Energies 2021 , 14 , 1161
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energy consumption and CO 2 emission of each of those products and to understand the sources of CO 2 throughout the process. In the second application, the model is used to calculate the energy consumption andCO 2 emissions of the entire sector in Austria, using as input the pulp and paper’s annual production. Since the pulp is sold separately as market pulp, the total production of pulp is not directly related to paper production, so the calculation methodology for the entire industry considered the production of pulp and paper separately (instead of pulp produced to sustain the production of paper). The two variants of the model diverge on the method used to calculate fuel consumption. Table 5 compares the two variants of the applied model.
Table5. Comparison of the two variants of the model used.
Individual Paper Grades
Austrian P&P Production
Considers the production of 1 ton of the specific paper grade, and the production of pulp necessary, according to pulp yield
Considers the total annual production of pulp and paper in Austria, unrelated to one another.
Pulp and paper produced
Similar
Energy consumption calculation method
Calculated from the industry reported values of heat and fuel consumption (according to Section 2.2)
Assumes the typical energy production technology used in P&P mills
Fuel consumption calculation method
Similar
CO 2 emission calculation method
Specific (Per ton of paper produced)
Absolute
Results
With both approaches, the impact of selected new technology on energy and emission savings, by considering the time required for the diffusion of the technology, can be analyzed. 3.1. Mathematical Formulation: Energy and Fuel Consumption for Specific Paper Grades The energy consumption to produce each paper grade depends on the characteristics of the paper produced, which are defined in the model by the following variables: • Paper grade produced (printing and writing paper, tissue, newsprint, or packing paper); • Mineral filler mass content in the paper ( mf ); • Integrated or non-integrated production; • Type of virgin pulp used: chemical (kraft, sulphite), mechanical (GW, TMP); • Recycled fibers (RCF) content in pulp ( r ); Seven different cases were studied (filler content is always considered 10%), shown in Table 6.
Table6. Production specifications of the cases studied.
Writing (n. int.)
Printing (int.)
Packing (int.)
Tissue (kraft) (int.)
Tissue (RCF) (int.)
Grade
Writing (int.)
News (int.)
Virgin Pulp
Kraft
Kraft
GW 10%
TMP 10% 50%
Kraft
Kraft
-
10%
10%
10% 50%
10%
10%
mf
0%
0%
0%
0%
100%
r
For each case, the impacts of producing one ton of paper are calculated ( M paper = 1 ton). The dry mass of fillers and pulp necessary for the production are calculated according to Equations (1) and (2), respectively. mf represents the mass percentage of paper fillers in thepaper. M f iller = M paper · mf (1)
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