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

From: <mrb22667@kansas.net>
Date: Mon Dec 07 2009 - 13:38:17 EST

If one wants to multiply the complicating factors, they would need to do it on
both sides for the sake of consistency. So if we take into account the energy
that delivers unprocessed food from field to plate, we would also need to
account for energy that delivers gasoline from crude oil wells to its processed
state in your gas tank. (& the fact that your car has to be manufactured in the
first place --which will be a smashingly decisive boot print right up front
compared to what it took to make your walking shoes for you.) Without all the
hard data, I'm reasonably certain autos lose this contest. Having said all
this, science & math can clarify just how big a gap there is, though. And I
should take care in the bravado of my pro-bicycle-biased response that some gaps
may not be as big as I would like to think. In my case my whole family (4 of
us) drive in the same car to school & work (the same place for all four of us).
 And we don't drive an SUV, but a car that gets about average gas mileage.
Given our shared vehicle, our auto foot print is a fraction of the average.
(Now factor in that our family is not above cheese-puffs & burgers... and well,
maybe my limited fair-weather biking doesn't win by as big a margin as I like to
think.)

But I'm with you Iain --though I wimp out during our wintertime here and hit the
gas-guzzling highways with everyone else. I think more (but perhaps not all) of
the complicating factors will end up favoring the pedestrians and especially the
cyclists. (One other related corollary: city folks are often healthier than
their rural counterparts because we rural & semi-rural folks drive everywhere,
distances being what they are. Whereas city folks put in a lot more walking and
are less likely to even own a car.

And Jon, you might accrue some hospital bills trying to walk that far (in cold
weather no less?) We have less of an excuse than you for not cycling since we
have only a six mile commute.

--Merv

Quoting Jon Tandy <tandyland@earthlink.net>:

> I think this response, while interesting, misses the point. The fallacious
> argument on food consumption, at least a more advanced version of it,
> doesn't just compare the energy consumed by eating and walking vs. driving.
> The question below talks about the energy consumed in "food production", not
> just the amount of energy in the food being consumed. And yes I do consider
> it a fallacy, a typical urban legend unless it's backed up with hard data
> about the amount of CO2 released in growing, producing, selling and
> distributing a 2000 calorie meal to my plate, as compared with the amount of
> CO2 released in driving my car to work. In my case, I would have to walk 70
> miles round trip, so I might need quite a bit more than 2000 calories (not
> to mention needing an extra 18 hours per day).
>
> Oh, another potential fallacy in the statement that would need to be backed
> up by data: it would need to take into account the differential amount of
> food consumed by walking, not just the 2000 total calories consumed per day
> but only the difference in food consumed as a result of walking vs. driving.
> It might not be negligible, but it might be. Then there are the health
> benefits that could result, including lower expenses and therefore energy
> consumption in the health care system, etc. It's one of those complex
> calculations that I can't image the (presumably) "urban legend" has fully
> addressed.
>
> Jon Tandy
>
>
> -----Original Message-----
> From: asa-owner@lists.calvin.edu [mailto:asa-owner@lists.calvin.edu] On
> Behalf Of Merv Bitikofer
> Sent: Monday, December 07, 2009 7:11 AM
> To: John Walley; asa
> Subject: Re: [asa] CO2 in Food Production...
>
> 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 "it's better to
> drive"
>
> Whether this is true depends on your diet. It's 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 "it's 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 13:38:51 2009

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