Monday, January 26, 2015

Canning and packaging

The energy to make things

An aspect of our consumption that is hard for people to understand is that of embodied energy. This is the energy that is required to make things and deliver them to us to use. It is difficult to estimate the embodied energy of a thing, because it's difficult to know where to stop.

Let's take a 2 L plastic container as an example. In Australia, these are typically made from HDPE or high-density poly ethylene. HDPE is an amazing material, and has many uses. It is a petroleum product. How much energy does it take to make a milk carton and get it to our home?

Obviously, we have the energy involved in the manufacture and delivery of the container -- but what about the supporting infrastructure? The more stuff like this that is transported, the heavier the burden on our highways (ie. a significant proportion of road upkeep can be attributed to the delivery of stuff). Also, since HDPE is a petroleum product, we need to include the raw oil that is destined to be made into our container. Also, we need to include (part of) all the ancillary machines and tools used to discover, extract, process, refine and distribute that oil. We also should really include (part of) the support infrastructure for all those machines -- how they are manufactured, delivered, serviced, repaired, and disposed of.

Clearly -- this is a bit of a rabbit hole. Where we draw the line (ie. where we stop counting) is a bit arbitrary, but we can be sure that we can't count all of the energy inputs that go to making a 2 L HDPE bottle.

I estimate that one 2 L HDPE container, such as those used for milk, has an embodied energy of at least 1 kWh [1]. 


This is a lot of energy. What is poorly understood is that, for plastics, recycling doesn't save that much energy.
Recycling plastic only saves about 1/3 the energy compared with making new plastic from oil [2]

To me this shows that disposable plastic packaging is very wasteful, even if it's recycled.

What to do?

Really, it's simple. If you want to use less energy, you need to reuse your packaging instead of throwing it away. This was normal only 50 years ago, so it's not really such a far-out idea.


Cook preserves (eg. jams, chutneys, stewed fruit) at home. If you find which neighbours have fruit trees, they will probably be happy to share their fruit with you when it's ripe -- particularly if you give them back a jar of preserve. I recently read that the cost of the jar is about 1/3 the cost of buying a jar of jam (can't find the reference, sorry). That's quite amazing when you think that people often buy cheap jam to save money. Making your own jam is really easy, it tastes better and you save money. Also, we're quite careful to make our preserves when our solar PV is producing, so we know that the electricity to make the jam is renewable(-ish) too.
Some of the fruit we gathered for free yesterday at a local park (beautiful nectarines)

Our preserves cupboard. The top jars are empty jars ready to be reused. The drawers have the beginnings of our preserving efforts. Very exciting!
Figs that we "gleaned" for free at the park yesterday. When we discovered this tree (almost a year ago) there were rotting figs all over the ground. There won't be this year!

Shop at places that allow you to bring empty packages to fill and reuse -- this is especially easy for dried goods (eg. beans, grains, flours, dried fruits, etc)
If you drink soy or nut milk, experiment with making your own (either from powder or from scratch) -- it's a lot cheaper too
Try making your own yoghurt -- it's about 1/2 the price of bought yoghurt

We do all these things at my place, and it's really not onerous -- it's quite fun. It's very satisfying to build up a store of beautiful home-canned fruits -- many of which we've got for free. Home-made jam is the best you can get, and you know exactly what has gone into it.



This article was written by Angus Wallace, and first appeared at


  1. Hi Angus. Good to see your preserving skills in action. Seriously I'm jealous of those freebie figs. ;-)! The fig trees here are a few years away from production and with the weather this year swinging between cold and hot it does those trees no good at all. Hope this week isn't too bad up your way? It certainly going to be toasty here.

    If you want some tree lucerne (tagaste) seeds, I can send some to you. If you're interested drop me a not for posting blog comment with your address. No stress though.

    I spotted this article recently which raised some interesting alarm bells:

    The 91% figure was alarming. Cheers. Chris

  2. Hi Chris,

    Thanks, Responded on your blog about the seeds.

    Yeah, the fig tree is awesome. I think we've taken 6 - 8 kg so far, and there are many more to go. I'll take the kids there this afternoon and get some more ;-) I have a tree at home, but it's very small (50cm tall), so figs are years away there. Hopefully the word doesn't spread too far about this tree -- at this point I'm not worried, as it's not clear anyone else is picking them (maybe they're scared of climbing a tree ;-)

    I read that article. Amazing. Although a regressive signal, I think increasing rego costs wouldn't be a bad thing. Maybe Aussies would start demanding better public transport (though perhaps there would also be more aggro to cyclists)

    Cheers, Angus


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