SparkFun Forums

[mistergreen]

Hi all,
New to this forum. I was just thinking, is it possible to somehow generate current by taking advantage of kinetic energy (by just moving specifically the human body)?

Just use you imagination on this general hypothetical question

[riden]

Besides generating static electricity in the thousands of volts by walking, it is possible to generate usable amounts of electricity (by usable, I mean enough to do things like charge an iPod or cell phone, light LEDs, etc.) There are a number of projects underway to capture kinetic energy. Do a Google search on "generating electricity by walking". Some of the projects are getting upwards of 7 watts or more of output just by walking, although the equipment is bulky. One setup would look right at home as part of the uniform of an Imperial storm trooper from Star Wars.

My son's science fair project this year was on this topic. He ended up using a DC motor with flywheel and a bit of mechanics to spin the motor each time he took a downward step. He was getting about 1/2 - 1 watt of output (enough to brightly light a 1 watt blue power LED) from his simple setup. However, there are a lot of drawbacks with his design, and it wouldn't fly as-is if mass produced. However, it was an interesting proof-of-concept.

I ran across an interesting project that was a twist on generating electricity by walking. There is quite a bit of research in nanotechnology based piezoelectric generators. Instead of generating electricity for charging personal electronic devices, a grid of piezoelectric plates were strategically placed in areas of high foot traffic, and the traffic generated (a bit of) electricity for the building.

[leon_heller]

Try Googling for "energy harvesting". I have a little module made by ALD that stores small amounts of electrical energy from virtually any source in a suitable battery. They are quite expensive, Farnell sells them.

Leon

[mistergreen]

Do you guys know if those kids shoes that lights up every time they walk is just using a battery or is it harvesting energy via Piezo material or something?

It would be nice to hack if it's already made or see what's inside.


thanks.

[riden]

I can't say for certain, but I strongly suspect they are battery operated. The costs for harvesting technology would add too much to the cost of the shoe. My son had these years ago and I remember that the lights stopped working at some point.

[leon_heller]

They are battery powered. Our secretary where I used to work asked me to extract the parts from her daughter's trainer which had stopped working for her to play with; I found a Li cell and a few very cheap components. A wire had broken.

Leon

[nick26]

From scouring the usual places like hackaday, stepper motors seem a good way to generate small amounts of power. One project I saw, was generating power by using a stepper motor between the legs. He had the insides of a tape measure (spring) attached to the motor, with a cord from the spring mechanism to the other foot.

In fact on my uni final year project, as I spun the motor, the power LED came on, even though the external supply was disconnected.

HTH

[mistergreen]

I was thinking in the line of a piezo material that would charge 2 coin size batteries to run a device.

Have you guys checked out the Adidas 1? The one with the microchip inside?
http://www.shopadidas.com/product/index ... 0&colorId=
I'm not sure if you have to insert a new battery once in a while for it.

[riden]

One of the technologies that my son looked into was piezoelectric. It wasn't able to generate nearly the electricity that a magnetic/coil combination did using the components available to him. However, there is work in the this area that looks promising: http://www.nanotech-now.com/news.cgi?story_id=31293

Here is the link for the other take on piezoelectric generation that I mentioned earlier: http://ourworld.unu.edu/en/2008/12/15/l ... y_walking/

[mistergreen]

I think there's a dance club somewhere, nyc?, where the floor is made of piezoelectric material. I'm sure it lights up a light bulb.

[riden]

There is no doubt that a piezoelectric pad can act as a switch to turn on and off a lamp. However, that is much different than powering the lamp via the piezoelectric pad. As far as I know, there aren't any widely available products that can do this. However, work is being done in this area, and perhaps your NYC club was a test site:

http://powerleap.net/index.html

[mistergreen]

how would one collect static electricity from clothing?

Obviously multiple point on the clothes where it is conductive and leads to a capacitor of some sort like ALD module leon_heller mentioned?

[jesrandall]

The piezo idea is possibly the easiest to implement. Simply attached any type of piezo electric material to moving parts can gather energy. However, always remember basic thermodynamics. By adding piezo components to moving parts will add extra load and resistance to the machine (human, etc.)

It may be advantageous to try to gather truly wasted energy, such as heat (which if not tapped would simply leave the system)... Muscles heat up when you walk and adding thermoelectric converters around them would generate electricity as well as help cool you down (since they would conduct the heat away, possibly better than sweat evaporation).... Current, efficient thermoelectric converters are lacking efficiency.

Another method to more directly steal the kinetic energy is by use of lasers and blue shifting. Shine a laser toward something in relative negative motion with your body ( I mean that something always approaching you, like the ground before you. If you choose the right angles, use photomultipliers, and very high efficiency optics you can actually trade in some of your body's momentum for a very low current, high voltage energy. Hmm... it would probably require technology to advanced currently. But essentially you could get very high yields back from it.

And finally, best for last!!! Use gyroscopes. As you move and change orientations, the highspeed gyroscope will rotate relative to you and if geared properly, it can directly spin a generator. I don't mean using the gyroscope's flywheel, i mean use the gyroscope's entire body to rotate a gear box to spin the generator. The gyroscope as a whole will only rotate around it's axis when you move. For this to work you will need zero friction bearings (they do exist), but it may still be an engineering challenge. Physically, it's pretty simple though, and simply converts your momentum to electricity. With a high wattage version of this system, your body WILL notice an increased difficulty in moving. Try taking a toy gyroscope spinning at 100,000 RPM... it's much harder to accelerate it!