The next time you leave the grocery store with plastic bags in tote and notice the disapproving glare from someone proudly carrying a canvas bag that’s printed (using earth-friendly ink) with words that one way or another say “I care more about the environment than you do,” you can now confidently look back and say “not so fast.”
From the study:
The conventional HDPE bag had the lowest environmental impacts of the lightweight bags in eight of the nine impact categories. The bag performed well because it was the lightest bag considered. The lifecycle impact of the bag was dictated by raw material extraction and bag production, with the use of Chinese grid electricity significantly affecting the acidification and ecotoxicity of the bag.
The study reports that a canvas bag is expected to last for 52 trips (Table A.3.1). With that as a reference, a cotton/cloth canvas bag user does over twice the damage to the environment that a plastic bag using grocery shopper who throws away every plastic bag they get immediately after each shopping trip, as they will likely have to replace their more environmentally-destructive bag at least once long before they reach 131 uses!
However, if a consumer reuses 100% of their conventional HDPE plastic bags (say as trash bags), the number of uses needed for the other bags to have a lesser environmental impact than the conventional HDPE plastic bag rises by a factor of anywhere from 2.2 to 2.5, which we see in the table above. For example, that re-usable canvas bag would need to be used at least 327 times to be less damaging to the environment!
Good intentions often come with unintended and undesirable consequences as I pointed out in a previous piece about the light bulb ban, and it looks as though the plastic bag hype is turning out to be no different.
During a recent business trip I went to a Home Depot in San Jose to buy some electrical materials for a project. Apparently San Jose has decided to take political correctness one step further as I was asked if I wished to purchase a bag. I refused out of principle and bundled everything up by hand and carried it out to my truck in disbelief.
So if you truly wish to protect the environment you should use either plastic bags or nothing at all and carry your goods out by hand. Of course dozens of contractors carrying loose nails bought in bulk out to trucks parked way out in the neither regions of the parking lot could prove to be a bit of a problem for the store’s clients and their tires.