You sure about that? The ones they use here in Texas (and in Oklahoma) are not RF-powered, but instead have a very-low-power consumption circuit which can vary its reflectance, therefore modulating the RF received back at the base (see http://www.amtech.com/technology/techapps.htm ). I believe that the internal workings are powered by a long-life battery.
Please, let’s not get confused with using RF energy to transmit information vs. using RF energy for the sole purpose of transmitting power.
Regarding the link… I’m going to go off on a limb and say this the stupidest thing I’ve ever heard of. Has anyone performed a complete system efficiency analysis of this idea?
I want to know:
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The total amount of energy (in watts) expended to manufacture the satellites. This will include the energy expended during all phases – R&D, design, testing, prototyping, and manufacturing.
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The energy expended getting the satellites into orbit. This will include energy expended to manufacture “one time use” hardware, and (obviously) fuel.
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Amount of solar energy collected.
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Efficiency of converting solar energy to laser or microwave energy (onboard the satellite).
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Efficiency of converting laser or microwave energy to electrical energy (on the ground).
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Projected lifetime of satellites.
After you take all these things into account, I am extremely confident you will find that much, much, much more energy will be expend that whatever energy you might get out of it.
Pure stupidity…
THe new tablet PCs rely on the base station briefly charging the capacitor on the pen to write. This means you can move the mouse while the pen is 5cm off the tablet and also never run out of batteries. Pretty cool IMHO.
There’s also new watch (I forget the brand) that recharges it batterries on a base station while never having physical contact between the battery and station…I think. It’s simialr to the tablet PC thing Shalmanese talked about.
That’s 0.5cm, and the “base station” is the tablet itself. I get to play with these at work. It would be really annoying if the mouse had to move 5 cm off the tablet to stop tracking.
The answer is in the quoted article, namely:
Nobody is claiming that solar power satellites are cost-effective with current technology. It’s viewed as an idea that’s potentially useful and worth investing some R&D money on.
Since the OP asks specifically about thin air, it’s worth noting that the thinner the air, the closer to “no” the answer is. Until you arrive at a vacuum, where we get an unqualified NO as the answer.
What?
You got it backwards. The thinner the air, the easier it is for arcs to jump, until you have a vacuum, when it becomes the easiest.
Attrayant, please share with us your definition of electricity, so we can make sense of you post.
I had an electric toothbrush that charged with no metal contacts between the toothbrush and the base station. It would even work about 1/2" above the base station.
Attrayant and Urban Ranger are both partially correct. When you lower pressure from one atmosphere, it becomes easier to create an arc because ionized molecules can move more freely. But beyond a certain point, you start to run out of molecules that can be ionized, and without them you can’t have an arc. So it becomes harder and harder to create an arc.
Moderately high voltage (a few thousand volts) is usually safe to use above 0.2 atmospheres or so, or below 10[sup]-8[/sup] atmospheres, but not in between. This of course depends on the size of the smallest gap, but that’s my rough rule of thumb working with typical laboratory equipment. If you want more details do a search for “Paschen Curve” which describes this relationship.
Just to clarify, “safe to use” in my case means no arc is produced. An arc is essentially a short circuit, and if it happens on a sensitive equipment it can cause severe damage. I’ve seen a very expensive detector destroyed by an arc because some gas leaked into the vacuum chamber where a 10[sup]-9[/sup] atmosphere had been maintained.
I don’t know about the others but I’m not confused. Power is transmitted and power is received in radio transmissions.
Quite sure. There are several different types. There are some that have a permenant long life battery, others that have a battery that you can change, and there are also beam powered ones as well.
From this site: http://www.dragg.net/users/romanj/info/state/rail/aeistandard-technology.html
The beam powered tags are a good example of what the OP is looking for, an instance where equipment is actually powered from transmitted power. The source of power for all of the active components in a radio or television receiver is the wall outlet, not the receiving antenna.