Environmental Engineering Reference
In-Depth Information
Air, liquid, and solid emissions
Air
Manufacturing of packaging and packaging materials produces direct and indirect emissions
of green house gases (GHGs), nitrogen oxides, sulfur dioxide, and other pollutants of various
compositions, which are dependent on the type of material used and the process. Direct emis-
sions of GHGs, nitrogen oxides, and sulfur dioxides come from burning fossil fuels for the
production of feedstocks, including:
Extraction of materials from the ground, for instance petroleum, natural gas, and metals.
●
Removal of trees from forests and transportation to paper mills and saw mills.
●
Cultivation of feedstocks and their transportation to processing plants (e.g., natural fibers
or corn to produce lactic acid).
●
During the transformation of feedstocks into packaging materials, direct emissions of
GHGs result from burning fossil fuels that produce thermal energy for the process, on-site
generated electricity, and from the process itself (e.g., perfluorocarbon compounds, tetrafluo-
romethane (CF
4
) and hexafluoroethane (C
2
F
6
) produced during aluminum smelting), whereas
indirect emissions come from purchased electricity.
Because production of packaging consist of different stages, the “scope” of the emis-
sions will depend on the stage of the process. Scope 1 emissions from mining mineral ores
for metal packaging, for instance, will become Scope 3 for the manufacturer of the metal
can (see Chapter 7 on conducting a GHG inventory). Unless electricity is produced on site,
all steps of the process will be subjected to a Scope 2 emission of GHGs from purchased
electricity.
Carbon intensity for different packaging materials is presented in Figure 12.2. By far, alu-
minum is the most carbon-intensive material, and paper is the least. Paper production from
virgin materials, though, is a energy-intensive operation; however, during chemical pulping to
10
8.8
9
8
7
6
5
4
3
2.4
1.7
2
1.2
0.8
1
0.36
0
Aluminum
Plastic
Steel
Paper
Cement
Allwood et al., 2010
Blanco et al., 2004
Figure 12.2
Carbon intensity of five packaging materials.
Data from Allwood et al., 2010 and Blanco et al., 2004.
