LETTERS: I was teaching sustainability to a group of engineering students. During a short break, I prepared a question for them. They were to respond via an online voting platform.
The question was: "Plastic bag or paper bag, which one is more environmentally friendly?"
The result of the vote was presented on screen. As expected, more than half the students went for the paper bag.
I was not surprised, given the bad reputation of plastic bags.
The students may also have pictured turtles with drinking straws in their nostrils and plastic products clogging sewerage lines.
Then I switched to the next presentation slide. It featured a comparison of the environmental impact of the two bags. The information was from a source on the Internet.
It stated that paper bags could heavily impact the environment due to greater greenhouse gas emissions from energy-intensive processes and high-water use.
The students looked astonished. I immediately gave them an explanation. The emissions could be from the machinery that was used to fell the trees.
Paper production or raw material extraction could account for the high-water intake. There are more studies which could give different perspectives on the debate. The study I was referring to may be biased or not robust enough.
I introduced them to a life-cycle assessment concept, usually abbreviated as LCA. The LCA is a methodology to quantify the environmental impact of a product.
The assessment covers the entire life-cycle stages, starting from raw material extraction, to manufacturing, transportation, use, until end of life or disposal of the product.
The adverse impact of paper bags may be from any of the life-cycle stages. There's a plethora of factors in assessing the impact, such as the embodied energy of the raw materials, distance from the manufacturers to the users, and whether the products are recycled.
So, which bag is more sustainable? There is no definite answer. I am not trying to promote the use of plastics over paper, or vice versa.
An LCA needs to be conducted and tailored to a situation, comparing the bags head-to-head with all details of their life stages. Each product must be assessed thoroughly to understand its environmental credentials.
I ended the session with one big hope that the case study had taught the students a vital lesson — nothing is straightforward when dealing with real-life situations.
Making decisions is truly challenging, especially when analysing the sustainability facets of a product or our own, daily actions.
Source taken from : NEW STRAITS TIMES
Image & News : https://www.nst.com.my/opinion/letters/2022/07/814150/paper-bag-or-plastic-bag-which-more-environmentally-friendly
