By Collin Dunn, Treehugger
Paper or plastic bags: which is better?
It’s an age old question, when it comes time to check out when grocery shopping: paper bag or plastic bag? It seems like it should be an easy choice, but there’s an incredible number of details and inputs hidden in each bag. From durability and reusability to life cycle costs, there’s a lot more to each bag than meet the eye. Let’s take a look behind the bags.
Where do brown paper bags come from?
Paper comes from trees — lots and lots of trees. The logging industry, influenced by companies like Weyerhaeuser and Kimberly-Clark, is huge, and the process to get that paper bag to the grocery store is long, sordid and exacts a heavy toll on the planet. First, the trees are found, marked and felled in a process that all too often involves clear-cutting, resulting in massive habitat destruction and long-term ecological damage.
Mega-machinery comes in to remove the logs from what used to be forest, either by logging trucks or even helicopters in more remote areas. This machinery requires fossil fuel to operate and roads to drive on, and, when done unsustainably, logging even a small area has a large impact on the entire ecological chain in surrounding areas.
Once the trees are collected, they must dry at least three years before they can be used. More machinery is used to strip the bark, which is then chipped into one-inch squares and cooked under tremendous heat and pressure. This wood stew is then “digested,” with a chemical mixture of limestone and acid, and after several hours of cooking, what was once wood becomes pulp. It takes approximately three tons of wood chips to make one ton of pulp.
The pulp is then washed and bleached; both stages require thousands of gallons of clean water. Coloring is added to more water, and is then combined in a ratio of 1 part pulp to 400 parts water, to make paper. The pulp/water mixture is dumped into a web of bronze wires, and the water showers through, leaving the pulp, which, in turn, is rolled into paper.
Whew! And that’s just to make the paper; don’t forget about the energy inputs — chemical, electrical, and fossil fuel-based — used to transport the raw material, turn the paper into a bag and then transport the finished paper bag all over the world.
Where do paper shopping bags go when you’re done with them?
When you’re done using paper shopping bags, for shopping or other household reuses, a couple of things can happen. If minimally-inked (or printed with soy or other veggie-based inks) they can be composted; otherwise, they can be recycled in most mixed-paper recycling schemes, or they can be thrown away (which is not something we recommend).
If you compost them, the bags break down and go from paper to a rich soil nutrient over a period of a couple of months; if you throw them away, they’ll eventually break down of the period of many, many years (and without the handy benefits that compost can provide). If you choose to recycle paper bags, then things get a little tricky.
The paper must first be re-pulped, which usually requires a chemical process involving compounds like hydrogen peroxide, sodium silicate and sodium hydroxide, which bleach and separate the pulp fibers. The fibers are then cleaned and screened to be sure they’re free of anything that would contaminate the paper-making process, and are then washed to remove any leftover ink before being pressed and rolled into paper, as before.
Next: Plastic Bags