Monday, April 23, 2007

Buy one pound, get one free!

Today, I purchased a package of grapes. On the label of the grapes, it says that the fruit was “grown in Chile.”

This doesn't surprise me. In my birth-given rights as a wealthy American, I deserve to consume any piece of food I feel like consuming at any given point in time, even if this requires shipping the piece of food halfway around the world for my personal self enjoyment. Obviously.

So, how much CO2 is produced by shipping grapes around the world? Let’s find out.

Some rough estimates:
The middle of Chile is about 5270mi from the middle of the US.
A 747 cargo plane uses about 6.8 gal/mi. Yikes.
At full capacity, a 747 can carry an impressive 450,000 pounds of cargo.

So, we use a little math magic and we get
(6.8 gal/mi x 19.4 lbs of CO2/gal gasoline x 5270 miles) / 450,000 lbs cargo =
1.5 pounds CO2 per pound of fruit

This is actually much less than I had expected. To put this number into perspective, the average American produces a whopping 122 pounds of CO2 daily. Although, eating grapes in April is rather unnecessary, and every pound I can keep out of the atmosphere makes a difference.

I’ll make up for myself at the farmer’s market this weekend, to free myself of liberal guilt.

2 comments:

Unknown said...

Grapes are shipped by truck, not by plane, no matter where in the world the come from.

The average heavy haul, long distance tractor trailer gets about 7-10 miles per gallon of diesel fuel.

You can load that truck with about 42,000 lbs of grapes.

Anonymous said...

According to NDRC, (http://www.nrdc.org/health/effects/camiles/grapes.pdf)
750 million pounds of grapes are imported into California by CARGO SHIP, not trucks or planes (although trucks will deliver them from POE to destination). NDRC estimates 14 million pounds of global warming pollution from this activity. Therefore per pound of grapes the global warmming gas produced by shipping is only .01867 pounds.

This doesn't mean I like the idea of buying Chilean grapes. I don't buy them, and I have several grape vines which I hope will produce something this year. I buy a lot of raisins, though -- I hope they come from California but I'm not sure.