Green energy solutions?

Which of these two white-noise sleeping solutions is more energy efficient?

• White-noise device: http://www.amazon.com/Conair-SU1W-Sound-Therapy-Silver/dp/B000F54AN8/ref=sr_1_2?ie=UTF8&qid=1390315741&sr=8-2&keywords=white+noise+machine Fan: http://www.amazon.com/Kaz-HT-900-Honeywell-TurboForce-Fan/dp/B001R1RXUG/ref=sr_1_1?ie=UTF8&qid=1390315492&sr=8-1&keywords=desk+fan I seem to need white noise to sleep well and am contemplating between these two white-noise solutions. As far as the fan, I would only be using it for its sound - its white noise - and not its blowing air.   Which of these two products is likely to run-up the electrical bill the least? Please tell me how you got the answer so that I can learn something.   As a bonus, aside from these two products, please feel free to comment and what you think is one of the most energy efficient white-noise solutions for sleeping.

• Answer:

  Generating sound alone is usually going to consume less energy than airflow AND sound. I can't find a power draw spec for the noise generator, but it runs on 4x AA batteries. If it runs for 8 hours straight, it can't be pulling more than around 1.5 watts. (A normal AA might have 3 W-h capacity). In comparison, one of the fan reviews says it draws: Low 27 watts at 380mA Med 31 Watts at 410mA High 35 Watts at 540mA (+/-2%) So I would guess the fan consumes more than 10x as much power. But energy in a battery costs far more (both in dollars and environmental impact) than energy from the power grid. So the noise generator is really only superior if you run it off a wall adapter or use rechargeable batteries.