Q: I have an aversion to creating garbage, and as such, I find disposable coffee cups abhorrent. When I mentioned this to a friend once, his retort was, "Think of all the water you waste washing your ceramic mug, and the energy necessary to produce the mug in the first place." What are the real equations at play here? How many times would I have to reuse my mug to make it the ecologically "better" alternative?
Asked by Erik Uzureau, '01, Tuscon, Ariz.
As a born and bred Seattleite, I care a lot about the environment and coffee. I can remember one cold winter day stepping into a Starbucks back home and feeling good as I purchased a green plastic tumbler. But then, I started to think about the petroleum used to make that plastic, and the energy used to fire the kilns that bake ceramic mugs like yours. Does the reuse outweigh the environmental impact of making these reusable cups? The answer, luckily, is yes, so long as you keep them around long enough.
Your friend's skepticism aside, you really only need to use a ceramic mug about 18 times, or a plastic mug eight times, to break even with a paper cup in terms of water use, energy and waste. Each use after that means more environmental savings, and less garbage. Mugs hanging around your office tend to be used, on average, 50 times. My personal favorite plastic tumbler has probably held tea at least once a week over the three years I've had it, adding up to 150 uses or more-and 150 paper or Styrofoam cups not produced, used and thrown away.
But what happens when you forget your reusable cup? At most coffee shops, you are handed your java in the industry standard: a paperboard cup lined with lightweight plastic, which makes them unsuitable for recycling. But even disposable cups are getting a little better. In January of 2009, Stanford Dining converted almost all of its cafes to compostable serviceware, including compostable beverage cups with a biodegradable corn plastic liner. Now, they can be composted, helping to build healthy soil rather than piling up as garbage.
In terms of environmental impact, however, your drink of choice can be just as important as your choice of cup. More than 50 percent of American adults drink coffee daily, amounting to nearly 150 billion cups of coffee every year. From production, to preparation to disposal, drip filter coffee can produce the equivalent of 150 grams of carbon dioxide per cup consumed. That means that American consumption of coffee is responsible for the same amount of greenhouse gas emissions as nearly 4 million passenger cars each year. Conventional coffee is also very energy intensive and uses huge amounts of water. In fact, a single cup of drip filter coffee requires nearly 20 times the amount of water used to make the ceramic mug you drink it in.
The good news is that you have options to make your coffee choice more sustainable. Check out the Nitty Gritty for a more comprehensive discussion of responsible coffee. For now, just look for the Fair Trade logo when purchasing coffee. This certification is a holistic measure of a product's environmental and social goodness. And, if you forget your reusable mug, why not ask for a "for-here" mug instead? As the person in front of you orders a 10-ingredient latte, you can scan the menu for a more sustainable choice. Then take a few minutes to enjoy both that steaming cup of coffee and the good you are doing for the earth.
Bethany Wylie, '10, is a graduate student in earth systems.