Sunday, February 19, 2012

Why I Don't Like Coffee From A Can

... because it just seems ridiculous that the metal can is used simply to transport ground beans. Unfortunately, coffee that comes in bags is about twice the price. So every time I need coffee, I buy the can, dump the coffee into a canister in my kitchen and then throw the can out. The can made precisely one trip from manufacture to the trash.


This is what it takes to make the can. What a waste!


Kelly the little black dog said...

You know I look at it like beer. I can buy less micro brew, or more of the cheap stuff. I don't need to drink that much and enjoy the micro brew more. Same for coffee, I don't need more that a split of a pot a day, and I enjoy the ground stuff more.

tim eisele said...

well, here's something that might make you feel a bit better about the steel coffee cans (or maybe worse about plastic or paper bags?)

It takes 3.75 Gigajoules of energy to make a metric ton of iron in a blast furnace [1] (and most of the steelmaking process kind of coasts along on the heat already imparted to the molten metal, so that's the main energy input).

For comparison, the fuel value of polyethylene is about 45 Gigajoules per metric ton. Paper is about 18 Gigajoules per metric ton[2]. So, even given that paper or plastic bags are lighter than steel cans, the energy tied up in the structure of the bag is pretty close to the energy used to make the steel.

Overall, it doesn't much matter what your container is made out of; one way or the other, it takes a lot of energy[3].

[1] By a fortunate coincidence, I'm going to be lecturing on the heat balance for blast-furnace ironmaking today, so I've got the numbers from "The Making, Shaping, and Treating of Steel" right here in front of me already.

[2] Basically, structural materials can be grouped into two classes: Those that take a lot of fuel to make (like steel, glass, concrete, cut stone, and ceramics); and those that are made out of fuel (plastic, wood, paper, and other organics). There aren't a lot of exceptions that I can think of.

[3] Some years ago, there was a factoid being passed around to the effect "more energy is used to produce food than the food contains", with the implication that farmers burned more calories of fuel to grow crops than the crops contained. That sounded crazy to me, so I searched out the original source (a paper in Science from the mid-1970s), and found out that where the energy was really going was in the post-farm handling and processing: transportation, cooking, and making the packaging. The farmers themselves were net energy producers