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When you look at the complete journey from bauxite to bicycle via China, a big container ship and the bicycle showroom, there probably is quite a lot of CO2 emissions involved in making a new bicycle.

Are their any easily quotable figures for this?

Are there any handy equivalent metrics, e.g. equivalent to x miles in a family saloon or equivalent to x hundred packets of Walkers Crisps (at 80g per pack)?

I would like to know a generally agreed figure as I have found myself being stumped in conversation with motorists that (after conversation has moved onto their planet trashing ways) have the cheek and audacity to criticise cyclists.

What happens is that they go ad-hominem, 'pointing out' that buying a new bicycle is 'bad for the environment', particularly one made on the other side of the planet. Rather than have no defence I would like to be able to say 'yeah but that is only equivalent to x hundred of your gas-guzzling miles/hours 'sat' in traffic.'

Has anyone done a carbon audit for a bicycle yet? If so, are there any particularly low-carbon bikes out there?

Note:

I mention the Walkers Crisps in passing - no I don't want to know that cycling has a huge footprint if the fuel (food) is caviar/fancy-mini-corn from Zambia/lamb from New Zealand/fish from the Arctic (or even a nice pack of Prawn Cocktail crisps prepared with sunflower oil grown in Eastern Europe). Just the carbon footprint from whatever bike brands have bothered to measure it, not the on-going fuel costs (food).

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Is it carbon frame? That will add to it significantly? –  zenbike Jul 6 '11 at 14:44
    
Run of the mill aluminium MTB - nothing special. I have heard carbon fibre costs more in energy terms. A useful figure would be nice, e.g. a typical Trek, etc. then in a metric that makes sense - a month's worth of driving - or is it a week? Something that makes sense without being overly technical. –  ʍǝɥʇɐɯ Jul 6 '11 at 14:50
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Actually, the carbon frame would be (in theory) sequestering carbon, which is a good thing. Of course, hard to say how much energy goes in to making the carbon frame. In addition, petroleum is used for the resin, though it isn't burned so thus once again is (in theory) sequestering carbon. –  Daniel R Hicks Jul 6 '11 at 17:26
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It was a joke. I mean, surely, a carbon frame has a major carbon price tag? –  zenbike Jul 6 '11 at 17:46
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Let's all remember, that for most people the car is a sunk (carbon) cost. Unless you go without a car (like me), then buying the bike on top of owning a car will result in a higher carbon footprint. So the question becomes, how many miles do you have to ride the bike before the carbon footprint of creating the bike to be offset. One thing to really think about is that when you burn gasoline there's carbon that's put into the atmosphere. But there's also a lot of carbon (and other chemicals) put into the atmosphere just getting that gasoline to the pump. –  Kibbee Jul 6 '11 at 18:19

6 Answers 6

up vote 6 down vote accepted

Has anyone done a carbon audit for a bicycle yet?

I managed to find one on the Brompton website - "Manufacturing a Brompton bicycle creates 113kg of carbon". I have been unable to find any figures from other manufacturers. The Brompton is a steel-framed folding bike, so that figure may not be particularly representative.

If so, are there any particularly low-carbon bikes out there?

Bike Bamboo make bike frames from bamboo and claim a "Reduced Carbon Footprint", however they don't back this claim up with any specific figures.

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Thanks a lot - the Brompton 'Carbon Calculator' was just what I was after: brompton.co.uk/cc - so it would be 120 miles in an average car that would be equivalent to a nice new bike (albeit of the Brompton variety). –  ʍǝɥʇɐɯ Jul 7 '11 at 12:26

I don't have numbers on hand. But if you're after a cogent argument, I would point out that the car they drive has a far larger manufacturing footprint, even assuming it is manufactured in the local economy, which is rare. If it is, then was the raw steel manufactured there or shipped in?

For that argument of theirs to be effective, they must start with the idea that their car popped out of thin air. Even assuming that the manufacturing footprint is identical, the car continues to build that carbon debt, while the bicycle mostly ceases to charge that card after the manufacturing is done.

Of course there will be minor maintenance items, and consumables like tires and tubes, but the car has those, too. No matter how you look at it, a bicycle doesn't burn fuel to function and a car does.

So the car will use far more resources over the course of it's useful life.

Also, whether you believe that global warming is real and important, or not, it will affect your finances far more to drive a car than to ride a bike.

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You do breathe out more carbon when riding than when driving, however, the conversion ratio is pretty good. –  Ladadadada Mar 5 '12 at 19:20

A simple answer from iBikeTO (2.11MJ/km over the lifecycle) and another from the Public Transport Users Association (0.8Mj/km) here in Victoria. Both are IMO unrealistically low. Brad Templeton has some numbers for the USA but focusses entirely on energy per mile, not purchase cost.

The easy numbers are for embodied energy of materials, and those you'll probably find in the building industry rather than manufacturing. For instance, this overview, this table and from this one I grabbed the following:

Type of material Thermal energy (MJ/kg) Cement 5.85 Lime 5.63 LP 2.33 Steel 42.0 Aluminium 236.8 Glass 25.8

Note that Aluminium is the outlier - five times more energy than the next highest material. For carbon fibre, the only numbers I found are in this paper and are in the range 5-30MJ/kg.

But this is only a tiny part of the answer. The manufacturing energy for a bicycle is likely to be much higher than the embodied energy of the materials, and then you have the common scenario of a 10kg bicycle being shipped in a 5kg cardboard box with 1kg of plastic packaging material in it. I would be tempted to add those costs to whatever numbers I was using.

Also, carbon/energy footprint is not the end of the argument. The toxic load of carbon fibre is quite high, which is a cost both to the people who work with it and the people who have the waste dumped on them. The elements used for alloying and doping can contribute more of the toxic load than the bulk materials, especially in a steel bike. Chrome and molybdynem, for example, are ugly things to work with but compared to the rare earth elements in a modern battery they are materials of rare beneficence.

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Very insightful and thoughtful - thanks! –  ʍǝɥʇɐɯ Jul 7 '11 at 0:53
    
Good research, but could use a bit more explanation of terms and organization. For instance how do you define toxic load? Is it alleviated by sound manufacturing processes, as required in US manufactories? Or does CF by the existence of the material itself automatically carry a high load, with no workaround possible (or currently available?) You would add the cardboard container and the plastics used to ship to the cost. Cardboard is recyclable and plastics used in our bike packing are minimal (180 grams) and reusable. Do these ameliorate any responsibility in your view? –  zenbike Jul 7 '11 at 8:31
    
FTR, I'm not attacking the answer, just seeking clarification. I would argue that the question is requesting a direct comparison of the complete manufacturing and use footprint of an automobile to that same footprint for a bicycle. It seems obvious based solely on material size and weight (for shipping) that the car will use more resources per manufactured unit, and in addition continues to increase that use through fuel and maintenance consumption throughout its useful life. Is there something counter intuitive here that I am missing? –  zenbike Jul 7 '11 at 8:35
    
Also, can you define or link definitions of the energy measurements you are using? You can get some referential data from the fact that a number is higher or lower, but there aren't good explanations of the measurement units, and frankly, although I assume higher is worse in this case, that could be the opposite in some systems. –  zenbike Jul 7 '11 at 8:37
    
It should be noted that, while the energy input to aluminum is high, a disproportionate amount of the energy is from renewable hydro power. –  Daniel R Hicks Mar 1 '12 at 13:34

This information is never gathered correctly, corporations really don't want you to know the actual numbers, otherwise it would have a very negative impact on manufacturing.

I own an older 91 GMC pickup truck, some greenies see me as a polluter, but I say I am not, I have owned the truck for 13 years, purchased used, keep it tuned and emissions test passes every year. I plan on keeping it another 5 years or more.

I have a relative that buys a new car every year, sometimes after 9 months, who pollutes less in 13 years, me or my relative?

There was a recent study, (can't find it right now) about notebook computers, they found that manufacturing one will consume more energy than the laptop will consume while using it for its life expectancy.

I know this does not quite compare to bicycles, but you see that global manufacturing has a high carbon footprint. Raw Materials come from all around the world to other countries that refine them into other base products, ship them worldwide to other countries to make final product used in manufacturing, then they ship the final material around the world to manufacturers to make the final product, then they ship the final product around the world to sell. You drive to the store to purchase it or UPS delivers it.

Re-use, keep and maintain, and do without is what I have always done. 90% of the stuff we own, we don't need and rarely use.

And yes, both my Bicycles are used. Upgrades and accessoried are used when I can find them.

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Assuming 113kg of carbon for manufacture of a bike this equates to 414kg of CO2.

A car with an MPG of 40 emits 272g of CO2 per mile.

This mean you would need to do 1500 miles on the bike to break even.

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Ah, but how much CO2 do you exhale in those 1500 miles? –  Daniel R Hicks Mar 1 '12 at 13:35
    
@DanielRHicks Most of your exhaled carbon is part of a closed loop: the plants you and your food eat pull the carbon out of the air. There's some petroleum-based fertilizer issues, though. –  freiheit Mar 1 '12 at 14:27
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Plants? Everything I eat comes out of a bag or box -- who knows were it came from?? –  Daniel R Hicks Mar 1 '12 at 16:17

http://www.technologystudent.com/enerflsh/foot1.html

found this. comparison is 2 versus 1440 3 mile commute car versus bike

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