Is replacing paper towels with electric hand dryer blowers beneficial to the environment?

Question

I'm sure paper towels don't harm the forests, because they are made from reforestation crops. So using them only harm trees that were already destined to being cut.

I found this article that tries to compare the carbon emissions of each "paper towel session" x "hand drying session", and came to conclusion that using the dryer is about 5 times less harmful.

But the article is 2 years old and uses data even older. The most complex issue is: How much carbon emissions are ther in a paper towel?

Anyone can find more recent and based opinion on that?

Answer 1

Salon commissioned a study comparing paper towels with hot-air dryers, which found that a hand-dryer meant 9-20g per press of CO2 emissions (depending on the wattage), and paper towels were 28g per sheet - so it's a question of how many presses or sheets it takes. The resulting article is here.

Another study - consider cautiously as it was conducted by a company producing hot-air dryers - found similar results, concluding:

The use of the drier results in lower global warming, acidification, ecotoxicity, human toxicity, nutrification, ozone depletion and photochemical smog burdens. The use of paper towels results in a lower resource depletion burden than the use of the drier. The use of paper towels results in double the global warming burden when compared to the use of the hand air drier.

(in case you were wondering, they figured paper to be a renewable resource, as you can grow new trees). They assumed one press of the hot-air dryer button vs two paper towels.

Note, however, that according to a study by Redway and Fawdar, hot-air dryers took longer to dry hands, and actually increased the amount of bacteria subjects had on their hands (by 2-4 times!), whereas paper towels reduced the bacterial counts. They, however, also considered jet air dryers (such as the new Dyson ones I've seen popping up in places).

Dyson's jet air dryers use up to 83% less electricty than conventional hot air dryers. According to Mitsubishi, their version uses a tenth of the energy of a 1725W hot-air dryer (that's a relatively low wattage). According to the Redway and Fawdar study, jet air dryers are just as effective at drying as paper towels, and, while they still increased bacterial counts, it was not by nearly as much as a hot-air dryer.

Answer 2

Let's see (US perspective on this issue):

A hand dryer probably uses around 3000W to run the motor and the heater. It might be on for about 30 seconds. During that time, it consumes 1.5 kWm (kilowatt-minutes) or about 25 watt-hours.

According to this source, about 45% of the US energy supply (the largest proportion) comes from coal as of 2010. (185 GWh / 412 GWh = 44.9%), so I'll pretend that the energy comes from coal. Of course, if it comes from wind turbines, then CO2 production will be almost nil.

This source tells us how much using 1 kWh of energy contributes to production of CO2 from coal (this is the latest data I can get, but it shouldn't drift too much):

1.341 pounds of CO2 per kilowatthour generated, also showed a slight change from 1.350 pounds CO2 per kilowatthour in 1998 (Table 1).

That means producing 25 Wh of electricity produces 0.034 lb of CO2 (about 15.4 grams.)

An average tree absorbs from 22 pounds (1 tonne / 100 years) to 48 pounds of CO2 per year (depending on who you ask - these are quite pro-tree planting, so I'd like to see if there is a source of raw data); there does not seem to be any definite figure given.

That means one tree could support from 647 to 1,411 hand drying sessions.

But you can get far more paper from the average tree. This paper suggests that from just one cord of wood (8ft x 4ft x 4ft), smaller than a whole tree, you could produce 942,000 sheets of paper (A5 size, normal density.) Even if you used 10 sheets per session, it's still 66x better (in the best case for hand dryers!) And, you can recycle the paper used.

So no, hand dryers are not better.

Answer 3

Modern hand dryers are faster and use less energy than the older ones. So the Xlerator, for example, uses 1500 watts and dries hands in about 12 seconds while the older standard hand dryers like the World Dryer Model A hand dryer use 2300 watts and dry hands in about 30 seconds.

But manufacturing paper towels is very energy intensive and it takes more energy to manufacture the paper towels you use to dry your hands than it does to dry your hands with even the older hand dryers. So hand dryers win on that count alone, not to mention the fact that you have to cut down the trees, use lots of chemicals and water to make paper towels, transport them, stock them, clean up after them and finally cart them to a dump where they fill it up after being used only once.

Hand dryers are much better for the environment, hands down.