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."

Comments

Not to optismitic about being commercialized yet

[external400kdiskette]

"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.

electric double layer caps

[Montressor]

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

Re:electric double layer caps

[Rei]

Thank you! Why is it that submitters randomly feel the need to pick out a buzzword to stick into the headlines?

Flywheels are not energy dense storage (very much the opposite, both on mass and volume). They're not efficient electricity storage. They're leaky storage. They're not cheap (for a given amount of energy storage). They'd interface awfully with wind power, which is variable RPM.

The main benefit of flywheels is that you can get a lot of power from one at once. What the heck does that have to do with wi-fi? With this, you want long-term storage in case power gets low; in that case, you want batteries. Sorry. Batteries aren't glamorous. They're not a buzzword. But they're the appropriate tool for the task.

Re:Larger applications?

[Barkley44]

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.

Re:not enough power for 802.11

[EnderWigginsXenocide]

A sensor need not be on the network 24/7. When it's onboard memory has been filled to a certain capacity (say 80%) if fires up the transceiver and transmits to the network. You only need peak power on occasion. Give your windmill plenty of time to charge up a big capacator (or a small battery.)

People Power!

[Max Threshold]

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?

Re:People Power!

[joelanders]

Along the same lines, I always wondered how much power could be harnessed from the 40 year old women at the gym on those bikes...

Re:not enough power for 802.11

[mr_jrt]

Surely though, unless all these wireless repeaters are time-synced to power up (once charged and ready) at a certain time, there's a pretty high probability that the neighbouring nodes will be powered down when your node is ready to go. Though, I suppose less power would be needed to run a simple sensor for nearby active nodes, upon which it could then actually transmit. Will still obviously require some power though. I can imagine the routing being a nightmare too.