Drunken Speculation

Are cans better for the environment than glass bottles?

green beacon windjammerMuch like low carb beer is often touted to be “healthier”, one of the frequently quoted advantages of cans versus glass bottles is the can is a more environmentally friendly product.

There’s two problems with this. The first is that it’s rarely made clear what constitutes “more environmentally friendly”*. The second is that this “fact” pops up almost as regularly as any myth about beer but no one quotes an actual source for it.

So let’s take a look at it because I’m sure this is totally not going to drive us insane and we’ll definitely come up with a satisfying answer.

The phrase “environmentally friendly” is always going to involve some value judgement. If I can dig up bauxite in the middle of nowhere then that may be preferable to mining sand where an endangered species of turtle nests, even though turning the bauxite into aluminium will require roughly ten times the energy and greenhouse gas emissions compared to turning sand into glass. What do you consider less friendly to Mother Earth: damaging one species’ habitat irreparably or contributing in a small way to the ongoing warming of the planet?

"What if the bauxite mine is in a panda habitat?" Shutup shutup shutup!

“What if the bauxite mine is in a panda habitat?”
Quiet you.

This number-less, qualitative thinking can render any quantitative analysis moot because to get around it, we’ll have to make some pretty heroic assumptions. Let’s just agree to keep this fairly big picture since the same information should apply everywhere. To the assumptions:

  • Bottles and cans hold the same amount of beer.
  • Mining of any raw materials is equally damaging to the local ecosystem.
  • All processing is powered by fossil fuels, preferably standard hard coal (let’s say anthracite) because it’s good for humanity. Side note: Tony Abbott is a dickhead.
  • The products are transported the same distance in the same way, although this will vary greatly by the proximity of the brewery to the packaging plant to the recycling plant/packaging manufacturer and to the consumer.
  • We’re only interested in carbon dioxide, even though it is one of an array of greenhouse gases and other noxious pollutants (ash and smoke are big killers of actual people right now) that result from industrial activities.
  • All beer density is the same while the difference can actually be around 2-3% depending on style.
  • The embodied energy in the glass/aluminium is the same as it is for building materials, otherwise I won’t be able to find the numbers and this analysis will end right here.

Now that I’ve stripped out all of the nuance, the difference between the two is the embodied energy in the packaging. Embodied energy is the amount of energy required to manufacture a given quantity of material. I’m not sure if this requires further explanation as a concept because I assume most people would be aware that glass and aluminium aren’t naturally occurring products and there’s an actual process requiring electricity and petrol to transform them from sand and bauxite respectively and the embodied energy represents this electricity and petrol used. If you didn’t know aluminium cans don’t grow on trees, this is about to get a lot harder and you should probably stop now.

"Would it be more efficient if we just drank straight from the tap?" Actually, yes.

“Would it be more efficient if we just drank straight from the tap?”
Actually, yes.

According to the internet, the embodied energy and the average weight of the packaging is as follows

Ignoring the variation in the values and taking the higher, a glass bottle takes about 2.9MJ to produce while an aluminium can takes 2.6MJ.

"What if it was a 375mL champagne bottle?" *silent glare*

“What if it was a 375mL champagne bottle?”
*silent glare*

In more concrete terms, a kilo of coal equivalent represents 29.3 MJ, and ignoring losses in the power generation and distribution system (it’s about 6% for those playing at home), so about 100g of coal is required to make a glass bottle and only 89g for an aluminium can.

On a grander scale, a 1000L batch fills 2,800 355mL packages. 797kg of carbon dioxide is released to make the glass bottles for that batch from scratch. A comparatively smaller 715kg of carbon dioxide ends up in the atmosphere for the canned option. Just think, the best part of three-quarters of a ton of carbon dioxide up there floating in the atmosphere, making the planet a slightly shittier place to live, just to make the packaging for one relatively small batch of beer. It doesn’t even have beer in it yet!

"What would be the embodied energy if it was kvass?" Fuck you, that's how much!

“What would be the embodied energy if it was kvass?”
Fuck you, that’s how much!

So does that mean cans are better than bottles you ask, hoping the math is nearly over? No, it doesn’t. What I’ve shown is that there’s a substantial amount of energy that goes into beer packaging and that the difference is about 11% between aluminium and glass. If you re-visit any of the assumptions above, you can build a case that glass may be the better alternative.

For example, aluminium smelters tend to be located closer to power stations due to the huge amount of electricity required. That 6% distribution loss quoted above could be more like 2-4% for aluminium because the electricity doesn’t have to be transmitted as far, which hands cans another 2% advantage. The problem is that power stations are usually located near the fuel source. So in Queensland, power stations (and aluminium smelters when we actually made stuff in this country) are located near coal mines. You may recognise this as being a place few want to live, meaning that the aluminium ends up being transported further to get processed into a can than glass.

Does that put it back in favour of glass then? Nope! Have you been paying attention? It matters how the material is transported. If the glass goes by train and the aluminium by truck, that might put it back in favour of glass. It might not. I’m not going to run any more numbers because this is getting dangerously close to work.

Also, yes.

Also, yes.

Let’s not start in to the relative recycle-ability of each material (aluminium only requires 5% of the energy used to create it to recycle it) or whether any part of the process is powered by renewable energy or how much energy is expended transporting raw fuels or whether we should compare 750mL glass bottles to 375mL cans or if co-generation is employed or whether the energy used to manufacture the packaging is actually a major contributor to the overall greenhouse gas emissions of the beer industry.

Actually, no, let’s take a brief detour to look at that. The 1,000L batch I mentioned before? If that entire batch was boiled, it would require about 334MJ of energy (assume pure water, 20C starting temp, etc, etc) just to get it up to boiling point. Add about 10% to account for inefficiencies and distribution losses and we’re at 365MJ or about 35kg of carbon dioxide or about 4-5%** that to make the bottle or can. Remember this is just the energy to get the water to boiling point, not the energy expended keeping it boiling for an hour or two. I’m not going to work that out because it will require a whole other set of assumptions.

Let’s also not forget the energy required for malting, mashing, hop processing, hop storage, transportation of all the raw ingredients, more processing, more storage, boiling, cooling the wort, pumping, temperature controlling fermentation before we even get to a product that can be packaged.

Lots of dinosaurs died and were put under incredible pressure for hundreds of millions of years for this process to happen.

The point is lots of dinosaurs died and were put under incredible pressure for hundreds of millions of years for this process to happen and we’re running out of them.

While I feel like I haven’t actually reached any substantial conclusions worth noting, I do now appreciate why this analysis is rarely, if ever, undertaken. Mostly because it’s freaking impossible to come up with something that is actually useful.

I’d also like to think that the industry – big and small – will take note of how much energy, from generally non-renewable resources, is used to produce what is essentially a luxury good. This has to become the industry’s number one priority. To really put some emphasis on this:

Fuck quality, global warming is going to hit the world like a brick in the face. We can at least try to soften the blow.

In the meantime, I’m off to get my carbon…dioxide…cylinder…refilled. God damn it.

*Although, if stated, it’s usually because aluminium cans weigh less than glass bottles and so take less energy to transport, a fact so specific as to be meaningless. Compare with the above, equally robust analysis.

**I’m sure there’s a physics tutor reading this and tearing their hair out because I’m not doing significant figures correctly and I’ve put exactly no error margins on my numbers.

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