A German student has designed an energy harvester that derives energy from electromagnetic fields in the air to recharge small batteries and appliances. Dennis Siegel, who is studying digital media at the University of the Arts in Bremen, Germany, outlines the design of the harvester on his website.
As he explains it:
The omnipresence of electromagnetic fields is implied just by simple current flow. We are surrounded by electromagnetic fields, which we are producing for information transfer or as a byproduct. Many of those fields are very capacitive and can be harvested with coils and high frequency diodes.
Dennis Siegel has created an energy harvester that can be used to harvest ambient energy from electromagnetic fields in the air, such as those present near power lines, plugged-in electric appliances, or mobile phones. Siegel is studying digital design at the University of Bremen. (Source: Dennis Siegel)
To take advantage of this capability, Siegel built harvesting devices that can tap into several electromagnetic fields and harvest energy, which is then stored in a typical battery. As he continues on his website:
So you can for example gain redundant energy from the power supply of a coffee machine, a cell phone, or an overhead wire by holding the harvester directly into the electromagnetic field whose strength is indicated by a LED on the top of the harvester.
With the energy harvested, it’s possible to charge a small battery in just a day depending on the size of the electromagnetic field. "The system is meant to be an option for granting access to already existing but unheeded energy sources," Siegel writes. "By exploring these sources it can create a new awareness of the invisible electromagnetic spaces while giving them a spatial dimension."
If you think about it, Siegel’s concept is not such a complex one. Electronic devices, even when switched off, emit electricity if they’re plugged in, as do any other devices that use electricity to run.
Indeed, his website features photos of people holding up the device in various places where ambient energy would be present, such as in close proximity to a coffee machine, a power line, and someone speaking on a mobile device.
Siegel describes two types of harvesters that can be developed -- a small one for lower frequencies below 100Hz that are found in general mains (50/60Hz, 16,7Hz), and a bigger one that can be used to harvest energy from both lower and higher frequencies, like radio broadcast (~100MHz), GSM (900/1800MHz), or Bluetooth and WLAN (2,4GHz).
Energy harvesting is emerging as one way to provide alternative energy for small, battery-powered devices. Options for harvesting are being explored for medical devices, small home appliances like smoke alarms, and a number of other applications.
Companies also are investing products that promote energy harvesting, such as Texas Instruments’ new low-power converter and a low-power circuit from Dutch startup Anagear that harvests energy to provide more efficient power management.
You're welcome, notarboca. I'm quite frankly surprised by the level of comment I've received on this one. You never know as a writer what is going to provoke a response, and there are opinions and angles to this story that people have posed that I have never thought of. Thanks for reading.
If you disrupt the broadcast RF or decrease the coverage area (e.g. by using a very large antenna or array), they might have a case against you. But it would be much harder for the provider to detect the loss, if you are a distance from the transmitter.
However, it is impractical to use RF energy transmitted at a distance. Transmitted EM waves follow the Inverse Square Law (http://en.wikipedia.org/wiki/Inverse-square_law) which states that the power density of an electromagnetic wave is proportional to the inverse of the square of the distance from a point source.
The power is reduced in proportion to the square of the distance to the source. i.e. - If you double the distance to a source, you will only have 1/4 of the power (you lose 3/4 of the power).
Power is monitored at substations or below, so there are not millions of killowatts being sensed. If he was stealing enough to power his entire house, they would detect the loss.
The first electric Co-ops were formed in rural areas like Oklahoma when neighbors would pay to run power lines between themselves and a nearby distribution line. The electric companies didn't want to power scattered rural homes because they would never get a return on the line investment. Even when the small communities ran their own lines, the power companies didn't want to hook them up and become liable for their distribution.
To force the issue, the co-ops would put poles next to the electric company's line for a distance and parasitically power their homes.
The EM field of conductors is NOT wasted energy and any EE should know that. It is simply the result of passing current through the conductor. Sheilding is not an option when considering the massive currents involved in power distribution.
You can use these devices all you want behind YOUR power meter where you get charged for the energy you consume. But using power you are not being charged for, plus causing additional distribution loses to the provider (find your own EE to explain); is increasing the provider's costs and decreasing the available energy to legitimate customers. IT IS THEFT! period!
Now I like this idea, shehan. If they don't like the idea of other people doing it, they should set up harvesters themselves...that way no precious energy is lost. We could perhaps solve the energy crisis this way. What a good idea.
There is still a basic misunderstanding of how transformers work. If we consider a perfect transformer with no load on it, there is only the initial surge as the first magnetic field builds up. Then the voltage is transferred to the secondary almost simultaneously. When the field collapses, the current used is put back into the system. This goes on at 50 or 60 Hz and no energy is consumed. The power company could do this all day and only have to pay for the generator's friction losses. It would see no drain on their system- no LOAD, we say. They would make no money, and they would lose no money, other than the friction losses, payment on the building, maintenance of the equipment, payroll, taxes, fuel, and payoffs to government officials.
But if Mr. Farmer comes along and runs a wire (a secondary, not primary), then when current flows through the voltage buildup in his home-made, extremely inefficient secondary copper skeleton key, the generator would know it, as the collapsing field no longer gives him his current back. There is a loss. There is a consuming of the power. But all his other bills go on with an increase in fuel costs and maintenance costs.
There, I hope that clears things up a bit. Power generation is only as expensive as the load on the system, minus the losses and bribes.
The farmer's setup was expensive because of the cost of the miles of highly insulated copper wire he had to run multiple times around the perimeter of his lot. It operated as the primary winding of a transformer and worked because one side of his lot was close to the high voltage wires and the rest was further away. It was extremely inefficient because this transformer's core was made of air.
@jhankwitz – I wonder why the farmers setup was expensive, are these large devices (large transformers) ? How could it be more efficient, did it have any problems with the functionality?
@Elizabeth - Thanks, I think collecting / harvesting this energy is not a crime. If not harvesting is a chime and a waste. At least the electricity companies need to set up stations to harvest this energy.
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