German Student Creates Device That Harvests Energy From Air
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)
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.
@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.
@warren – I wonder how the farmer got caught, as you said we are talking of millions of kilowatts. I think it was the word of mouth or someone might have seen wires connected to the towers from his house.
Maine-Bob, the graveyards are full of people whose gravestones should have read, "Nope. That didn't work!"
I was driving on I-8 in San Diego one evening and saw a man on the high voltage platform next to the freeway. Then I saw a flash of fire and he was burning! He was drunk and decided to climb the tower. He survived. "Here's yur sign..."
One million volts DC! Imagine! So with a dry-air dielectric breakdown of 35KV per inch, a million volts would require a minimum of 28" for dry air, quadruple that at least for moist air (once an ionized trail starts, avalanche breakdown will soon follow. I think I'd rather buy a battery charger. People trying to steal by making any kind of contact with a million volt DC power line would immediately qualify for a Darwin award.
Very clever, Mainly Bob. I didn't think about sending other signals over the line to find losses.
They switched to DC for a number of reasons, not the least of which are skin-effect losses. I understand they run to 1,000,000 volts on these lines. That would make it harder to steal by transformer effect.
However, if you were really stupid, had a really long pole, a bunch of voltage-drop high-voltage resistors, and I repeat really stupid, you could possibly drop the voltage enough to light a small lamp for free.
@warren; Helicopters and aircraft overfly power lines fairly frequently, they can measure the strength of the electric field and notice 'dips' where the field is interracting with something. Also sending/receiving FM signals over the power lines allow power companies to locate loss. Power companies lose a siginificant amount of power through parasitic inductive loss. The national grid loss is dramatic. I've read that some power lines have changed to DC to reduce this loss.
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