Energy Scavenging

Thread Starter

TheComet

Joined Mar 11, 2013
88
This idea has been floating around in my head before, and sure enough, it's a pretty hot topic of study right now. Here's a small introduction to what it is.
http://www.gizmag.com/scavenging-ambient-electromagnetic-energy/19163/

My question is, what happens when a lot of these devices are being used? The stations that generate the signals powering scavenging devices would have to up their power output in order to reach the same range they do today, wouldn't they?

And from another perspective: This is a form of energy robbery. I wonder if there would be any legal implications with using scavenging devices?
 

Alec_t

Joined Sep 17, 2013
12,269
The article says:
It is expected that multi-band systems would generate one milliwatt or more, which is enough to operate small electronic devices, including a variety of sensors and microprocessors.
Anyone know of a micro which only consumes 1mW?
My question is, what happens when a lot of these devices are being used? The stations that generate the signals powering scavenging devices would have to up their power output in order to reach the same range they do today, wouldn't they?
I doubt it. The energy would be absorbed in the ground or elsewhere if it weren't scavenged.
 

Metalmann

Joined Dec 8, 2012
703
Then, there is this comment:



"Many years ago I discovered I could light up an LED by placing it behind a TV aerial in the loft of my parents house. Great I thought we could power all manner of things this way.


I was told when I researched it that there was a case of a man who had tried the very same thing and had been prosecuted for stealing electricity from the BBC. His antics had created a shadow of reduced signal behind his house and people had complained about no TV signal.


If it is possible to legally, scavenge EMR and turn it into a useable supply could I run some copper wire round the enclosure of the substation at the end of my garden and power the house from that, or put a load of TV aerials in the loft and light the house with LEDs?"


:confused:
 

THE_RB

Joined Feb 11, 2008
5,438
...
Anyone know of a micro which only consumes 1mW?
...
Most of the the 3.3v ones these days.

1mW on a typical low power 3.3v micro would be;
I = 0.001W/3.3v = 0.3mA.

Remember that only has to be an average, so even though some will run constantly on 0.3mA you could still run a 3mA micro just fine on 0.3mA if it sleeps for 90% of the time.
 

vk6zgo

Joined Jul 21, 2012
677
Yeah,& over in Sydney,a mate of mine has this really big bridge for sale, cheap.

He also sells building blocks on the Moon!:D
 

WBahn

Joined Mar 31, 2012
26,398
If you are scavenging truly parasitic energy, then you should have little to no effect on anyone else. Being able to scavenge enough energy to cause shadows is probably a pretty hard thing to do.

A number of remote sensors are intended to run off scavenged energy. There are small UAVs that have been demonstrated (perhaps even deployed by now) that can perch on or near a power line and use the alternating EM fields fields to recharge their cells. Now that is pretty much definitely stealing power, but it is lost in the noise.

Powering a seismic sensor that reports activity once an hour and powering your home entertainment system are two very different things.
 

tcmtech

Joined Nov 4, 2013
2,867
There are small UAVs that have been demonstrated (perhaps even deployed by now) that can perch on or near a power line and use the alternating EM fields fields to recharge their cells. Now that is pretty much definitely stealing power, but it is lost in the noise.
Not necessarily. If they are scavenging power from the coronal discharge that every HV power line emits its lost energy anyway.

BTW large HV power lines can lose several to tens of KWh's of power per mile just to coronal discharge.

In a way using that normally lost energy to do something useful, even if it is rather small, would be like your neighbor setting up a parabolic lens that is focused on a solar cell to steal power from your yard light at night. Yes it started out as your energy and yes he is doing something with it but if he didn't it was lost anyway. :rolleyes:

Lots of free normally wasted power to scavenge if you know how! ;)
 

Thread Starter

TheComet

Joined Mar 11, 2013
88
Anyone know of a micro which only consumes 1mW?
Sure!

MSP430L092 - Operates at 0.9V-1.5V, consumes 45uA/MHz active, and down to 3uA in idle. I'd assume this one would be ideal for scavenging applications, as the voltages levels you can reach when scavenging ambient radiation are extremely low.

I believe Microchip also recently brought out a series of MCUs that operate in the nanoamp to picoamp range. So yes, entirely possible.
 

Alec_t

Joined Sep 17, 2013
12,269
Thanks for the info on the micros. I guess actually using them would mean interfacing with I/O devices much greedier on power.
 
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