• Wireless Device Converts 'Lost' Energy Into Electric Power
    23 replies, posted
[quote]Using inexpensive materials configured and tuned to capture microwave signals, researchers at Duke University's Pratt School of Engineering have designed a power-harvesting device with efficiency similar to that of modern solar panels. The device wirelessly converts the microwave signal to direct current voltage capable of recharging a cell phone battery or other small electronic device, according to a report appearing in the journal Applied Physics Letters in December 2013. It operates on a similar principle to solar panels, which convert light energy into electrical current. But this versatile energy harvester could be tuned to harvest the signal from other energy sources, including satellite signals, sound signals or Wi-Fi signals, the researchers say. [...] [B]They used a series of five fiberglass and copper energy conductors wired together on a circuit board to convert microwaves into 7.3V of electrical energy. By comparison, Universal Serial Bus (USB) chargers for small electronic devices provide about 5V of power.[/B] [...] "Our work demonstrates a simple and inexpensive approach to electromagnetic power harvesting," said Cummer. "The beauty of the design is that the basic building blocks are self-contained and additive. One can simply assemble more blocks to increase the scavenged power." For example, a series of power-harvesting blocks could be assembled to capture the signal from a known set of satellites passing overhead, the researchers explained. The small amount of energy generated from these signals might power a sensor network in a remote location such as a mountaintop or desert, allowing data collection for a long-term study that takes infrequent measurements. [/quote] [url]http://www.sciencedaily.com/releases/2013/11/131107154818.htm[/url]
[QUOTE]They used a series of five fiberglass and copper energy conductors wired together on a circuit board to convert microwaves into 7.3V of electrical energy. By comparison, Universal Serial Bus (USB) chargers for small electronic devices provide about 5V of power.[/QUOTE] This is extremely misleading, 7.3V means nothing if the current isn't useful as well. Like if it's producing 7.3V @ 2nA then this is absolutely useless, and I can't seem to find anywhere where it specifies the current
Well they said it could charge a phone. Does this mean I can soon charge my phone via connecting to WIFI? This would be awesome, but I'm not sure it's practical, how much energy is in wifi anyway?
[QUOTE=draugur;42816109]Well they said it could charge a phone. Does this mean I can soon charge my phone via connecting to WIFI? This would be awesome, but I'm not sure it's practical, how much energy is in wifi anyway?[/QUOTE] Marketing speak, man. Even if it takes 2 years to fully charge an iphone or something it's still technically "charging a phone" :v: Wouldn't trust for a second without a consumer demo
To clarify, draugur, if the voltage is sufficient then the phone will say it's being charged. Regardless of how quickly it's charging.
[QUOTE=Elspin;42816097]This is extremely misleading, 7.3V means nothing if the current isn't useful as well. Like if it's producing 7.3V @ 2nA then this is absolutely useless, and I can't seem to find anywhere where it specifies the current[/QUOTE] Thank you for clearing that up, Mr.Tesla.
I'm pretty sure I Saw something like this a year ago with a device that was a battery backup that harvested WiFi power, but it was incredibly inefficient taking well over a day of continuous WiFi signal to charge..... [editline]10th November 2013[/editline] ah the brake through is that is able to convert microwave to electricity at an efficiency of 36% and isn't made of exotic and hard to make stuff
[QUOTE=Elspin;42816097]This is extremely misleading, 7.3V means nothing if the current isn't useful as well. Like if it's producing 7.3V @ 2nA then this is absolutely useless, and I can't seem to find anywhere where it specifies the current[/QUOTE] I cringed a little at '7.3V of electrical energy'.
gotta love them volts. I can make a few kV with my hands, but it won't charge my phone.
[URL]http://dukespace.lib.duke.edu/dspace/bitstream/handle/10161/8006/1.4824473.pdf?sequence=1[/URL] (can scroll to bottom) 7.3 volts, 70-80 ohms, so what, ~0.1 amps? edit: If, I'm reading that right, this is what's going on: a total cell area of 2.48 sq inches is generating that kind of electricity from 900 Mhz radio waves at a power of 25 dBmW Is this good?
[QUOTE=Elspin;42816162]Marketing speak, man. Even if it takes 2 years to fully charge an iphone or something it's still technically "charging a phone" :v: Wouldn't trust for a second without a consumer demo[/QUOTE]I can see why your avatar is Tesla.
[QUOTE=Ltp0wer;42816830][URL]http://dukespace.lib.duke.edu/dspace/bitstream/handle/10161/8006/1.4824473.pdf?sequence=1[/URL] (can scroll to bottom) 7.3 volts, 70-80 ohms, so what, ~0.1 amps? edit: If, I'm reading that right, this is what's going on: a total cell area of 0.31 sq inches is generating that kind of electricity from 900 Mhz radio waves at a power of 25 dBmW Is this good?[/QUOTE] Not really possible to calculate an efficiency without the energy flux of the radio waves over an area.
Efficiency is going to be really poor no matter what you do, Wifi only transmits at a maximum of 20dBm (100mW) which is just enough to fully light a LED let alone change a phone, in practice the received power is going to be much much less unless you use a large array which is rather impractical for anything but use in remote locations. RF inductive charging is still many times better.
[QUOTE=Chryseus;42818581]Efficiency is going to be really poor no matter what you do, [B]Wifi only transmits at a maximum of 20dBm (100mW) which is just enough to fully light a LED let alone change a phone, in practice the received power is going to be much much less unless you use a large array[/B] which is rather impractical for anything but use in remote locations. RF inductive charging is still many times better.[/QUOTE] No, it's going to be much less no matter whatsoever. If you put the wifi transmitter into a cage which would turn the waves into electricity, the more effort and better encasing you would achieve, the closer you would get to the 100mW (which aren't jack shit) the wifi transmitter outputs, but then you run into a problem - you just completely shielded your wifi transmitter and it will be completely useless. This idea is practically useless because the amounts of "lost energy" in our signals is, firstly, negligible - our transmissions today are quite efficient and can work with quite low energy density, and secondly - if you captured back any amount of the energy you were using to carry the information of the transmission, you just killed the signal and the device that would have received it won't be able to anymore (in practice, the signal the receiver gets would be simply worse). This entire idea is moronic and it's actually more stupid than suggesting that we should put photovoltaic (solar) panels onto our devices and charge them indoors from the indoor lightning of buildings. [editline]10th November 2013[/editline] Or, better; I imagine the scientists did it in good faith and were fiddling with something fun and interesting which might have practical uses, but science journalists jumped onto it with "TOMORROW, YOU WILL BE RECHARGING YOUR PHONE USING YOUR WIFI"
[QUOTE=Elspin;42816097]This is extremely misleading, 7.3V means nothing if the current isn't useful as well. Like if it's producing 7.3V @ 2nA then this is absolutely useless, and I can't seem to find anywhere where it specifies the current[/QUOTE] No it's not exact numbers, but it seems to be capable of charging small electronics. Even if it is just marketing speak, it's supposed to be a proof of concept rather than a product. [quote]The device wirelessly converts the microwave signal to direct current voltage capable of recharging a cell phone battery or other small electronic device, according to a report appearing in the journal Applied Physics Letters in December 2013.[/quote]
I would want this to be embedded into smartphones and such, sure it won't actually recharge the phone on the fly. But it should be able to extend the battery a bit, and more battery time is always good.
[QUOTE=ace13;42819664]I would want this to be embedded into smartphones and such, sure it won't actually recharge the phone on the fly. But it should be able to extend the battery a bit, and more battery time is always good.[/QUOTE] It would cannibalize the signal the cellphone would both want to receive from the transmitters of the cell network and wifi spots as well as that it sends back, and worsen the signal quality, which actually increases the power required to keep a stable connection. Unless you shut your phone down and don't use it for a long periods of time, bad idea.
[QUOTE=Falubii;42819320]No it's not exact numbers, but it seems to be capable of charging small electronics. Even if it is just marketing speak, it's supposed to be a proof of concept rather than a product.[/QUOTE] Their actual test setup is bullshit though, the test is done inside a waveguide to minimize losses, the only way for it to be in the slightest bit useful would be using a transmitter able to deliver several hundred watts into a narrow waveguide which is pointless when you could just go use a solar or thermoelectric cell.
[QUOTE=Awesomecaek;42819964]It would cannibalize the signal the cellphone would both want to receive from the transmitters of the cell network and wifi spots as well as that it sends back, and worsen the signal quality, which actually increases the power required to keep a stable connection. Unless you shut your phone down and don't use it for a long periods of time, bad idea.[/QUOTE] Couldn't the thing that receives it and turns it into electricity also interpret it as a wifi signal?
Could be used as an idle charger for those that keep their phone off when not in use as a along term alternative to induction charging
[QUOTE=Map in a box;42820787]Could be used as an idle charger for those that keep their phone off when not in use as a along term alternative to induction charging[/QUOTE] Yeah, I can't wait until I can leave my device off and have it gained 1% by a month.
[QUOTE=Oscar Lima Echo;42821080]Yeah, I can't wait until I can leave my device off and have it gained 1% by a month.[/QUOTE] Honestly I am really sceptical about it beating the self-discharging rate of the battery.
[QUOTE=Awesomecaek;42821489]Honestly I am really sceptical about it beating the self-discharging rate of the battery.[/QUOTE] Not fucking happening.
[QUOTE=ace13;42819664]I would want this to be embedded into smartphones and such, sure it won't actually recharge the phone on the fly. But it should be able to extend the battery a bit, and more battery time is always good.[/QUOTE] Or instead of wasting all that weight on needlessly stupid components you could just put a bigger battery in it and get several orders of magnitude more of an increase in battery life.
Sorry, you need to Log In to post a reply to this thread.