Plastic, paper or cotton bag – the choice might depend on where you live
What bag is the best for the environment? The question is simple, but the answer more complex. IVL Swedish Environmental Research Institute compiled information from life cycle assessments on behalf of UNEP. The studies were conducted in Europe, Asia and the US, and the compilation identified geographical variations.
"The environmental impact of a bag depends not only on what it is made of, but also on how heavy it is and how many times it is used. A bag with twice the weight affects the environment twice as much. On the other hand, if the number of times the bag is used is doubled, each shopping round has only half the environmental impact," says Tomas Ekvall PhD, LCA expert at IVL Swedish Environmental Research Institute.
How much the bag affects the environment also depends on how the material is produced and how the bag is treated once it has become waste. The production of materials and the waste management are the parts of the life cycle that affect the environment most; the transport of the bags, for example, is not as important.
"The biggest problem with plastic bags is perhaps the plastic debris and microplastics that follow from littering. From a climate perspective, a single-use plastic bag performs rather well in comparison to other bags, especially if it is made from recycled raw materials. This is because of its light weight. A cotton bag or durable plastic bag can be even better, but only if they are reused many times," says Tomas Ekvall.
A paper bag can be a good option for the climate if it is produced with renewable energy, reused multiple times and/or recycled or incinerated after use. Avoiding landfilling of paper bags is important for the climate, because the paper decomposes forming methane.
"A plastic bad, produced from fossil fuel, affects the climate more if it is incinerated," says Tomas Ekvall.
The study indicates that the environmental impact of a bag depends on where you live:
- Single-use plastic bags are two to three times heavier in Sweden and Finland, compared to China, India, and the US, which means they are likely to affect the environment more.
- Paper bags have about the same weight in all LCAs investigated, but the paper production seems to affect the climate much less in Sweden and Finland, compared to other countries in the study.
- Single-use plastic bags are a bad option for the environment in poor regions without well-organized waste management system, because the risk of littering is high. Cotton bags might be a good way to reduce the impacts of littering in these areas.
- In regions where littering is low and waste management is dominated by landfills, plastic bags might be a good option for the environment. They should be durable if consumers use them many times, and preferably produced from recycled material.
- Where the waste management is dominated by incineration, paper bags might be a good option for the climate. A cotton bag can also be a good option if used many times.
- All bags can benefit from a high rate of recycling after use, but the environmental gain of recycling depends on the environmental impacts of the recycling processes and of the virgin material production it replaces.
"Since all bags benefit from a high rate of reuse, the best choice for the environment remains the same in all cases: use a bag you already have at home, to avoid the need for producing a new bag," says Tomas Ekvall.
This compilation of LCAs was commissioned by the UNEP Life Cycle Initiative.
"We are conducting several meta-studies on single-use plastic products and their alternatives, on behalf of UNEP. This is just the first," says project manager Christin Liptow PhD.
For more information, please contact:
Tomas Ekvall, firstname.lastname@example.org, phone +46-(0)10-788 68 31
Christin Liptow, email@example.com, phone +46-(0)10-788 68 72