Creating a reusable ceramic mug requires more energy than the making of a disposable paper cup. So does bringing my own reusable mug really help the environment if I have to replace it every few months? Ask Science answers a reader question about environmental responsibility.
Hi I’m Dr. Sabrina Stierwalt, and I’m Ask Science bringing you Quick and Dirty Tips to help you make sense of science.
In episode 135, called Why We Dump 28 Billion Pounds of Plastic into the Ocean, we discussed a recent study tracking the large amounts of plastic being dumped into the world's oceans each year. I gave the following tip for those looking to reduce their plastic waste:
"Give up the plastic items that aren’t necessary, like foregoing a straw in your drink and carrying your own reusable shopping bag or coffee cup."
This inspired a great question from an Ask Science listener named Thor. He asks:
"Is this advice always the best for the environment? What if you lose a mug per year - is it still better than using paper cups? What if you lose a mug every 2 years, or every 5? Where is the break even point? … Put another way, the construction and destruction of a metal and/or plastic travel mug has the same environmental burden as how many paper cups?"
As Thor points out, the metal and plastic used to make those travel mugs are both non-renewable resources, while the paper making up the disposable cup is not. (Although the disposable lids are usually plastic.) Reusable mugs also don’t stay with us forever. We break them, we lose them, or we just plain forget to bring them with us to the coffee shop. So are we really doing the environment any favors with our reusable products?
When we decide whether to go reusable or disposable to have the most positive impact on the environment, we have to evaluate an item’s so-called “lifecycle assessment.” In other words, we must take into account a variety of possible environmental impacts, like global warming, carbon footprints, harmful chemicals, resource consumption, or ozone depletion that the item will have throughout its entire life. Then we must decide which ones outweigh the others or are the most important to us.
For example, I used a mix of cloth and disposable diapers with my child. Cloth diapers may seem like the obvious choice for the best environmental benefits – less waste! – but they are far from it. They may not fill up landfills quite as fast, but they require a large amount of water to wash, as well as energy to heat that wash water. Cotton crops also require a lot of water to grow and almost a quarter of all pesticides are used in cotton farming.
Since the overall effects on the environment of cloth versus disposable diapers are similar, I can opt for which kind of impact I’m more willing to make. If I lived in a drought-ridden place like southern California where water needs to be conserved, I may not have made the decision to use cloth.
How Many Disposable Cups Make One Reusable Mug?
Making disposable and reusable mugs requires resources. A ceramic mug has to be forged in a kiln and it takes energy to get to those high temperatures. That mug will also have to be washed which requires water and, you guessed it, more energy to heat that water. Let’s also not forget the packaging that mug came in when you bought it.
The paper industry has a reputation for not being the most efficient as far as waste and use of resources, so you can expect that more greenhouse gases were emitted to produce a paper cup than a plastic one. We are taught that Styrofoam, for example, is horrible for the environment because it never biodegrades, but it takes less energy to produce that Styrofoam cup than to produce a paper one.