Energy Harvesting

[hek]

I've been thinking of how to do some energy harvesting like EnOcean is doing for powering sensors.

http://www.enocean.com/en/energy-harvesting/

Does anyone know if it is possible to get hold of modules for doing perpetuum - Thermo Energy Harvesting. Found this but can't download any datasheet.
http://www.perpetuum.com/pmg17.asp

[John]

This one?

http://www.perpetuum.com/resources/PMG17 Datasheet.pdf

[hek]

@John

Opps.. Clicked the other link.

The question is if it would give enough energy to power a sensor.

[Yveaux]

@hek Where do you want to stick this? It requires vibration of 100..120Hz.... Under your bed?
It's meant for industrial use. Any idea of the costs of such a module?

[John]

Well, 9 volts, with 1.0g vibration at 17Hz should theoretically give 45 Mw... Put it on your washing machine when setting to spin and it will work? (if i read the sheet right)

Well, would be more then 1g i think and too fast... It would work theoretically but it should be quite stable.. If you are for example in a windy environment and put it on a windmill and with the correct measurements it could support a battery setup where the battery is the backup or supply's where this thing ain't sufficient.

[Edit]
Wrong table, looked at the band
[/edit]

[hek]

@Yveaux

Ha, don't know if 120Hz would work under the bed... Should be more like 2 Hz harvester there.

This was just an example unit I found after a googling.. I wonder if there are more easily accessible units out there. For the DIY people!

[Yveaux]

@hek In principle a magnet & coil and some electronics would be enough to generate some current from vibration. Takes some tuning, but should work (even at 2Hz!)

Here's an interesting article & schematic: http://edn.com/design/analog/4327094/Harvest-energy-using-a-piezoelectric-buzzer
Using a piezo-electric buzzer to turn motion into a 3v3 power source, using a supercap for energy storage:

This look prototypeable!

Now I got excited! https://www.youtube.com/watch?v=uNKMD8Z3-e4

[hek]

@Yveaux

Seems really cool!

[John]

That would be cool to put on my sons bike on between two spoke cards, light AND sound!

But if you took the above as an example.. would it then be supporting batteries for example?

[korttoma]

Not sure what kind of application you had in mind but there is always the peltier element if you have something hot and a possibility to cool it on the other side. Tons of them on ebay.

Or why not a stirling generator -> http://www.instructables.com/id/Tin-Can-Stirling-Engine/

[John]

A little bit overkill for a temp sensor i think.

With those small harvesting things i think you will always end up with those industrial things. With those peltier elements you would need input for output, so not much harvesting there. Unless, you would live in a quite cold environment, stick one side to the window and the other side facing indoors for some temperature differences which then could be usable for supporting purposes. But i do not think enough for real powering unless you have some real low power sensors?

I don't have any knowledge about these kind of energy harvesting btw.

[daulagari]

Some recent news:

Combining OMRON’s electret energy harvester with a Holst Centre/imec power management IC, it can convert and store energy from vibrations in the μW range with high efficiency to the driving voltage of general sensors.

μW .. say 10 μW then with 3 V you have a current of 1 μA and if you believe Power saving techniques for microprocessors that should be possible in sleep with the watchdog disabled (0.1 μA) but not with the watchdog enabled (4 μA)

But .. just wondering why not using a battery? Is it because you think it saves energy?

The embodied energy used to produce these devices is for sure larger than they ever will generate, see the articles on http://www.lowtechmagazine.com or http://www.lowtechmagazine.be, for instance The ugly side of solar panels.

Is it fun? Yes! But do not foul yourself thinking this is saving energy.