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I was wondering which drink container is the most sustainable one, when looking at the big picture (complete life cycle analysis).

So far, I can see the few following points:

  • Transport: plastic and aluminium are lighter than glass, and they can be crushed on their way to recycling, which means less transport-related use of energy.
  • Raw material: I think glass is probably the most sustainable in terms of resource availability and number of recycling cycles - is that right?
  • Pollution: again, glass would be the best at not disrupting the environment.
  • What about the energy needed for recycling each of those products?

I reckon this should be assessed on a contained liquid volume base.

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    You forgot reuse - plastic bottles can be reused, in fact, a lot of the bottles I use in my house are old cold drink bottles
    – elssar
    Feb 5, 2013 at 23:19
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    Are you asking strictly about buying drinks as products in a store?
    – Jay Bazuzi
    Feb 5, 2013 at 23:49
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    The extra weight and breakage in transit of glass needs to be included. A plastic or aluminium container for 500ml of water weighs 10-20 grams, while an equivalent glass bottle weighs about 300g (via Alibaba). Also, same question here: articles.philly.com/2012-07-23/news/…
    – Móż
    Aug 5, 2013 at 4:53
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    A lot depends on where manufacturing happens - a glass bottle made in China, shipped to Italy, filled with wine then shipped to New York is going to lose out hugely to a paper-and-aluminium cask made in China+USA, filled in California and shipped to New York.
    – Móż
    Aug 5, 2013 at 4:57
  • @Mσᶎ and Jay: I guess I limited my question to the choice I have to make if I see the exact same drink, same volume, but in three different containers in a shop: what should I choose if I want to make the most sustainable choice considering (1) availability of raw material, (2) enviro. cost of first production, (3) enviro. cost of recycling the material, (4) pollution if released in enviro. and (5) enviro. cost of transport, assuming that all sites involved (production, bottling, sale and recycling) are the same (and fairly local) for the 3 streams, and that I use the container only once. :)
    – stragu
    Apr 2, 2014 at 5:57

5 Answers 5

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I found a comparison here. My take on reading that is the following:

  • Aluminum is the most efficient in terms of energy saved in making a new can taking only 5% that compared to working from scratch.
  • Glass comes in second saving 20-30% of the energy in making new glass.
  • Plastic is a distant third since you keep degenerating to a lower quality plastic formula. (e.g. PET (type 1) soda bottles becomes carpeting and jackets)

Now I'm not sure if glass beats aluminum in a total energy consumed to make say a 12 ounce container in that perhaps the amount of energy required for glass is so much less than aluminum that using 70% of the glass number still beats 5% of the aluminum number. However, with no facts to back this up, my intuition tells me aluminum would still win in a side by side comparison.

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    Your intuition served you well! From this source, the energy to create a new soda can is about twice that of a glass bottle, so 2 * 0.05 is still less energy than 1 * 0.70. Aluminum cans are more sustainable from a pure energy standpoint. See Chris's answer and my comment below it for another derivation of this figure.
    – Nate
    Aug 3, 2013 at 21:43
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    Number of re-use cycles for glass bottles is much higher though, so even allowing for reuse energy I think glass would be lower. Not enough to matter, but lower :)
    – Móż
    Aug 5, 2013 at 4:59
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    @Ӎσᶎ Can you cite a reference to support your claim on use cycles for glass greatly exceeding aluminum?
    – WilliamKF
    Aug 5, 2013 at 22:21
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    WilliamKF: no, because I can't find a reference to commercial reuse of aluminium containers. en.wikipedia.org/wiki/Reuse_of_bottles, for example, only talks about glass bottles being designed for reuse. banthebottle.net/articles/… suggests that reusable aluminium bottles are problematic. Stainless steel is the other main food-grade reusable container (beer kegs, for example), but seems to be rarely used at a consumer level.
    – Móż
    Aug 5, 2013 at 23:09
  • if you mean recycle cycles, I suspect but don't know that glass, steel and aluminium are all effectively infinite, but stainless steel might be harder to recycle rather than downcycle because of the precise alloying requirements. Aluminium food containers are probably less fussy about alloying (speculation on my part) allowing easier recycling.
    – Móż
    Aug 5, 2013 at 23:11
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Before plastic bottles became popular, recycle meant something different than today. It used to mean 'reuse' not 'remanufacture'. I would think reuse of glass bottles would be the most sustainable. Although I'm not aware of any soda manufacturers that reuse bottles in the US, there are dairies that reuse milk bottles now that glass milk bottles are making a comeback at local dairies.

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    In Germany most glass bottles are reused (not remanufactured) by law, to which there are some exceptions. Even some thick-walled plastic bottles (mainly mineral water) are reused. Other plastic bottles have a 25 cents "refund", which makes sure that they are recycled properly. In Japan nothing gets reused and little recycled. I guess a good answer must take into account: Do you have to assume that your whole packaging gets remanufactured rather than just reused?
    – Earthliŋ
    Feb 6, 2013 at 3:04
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    I spent three years living in Germany (I'm from the UK) and there, recycling is done properly. Every nation would benefit from copying their laws and psychology in this regard. One thing to worry about though is the risk of fraud: importing bottles from countries without a levy so as to claim the levy refund.
    – Nicholas Shanks
    Feb 7, 2013 at 10:03
  • @Nicholas, I did that in US: hauled recycling across the state lines to collect cash refund. Given the amount of work and time, it was not worth it, but if on the way, it is possible to offset some of the fuel costs.
    – theUg
    Mar 2, 2013 at 0:13
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Interestingly glass and aluminum have the same specific heat or close to it (about 0.2 J/g) but the mass of he container is much different, and aluminum has a much lower melting point (about half that F of Glass).

Estimating weight of a 12 oz beer bottle at 140 grams (that's prob. low), and going by internet searches to find that empty soda cans weigh about 14 grams, we get a sense that the amount of energy required to bring to melting point is about 5% that of the aluminum can than the glass bottle.

140 * 2700 * 0.2 = approx 75600 J to melt the glass bottle discarding enthalpy of fusion (which iirc doesn't affect glass).

14 * 1100 * 0.2 = approx 3080 J to reach melting point plus 398 * 14 = 5572 J to melt, approx 9kJ to melt the soda can vs 76kJ to melt the glass bottle.

As are all answers this is necessarily incomplete. It isn't clear to me what else goes into recycling either and whether there are other embedded complexity costs, but that's a base line.

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    The equations you show aren't really valid. The units are all messed up. The correct equation is Q = mc(T1-T0), but to be consistent, you'd need T1-T0 in K, not F. Specific heat is in units of J per G per degree K. However, since you've made the same mistake in both places, the ratio of the energy to melt down the glass vs. aluminum bottle (~8:1) is about right.
    – Nate
    Aug 3, 2013 at 21:28
  • Breaking the glass into bits and cutting up the can would help get you up to temp quicker. Your calculation is just for the melting part. Therefore, you need more energy to get the volume up to the temps.
    – Some Free Mason
    Apr 7, 2016 at 14:13
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What's best is if you pipe the water into your house, making for huge savings in transport costs.

Now, while this doesn't really apply to fancy things like pop and beer, it's really, really better to not drink bottled water at all. Systemically speaking, the rate that bottles and cans are actually recycled is dismal at around 15%. So in the end the difference in recycling costs don't really matter that much anyway.

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    Can even work for beer: most of what I drink (I'm not a big beer drinker, though) comes from my neighbor whose hobby is home brewing. Bottles last pretty much forever. Though even the plastic 1-2 liter soft drink bottles I use for water when hiking &c have lasted for years and years.
    – jamesqf
    Feb 13, 2015 at 19:49
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When I lived in IL I was told that any broken glass went into the landfill. How much glass do you think is not broken when it is dumped into the recycling garbage truck? I think it is a terrible waste of energy to not recycle glass. Here is a good site for information: http://www.greenlivingtips.com/articles/182/1/Recycling-energy-savings.html Glass, plastic, and aluminum are discussed

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    Thanks for your input, Lorna. Your answer might benefit from outlining the main information contained in the article you linked.
    – stragu
    Aug 20, 2017 at 7:06

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