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SINGAPORE: Scientists from Nanyang Technological University (NTU) have found that single-use plastic bags have “a lower environmental footprint” compared to single-use paper bags and multi-use cotton bags.
But the study came with the caveat that the findings applied only to Singapore and possibly similar cities, where incineration was part of the city’s waste management structure.
In the study, the scientists conducted a life cycle analysis of five types of bags to assess the environmental impact associated with their production, distribution, transportation, waste collection, treatment and end-of-life disposal.
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The study found that reusable plastic bags made from polypropylene non-woven plastic were “the most environmentally friendly option,” followed by single-use plastic bags, NTU said in a press release.
Using plastic bags “may be the best option currently available” in cities like Singapore, said assistant professor Grzegorz Lisak, director of the Center for Waste and Resource Recovery at the Nanyang Water and Environment Institute (NEWRI), who led the investigation.
“Our main message is that reusable plastic bags are the best option, as long as they are reused many times, more than 50 times to be precise,” he added.
“However, a surprising conclusion is that, in our model, in a single-use case, plastic bags, if properly treated afterwards, are less harmful to the environment than the other types of bags in this study.” .
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The scientists found that the global warming potential of a single-use kraft paper bag was more than 80 times greater than that of reusable plastic bags. Reusable cotton and single-use plastic bags that have been reused 50 times were found to have more than 10 times the global warming potential of reusable plastic bags that have been reused 50 times.
According to the study, a reusable plastic bag should be reused four times to offset the emissions equivalent to creating a single-use plastic bag.
Cotton and kraft paper bags have a relatively higher environmental footprint due to their “greater contribution to global warming” and the “ecological potential of their production,” the study showed.
Stock photo of a kraft paper bag. (Photo: Pexels)
Cotton bag and kraft paper production processes that consume “immense amounts of water and natural resources” are to blame for the relative negative environmental impacts, according to the study.
“Therefore, improving production methods, optimizing the use of resources and following sustainable practices could favor the use of bags made of cotton and paper in the future.”
The study found that both single-use and reusable plastic bags were less harmful to the environment than paper and cotton bags in cities like Singapore. (Photo: NTU)
Adding that it is essential to assess the implications “on a case-by-case basis” for dealing with plastic waste, Assistant Professor Lisak said: “In a closed and well structured metropolitan waste management system with incineration treatment, the use of plastic bags can be the best option currently available, as long as there is no significant leakage of waste to the environment. “
MODEL APPLICABILITY
The NTU team emphasized that their model applies specifically to Singapore and may be applicable in cities such as Tokyo, Hong Kong and Dubai. This is due to the model’s focus on densely populated metropolitan areas that have waste management structures with similar end-of-life incineration facilities.
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For Singapore, the scientists recommended that reusable plastic bags be used “to the greatest extent possible” to reduce the consumption of single-use plastic bags. Reprocessing single-use plastic bags would be “a good policy goal” to reduce their environmental impact, they said in the statement.
According to Singapore statistics from 2018, cutting single-use plastic bag consumption in half could prevent more than 10 million kg of CO2 equivalent emissions in one year, said assistant professor Lisak.
In the future, the team will conduct more studies on plastic waste management, plastic waste improvement and new product development, NTU said in the press release.
