Doing a Carbon Footprint Analysis

Soon after I was laid-off, a friend of mine asked me to do a carbon footprint analysis on her company's product for the marketing department. It was an interesting project and one I jumped on.

Poking around the web for the current standards of what is and what is not included, I discovered their request showed up in my in-box days after the very first Carbon Footprint for Consumer Products Conference had taken place. (Info on the 2008 conference here.) If folks like Starbucks are meeting to define what the carbon footprint of a consumer product is defined as, what chance do I have? I have the chance to define my scope narrowly and find what I can find on it.

I started by doing a system analysis of the problem. A system analysis is a way of figuring out which intersection of threads you want to confine yourself to in a web. If I generated a figure that reported the amount of CO2 emitted in manufacturing the product and delivering it to the customer, that would be an interesting number, but ultimately pointless. This is a unique product that is bought because of what it delivers, not because it is the best of a set of similar products. (And because it is a unique product, I am going to try to avoid giving any specifically identifiable information about it.)

Additionally, it isn't much of a stretch to say that any product's carbon footprint is directly related to i's weight. We can see that in the formulas shipping companies use for products. If it weighs more, it uses more fuel to move, and therefore releases more carbon dioxide.

So I decided the best thing to look at was the carbon released to power the product over its lifetime and to compare that to the carbon released to replace the benefit of the product over its lifetime. Imagine a counter-top cappuccino machine. I decided that since the same amount of coffee is going to travel similar distances to get to your mouth, I should look at the energy consumed by the machines. So I compared the carbon in making the electricity to run our product to the carbon released by going to the store for a similar amount.

Another way of phrasing my results looks like this: Is it better to run a 60 watt light bulb for 18 hours every day or to go to the store twice a week to pick up an item shipped from 1500 miles away?

It turns out that shipping food is very efficient. But getting to the store is not. My estimates were based on finding out the fuel costs of running a refrigerated semi-truck and how many of these items would be shipped in a container, and then comparing that to the average fuel economy of a car sold in the US in 2006 (21: EPA 2006 Fuel Economy Trends Report), and figured a round-trip to the store as 3 miles. To convert a gallon of gas to lbs of CO2, I used the Department of Energy's conversion factor of 19.554 lbs of CO2 released in burning a gallon of gas.

For the home-based part of the equation, I took the watts consumed by the product and multiplied that into daily, monthly, and lifetime figures. I used the EPA's figure of 1.55 lbs of CO2 released per kilowatt hour to calculate the energy.

Let's use these numbers to analyze working at home under a halogen light verses driving to a coffee shop or office where the lights would be on either way.

If you drive a standard car 3 miles, that's 1/7th of a gallon of gas. 19.564/7 = 2.79 lbs of carbon. A halogen desk lamp uses 300 watts, so it takes 3.3 hours to use one kilowatt hour. One kilowatt hour off the US grid* results in 1.55 lbs of carbon. So driving your car a tiny three miles will use produce as much carbon dioxide as staying at home with your lamp for nearly 7 hours.

But if you were to walk or ride a bike that 1.5 miles out and back, you get a double savings. Nearly 3 lbs. of carbon dioxide you didn't consume which you might "normally" have.

What could you "buy" with that 3lbs? 142 hours of using a 14 watt florescent bulb. 2 hours of cooking food in a GE convenction microwave oven. 15 hours of watching a 32" HD LED television. Or since we don't have a way to sequester surplus CO2 yet, maybe the life of a migrating bird.

*Whether you buy wind power or not, the power you use comes out of a reservoir of electricity generated by a number of means. You contribute more wind power to the total than might otherwise exist, but any electricity you use comes from all the streams if it comes from the grid. If you're generating your own power, you already know better than to use the $12 halogen lamp from the big box store. ;-)