and for a while I've been wondering -- especially in light of my local natural food store's comical attempt to banish plastic packaging from their beverage aisle which they then had to walk back a couple weeks later -- is plastic actually worse than other forms of beverage packaging, in terms of carbon footprint?
I was working on doing the research myself but in the middle of writing the post I found this LCA that was done by Franklin Associates/ERG (a sustainability consultancy) on behalf of -- caveat emptor -- the PET beverage container industry a few months ago:
in its defense it seems to use basically all the same sources I was digging up on my own and is a lot more thorough than I could ever be1. the numbers it comes up with:
- 1,000 gallons of soda worth of PET bottles, at prevailing recycling rates (29.1% recycling rate, new bottles made out of 10% recycled content), produce between 296 kg CO2e (2-liter bottles) and 623 kg CO2e (16.9 fl oz bottles) of global warming potential depending on bottle size;
- 1kgal worth of 12oz aluminum cans at the prevailing recycling rates (50.4% recycling rate, 62.3% recycled content) produce 1,241 kg CO2e;
- 1kgal worth of 16oz cans produce 969 kg CO2e;
- 1kgal worth of 12oz glass bottles at the prevailing recycling rates (39.6% recycling rate, 38% recycled content) produce 2,608 kg CO2e.
glass and aluminum also do (somewhere between a little and a lot) worse on energy and water consumption, solid waste production, production of nitrogen and sulfur oxides and ozone. the only place where they win is on ozone depletion, where aluminum and glass produce ~milligrams of CFC-11 equivalent per 1,000 gallons, instead of ~centigrams.
the main drivers seem to be:
- while manufacturing glass packaging produces less carbon dioxide per kilogram of packaging material, a glass bottle weighs an order of magnitude more than either an aluminum can or plastic bottle of the same size;
- manufacturing finished aluminum cans from aluminum ingot consumes almost 3 times as much energy as manufacturing plastic bottles from PET pellets.
anyway, the real solution here is obviously for americans to get over our phobia of reusing drink containers and establish glass bottle collection, sterilization, and reuse programs. but it's wild that the contemporary hippie wisdom is actively harmful, to the tune of a potential fourfold increase in carbon footprint.
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I care a lot about soda bottles. I do not care this much about soda bottles.
imagine a world where the only thing that's different from Earth Prime is that instead of 12 fluid ounce glass bottles, soda comes in 2-liter glass growlers; besides this world being slightly more whimsical than our own, the decrease in the amount of dead weight per kilogram of packaged soda alone decreases the carbon footprint of glass by 700 kg CO2e/kgal -- about 25%.
thanks to @JhoiraArtificer for weighing a bunch of glass bottles she had around her kitchen for the original version of this post
what am I supposed to say to "can I get you to do some science for me"? no???
bonus:
official @vogon science rating: thorough (it was only 9 bottles!)

vogon: hey can I get you to do some science for me
Liz: most likely
vogon: you've got a kitchen scale, right
Liz: Yeah
It hates 15 grams tho1
vogon: do you have any glass beverage containers? specifically thinking of soda bottles and beer growlers
Liz: Full or empty? I've got empty growlers for sure
vogon: empty
Liz: Yeah
vogon: could you weigh them for me and give me the weight and nominal volume
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it really does, it almost always skips straight from 14 to 16 grams
