Discussing a 'good' bag for doing your groceries is not an easy feat. You quickly get caught up in a bar-fight where someone mentions he always takes a cotton bag from home to do grocery shopping. Or one might think paper or cotton bags are made from natural ingredients and for that reason are better than plastic bags. However, is that paper or cotton bag really better?

In an idyllic world, a bag made from plant fibers gives nutrients back to earth when decomposing, but what is as important to consider when discussing the impact of products on our environment is the energy and extra material required for the production, the likelihood the product will ever get recycled (or decomposed) or if the product rather ends up in landfill or even worse, gets digested by animals.

Life Cycle Analysis

In 2011 the Environmental Agency of the United Kingdom performed a life-cycle-analysis for the most commonly used single-use bags in where they compared the material and energy used for producing four different types of bags, looking at how often bags get reused and the likelihood the bags will ever get recycled or if they rather end up in landfill or get incinerated.

They found that the thin plastic bags at grocery stores are actually much better than all other bags when it comes to its global warming potential: a paper bag has to be used four times to outperform these thin plastic bags and a cotton bag has to be used 173 times.

The reason countries and governments are banning single-use plastic bags has nothing to do with the production, energy or material used for these plastic bags but mostly with the end-of-life of this product, when it gets disposed ending up on the beaches, urban litter or piling up our landfills.

How about Hong Kong?

Let's look at my hometown, Hong Kong. The Environmental Protection Department from the Government of Hong Kong calculated in a 2005 survey that around eight billion ton of plastic shopping bags ended up in landfill every year. Eight billion bags yearly is a staggering amount and means about three shopping bags per person daily. Implementing a levy scheme in 2009 (50 cent per plastic bag) reduced the amount of plastic bags being used in Hong Kong significantly.

This is not enough however. As Hong Kong is a service-based economy it relies heavily on the willingness of other cities and countries (mainly China) to import the Hong Kong waste or recycled material and as space is a very valuable asset in Hong Kong landfill costs a lot of money. According to Environmental Protection Department of Hong Kong, from all the domestic waste generated in Hong Kong around 11% consists of paper bags and around 8% consists of plastic bags. This doesn't sound like much but, besides food waste counting for 37%, paper bags and plastic bags combined are the two biggest factors for domestic waste in Hong Kong and a very small margin of these paper and plastic bags gets recycled due to the effort required to pick these items out of the pile of waste.

The paper or biodegradable bag that ends up in landfill is there to stay for decades if not hundreds of years as it lacks proper conditions to decompose: moisture, bacteria, the right fungi and oxygen for paper bags and a temperature of above sixty degrees Celsius and oxygen for biodegradable bags. When biodegradable bags end up in landfill they release dangerous methane gas or the degenerated residue seeps into the soil. On top of that, biodegradable plastic bags are hard to distinguish for consumers from normal plastic bags and might pollute the good recyclable plastic material if thrown in the plastic recycling bin.

What can we do?

First of all, treat paper and plastic bags equally. If we do a levy on plastic bags, we need to have a levy on paper bags as well, which are just as polluting if not even more as they take more resources for production and take up much more space in landfill.

Second, we need to find smarter ways to reuse our carriers, instead of charging 50-cent per shopping bag there should be a 50-cent discount if you bring your own shopping bag.

Third, in Hong Kong where so many people eat order from Deliveroo, Foodpanda or Uber Eats the paper bags should be designed so they can be reused (for groceries for example). Or let them give a discount for your order if you give them back paper bags that can be reused again by them again.