What's the carbon footprint of ... cycling a mile?
Ian.B
Posts: 732
This article is in today's Guardian:
http://www.guardian.co.uk/environment/2010/jun/08/carbon-footprint-cycling
TfL seem to be doing their calculations on the basis of 260g per mile, which means we're powered by cheeseburgers (apparently).
http://www.guardian.co.uk/environment/2010/jun/08/carbon-footprint-cycling
TfL seem to be doing their calculations on the basis of 260g per mile, which means we're powered by cheeseburgers (apparently).
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I saw this.
I also liked this assumption:All my figures include 50g per mile to take into account the emissions that are embedded in the bike itself and all the equipment that is required to ride it safely. In the lower-carbon scenarios, the food accounts for only a small part of your impact, and the maintenance of bike and sundry equipment dominates.
How long is the bike supposed to last for this?
At a (not light) 14kg, my bike is about 1/50th of the weight of a Ford Fiesta (according to wiki). Therefor for an equivalent 50g/mile a ford fiesta would need to travel 50 times further in its lifetime. (to say nothing about the carbon cost of transporting the tyres etc to the car)
In a year my milage is about 5000 miles, so if I ditched my bikeevery year, a ford fiesta would need to travel 2.5-million miles in its lifetime to better the material cost of the bike.
I don't intend to change my bike so frequently, so I think the article is grossly pessimistic about the materials for the bike and optimistic for the cars.0 -
although someone will probably disagree with me it's just more pseudo-science and not worth worrying about.FCN = 40
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I had cross posted this at badscience.net (I was going to anyway before I saw this thread)
this is the discussion there
And here are my sums:I've decided to look at the emissions for making a tonne of steel and the usual value seems to be 1.175 tonnes CO2/tonne.
So for me, and 10,000 miles (for ease of calculation and just under two years cycling) on a 14kg steel bike I work this out at 16.45kg/10,000 miles, which comes to about 1.6g/mile...
For the 50g/mile, I'd need to throw my bike away after about 500-miles... Which I think is the Running Man does in a fortnight.
A 700kg ford fiesta lasting 200,000 miles would have 820-odd kg of CO2 emissions with these figures due to the manufacture, which comes out at about 4g/mile.
Now I know that a lot of the car's weight isn't steel, but then neither is the bike.
Those figures look more realistic than the ones in the article. And I am still choosing a fairly light car with a fairly long expected total distance covered, compared to a fairly conservative figure for the bike.
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Wierd Science!!0
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Carbon footprints are notoriously difficult to calculate with any degree of accuracy, due to the large number of assumptions you have to make, and the whole question of what you include in the calculation and what you leave out.
Those in the construction industry may know about SAP calculations: six densely typed pages of calculation worksheet, together with several more pages of tables to reference in, and this is just to calculate the CO2 emissions 'in operation'. CO2 emitted in the production of the materials for the building itself, plus its construction, are not included. Even so, this calculation is considered a bit crude by many, and in the interests of making it (relatively) easy to use and standardised, makes a lot of assumptions, which bias it towards new buildings rather than upgraded old buildings.
And don't even get me started on EPCs.
So to respond to the Guardian article: please show your workings!1985 Mercian King of Mercia - work in progress (Hah! Who am I kidding?)
Pinnacle Monzonite
Part of the anti-growth coalition0 -
