Eco-friendly cloth bag is a myth
Dec 13 2012
Rs 160 per kg of cloth bags as against Rs 60 per kg of plastic bags (the paper bag would most likely cost more than
Rs 60 per kg). Although the costs of paper and cloth bags are high compared with the plastic bag, the important question to ask is whether paper and cloth bags are really more eco-friendly compared with the plastic bags?
The answer to this question comes from a 2011 report published by the UK Environment Agency titled, “Life Cycle Assessment of Supermarket Carrier Bags.” In this report, Chris Edwards and Jonna Fry compare the conventional plastic bags (or high-density polyethylene (HDPE) bags) with other kinds of paper and cloth bags for their environmental impacts. The conclusions are very different from what one might believe: The conventional HDPE bag had the least impact upon the environment of all the bags considered in the study, which considered a number of bags made from different plastics, as well as both paper and cotton-based materials. This conclusion is very dramatic because here we compare the use of plastic bags only once.
The study went ahead and considered multiple uses of different bags. Thus, finding the number of times alternatives to the conventional (HDPE) plastic bag would have to be reused to overcome their own negative impacts to the environment. The report found that if a consumer only uses a conventional HDPE plastic bag just once (say to carry their groceries home before throwing the bag away), a paper bag would have to be reused 3 times, a heavy-duty plastic bag made from low-density polyethylene (LDPE) would have to be used 4 times, a plastic bag made of non-woven polypropylene (PP) would have to be used 11 times, and a cotton bag would need to be re-used 131 times.
The report also concluded that given the durability constraints, a cloth bag is expected to last for 52 trips. Thus, with that as a reference, a cotton/cloth bag user does over twice the damage to the environment that a plastic bag using grocery shopper, who throws away every plastic bag they get immediately after each shopping trip. This is because they would likely have to replace their more environmentally-destructive bag at least once long before they reach 131 uses.
Furthermore, if a consumer reuses 100 per cent of their conventional HDPE plastic bags (such as trash bags), the number of uses needed for the other bags to have a lesser environmental impact than the conventional HDPE plastic bag which rises by a factor of anywhere from 2.2 to 2.5. For example, that re-usable cloth bag would need to be used at least 327 times to be less damaging to the environment. Thus, the eco-friendly cloth bag users are over six times as destructive to the environment as the conventional consumer who simply re-uses all the plastic bags they get from the grocery store just once.
Some others researchers have called the paper-is-better-than-plastic a “myth.” According to a 2005 report by Scottish government, “There is a popular misconception that paper bags are more environmentally friendly than plastic bags.” According to this report, studies sponsored by independent retailers or governments generally agree that paper bags are less of a litter problem, but also that plastic bags consume less water and energy, and produce less pollution, including greenhouse-gas emissions.
According to reuseit.com, a 2007 study by Boustead Consulting and Associates found that it takes almost four times the energy to manufacture a paper bag as it does to manufacture a polyethylene bag. As most paper comes from tree pulp, so the impact of paper bag production on forests is enormous. A 2008 article from the National Cooperative Grocers Association states that each year the US consumes 10 billion paper grocery bags, requiring 14 million trees. Thus, although plastic bags are produced from crude oil, producing paper or cloth bags causes global warming: forests (major absorbers of greenhouse gases) have to be cut down, and then the subsequent manufacturing of bags produces greenhouse gases.
Reuseit.com says that several people choose paper over plastic because they believe that paper biodegrades faster than the rate at which the plastic breaks down in a landfill. However, according to the website, there are a number of factors that determine how quickly, if at all, paper degrades — this includes temperature, pH, the type of bacteria present and the form of paper (shredded paper degrades faster.) That being said, it makes more sense to opt for a reusable bag that will last for thousands of uses over a disposable that will end up in the landfill.
In summary, whether the move from plastic bags to paper or cloth bags is really ecofriendly is not as clear as one might imagine. A better option, perhaps, might be adopt and promote biodegradable plastic bags while banning the use of conventional plastic bags.
(The writer is on the faculty of Indian Institute of Technology, Mandi, India)