Dear Pablo: With the energy and water used in washing and drying, isn't it actually more environmentally friendly to use paper napkins instead of cotton?Cloth napkins not only use water in washing and a lot of energy in drying but the making of them is also not insignificant. Cotton is a highly irrigated crop that also requires a lot of biocides and defoliant chemicals. In many cases napkins are actually made from linen, which is made from the fibers of the flax plant, and is significantly more environmentally friendly. Additional considerations include the fact that paper napkins are used once, while cloth napkins can be used multiple times. Of course, in the case of restaurants, you don't want a napkin used twice!Setting up the Napkin analysis

I begin by weighing some napkins. My paper napkins weigh only 4 grams each, while my cotton napkins weigh 28 grams, and linen napkins weigh 35 grams. Of course the exact weight will vary but the relative weights will be roughly the same. I am again turning to James Norman, a life cycle analysis expert and the Director of Research at Planet Metrics for some of the data that I need.

As mentioned already, producing cotton is not a very environmentally friendly process. In fact, each 28 gram cotton napkin causes over one kilogram of greenhouse gas emissions and uses 150 liters of water! By comparison, the paper napkin causes a mere 10 grams of greenhouse gas emissions and uses 0.3 liters of water use while the linen napkin causes 112 grams of greenhouse gas emissions and uses 22 liters of water.

Based on an average washing machine, each napkin will cause 5 grams of greenhouse gas emissions through the electricity used by the motor, and 1/4 liter of water. In addition to these impacts, the laundry soap used may have downstream impacts on aquatic life. You can reduce the impact of washing by washing in cold water and using biodegradeable and phosphate free laundry soap.

Drying napkins causes about 10 grams of greenhouse gas emissions per napkin. Of course, to reduce this to zero you could line dry. One of the advantages of the paper napkin is, of course, that you don't incur the emissions or water use from washing and drying.

If you add up the emissions from growing the raw materials, manufacturing the napkins, as well as washing and drying, the paper napkin is the clear winner with 10 grams of greenhouse gas emissions vs. 127 grams for the linen and 1020 grams for the cotton. Of course this isn't a fair comparison because it assumes only one use. Instead, we need to divide the raw material and manufacturing emissions by the number of uses over the lifetime of the napkins.

In a food service scenario we can assume that the napkins are too worn out or soiled to be used after about 50 uses. With this assumption, the emissions for the cotton napkin are 35 grams per use and for the linen napkin are 18 grams per use. The water use is 3.3 and 0.7 liters, respectively. Add to this the fact that restaurant napkins are often washed using a significant amount of bleach to keep them bright white. Of course the emissions and water use for the paper napkin remain at 10 grams and 0.3 liters.

At home you probably aren't going to be washing your napkins after each use. In my house we have found that washing the napkins every week is sufficient. With this assumption, how do the reusable napkins stack up to paper napkins? Over the course of a year you might wash your napkins 50 times and during the same time you might go through 350 (50 x 7) paper napkins. This scenario is much more favorable towards the reusable napkins, with 5 grams of greenhouse gas emissions for the cotton versus 10 grams for the single-use paper napkins. The linen napkin was even lower at 2.5 grams. In terms of water use, the cotton is still higher (0.5 liters) than the paper napkins (0.3 liters), and the linen is the lowest, at 0.1 liters.

Surprisingly in the restaurant scenario the paper napkin is the winner, while at home, the cloth napkin is king. Here are some tips for reducing your impact:

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