of total cement produced, so
that national cement production is predominantly geared towards
the domestic market. Still according to the SNIC, the south/south-
east region, responsible for the majority of national production,
has not registered cement exportation in the year of 2007, with
the exception of the State of Paraná which has exported about
1% of its production [3].
Another important prerequisite for the acceptance of the CDM
project is that this presents what is named on the methodology
as “additionality”. Additionality occurs if emissions arising from the
implementation of the project are lower than those that would have
occurred in the absence of the project. In addition, it is necessary
to prove that the project is only feasible or becomes economically
advantageous only if approved as CDM and if carbon credits are
obtained. Projects considered more attractive than others when it
is evaluated only the financial returns they bring, so that they could
be deployed without even the gains of the carbon credit, do not
have additionality. Projects resulting from the introduction of unfa-
miliar technologies and which face market acceptance barriers are
examples of projects which may be legitimized as CDM.
The use of SCBA as an additive in cement is a non-existent prac-
tice on the market. The use of this agro-industrial waste, which
emissions balance is null, is a new technology, consequently being
incipiently studied by academia, indicating that the use of ash as
additive generates additionality.
5.1 The calculation of emissions
According to the ACM 0005 methodology, the analysis of emis-
sions is not made for all greenhouse gases, but only for CO2, since
reductions in emissions of CH4 and N 2O by changes in combustion
process are not significant.
The methodology requires definition of two distinct realities (sce-
narios) for the calculation of emissions. The first, so-called Base-
line Scenario, reflects the emissions that would occur in a particu-
lar future period if the current processes of production were not
changed, representing a historical trend in emissions. The other,
called Project Scenario, represents the emissions that would occur
as a result of project implementation. The Baseline should con-
sider the situation in which occur the lowest possible emissions, so
that the calculation of emission reductions is conservative.
The calculation of emissions involves four main steps: Baseline
emissions, Leakage, Project emissions and Emissions reduction.
5.1.1. Baseline emissions
The Baseline emission is calculated using the following equation:
(2)
BC ADD ele y Blend clin y BC BE B BE BE _ _ ) ,
ker , ( + × =
where 〖BE〗BC,y is the Baseline CO2 emissions per ton of blended
cement type; 〖BE 〗clinker the clinker CO2 emissions per ton of clinker
in the baseline in the project activity plant; 〖BE〗blend the blend Base-
line benchmark of share of clinker per ton of blended cement and〖BE〗ele_ADD_BC the emissions relating to electricity for grinding and
preparation of additives in the Baseline, including gypsum, given in
tons of CO2 per ton of cement.
The terms of the above equation are in turn calculated as below:
(3)
CLNK sg ele CLNK grid ele fuel fossil calcin clin BE BE BE BE BE _ _ _ _ _ ker + + + =
The term 〖BE〗calcin refers to emissions arising from the calcination
of calcium and magnesium carbonate. The calculation of this term
involves the determination of the levels of calcium and magnesium
oxide both in raw flour and clinker and the use of emission factors
provided by the methodology for both oxides. The term 〖BE〗fossil_fuel
refers to emissions from the burning of fossil fuels for the produc-
tion of clinker. This term is calculated by the sum of the quantity of
various types of fuel consumed weighted by their emission factors.
The term 〖BE〗ele_grid_clnk refers to emissions arising from the use of
grid electricity for the production of clinker. This term involves the
total energy used weighted by the grid emission factor. Finally, the
term 〖BE〗elec_sg_CLNK refers to emissions arising from the electrical