What's greener?
What's greener? Plastic bags vs reusables
Andrew Mackintosh
For both kinds of bags, sourcing raw materials and manufacture account for much of the effect on the environment. So the more times you reuse either kind of bag the more resources are saved, and the greener it becomes. Likewise heavier bags use more resources and are worse for the environment. So you need to reuse heavier bags more times to break even
Plastic bags | Reusable bags |
| Ordinary plastic bags are made from polyethylene. Polyethylene is made from ethylene gas – a by-product of the petrochemical industry. | The typical reusable 'green' supermarket bag is made from polypropylene, the same material as thermal underwear. They appear to be woven but are actually a non-woven plastic. Polypropylene is made from propylene gas – a by-product of the petrochemical industry. |
| Plastic bags are a very efficient use of resources. They weigh only 6-8 grams, yet can carry 6 kilograms or 1000 times their own weight. | Making reusable bags takes more resources – they weigh 109 grams, or 15 times more than plastic bags. However, a reusable bag can carry almost twice the weight of a plastic bag. |
| Plastic bags are designed to be used only once then thrown away. However, about 75 per cent of plastic bags are reused as lunch bags, or bin liners. | Reusable bags are designed to function until they wear out. |
| Plastic bags aren’t biodegradable. They may last centuries before being broken down by UV light. In the dark of a landfill they may last even longer. | Reusable bags are not biodegradable. When thrown away they last as long as plastic bags. |
| Plastic bags pollute the ocean. They can kill animals such as turtles when they’re mistaken for jellyfish and eaten. A study of turtles in Florida found that 71 per cent of turtles surveyed had ingested plastic debris of some kind. | Because they’re heavier, making reusable bags has a bigger impact on global warming per bag than making plastic bags. You need to reuse this kind of bag 11 times before it has less global warming impact than plastic bags that are thrown away as soon as they’re used. |
| Plastic bags create 50 times more visible litter than reusable bags. | You need to reuse this kind of bag 26 times before it has less global warming impact than plastic bags that are used twice (eg. as bin liners). |
The verdict
While reusable bags aren’t a perfect solution, they’re greener than plastic bags if you use them over and over. Taking reusable bags to the supermarket makes a difference!