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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.
I have no concept of electrical quantities. What I see here is "tiny windmills make electricity."
So, for someone with more of a clue: does this sound like something that could be scaled up? Like, could you put them all over your roof and generate green power, or would there not be enough juice?
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
RE Flywheel
Those will be cool when we have lightweight cheap materials we can use to shroud a flywheel. Why shroud them? Two reasons.
First is drag. Can't have resistance from air slowing down your wheel. Keep it in an evacuated container.
Second is saftey. If you want to store a meaningful bit of power you'll either need alot of mass or rotational velocity, or both even. Now, think of what happen is there's a defect in your high-speed high-mass flywheel and its parts decide to take seperate vacations. Did you think FRAGMENTATION GRENADE? Good, go to the head of the class. You need to keep potentialy dangerous fast-moving high-density bits from coming into contact with people and things that people value.
Another problem with flywheels of any significant mass or speed is the gyroscope effect. But, that's not as big a deal as finding a wonder-material to protect the flywheel from the atmosphere, and us from the flywheel.
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!
How about a wifi powered wind detector?
I cant seem to find the page but I was looking at flywheels a while back and a simple solution to the 2 problems you list where solved. Basically the flywheel was floating on magnets in a vacum in a steel drum. the company listed the life of the flywheel at 50 years with zero maintinance. basically you could bury them and that takes care of the vacation problem. I think i may have missed your point though, because i dont really understand why you think this would require a lightweight material or that we dont have it yet. it would be easy enough to create a really dense and strong flywheel and not push it to its limits, reducing the need to worry about the thing exploding.
"Alcohol, cause of, and solution to, all of life's problems" -Homer Simpson
What's with all these over-engineered solutions for the developing world? My mom still has an old foot-powered sewing machine. If people could run a sewing machine with their feet, why not a generator?
In Soviet Russia, the Wi-Fi powers the Wind!!!!