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Are you guilty of getting your daily caffeine hit out of a disposable cup? If you are, you probably don't want to know that a three-cup-a-day habit will create a one thousand-cup mountain every year!
It seems grossly wasteful, since a reusable ceramic cup is better for the environment. But is it really?
The surprise report
A good way to compare the impact of disposable cups with reusable mugs is to look at the impact they have throughout their entire lives. Analysing the cradle-to-grave environmental effects of a product can sometimes tell an interesting story.
One well-known report on reusable versus disposable cups was conducted by Martin Hocking at the University of Victoria, Canada in 1994. What he has to say about disposables might surprise you.
Making the cup
The major environmental impact of a paper cup occurs during producing of raw materials and cup manufacture. Felling timber, making the paper and fabricating a single paper cup takes 549 kJ, according to Hocking.
To produce a ceramic cup requires nearly three times the energy because kilns are so energy intensive.
Ceramic cups are, however, reusable, so this energy needs to be spread over the mug's lifetime. Hocking calculated that it doesn't take long - about 500 uses, or the equivalent to using it twice a day for eight months - before the manufacturing energy becomes insignificant.
Cleaning the cup
What is significant is the energy used to wash the mugs. According a study by Dutch researchers 90 to 100 per cent of the environmental impact of ceramic mugs is from their cleaning, specifically, the energy needed to heat the water and the impact of the detergents. Because washing is an ongoing need, the impact of cleaning will last the lifetime of the mug.
It turns out that the energy required to wash a ceramic mug is half of the energy required to manufacture a paper cup. Hocking calculated that a ceramic mug must be used at least 39 times before breaks even with the energy needed to make one paper cup. Since paper cups don't need washing, the ceramic is a clear water winner.
End of life
What about the impact of disposing your cups - surely disposables are worse than ceramic? Compared to cleaning and manufacture, the waste disposal is relatively minor player for both paper and ceramic.
Since most paper cups are not recyclable or compostable due to a thin plastic lining - they end up in landfill.
In theory the polystyrene (number 6) lids are recyclable - although few lids probably make it to the recycling bin! Ceramic mugs are also not recyclable - in fact one tiny shard of ceramic the size of a fingernail can contaminate 20 tonnes of glass!
However, you would expect a ceramic mug would last well over 10 years so many more paper cups would end up in landfill before the ceramic would make it in there.
What seemed to be a cut and dried argument turns out to be much closer than you'd expect. Ceramic cups have to be used a lot and washed efficiently if they are to compete with disposables - although with their high manufacturing footprint, it seems the real eco-sin is buying a spare tea-set that sits in the back of the cupboard without being used.