A little thought experiment....
1 - put aside any subsidies for the time being
2 - put aside any differences between the amount you pay for energy and the amount a manufacturer pays for energy
3 - put aside different carbon intensities of energy saved and energy of manufacture/tranpsort
4 - the following diagram therefore must be true when the product has paid itself off:
Picture
Therefore in a simple situation (without subsidies and with no difference in energy prices) when a product has paid for itself in energy savings it has also necessarily paid for itself in embodied energy. 

So the only question is how much to 1, 2 and 3 change things? My view is not very much. What are your thoughts - anything major missing here?  I'd love to have your thoughts.

Because of this for my project, I have decided to concentrate on paybacks and CO2 savings rather than embodied carbon as it will come out in the wash so to speak...
 


Comments

Jamie Bull link
19/04/2011 19:28

That's a good way of looking at it. Of course you're right that if something pays back financially it is very likely to pay back in energy terms - unless it's heavily subsidised like corn ethanol. And there need to be some serious reasons to subsidise something to that extent.

With insulation the point where the embodied carbon of an additional sheet outweighs the saving is way beyond the point where it stops being financially viable, even with a high assumed cost of carbon and rapid fuel price escalation.

I'm not sure that entirely validates your suggestion that embodied energy is a canard though - or at least that it's canard status only applies when talking about energy saving kit.

On the other hand it's worth bearing in mind that the cost of that embodied energy is being passed on as part of the purchase price. Lower embodied energy products often cost less than higher embodied energy ones.

And finally, embodied energy/carbon isn't the whole picture. There are questions of toxicity, other greenhouse gas emissions, resource depletion, etc to consider too, but I'm sure you'll considered all that.

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Toby link
20/04/2011 10:05

Interesting stuff, somthing I've pondered myself.

Another way to look at it is what are the company's cost actually going on, and what is the carbon impact of each of these things. You mentioned manufacture and transport. What about R&D? Raw Materials? ... If your R&D is mostly desk based the carbon intensity is probably less per pound spent than manufacturing. Gold might have a (relatively) similar carbon intensity to extract and process (per unit mass) as iron, but the cost difference is massive. Silicon for PVs?

But maybe these things pale into insignificance compared to the business of making and transporting stuff. I don't know!

Not energy saving products, but is there a parallel comparison between a $3000 Gucci handbag and the $10 Primark one.

And just how far do you want to go dig with the carbon impact - A slightly silly argument would be that the caron per pound is much less for the Gucci handbag, so a true environmentalist would get that one. But if its made in an air conditioned boutique in Italy by a craftsperson who drive home in a range rover, and the Primark one is made (humanitarian issues aside) by a swaet shop labourer with a personal carbon foot print one hundredth the size. But this path leads to madness.

There is certainly a link between cash spent and carbon, the question is how tight is that correlation?

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Chris Newman link
20/04/2011 21:27

Thanks both for your thoughts.

@Jamie Yes, I'm only talking about energy saving kit- especially insulation. I can see why it doesn't apply to concrete for example.

@Toby. Yep, R&D costs will also be in there but is really just a subset of the others. There are also other costs that could be split out but I don't think they actually change the crux of the thought experiment. The handbag analogy breaks down as the main price differences probably come into labour costs, profit! and maybe raw material costs.

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