Digging Deeper:
Throwaway or Takeaway Cups

The Question
How many disposable coffee cups do we use in the United States every year? What is the environmental impact? How many times would I need to use a thermal mug to achieve an environmental benefit and cost benefits?

The Explanation
Disposable coffee cups can be made from paper or polystyrene (commonly known by the brand name Styrofoam).  Reusable options include ceramic or plastic mugs or insulated travel cups.

Life-Cycle Analysis
A typical polystyrene cup is made from a petroleum-derived thermoplastic. To make one eight-ounce cup, it takes around 55 kilowatt hours.   Production also requires a quarter-ounce of raw materials and about a half-quart of water.  In the process, a small amount of greenhouse gasses are emitted into the atmosphere.  These numbers really add up when billions of cups roll off the factory line.

Common practice is to use the paper cups provided at coffee shops— sometimes two if the beverage is really hot. Paper cups are a strain on forest resources, using almost three times their weight in bark and wood. Surprisingly, producing an eight-ounce paper cup from raw materials is even harder on the environment than making an eight-ounce polystyrene cup: it takes more water, generates more toxins, takes up more landfill space due to its larger size, produces 1.5 times the greenhouse gasses, and uses nearly three times the amount of energy (see figure).  Even worse, paper cups require the destruction of trees that would otherwise be removing carbon from the atmosphere. Making cups from recycled paper can somewhat mitigate their environmental impact.

One option is to consider a stainless steel thermal travel mug. Producing an eight-ounce mug requires more than six pounds of steel.  Although 60 percent of steel is recycled, there is still a chance that virgin material with its high-energy costs resides in the mug. Making the mug also requires almost 10 gallons of water and releases about a pound of greenhouse gasses into the atmosphere.

The Energy Cost of Reusable Mugs Declines Over Time

Figure - The energy per use of each reusable cup (black lines) declines as it is used more often. The energy per use of each disposable cup (green lines) is a constant equal to the manufacturing energy, because it is used only once and is never washed. The numbers indicated with arrows are the manufacturing energies for the different cups. Source: http://www.ilea.org/lcas/hocking1994.html

The Cost
Although the cost of a disposable cup is not evident to consumers, retailers can buy them cheaply, at around $23 for a thousand polystyrene cups. A thermal mug can cost anywhere from $5 to $20, but many coffee shops will give you a discount—often 10 cents—if you take your own mug, which helps offset the purchase price.

Is a reusable mug a waste of money and harmful to the environment, because the energy cost of producing it is so high? Consider the alternative: the 25 billion disposable polystyrene and more than 14 billion paper cups that end up in the landfill every year! Just keep your mug handy, use it often, and try to wash it in your normal dishwasher run. Cut down on energy and water use by only running full dishwasher loads, investing in an Energy Star machine, and limiting hand-washing.

For More Information
Survey: U.S. coffee drinking reaches highest level in decade - Supplier News - Brief Article - Statistical Data Included, Nation’s Restaurant News. 1 July 2002. http://findarticles.com/p/articles/mi_m3190/is_26_36/ai_88268882

Reusable vs. Disposable Cups, Institute for Lifecycle Environmental Assessment. 1994. University of Victoria. http://www.ilea.org/lcas/hocking1994.html

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