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From the article… > Glass requires so much energy to make - or recycle - that it is always more eco-friendly to use aluminium cans, even if one is talking abou

From the article… > Glass requires so much energy to make - or recycle - that it is always more eco-friendly to use aluminium cans, even if one is talking about virgin cans compared to recycled bottles. Since when?!? Growing up, in a part of the country that was once known for glass making (but had stopped by the time I was a kid), we were taught in school that glass was cheaper to make resource and energy wise than aluminum, due to the lower technology overhead and ready access to the sand used to make it. Since then, based on my own reading, I understood that aluminum was really expensive to make due to the high electrical requirements for the process of cracking ores to get the pure aluminum out (a substance that is hard to find in nature in pure form, since it’s readily makes compounds and ores due to its reactivity.) It was this basis that politicians and activists gave to push the first recycling programs here in the States. (Which always, without exception AFAIK, started with aluminum.) My understanding is that glass was phased out in favor of aluminum not due to container creation costs, but storage reasons, since cans take up less room and shelf space than glass and were easier for stock boys and shoppers to carry. (The only eco-reason I came across was increased fuel use to ship glass bottles for the old returnable bottle programs. But this reasoning didn’t make sense to me since I thought shipping a pre-existing container was much cheaper than destroying and making new ones.) Did some technology in recent years dramatically reduce the energy cost of making aluminum? Or has the modern requirements of glass making added too much overhead to what was once a cheap process?

kragen 16y ago
No, aluminum production still costs the same as it has for more than a century. The cost of the Hall-Héroult electrolytic process dwarfs the cost of mining bauxite, so the easy access to the sand is irrelevant. Perhaps the distinction between what you were taught and what the article says amounts to a distinction of denominators. Glass is much cheaper per kilogram (https://secure.wikimedia.org/wikipedia/en/wiki/Embodied_energy#Embodied_energy_in_common_materials https://secure.wikimedia.org/wikipedia/en/wiki/Embodied_ener... says glass is 18–35MJ/kg, while aluminum is 227–342) but aluminum is cheaper per container, because the weight of the container is smaller by more than a factor of 10. Also, recycling aluminum costs less than a tenth as much energy as smelting it afresh. This reduces the "embodied energy" of a kilogram of aluminum destined for recycling to the same ballpark as the "embodied energy" of a kilogram of glass. However, washing out bottles and reusing them is cheaper still.
- eru 16y ago
  > However, washing out bottles and reusing them is cheaper still. Do you have a source for this? I am quite amazed that the British drink their bear out of virgin bottles. In Germany re-using bottles is common place.
  - kragen 16y ago
    A source for the cost of washing out bottles? No. I guess you might use about 100mℓ of water that you've heated from, say, 28°C up to 40°C, which is 1200 calories, or about 5 kilojoules. But the cost of the detergent and the new bottlecap might be more. The cost of recycling an aluminum can, however: an aluminum can is about 14 grams of aluminum, which is about 300 kilojoules according to the above; supposedly (sorry, no source handy) recycling it takes about 10% of that amount, or 30 kJ; that's about US$0.0004 of energy. I recommend never putting a bear in a virgin bottle.
    - eru 16y ago
      You can probably reuse some of the heat for the washing up. And perhaps even some of the water. I've heard that glass bottles are more convenient to wash, because you can use hotter water. (That's from a reliable source --- a visit to a beverage bottler on their open day.)
- DLWormwood 16y ago
  That is probably what it all boils down to: destructive verses non-destructive recycling. In short, aluminum is better if you always break down the container before remaking it, but glass is better if you try and preserve the form of the container. That is a shame, and makes the recent effort by beverage companies to make aluminum bottles make more sense. What’s disgusting given this realization is the recent popularity of Mexican sodas as a pushback against HFCS. Guess what containers are still in use south of the border? Guess we shouldn’t have dismantled out returnable bottle infrastructre so soon… /-:

kragen 16y ago

No, aluminum production still costs the same as it has for more than a century. The cost of the Hall-Héroult electrolytic process dwarfs the cost of mining bauxite, so the easy access to the sand is irrelevant. Perhaps the distinction between what you were taught and what the article says amounts to a distinction of denominators. Glass is much cheaper per kilogram (https://secure.wikimedia.org/wikipedia/en/wiki/Embodied_energy#Embodied_energy_in_common_materials https://secure.wikimedia.org/wikipedia/en/wiki/Embodied_ener... says glass is 18–35MJ/kg, while aluminum is 227–342) but aluminum is cheaper per container, because the weight of the container is smaller by more than a factor of 10. Also, recycling aluminum costs less than a tenth as much energy as smelting it afresh. This reduces the "embodied energy" of a kilogram of aluminum destined for recycling to the same ballpark as the "embodied energy" of a kilogram of glass. However, washing out bottles and reusing them is cheaper still.

eru 16y ago
> However, washing out bottles and reusing them is cheaper still. Do you have a source for this? I am quite amazed that the British drink their bear out of virgin bottles. In Germany re-using bottles is common place.
- kragen 16y ago
  A source for the cost of washing out bottles? No. I guess you might use about 100mℓ of water that you've heated from, say, 28°C up to 40°C, which is 1200 calories, or about 5 kilojoules. But the cost of the detergent and the new bottlecap might be more. The cost of recycling an aluminum can, however: an aluminum can is about 14 grams of aluminum, which is about 300 kilojoules according to the above; supposedly (sorry, no source handy) recycling it takes about 10% of that amount, or 30 kJ; that's about US$0.0004 of energy. I recommend never putting a bear in a virgin bottle.
  - eru 16y ago
    You can probably reuse some of the heat for the washing up. And perhaps even some of the water. I've heard that glass bottles are more convenient to wash, because you can use hotter water. (That's from a reliable source --- a visit to a beverage bottler on their open day.)
DLWormwood 16y ago
That is probably what it all boils down to: destructive verses non-destructive recycling. In short, aluminum is better if you always break down the container before remaking it, but glass is better if you try and preserve the form of the container. That is a shame, and makes the recent effort by beverage companies to make aluminum bottles make more sense. What’s disgusting given this realization is the recent popularity of Mexican sodas as a pushback against HFCS. Guess what containers are still in use south of the border? Guess we shouldn’t have dismantled out returnable bottle infrastructre so soon… /-: