Electric hand dryer vs paper towels: a practical guide.
Summary: Using one paper towel is environmentally better than using electric hand dryer. Using two paper towels isn't.
The average electric hand dryer, like the one on the picture, is rated at about 2000W, and operates for 30 sec. at a time. That means it uses about 0.017 kWh of electricity for each pair of hands dried. Look at the environmental impact of the electricity, in average: 383 units per kWh, or 6.4 units per one hand drying.
Now, lets consider paper towels: environmental impact of one of them is 3.3 units. Wow. It is just half of the impact of the electric hand dryer! Paper towels, as dirty as they seem, are actually better than electric dryers. Right?
Maybe not. The study by Nancy VandenBerg et.al. indicates that people, in average, use two paper towels to wipe their hands. That means 6.6 units of environmental impact, and electric hand dryer becomes the better choice.
So, for the environmentally conscious folks: if you can use just one paper towel, do it. If you usually use more, opt for the electric hand dryer.