The Straight Dope 

Dryers Blow

When drying my hands in a public bathroom, I frequently have the choice of an electric hot-air dryer or paper towels. Since the label on the hot-air dryer proclaims it is environmentally friendly and reduces paper towel waste, I generally use it. But the dryer requires no little electricity, the production of which is often detrimental to the environment. So, which is less damaging for the planet?
—Marcus Evans, Nottingham, U.K.
 
You think this job is easy? Well, it’s a damn sight easier than it used to be now that I can fob the hard parts off on my hardworking assistants, in this case Una. She came up with a spreadsheet that, as I understand it (she glossed over a few bits in the PowerPoint), reduces all human activity, or anyway all activity involved in electric dryers and paper towels, to its equivalent in kilowatt-hours. Her conclusion is … well, we’ll get to that.

While electric dryers consume energy, a lot of energy goes into drying hands in the industrialized world no matter what the technology. Here in the United States each year we use more than 2.5 million tons of paper towels, a product that takes energy to manufacture, transport to the end user, and haul away afterward. How much energy? Depends. For one thing, are the towels made from virgin or recycled paper? Turning recycled paper into newsprint takes at least 70 percent less energy than virgin material, and presumably the savings in paper towel manufacture are similar.

The energy used by dryers is also highly variable. Different models can use anywhere from 1,500 to 2,400 watts and can take more or less time to dry your hands. Manufacturer estimates are typically optimistic—most hot-air units operate on cycles ranging from 20 to 40 seconds, and some newer cool-air models like the Dyson Airblade claim to require only 10 seconds. I’ve tried them all, and I say bunk—drying my hands almost always takes two or more cycles, and researchers at the University of Westminster back me up. They studied the drying efficiency of paper towels, cotton towels and hot-air dryers and found that 1. it typically took 43 seconds under a dryer to dry as well as 12 seconds with a paper towel, but 2. most dryer users lose patience well before then, and 3. about 40 percent end up wiping their hands on their pants.

Despite the uncertainties, many studies claim to show that paper towels made from virgin material are an energy sink. Data developed by Franklin Associates shows that using recycled paper towels requires about 62 percent of the energy expended on virgin towels, standard hand dryers need about 30 percent, and one model of high-efficiency hand dryer required only about 10 percent. According to a study conducted by Environmental Resources Management for two manufacturers of hot-air dryers, paper towels required about 64 percent more electricity over five years.

You’re thinking: Research paid for by hot-air-dryer makers favors hot-air dryers—there’s a shock. Enter Una and her spreadsheet to take an objective look. With everything she could think of accounted for (admittedly different assumptions might produce different results), Una’s best guess is that standard hot-air dryers use 5 percent less energy than paper towels in the first year, and about 20 percent less over five years. If high-efficiency dryers like the Airblade really provided acceptable drying in 10 seconds, then they’d use 80 percent less energy. (I’ve used an Airblade and, while 10 seconds is a stretch, I have to admit it’s close.)

Electric dryers might be better for the environment in other ways, too. Assuming the same five-year life span, Environmental Resources Management estimates paper towel production generates 35 percent more acid rain and 286 percent more greenhouse-gas emissions. A World Dryer study of 102 hand dryers installed in public schools in Topeka, Kansas, claimed an annual savings of 34.5 tons of solid waste, 690,000 gallons of water and 587 trees; another World Dryer study of 153 hand dryers in the Iowa state capitol showed an annual savings of 10.5 tons of solid waste and 176 trees.

What about those reusable cloth towels mounted on a big roll? An EPA study found that continuous cloth towels, as they’re known, have a low environmental impact, requiring only about 8 percent as much energy as paper towels and about 13 percent as much water (including what’s needed for manufacturing and laundering). The drawback of cloth towels is that they’re more of a pain—seems like half the time I run across one in a public restroom, the mechanism is jammed or the towel is torn, dirty, or otherwise gross. But don’t rule them out. What with global warming and scarce energy, the world’s in for some big changes over the next 50 years. If we have to swap paper towels for cloth, well, we’re going to see a lot worse than that.
 
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