In Singapore, single use plastic bags that made from high-density polyethylene plastic “have a lower environmental footprint”, compared with the single-use paper and multi-use cotton bags, according to the report released by Nanyang Technological University (NTU).
In its press statement on Wednesday (14 October), scientists from NTU said that reusable and single-use plastic bags “would be a comparatively better environmental option” in the countries like Singapore, Tokyo, Hong Kong, and Dubai, with densely populated metropolitan areas that have waste management structures with similar end-of-life incineration facilities.
The statement also stated that reusable plastic bags that made from polypropylene non-woven plastic were the most eco-friendly option, followed by single-use plastic bags.
It was because the cotton and kraft paper bags “have relatively bigger environmental footprints” due to their greater contribution to global warming and eco-toxicity potential in their production.
This conclusion was made after the NTU’s research team conducted a life cycle analysis of five types of bags to evaluate the environmental impacts associated with their production, distribution, transportation, waste collection, treatment, and end-of-life disposal.
According to the Director of Residues & Resource Reclamation Centre at the Nanyang Environment and Water Institute (NEWRI), Assistant Professor Grzegorz Lisak, who is also the lead of the research, the “surprising conclusion” of this study is that single-use plastic bags, if treated properly afterwards, are less environmentally detrimental than the other types of bags.
“It is essential to evaluate the implications case by case for dealing with plastic waste. In a well-structured closed metropolitan waste management system with incineration treatment, using plastic bags may be the best option that is currently available, provided that there is no significant leakage of waste into the environment,” said Assistant Professor Lisak.
He noted, “Our main message is that re-usable plastic bags are the best option, provided that they are re-used many times – over 50 times to be precise.”
The research team observed that a reusable plastic bag would need to be reused four times to offset the emission equivalent to equal that of the creation of one single-use plastic bag.
It also reported that the global warming potential of a single-use kraft paper bag was the highest, which is over 80 times that of reusable plastic bags.
While the global warming potential of single-use plastic and reusable cotton bags that reused 50 times were over ten times of reusable plastic bags that reused 50 times.
The negative environmental impacts of cotton and kraft paper bags, according to the team, are due to their production processes that consume immense amounts of water and natural resources.
However, the team said that improving the production methods, optimizing resource usage, and following sustainable practices could in future favour the usage of cotton and paper bags.
NTU’s research team also recommends the usage of reusable plastic bags to reduce consumption of single-use plastic bags in Singapore as they suggested the reprocessing single-use plastic bags would be a good policy goal to cut down on their environmental impact.
Citing the 2018 statistic in Singapore, Assistant Professor Lisak noted that reducing the single-use plastic grocery bag consumption by half could prevent over 10 million kg-CO2 equivalent emissions in a year.