Carbon footprint of our glass (glass and shipping)

by Erin McKittrick || February 27 2007
strip of drops

Last week I talked about the impact of the glass industry in general. Today I'm going to get a little more specific.

Bullseye Glass

Some of our glass comes from recycled bottles, but most of it comes from the Bullseye Glass Company in Portland, Oregon.

Bullseye Glass being made - from their website
I emailed Bullseye about their energy usage and was pleased to find that not only were they super helpful, they were a few steps ahead of us in figuring out how to reduce their own carbon footprint and impact on the environment.

The chemicals to color the glass come from all over the world, but most of the bulk raw materials (sand), come from relatively nearby in the northwest U.S. - minimizing shipping.

And in the past few years they've put in a couple new systems designed to reduce the impact of glass manufacturing. The first is a liquid oxygen system. Natural gas is burned to produce heat to melt glass. In order to burn, the hydrocarbons of the gas are reacting with the oxygen in the air. But oxygen is only about 21% of air, so a lot of what gets heated and reacted is nitrogen. By using pure oxygen instead of ambient air, much less natural gas is needed, and much less nitrous oxide pollution is produced. According to Bullseye, this system "will eventually reduce our carbon emissions by as much as 40%, and our nitrous oxide emissions by more than 90%."

The next cool thing is the cooling system. In 2004 they switched to a recycling water cooling system, cutting their water use by more than half.

Other enviro-friendly things they do are encouraging employees not to commute by car, and internal recycling (using the ends of glass sheets to make things that are supposed to be in small pieces, like frit, and lumping broken bits together to make black glass).

So, although we've been using Bullseye for the colors and quality of glass, it seems like they're a pretty good choice from an environmental standpoint too.

How does this add up for Sundrops?

To figure the impact of the glass we start out with, we took the carbon footprint of glass production, and combined it with the costs of shipping the raw materials and finished glass. Bullseye provided us with precise numbers for their glass production. I can't publish them here because they're a trade secret, but have used them in my own calculations.

Shipping Footprint

The best info I was able to find actually came from a study on the impacts of food transportation in Iowa from the Leopold Center for Sustainable Agriculture

They broke up transport into big, small, and medium trucks, and looked at how much they carried and what their fuel mileage was. It ends up being more efficient to carry stuff in big trucks.

gas miles
Gas it takes to move 1000 pounds of stuff 1000 miles
in different trucks.
I don't know exactly what size truck my glass moves in, but it seems safe to assume that relatively big trucks are moving raw materials, and moving large chunks of glass, and relatively small trucks are involved at the end of the chain, bringing glass to my local store: Seattle Stained Glass.

The ever helpful Energy Information Administration has a page giving the CO2 emissions for different fuel types

Carbon Footprint of Glass

Plugging in the different kinds of fuel (natrual gas to melt glass, diesel to move it around), and the distances, I get a carbon footprint of 4 pounds CO2 per pound of glass. This is the impact of the glass when I pick it up from the store (I walk to and from the stained glass store, so I'm not counting any extra transport cost there), before we melt it into earrings.

carded drops Luckily, the amount of glass in a pair of earrings is pretty small. Based on this number, the glass in a thousand pairs of Sundrop earrings is responsible for about 7 pounds of carbon dioxide emissions. One flaw in this calculation is that it doesn't account for any breakage or waste of glass on our end, between buying the glass and the final product. I suspect the number is closer to 10 pounds of CO2 per thousand pairs of earrings, but I'll get a better number for that soon. On the other side, I'm not including our use of recycled glass (about 10%), which will make that number smaller.

Sundrop Jewelry's footprint comes from glass, silver, plastic, paper, manufacturing, and sales. I've got the number for glass. What will the rest be? Where's the easiest place to cut the impact?