Environmental Engineering Reference
In-Depth Information
Table 4.5
Estimate of Plant Energy Distribution for Three Plastic
Processes
Source: Based on data from Guide to Energy Efficiency Opportunities in the
Canadian Plastics Processing Industry (2007).
Operation
Extrusion Injection molding Blow molding
Plant
3
10
12
Barrel heating
4
19
6
Extruder drive
41
18
38
17
46
Mold clamping
36
a
Includes dryers, coolers, granulators, compressed air generators, and material
handling.
4.4 THE ENVIRONMENTAL FOOTPRINT OF PLASTICS
Does the manufacture and processing of plastics contribute significantly
to energy use and climate change? Do the societal benefits derived from
plastics justify this footprint?
4.4.1 Energy Considerations in Resin Manufacture
In the United States, liquid petroleum gases (LPG), natural gas liquids
plastic production accounted for only about 2.7% of the total petroleum
and 1.7% of the natural gas consumed. The electricity used was estimated
at a further 1% of the consumption. Then estimating conservatively, only
about 5.4% of petroleum resources were devoted to manufacturing plastics
7
(US Energy Information Administration, 2013). The operational or process
energy may add another approximately 3-4% to this, bringing the total
fossil fuel investment in plastics to about 8.6%.
The question is whether the improvements in human condition
(convenience, comfort, and safety) as well as energy savings due to use
of plastics (see
Chapter 5
) justify the investment of 8-9% of the crude
oil resources in the plastics industry. Fossil fuels are used efficiently in
manufacturing plastics with little waste. In the United States, over 70% of
