What's the Buzz on Batteries?

What's the Buzz on Batteries?

To start with the report via BBC:

Researchers at the University of Bedfordshire have developed a new technique for powering electronic devices.

The system, developed by Prof Ben Allen at the Centre for Wireless Research, uses radio waves as power.

Believed to be a world first, the team claims it could eventually eliminate the need for conventional batteries.

The university has now filed a patent application to secure exclusive rights to the technique.

Prof Allen and his team, including David Jazani and Tahima Ajmal, have created a system to use medium wave frequencies to replace batteries in small everyday gadgets like clocks or remote controls.

The new technique uses the "waste" energy of radio waves and has been developed as part of the university's research into "power harvesting".

Prof Allen said that as radio waves have energy—like light waves, sound waves or wind waves—then in theory these waves could be used to create power.

"The emerging area of power harvesting technology promises to reduce our reliance on conventional batteries," he said.​

To the one, it seems like a really cool idea to my untrained eye. To the other, I'm almost reflexively dubious. My instinct is that the math—which most definitely transcends my comprehension—is going to be a contentious argument in this.

Is there literature beyond early news reports that will give us a better sense of how this works? Or is it one of those alleged breakthroughs that will prove, in a couple years' time, to be a pipe dream? Everything I've found so far seems to be some sort of news item.
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Notes:

British Broadcasting Corporation. "Researchers develop new system to 'eliminate' batteries". BBC News. February 11, 2012. BBC.co.uk. February 11, 2012. http://www.bbc.co.uk/news/uk-england-beds-bucks-herts-16869064

 

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Researchers have devised a new technique to use sound waves, opening the way for simple acoustic compressors, speedy chemical-process reactors, and clean electric-power generators.

Ever since electricity became a familiar part of everyday life, people have grown accustomed to the idea of getting the power for various mechanical tasks from unseen electromagnetic waves traveling through metal wires. Few, however, have witnessed the acoustic analogue of electromagnetism—sound waves, or pressure waves, propagating through gas-filled chambers—doing much in the way of useful work.

That situation may change, as a new way of packing large amounts of power into sound waves can now be used as a prime mover for a range of industrially significant processes. Over the past decade, Tim Lucas, an acoustician who is president and chief executive officer of MacroSonix Corp. in Richmond, Va., has developed a technique by which standing sound waves resonating in specially shaped closed cavities can be loaded with thousands of times more energy than was previously possible. For example, the new devices can generate dynamic (oscillating) pressures exceeding 500 pounds per square inch in gases, more than what is needed for commercial applications. "You've heard about researchers using sound to levitate Ping-Pong balls inside tubes," he said. "Our technology should allow us to levitate bowling balls with sound waves."

Lucas's wave-shaping technology is known as resonant macrosonic synthesis (RMS). With some clever engineering, he said, the elevated acoustic-energy levels produced using RMS can be tapped for a wide range of industrial applications, including simplified compressors, pumps, speedy chemical-process reactors, and clean electric-power generators. MacroSonix has already licensed the RMS technology to a large appliance manufacturer to develop acoustic compressors for home refrigerators and air conditioners.

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You could use the sound amplification to power a disruptor as well.

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The radio waves would need to be pretty intense to harvest for electric power...kinda like standing in a microwave which, as I recall, is pretty much a box full of electromagnetic radiation which heats water molecules.

Both appear entertaining at least.

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Such techniques absolutely work; they've been used to power remote monitoring equipment and data acquisition systems.

However the available ambient RF energy is in the microwatts for reasonably sized antennas, milliwatts for ideal cases (large antennas near access points or AM radio station transmitters for example.) Crystal radios are a classic example of this; with a large enough antenna they can capture enough energy to drive a speaker.

 

transmission of power by "radio waves" might be new but the concept has been around for many years.
nikola tesla was a pioneer in the technology.

the transmission of power by microwave is basically the same thing but at a much shorter wave length.

 

I wonder about the efficiency of such a technique.

Might there be advantages for electronic devices requiring very little energy, while the technology is not feasible for devices requiring more energy.

Consider a device which only needs 1-2 AAA batteries compared to a vacuum cleaner or a golf cart. Could such a technology replace my OPC power supply which provides power for 3 hard disks & a DVD/CD reader/burner?

Even if less efficient, there are obvious reliability advantages to a device which gets energy without relying of batteries which can run down at some some critical time.

 

Isnt this just the big brother version of induction charging? However I do see some problems with this, waste would be HUGE, range minimal (compared to batteries which can go anywhere) and there are potentual dangers in having this much EM radiation around you constantly.

 

Missing in this statement is the amount of energy he is talking about. While some transmitters do run at enormous power levels, enough to raise concern about an unspecified hazard to health, the idea that the spectrum is blasting out enough radiation to light up - what ? - the screens on our phones? Hah! Plug me in, Scotty, there's no intelligent renewable energy source down here!

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A typical power level at the input of a receiver might be, say, -65 dbm. Admittedly, that's my channel power, and who knows what kind of bandwidth he's integrating over. But here's what gets me about this. If that works so great, why not just collect all the cosmic noise that sits not too far below a weak signal? Yeah, that's what I'm talkin' about! To hell with Ma Bell spinoffs taking their share of the energy payola - I want mine straight from the batteries of God - yeah, it would truly be the electromagnetic version of milk and honey (and it's about damn time the Big Bang gave us something back for putting us in this predicament!)

All BS aside, here's a good technical question for the fun loving folks at Sci Forums, and the homework visitors, too: If I could capture ALL of the cosmic energy into my very efficient 1 or 2 inch antenna, how many Joules could I capture in ... 24 hrs.?

My guess is we're talking nanowatts.

I might seem to have wandered off point, but methinks this is the crux of the little beast that will make or break this ingenious new technology.

 

At the surface, with no other sources (like AM radio stations?) Cosmic background radiation (primarily microwave) is about 3uW/M^2. So for a 2 inch (.0025 square meter) antenna you might get around 7 nanowatts assuming near 100% conversion efficiency.

The only source that makes any sense for such devices is ambient light. Even inside an office with no windows you generally get about 4 watts/sq m, which means 10 milliwatts for a 100% efficient 2 inch square converter.

For a typical cellphone you'd need a panel about 10 inches by 10 inches to keep it charged indoors if the lights were on all day - again assuming 100% efficiency in the cells and no calls. For more reasonable cells you'd need a panel about 20 inches on a side. Doable but not all that portable.

Alternatively you could do it with a tiny panel with just a few hours of sun a day, or a slightly larger panel if you could get close to a window. Wouldn't even have to be direct sun; even a northern exposure gets you about 50 watts/sq m.

 

Well now you're headed where this was taking me. Even ambient light - and no doubt full sunlight - is so much more energetic than most ambient radio waves (post detection energy) - how is this guy pulling this off? Obviously he's exploiting bandwidth. I mean, 7 nW at, say, 3 GHz is a pittance, but if I also collect that much, say in 100kHz channels, and I have 10,000 of such collectors, that gets me all the way to...4 GHz? And now I've got 7 nW * 10k = a whole 70 uW to work with (ideally)? So he could get a little juice drawing from transmitters this way. But is he really packing 10K tuned collectors (or maybe more, whatever), and under practical conditions, what kind of antenna efficiency and losses will he actually see. That seems inordinately unlikely, just from trying to reach a ballpark estimate like this. I'm trying to imagine the power divider that splits his RF into thousands of collectors without loss. Probably he's doing something entirely different. I wonder what, though? I find it hard to believe he can compete with these tiny high density batteries that are so reliable. He will still need a battery anyway, since the minute Rover yawns, the change in path losses will eat up all of the in-band energy you were depending on.

Besides, I wouldn't count on something that exploits spectral pollution as a hopeful remedy to human impact on the environment! What would be really cool would be a solar collector that splits light with a prism, then gathers up all the available energy in each band. I assume that would require as yet unknown wavelength specific photovoltaics, and you still have optical losses. In other words, increase the effective bandwidth for a voltaic. I guess some form of this has been tried.

 

Those are called multi-junction cells. I think they've gotten to 42% efficiencies in the lab, and commercial (space grade) cells can get to the mid 30%'s.

 

So there's no working prototype and their dream is to power TV remotes & clocks- very low power devices with batteries replaced once a year at most.

They do admit this is something they've been doing in their spare time. I read that as 'no-one's convinced enough to pay them'

Given the maths in the above posts, the cynical side of me wonders if I'll next hear of this research via dodgy websites sending out D.I.Y. 'power your house for free' kits.

 

IMPO. . . . well-on-our-way to tapping/amplifying the Casimir Effect!!! . . . might also try a 'reverse Tesla coil' apparatus . . . one of N. Tesla's ideas.