The problem with mugs.
So much in sustainability is not quite what it appears to be: this is especially true of embodied energy. The energy that is embodied in an object is all that which was used in its manufacture, including getting the raw materials, making the item and then transporting it to wherever it will be used. So, Embodied energy is very important when considering knocking down energy inefficient housing in order to replace it with the more efficient kind. There’s no such thing as a carbon zero house, a lot of carbon went into making the bricks, cement and so on.
But what has this got to do with mugs?
There is a widely held belief that plastic disposable cups are totally terrible whilst good old ceramic ones are the bee’s knees, for environmentalists. The truth, however, may be very different. Old fashioned china mugs are made from clay that is mined from the ground, moulded and then fired in a kiln. These kilns are heated to fairly high temperatures for periods long enough to effect a chemical change in the clay and to melt the glaze. One Australian university’s research suggested that a china mug would need to be used at least 1,000 times to cover that energy input – compared to a thin, lightweight disposable plastic cup.
1,000 uses in a commercial catering environment is a very long time for a mug to remain undamaged and we haven’t factored in the hot water and electricity used in dishwashing machines. In energy terms, plastic wins. But energy isn’t the only consideration; what happens to the disposable cup when we throw it away? If it’s into landfill then we are creating another problem, if it’s burned to create electricity and heat then maybe it’s not a problem. If we could ensure that disposable cups were shredded and baled up and then returned for reprocessing into new cups then we would have a win situation. Shredding would considerably reduce the amount of water used for washing, before recycling, and the plastic is light and would compress for easy transportation.
We can use plant materials and various forms of waste to produce the raw materials from which we produce plastics. China clay, on the other hand, is produced by the chemical weathering of rocks, primarily feldspar. This occurs over geological periods, that is, a very long time. So another reason why plastics are better. Aesthetically plastics are unlikely to replace ceramics in the near future. A mug of coffee feels that much better than a thin plastic cup in a flimsy holder.
Should we be using thicker plastic cups then? Maybe, but that depends on the plastic, not all plastics are easily recyclable and a thick plastic mug can’t easily be shredded and bailed for transport. So, most solutions involving energy are not as simple as they may, at first, appear.
Finally, a simple observation:
we still use electrically heated, un-insulated kettles, urns and coffee machines. Why? Their surfaces are hot enough to burn people and that’s clear evidence of the heat that is being lost. I keep an insulated flask next to the coffee filter. When the coffee has been made, the surplus is poured into the flask and even a stainless steel one keeps the coffee hot for a long time. The coffee tastes better when it’s not heated for a long period and the electricity bills are lower but when will kettles and coffee machines be insulated. If it’s good to unplug mobile phone chargers, how much better to insulate coffee machines!
Roy Tindle Chair, London 21 Sustainability Network
