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Wind-powered Wi-Fi Sensors
Glenn Fleishman writes "According to an article at Indolink a 10-centimeter diameter windmill can produce the 7.5 milliwatts needed for a wireless sensor. The paper was published earlier (available as a PDF), but Nature magazine has apparently picked up the tidbit. The process flexes piezoelectric crystals to create a current. Although flywheels aren't mentioned in this article, it seems like a windmill, a flywheel, and a solar cell could in combination produce effective power in a range of conditions for remote wireless devices, including network relays obviating batteries entirely."
802.11 cards typically consume around 1 or 2 watts. They are probably targeting much simpler radios, like those used in motes.
"Dr. Priya foresees piezoelectric bimorphs being utilized to power a variety of small devices" but I foresee nothing practical unless the efficiency is as high as enviromentally unfriendly stuff known as batteries. People just aren't going to go for this sort of thing anymore than other alternate energies unless it's going to work just as well sitting alone with no vibrations ... I mean he mentions a discman but is it still going to be fine if your lying down with it on a table playing for hours on end lacking vibrations , indoors with no wind in sight... if not it's not ready to be commercialized.
That's the problem with alternate energies, they're cool and great for the environment but lack of efficiency means you usually have to suffer to be a good citizen.
Flywheels? The simplest way to store power would be an electric double layer capacitor. No moving parts. They can come in up to 70F at 2.1V - that's 140 C of charge. At 10 mW of power, 2.1V is 5mA of current; that means that it can stay above 1.5V for 2 hours. If a higher voltage is needed, put the capacitors in series. And these are not huge devices. Here's a datasheet for one
Why not use windmills to power our computers coolingfans?
How about bring them back with a geeky Wi-Fi vengeance?
Possibly even attach an LED headband to it to tell others how close to a hotspot they're in. C'mon, I see profits galore!
Propeller Beanie hats :)
First, these aren't wind powered sensors that transmit over wi-fi -- they're wind-powered sensors that detect a wi-fi node nearby. There's a big difference in power levels there. The first sounds really nifty, and with lower-power radio systems would be really cool. The second sounds like something ThinkGeek will have on clearance in about two years.
Likely not enough - I suggested small normal windmills on roofs of our house in a previous post and someone said even that wouldn't be enough (ie. it would barely make a difference). I thought if each house had 6 small windmills they could reduce the load (imagine every house having this). But I was told it wasn't enough even still. Too bad, I would love to know in the middle of summer with solar and wind power I was generating enough power to reduce my electric bill by 40% or something.
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Will people stop applying this term to everything? Wi-Fi is referring to wireless LAN, not to any device that happens to use the radio spectrum. Use "wireless", or "radio", or "remote".
You missed my flywheels reference! See the Wired article in May 2000 (it's free online) that talks about the future of flywheels as battery replacements. It's not that far out there that you could have a tiny windwheel and a tiny flywheel that would provide enough storage for a day's worth of power, say.
Freelance tech journalist for the Economist, MIT Technology Review, Macworld, and others
Also found on the internet: " The piezoelectric generator is a much more efficient way of converting wind energy on a small scale than the conventional generators that create energy for the national power grid from wind turbines.
A conventional generator that used a 10-cm turbine would convert only 1 per cent of the available wind energy directly into electricity. A piezoelectric generator ups that to 18 per cent, which is comparable to the average efficiency of the best large-scale windmills, says Priya. "
Blessed are the pessimists, for they have made backups. -- 0 1 My two bits
10cm?!?! You'll decimate the local Japanese beetle population! We can't have that. Somebody alert PETA!