Sunday, November 26, 2006

Food CO2 and Land Footprints

I have written previously about my hope for acre and gallons labeling for food to tell how much energy and land it requires to produce various foodstuff. I ran something similar at the LCA Food Database. It collects data using a Life Cycle Assessment method to determine the amount of resources and wastes from soil to kitchen created by different food items. The numbers were collected off of Danish farms, but I would guess the ones in the US would be similar.

The following table shows the amount of CO2 emissions and square meters of land (for one year) used to create 1kg of the food item. I also added the amount of calories per kg of the food and then sorted based on square meters used per calorie.

item (1kg) g CO2 m^2 year calories m^2/ 1,000 cal co2/ calcal/ m2
beef steak 42,400 56.0 1980 28.3 21.435
frozen chicken 3,650 5.0 1840 2.7 2.0368
fresh chicken 3,160 5.0 1840 2.7 1.7368
oats, organic 594 3.3 3890 0.8 0.21,179
soy beans 620 3.3 4160 0.8 0.11,261
wheat, organic 376 2.5 3420 0.7 0.11,368
oat flakes 790 2.5 3820 0.7 0.21,528
oats, conventional 580 2.3 3890 0.6 0.11,691
soy/rapeseed oil 3,630 4.5 8840 0.5 0.41,964
wheat, conventional 727 1.5 3420 0.4 0.22,280
wheat flour 1,130 1.4 3390 0.4 0.32,421
frozen wheat bread 1,200 1.0 2600 0.4 0.52,600
wheat bread 840 1.0 2600 0.4 0.32,600
potatoes 184 0.3 930 0.3 0.23,000
potatoes, retail 161 0.3 930 0.3 0.23,000
sugar 960 0.5 4000 0.1 0.28,889
sugar beet 160 0.2

rape seeds, organic 1,320 5.7

rape seeds, conventional 1,550 3.5

A couple of observations. First, from a land usage/calorie created standpoint, meat comes out as the most intensive and potatoes and sugar comes out as the least. Beef is way higher than everybody else, more than 10 times higher than chicken and 280 times higher than sugar. Substituting chicken for beef decreases your land usage by 90%. While I don't think sugar is particularly healthy, from a resource standpoint, it is very efficient needing much less space per calorie than any grains.

Second, the more processed, the more CO2 is emitted. Eating raw food, therefore emits less CO2 per calorie eaten. You might also think that this would mean it is better to buy raw ingredients and cook at home. Actually though, as this report shows (p9), baking bread in an industrial setting is more energy efficient than everybody baking at home. So unless you are going to eat the food raw, from an energy standpoint better to have it processed for you.

item (1kg) g CO2 m2 year extra energy extra land
rape seeds, organic 1,320 5.7
rape seeds, conventional 1,550 3.5 17%
wheat, organic 376 2.5
wheat, conventional 727 1.5 93%
oats, organic 594 3.3
oats, conventional 580 2.3 -2%

Comparing organic with conventional farming, there is a trade off between using more land and using more energy (currently in the form of fossil fuels). Organic oats required 43% more land, rape seeds 62% more and wheat 66% more. On the CO2 side, conventional farming emits 17% more for rape seeds, 93% more for wheat and 2% less (huh?) for oats. I am not sure how to access which is more valuable: extra land for nature or less carbon emissions. But, the idea that organic is better for the environment in all ways does not appear to be true. Hopefully in the future we will have sustainable artificial fertilizer made from renewable energy, so we won't have to make this choice.


crush41 said...

Thanks for giving me another supercilious talking point to use in social situations explaining to others why I'm a vegetarian :)

Fat Knowledge said...


Wouldn't have pegged you for a vegetarian, but I am impressed. I tried once, but it didn't last very long. :)

Being a vegetarian is one of the best things you can do from an environmental standpoint. I read somewhere that it is better to go from eating meat to a vegetarian diet than to switch from a Hummer to a Prius. Don't know how that was calculated (hmmm, maybe something to look into), but it doesn't surprise me.

Anonymous said...

I was wondering if anyone knew home much carbon is in a peanut butter and jelly sandwich?

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