Lifecycle Assessments

The science is clear. Plastic shopping bags are the best environmental option. They are reusable, recyclable, and the most hygienic bag on the market. On top of that, they have the lowest carbon footprint of any bag.

A number of government scientific studies called Life Cycle Assessments (LCAs) prove that plastic shopping bags have a much lower carbon footprint and the lowest global warming potential of any carry bag on the market.

The three most recent have been done by the United Kingdom, the Government of Denmark, and the Government of Quebec (Canada), and they all reached the same conclusion that plastic shopping bags have the lowest environmental impact. They all found that plastic shopping bags are not single-use, but multi-purpose, multi-use bags with very high reuse rates. In the Quebec study, the reuse of “single-use” plastic shopping bags was 77%.

Click below to explore how plastic shopping bags are by far the best bag environmentally.

Quebec Government LCA

Environmental and Economic Highlights of the Results of the Life Cycle Assessment of Shopping Bags 

The Quebec Government’s Life Cycle Assessment (LCA) compared the environmental impact of all shopping bags available in Quebec in order to determine which bag has the lowest carbon footprint using North American data.

The LCA showed definitively that the thin 17-micron HDPE plastic shopping bag is the best bag environmentally and economically. It found that reusable bags have a much greater carbon footprint because of their resource intensity and require multiple reuses to match the environmental impact of the 17-micron thin bag used just once.

According to the Quebec Government LCA, the Polypropylene (PP) woven and PP non-woven bags need an equivalent number of reuses to equal one use of the thin plastic bag ranging from 16 to 98 reuses for the woven PP reusable and 11 to 59 reuses for the non-woven, depending on the environmental indicator.

The key finding of the report is that “no alternative to banning plastic bags offers an environmental benefit. …] In this context, banning [thin HDPE bags] would not be advantageous.

Quebec Life Cycle Assessment

Denmark Government LCA Ministry of Environment and Food

Life Cycle Assessment of grocery carrier bags

The Government of Denmark LCA of grocery carrier bags found that thin plastic shopping bags have the lowest environmental impact of all bags in their marketplace and that reusable bags have to be reused multiple times to provide the same environmental performance of the average conventional LDPE carry bag reused as a waste bin bag before incineration.

They measured the carbon footprint and global warming impact of each reusable by comparing each reusable bag against the environmental impact of a thin plastic bag used just once; the thin plastic bag was used as the standard.

This piece of science found that the minimum number of reusable bag reuses to equal the environmental impact of the thin plastic shopping bag was very high.

The Nonwoven PP Reusable had to be reused 52 times and the Woven PP Reusable had to be reused 45 times to equal the environmental impact of the thin plastic bag used just once. Similarly, Recycled PET Reusable Bags had to be reused 84 times; Polyester PET bags – 35 times, Unbleached paper – 43 times, and Organic Cotton – 2,000 times.

Government of Denmark Life Cycle Assessment

U.K. Government LCA Environment Agency

This LCA, as with the Quebec and Danish LCAs, found that the conventional plastic shopping bag (HDPE) outperformed all alternatives, even reusables, on environmental performance.

Conventional plastic bags have a much lower global warming potential than all other bags on the market. Heavier, sturdier reusable bags of all materials have a higher global warming potential. For example, the production of cotton with its heavy pesticide and water use has a negative impact on the environmental benefit of cotton bags.

A cotton reusable bag has to be reused 131 times to be as good environmentally as a plastic shopping bag used just once. Non-woven polypropylene bags would have to be reused 11 times to match environmentally the conventional thin bag used just once. Paper bags would have to be reused three times to lower their global warming potential to match that of a conventional HDPE plastic shopping bag being used just once.

Amount of Primary Reuse Required for Reusable Bags to Match Environmental Performance of Conventional Plastic Shopping Bag Used Just Once

Type of Carrier Bag HDPE Bag
(No Secondary Reuse)
HDPE Bag
(40.3% reused as kitchen catchers)
HDPE Bag
(100% reused as kitchen catchers)
HDPE Bag
(reused 3 times)
Plastic Bag 1 2 2 3
LDPE Bag 4 5 9 12
Non-woven PP Bag 11 14 26 33
Cotton Bag 131 173 327 393

 

UK Government Life Cycle Assessment

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