Technology Electricity from Radio Waves

[Debi]

New tech turns radio waves in to electricity - Unexplained Mysteries

A new energy harvesting technology is capable of powering a device from ambient radio frequency waves.
Known as 'Freevolt', the system was revealed by former British science minister Lord Paul Drayson in the same theater in which Michael Faraday originally delivered his lectures in the 19th century.

By using a multi-band antenna and rectifier ( a battery capable of turning alternating current in to direct current ), the mechanism can absorb energy from several different radio frequency bands and then use it to charge up low-power electronic devices.

"Companies have been researching how to harvest energy from Wi-Fi, cellular and broadcast networks for many years," said Drayson. "But it is difficult because there is only a small amount of energy to harvest."

To demonstrate the technology Drayson set up a loudspeaker in the lecture hall and then used the radio wave energy harnessed from the mobile phones in the audience to power it up.

"The idea isn't too far-fetched - and I'm sure it'll be improved," said antenna technology expert Professor John Batchelor from the University of Kent.

Whether we will ever see a future in which our electronic devices can be charged up without having to be plugged in to an electrical outlet however remains to be seen.
_____________________________________________________________________

Very cool technology here....

 

[CapinCooke]

Interesting science experiment. But like the last sentence of the article states; "...it remains to be seen.". Harvesting meaningful POWER from the airwaves of devices not designed to transmit meaningful power might be a "something for nothing" scenario. If your WiFi router at home is powered by a "Wall-Wart" and transmits ~ 100 milliwatts (It varies, don't ask ) of RF into the airwaves (one TENTH of a single watt) and you stood right at the transmitting antenna with your power "grabber" you MIGHT get one tenth of THAT, or one HUNDREDTH of a single watt.

Maybe.

Across the room? Maybe one THOUSANDTH of a single watt.

Maybe.

Across the state? Well, radio receivers can work with a fraction of a millionth of a volt at a millionth of an amp. Lets round that UP a couple of decimal places and call it a BILLIONTH of a single watt.

You just can't do anything POWERful with that. Receive information with a radio receiver (that consumes power to operate)? Sure! Power up your TV, or even your cell phone? Not so much.

* * * * * * * * * * *
Now a cell phone itself puts out 10x to 100x (approx. It varies too. Don't ask ) the RF power of a WiFi router. In an auditorium full of students (500?) with cell phones (some transmitting, some not) you might grab 1,000x the power out of the airwaves compared to grabbing power from a single WiFi router.

Maybe.

Be generous and call it call it one full watt! You can run a small amplified speaker with that. Light up some LEDs even. But remember that you have 500(?) cell phones transmitting to make ONE "device" do something.

* * * * * * * * * * *
The math changes somewhat with a purpose built powerful transmitter putting THOUSANDS of watts "into the air" with a purpose built "power receiver" and directional (High-gain) antennas on both ends.

I'd suspect tens of watts across the room is possible, if you are willing to "burn" thousands of watts to DO that. Pretty inefficient, but possible.
* * * * * * * * * * *
Our old buddy Mr. Tesla claims to have transmitted THOUSAND watts of power over a distance of miles from his laboratory in Colorado. He burned out the power station in Colorado Springs DOING that, but, still... Other observers say much much less. A few light bulb's worth, maybe. But still, Tesla was successful at some level.

PBS: Tesla - Master of Lightning: Colorado Springs

* * * * * * * * * * *
This idea has been around for a long time. Some commercial, short range, products are in existence now. But there is LOTS of work needed to make the technology viable at a large scale over a large distance... If ever...

I remain curious, interested and (currently) skeptical of this technology.

 

[Debi]

Interesting science experiment. But like the last sentence of the article states; "...it remains to be seen.". Harvesting meaningful POWER from the airwaves of devices not designed to transmit meaningful power might be a "something for nothing" scenario. If your WiFi router at home is powered by a "Wall-Wart" and transmits ~ 100 milliwatts (It varies, don't ask ) of RF into the airwaves (one TENTH of a single watt) and you stood right at the transmitting antenna with your power "grabber" you MIGHT get one tenth of THAT, or one HUNDREDTH of a single watt.

Maybe.

Across the room? Maybe one THOUSANDTH of a single watt.

Maybe.

Across the state? Well, radio receivers can work with a fraction of a millionth of a volt at a millionth of an amp. Lets round that UP a couple of decimal places and call it a BILLIONTH of a single watt.

You just can't do anything POWERful with that. Receive information with a radio receiver (that consumes power to operate)? Sure! Power up your TV, or even your cell phone? Not so much.

* * * * * * * * * * *
Now a cell phone itself puts out 10x to 100x (approx. It varies too. Don't ask ) the RF power of a WiFi router. In an auditorium full of students (500?) with cell phones (some transmitting, some not) you might grab 1,000x the power out of the airwaves compared to grabbing power from a single WiFi router.

Maybe.

Be generous and call it call it one full watt! You can run a small amplified speaker with that. Light up some LEDs even. But remember that you have 500(?) cell phones transmitting to make ONE "device" do something.

* * * * * * * * * * *
The math changes somewhat with a purpose built powerful transmitter putting THOUSANDS of watts "into the air" with a purpose built "power receiver" and directional (High-gain) antennas on both ends.

I'd suspect tens of watts across the room is possible, if you are willing to "burn" thousands of watts to DO that. Pretty inefficient, but possible.
* * * * * * * * * * *
Our old buddy Mr. Tesla claims to have transmitted THOUSAND watts of power over a distance of miles from his laboratory in Colorado. He burned out the power station in Colorado Springs DOING that, but, still... Other observers say much much less. A few light bulb's worth, maybe. But still successful at some level.

PBS: Tesla - Master of Lightning: Colorado Springs

* * * * * * * * * * *
This idea has been around for a long time. Some commercial, short range, products are in existence now. But there is LOTS of work needed to make the technology viable at a large scale over a large distance... If ever...

I remain curious, interested and (currently) skeptical of this technology.

Thanks for that perspective and information, Capin. The techie world continues to be my weak point, and that made a lot of sense for me.