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Thread: Harvesting energy... from the air!

  1. #1
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    Default Harvesting energy... from the air!

    We capture energy from wind, and from solar.... but there's another source of energy available absolutely EVERYWHERE:

    RF energy. We are bombarded by it, constantly: radio and TV transmissions, cell phones and cell towers, virtually any sort of RF communications.

    How much energy? Well... not a lot.. but then again, the energy requirements of many things we use these days are getting lower, and lower. What used to consume milliamps of current, now require microamps... and it's getting lower, all the time.

    In my career as a circuit design specialist, I've seen the power requirements for electronic components go down radically. 30 years ago, an operational amplifier might consume several milliamps of current, and require voltages in the 10-30 volt range.... but nowadays, an op amp with superior performance might require only a microamp or two, and at voltages below 5 volts, to operate. A colleague and mentor of mine designs accelerometers, portions of which can operate on pico-amps!

    Consider, for example, the key fob of your recent automobile. It operates on a single 3 volt lithium cell, radiating enough power to unlock or start your car, several times a day... and the battery can last 5 years or longer. The RF power it generates is miniscule, but it only needs to generate it for a few milliseconds.

    Wouldn't it be great if the thing didn't really need a battery at all... but just a supercapacitor, to store small amounts of charge derived from rectifying ambient RF, until needed?

    No, we're not going to light up a flashlight that way... but increasingly, we're seeing devices operating with lower and lower power requirements. The kinds of microprocessors I currently use, in circuit design, can operate at MHz speeds on just a few microamps... so devices using these parts don't need a great deal of power.

    For the technically inclined: https://www.allaboutcircuits.com/tec...b2c-278616029/
    "Reason and facts are sacrificed to opinion and myth. Demonstrable falsehoods are circulated and recycled as fact. Narrow minded opinion refuses to be subjected to thought and analysis. Too many now subject events to a prefabricated set of interpretations, usually provided by a biased media source. The myth is more comfortable than the often difficult search for truth."







  2. #2
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    Default Re: Harvesting energy... from the air!

    Cool.

    We see that at work all the time. Often, they'll hook up some simple antennas to "sniff" for signal or leakage. Levels of power detected are very low - micro- or milli-watt levels, but amazingly broadband, and amazingly consistent. I'm sure the guys in the article have really worked hard to optimize the antennas. IEEE had an article about it a while back, but don't recall much about it.

    Frankly, I'm waiting for someone to design a cell phone that will be able to harness it's power from "wild RF" so that you never need to plug it in to charge it. Display technology will likely have to become much more efficient (e-ink displays or the like) before this becomes practical.
    "The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails."
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  3. #3
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    Default Re: Harvesting energy... from the air!

    Quote Originally Posted by Canoez View Post
    Frankly, I'm waiting for someone to design a cell phone that will be able to harness it's power from "wild RF" so that you never need to plug it in to charge it. Display technology will likely have to become much more efficient (e-ink displays or the like) before this becomes practical.
    Yeah, e-ink solves THAT problem, although I'm not sure that too many people would be thrilled to have a black and white cell phone screen without a backlight.

    I don't think that display technology is really the problem, though. The power consumption of a static LCD screen is pretty minimal... just whatever it takes to charge the parasitic capacitances while the LCD 'bits' are being refreshed. It's the computing power that is the real killer, especially with all the compute-intensive apps these days.

    More likely, the initial use of 'harvested RF' would be things that are extremely low power to begin with... or things used only very intermittently. An example: the garage door opener in your car, which is typically used only once or twice a day, for mere milliseconds, and has nearly 24 hours to accumulate enough charge in a supercapacitor, to open or close the garage.
    "Reason and facts are sacrificed to opinion and myth. Demonstrable falsehoods are circulated and recycled as fact. Narrow minded opinion refuses to be subjected to thought and analysis. Too many now subject events to a prefabricated set of interpretations, usually provided by a biased media source. The myth is more comfortable than the often difficult search for truth."







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    Default Re: Harvesting energy... from the air!

    Shades of Nikolai Tesla
    "Rudeness is the weak man's imitation of Strength"

    -Edmund Burke

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    Default Re: Harvesting energy... from the air!

    Oh great, just what we need. Solar energy is already draining the sun and will make it dimmer as more and more solar panels are deployed. Wind energy is using up the wind and making it weaker. Now you want to use up all of the RF stuff. How are radios and cell phones going to operate in the future if all of the RF is used up?

    Crazy engineer! Just because we CAN do something doesn't mean we should!






























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    Default Re: Harvesting energy... from the air!

    Quote Originally Posted by BrianY View Post
    Oh great, just what we need. Solar energy is already draining the sun and will make it dimmer as more and more solar panels are deployed. Wind energy is using up the wind and making it weaker. Now you want to use up all of the RF stuff. How are radios and cell phones going to operate in the future if all of the RF is used up?

    Crazy engineer! Just because we CAN do something doesn't mean we should!


    Now consider this: the local broadcast radio station transmits with a power of 50,000 watts... but the amount of that power received by even 100,000 or more listeners, sufficient for a clear reception, is maybe 1 watt, total.... the rest of that 50,000 watts is radiated into space, unused!
    "Reason and facts are sacrificed to opinion and myth. Demonstrable falsehoods are circulated and recycled as fact. Narrow minded opinion refuses to be subjected to thought and analysis. Too many now subject events to a prefabricated set of interpretations, usually provided by a biased media source. The myth is more comfortable than the often difficult search for truth."







  7. #7
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    Default Re: Harvesting energy... from the air!

    Quote Originally Posted by BrianY View Post
    Oh great, just what we need. Solar energy is already draining the sun and will make it dimmer as more and more solar panels are deployed. Wind energy is using up the wind and making it weaker. Now you want to use up all of the RF stuff. How are radios and cell phones going to operate in the future if all of the RF is used up? Crazy engineer! Just because we CAN do something doesn't mean we should!
    Damn yer eyes, now I got tea up my nose.
    "For a successful technology, reality must take precedence over public relations,
    for nature cannot be fooled."

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    Default Re: Harvesting energy... from the air!

    The funny thing is that enough solar panels will dim the sun enough that globl warming stops. Wind turbines will eventually take enough wind so that there are no more hurricnes and tornadoes. LMAO!
    Will

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    Default Re: Harvesting energy... from the air!

    Quote Originally Posted by Norman Bernstein View Post


    Now consider this: the local broadcast radio station transmits with a power of 50,000 watts... but the amount of that power received by even 100,000 or more listeners, sufficient for a clear reception, is maybe 1 watt, total.... the rest of that 50,000 watts is radiated into space, unused!
    Well, that power's not wasted. If my 100W microwave can boil water in 1 minute, think of how much heat a 50,000 watt radio station can generate! All that unused power is heating up space so that in the long run it will make it a lot warmer out there so our brave SPACE FORCETM soldiers will not have to wear thick space suits when they're fighting for our freedom.
    I rather be American than a Republican.

  10. #10
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    Default Re: Harvesting energy... from the air!

    Man, if you want innovation, come to the Bilge!
    Well, Mr. Botard, do you still deny all rhinocerotic evidence?

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