Re: [asa] CO2 in Food Production...

From: Merv Bitikofer <mrb22667@kansas.net>
Date: Mon Dec 07 2009 - 08:10:45 EST

The trivia you mention below is a fallacy. From David McKay's
"Sustainable Energy - Without All the Hot Air"
(Book is available on-line)

Here is an excerpt from his "Mythconceptions" section on p. 79:

"I heard that the energy footprint of food is so big that its better
to drive"

Whether this is true depends on your diet. Its certainly possible to find
food whose fossil-fuel energy footprint is bigger than the energy delivered
to the human. A bag of crisps, for example, has an embodied energy of
1.4 kWh of fossil fuel per kWh of chemical energy eaten. The embodied
energy of meat is higher. According to a study from the University of
Exeter, the typical diet has an embodied energy of roughly 6 kWh per kWh
eaten. To figure out whether driving a car or walking uses less energy, we
need to know the transport efficiency of each mode. For the typical car
of Chapter 3, the energy cost was 80 kWh per 100 km. Walking uses a net
energy of 3.6 kWh per 100 km 22 times less. So if you live entirely on
food whose footprint is greater than 22 kWh per kWh then, yes, the energy
cost of getting you from A to B in a fossil-fuel-powered vehicle is less
than
if you go under your own steam. But if you have a typical diet (6 kWh per
kWh) then its better to drive than to walk is a myth. Walking uses one
quarter as much energy.

<end of excerpt>

... and the "typical cars" he refers to are probably including European
cars which are better on average then U.S. cars. Also, bicycling (I know
this from personal experience) involves even less energy expenditure
than walking or running. But of course, this is just the activity itself
and doesn't take into account the carbon footprint of building the
needed bicycle. But if we are to take production footprints into account
then the car falls even more dismally behind. So bicycling probably has
cars beat no matter how many hamburgers & cheese crisps you eat. Beating
the auto transport industry's carbon footprint is like taking candy from
babies. We would have to seriously try in order to be any worse. Shoot,
--even loaded 747 jetliners can do it if the alternative was to put each
driver into his own S.U.V. (which would nearly be typical here in the U.S.)

--Merv

John Walley wrote:
> Here is an interesting tid bit of trivia I found while researching this. Does anyone know if this has any basis to it or not?
>
> John
>
> Here's a fun fact for you: If you live within walking distance of work, which do you think would put more CO2 into the atmosphere, driving to work, or walking to work? Contrary to what most would expect, the correct answer is walking to work! The food production that would be necessary to replace the calories that you would burn would put three times as much CO2 into the atmosphere than driving your car the same distance! Thus, if you buy into this global warming stuff, you better not exercise, because you are "causing global warming!!"
>
>
>
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Received on Mon Dec 7 08:10:47 2009

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