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Focused Microwaves Could Enable Wireless Power Transfer
Posted by
Soulskill
on Fri Apr 25, 2008 06:33 PM
from the pushing-pinpoint-power-production dept.
from the pushing-pinpoint-power-production dept.
esocid alerts us to news out of the University of Michigan, where physics researchers have found a way to focus microwaves to a point 20 times smaller than their wavelength using a new 'superlens'. Such resolution was thought to be impossible until recent years, and it could bring about the capability to transfer power wirelessly.
"No matter how powerful a conventional lens, it cannot focus light down to more than about half its wavelength, the 'diffraction limit'. This limits the amount of data that can be stored on a CD, and the size of features on computer chips. The new lens is a 127-micrometer-thick plate of teflon and ceramic with a copper topping. 'The beauty of these is that they're planar,' Grbic says, 'they're easy to fabricate.' The lenses can be made through a single step of photolithography, the process used to etch computer chips."
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Ant colonies, beware! (Score:2, Funny)
Re:Ant colonies, beware! (Score:5, Funny)
Parent
Misleading title (Score:3, Insightful)
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Smaller rectennas. Higher efficiencies. Less land use for the receiving end. Lower cost as a result of all three.
Less power beam soaking into other things, too, which means you can find a receiving site closer to the load and shorten the transmission line.
Superlens = spillover = irradiation (Score:5, Informative)
Irradiation, perfect! (Score:4, Funny)
Parent
You may have forgotten... (Score:4, Informative)
Parent
Re: (Score:3, Funny)
No registration required (Score:3, Informative)
Here's what the diffraction pattern [sciencemag.org] looks like, quite impressive.
Here is their other paper [arxiv.org] (no registration required) on the design of these near-field focusing plates. The results are quite impressive indeed; there are no sidelobes or spillover to speak of. The concept to understand here is that the final radiation pattern is designed (it's the starting point, in the math), and the required focusing plate geometry is the result of solving the equations in the paper.
Doesn't anyone here get it? (Score:4, Interesting)
Parent
Never mind the power thing (Score:4, Funny)
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The feature size to be able to lens visible light will be much much smaller, and to lens x-rays, will be smaller still.
Since they are using photolithography to create these devices now, they are using a much shorter wavlength of light to make features that allow
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And in 10 years when the price of the media drops to the point of affordability, 5 terabytes will still be too small to back up your hard drive without using a hundred of them.... :-)
Nothing new here; still not a good idea (Score:4, Insightful)
Firstly, it's horribly inefficient. There are significant losses over the signal path that hand waving won't make go away. And then there's the real show-stopper: high power microwave beams would be a hazard to aviation, shipping, or anything or anyone else who got in the way.
There'd be enough scattering of the beam to spread the danger around. Sure, this technology is possible - but there just don't seem to be any practical applications for it. Wire is much more efficient and airmen have a chance to see and avoid it. They'd never know that microwave beam was there until they entered it.
Beaming power in from space is a perennial favorite - but nobody ever seems to be able to get around the atmospheric effects. And I'd prefer to not have any randomly scattered ionizing radiation impinging on my home, thanks.
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I've been fascinated with this topic ever since my "Gamma World" days, where broadcast power was used to provide energy to remote robots, computers, machine-gun emplacements, etc.
And, as for effeciency, I always thought a directed form of energy would avoid the incredible waste you'd find with a pure broadcast-type of power (which would probably decrease in strength proportional to the c
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Yeah, you're probably right. Maybe that's why I don't play Gamma World anymore
Re:Nothing new here; still not a good idea (Score:4, Informative)
Parent
Re:Nothing new here; still not a good idea (Score:4, Funny)
Wireless Extension Cords [thinkgeek.com]
Parent
Re: Not likely to happen (Score:3, Interesting)
Tags (Score:2)
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what's wrong with induction for wireless power?
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I'm still laughing at the image of holes in people's bodies. I certainly didn't miss the humor.
In other news... (Score:3, Funny)
Tesla (Score:3, Informative)
I just want to say: if you don't know or barely know something about this man, I really really recommend reading about him.
He's one of the greatest geniuses of the last few centuries. Called "The Father Of Physics" and "the man who invented the twentieth century".
Especially the latter is NO understatement. His list of inventions is huge and the combination of genius and being a workaholic (sleeping 3 hours per day) resulted in something over 700 patents on his name. He can even be related to over 1200 patents!
Although he is sadly barely mentioned in schoolbooks, he is the inventor of things like:
- The Inductor/AC motor
- The Tesla Coil
- The radio (a court ruled he was first, not Marconi!)
- The AND logical gate
- Wireless transfer of electricity
- Tesla turbines (bladeless turbines)
- X-ray tubes
- Robotics
- Fluorescent lamps
- VTOL aircraft!
- Polyphase systems
- Remote control; he had a remote controlled boat in 1898!
This list is NOT COMPLETE
See:
http://en.wikipedia.org/wiki/Nikola_Tesla [wikipedia.org]
And the really big bang is that it's very very likely that he managed to extract free energy from the vacuum/atmosphere.
Together with two other people, he has been riding a car for a week long... a silent car which had just an antenna system... reaching speeds in the order of 90 miles per hour.
He really was one of the most extraordinary persons to ever walk on this planet.
Sadly the problem was that, despite his genius, he was not a great business man. Money was always a problem and basically everyone (Edison, JP Morgan, etc.) tried to make money of this man who was so hard to make this a better world.
Now why is this man barely recognized for his achievements?
And why does he not have AT LEAST one Nobel Prize?!?
Interesting interview:
The Tesla Conspiracy: Mark DeMucha Part 1 of 11
http://www.youtube.com/watch?v=yzxvhA72vGI [youtube.com]
Re:We tried that (Score:5, Funny)
Parent
Actually it was a very GOOD idea but NASA blew it. (Score:5, Interesting)
Actually it was a very GOOD idea. But NASA blew it.
The plan was to site solar power satellites in geosync orbit and bring the power back via microwaves.
Unlike microwave ovens (which are tuned to a frequency that is strongly absorbed by water), these would be tuned to a frequency where water - clouds, rain, birds, cows, people - is essentially transparent. This is good both for getting the power through the atmosphere and avoiding rains of roast duck.
I could go into detail on why there's no problem from the millimeter waves, but that would take time. Short form: System failures defocus the beam so much it becomes just radio interference in directional antennas pointed at the satellites. Even when fully focussed it's not an issue for tissue: You can grow crops and graze cattle under the (rather spindly) rectennas, so they don't even use up the chunk of land they're on.
Benefits:
- Enough power to completely replace fossil fuel AND nuclear plants and absorb forseeable energy use expansion for decades.
- 'Way cheaper, too. (Even at '60s fuel prices.)
- Essentially no pollution at ground level.
- Bootstraps a space program that can then move other manufacturing processes, and THEIR pollution, off the planet as well.
NASA blew it by doing a study that purported to show it would be too expensive. But they did that by splitting the design teams for the rockets and the power plant. The power plant designers made a turbine very large to get a couple extra percent of efficiency. Then the rocket designers came up with a heavy lifter sized to take the biggest piece. Result: Enormous rockets with few trips to ammortize the design/construction costs, rather than moderate sized ones with many trips. Cost skyrockets versus a properly integrated design with a small turbine and a fleet of smaller lifters.
Parent
Re:Actually it was a very GOOD idea but NASA blew (Score:4, Insightful)
Actually, NASA's study got it exactly right. The amount of solar-collecting material you'd need to place into orbit is large enough that you'd spend a lot more energy and money getting it into orbit then you'd ever get back from it once it was functional. Things may have improved since then (more efficient rockets, lighter solar panels, etc), but I doubt they've improved so much as to make the plane feasible yet. I'd re-do the feasibility studies after the space elevator is up and working, getting enough mass into orbit will be a lot cheaper then
Parent
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In tha
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Benefits:
- Enough power to completely replace fossil fuel AND nuclear plants and absorb forseeable energy use expansion for decades.
- 'Way cheaper, too. (Even at '60s fuel prices.)
- Essentially no pollution at ground level.
- Bootstraps a space program that can then move other manufacturing processes, and THEIR pollution, off the planet as well.
I'd like to add another:
- Completely change the balance of power in the middle east by dropping a significant fraction of daily demand for oil.
Re:Actually it was a very GOOD idea but NASA blew (Score:5, Insightful)
* No exposure to the elements, thus reduced maintenance cost from wind/weeds/corrosion
* No land cost
* No clouds, no day/night cycle
* Cost is based on weight, not on land, potentially allowing for use of extremely large light cheap panels instead of smaller denser more expensive ones
Does it make up for the difference? I couldn't say. But there's four ways in which space beats land in terms of efficiency.
Parent
Re: (Score:3, Insightful)
First off, geosynchronous may or may not be a good idea. Geosynchronous orbit is painfully expensive, and in most cases it's far more cost-effective to launch a large number of low-orbit satellites. If receiver stations were placed in various locations, satellites could just lock on to a different receiver as they pass over the globe. (On top of this, it means that a lot of different countries could theoretically buy energy at various times from this - it might even be worth placing receiver
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My position is still that I, and most of the people in this thread, don't act
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I don't claim to be (though I did work on NASA projects and have some idea where I stand among the mind power of the rocket science community B-) ).
But I'm not talking from my own work. I'm summarizing what I heard from some of the braniacs who were paying attention to the problem.
Then you can certainly explain how 1300 watts per square meter and putting it...IN FUCKING OUTERSPACE...is better than 1000 watts per m^2 on the ground.
Well for starters:
Re:We tried that (Score:4, Interesting)
Parent
Re:We tried that (Score:5, Insightful)
Depends on how much the power is needed, and how soon. The space elevator seems like it's a long time away, still in need of new materials to be invented, and so on. On the other hand, solar power in space is feasible now, at least technically.
Without power people die. So the risks of catastrophic failure of microwave power transmission from space, must be weighted against the possibility of many people not getting electricity. It might be safer to build powerplants now, than to wait for a hypothetical space elevator.
Parent
Re:We tried that (Score:4, Funny)
Parent
Re:We tried that (Score:5, Interesting)
On the other hand, if you beam the energy down, you will have much lower losses provided the atmosphere is transparent at the wavelength you use to send the energy. All you will get from beam spread will be a lower energy density but the same total amount of energy (aside from absorption and scatter losses) will be available.
Beaming power down is probably a much more efficient way to go depending on conversion losses at the source, the scatter and absorption losses, and the conversion losses again at the receiver.
I don't know about the efficiencies and losses of beaming but would guess they would be much less than however many miles of cable would be required and would bet the cost would be lower as well.
You would just need to make damn sure you switch the beam off if it quits tracking the target receiver. Bu as the other person commented, I think this isn't intended to beam power from space.
Parent
Re:We tried that (Score:5, Informative)
Likewise, the IR drop is also just Ohm's law which equals voltage. The resistance will have some value per unit length and the longer the length, the more voltage drop.
The way to drop the current, so the I^2R (watts) losses can be reduced is to increase the voltage. But as you go to higher voltage, and higher altitude, where the air pressure starts getting low enough to support a plasma discharge, insulation starts getting important which just leads to more weight, etc.
Parent
Re: (Score:3, Interesting)
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I'm not sure solar power from orbit is going to be that good an idea as a primary world power source, at least until global warming is already largely solved. I may well be over simplifying things, but isn't the basic problem of global warming a matter of too much energy in the biosphere? How is adding more energy to the equation going to do anything but make it worse? I know that ideally it would replace hydrocar
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Beaming the power in, where some of it (depending on efficiencies in transmission and use) would be turned into heat energy, would actually release less energy into the biosphere than nuclear or fossil fuels where the inefficiencies in power production itself, since it occurs in the biosphere, release additional heat energy.
Re:We tried that (Score:4, Interesting)
To a certain extent, the effect will be the exact opposite of what you are thinking, as the sunlight would have most assuredly heated the land, sea and air, but beamed down to the electrical grid, it will be stored in other forms, such as the potential energy of a high-rise building, or in places where the increased warming isn't terribly important, like the area immediately around a ski lift.
Parent
Cutoff Point. (Score:4, Informative)
So if the energy efficiency of the panel/beam is greater than about 100%-37%-5% = 58%, then this system will result in more heat than would normally occur from the sunlight.
Of course, even if it does significantly increase the amount of heat generated for the fraction of sunlight that it captures, that is still a tiny fraction of the sky that is covered, and the net result will be completely negligible compared to just about anything else.
Parent
Re:We tried that (Score:4, Insightful)
No, the problem is that carbon dioxide is acting as a blanket, trapping too much heat beneath it.
How is adding more energy to the equation going to do anything but make it worse?
It's not a heat beam, it's a microwave beam. There's a big difference between the two. The amount of heat generated by the beam when it reaches the receiver would be insignificant, and it would generate no heat when going through the atmosphere, because the wavelength chosen would be one that is transparent with respect to air. So the net effect would be practically zero added heat. (Even if you count the heat generated by the motors powered by the resulting electricity, it's still insignificant compared to the heat trapped by CO2 in the atmosphere) And if we use that device to replace traditional fossil fuels, then its net effect would be a significant reduction in CO2 output.
There are good reasons why in-orbit solar power isn't a good idea at this time, but your reason isn't one of them.
Parent
Better than that. (Score:4, Insightful)
Actually, replacing ground-generated electricity with space solar power REDUCES the heat load.
First: Ground generated electricity is made with big heat engines, limited by the carnot cycle. In addition to the heat released by using the energy, there's the heat released on the cold side of the heat engine. The total is a lot more than you bought and used.
But with space solar power the cold side of the heat engine is in space, radiating toward the sky (with it's black body temperature of 4 degrees absolute). The dumped heat misses the earth. All you heat with is the useful power and a few percent losses. (The sky-to-ground system is estimated to run in the range of 90% efficient and only part of its losses are on the ground.
But far more significant: Fuel-driven ground generators release carbon dioxide, which continuously traps solar power as heat until it's eventually scrubbed from the atmosphere decades or centuries later. That is a big multiple of the useful power actually delivered. No fuel burned on Earth, no CO2 pumping the greenhouse.
The main problem will be keeping us from sliding into an ice age over the next 400 to 1,200 years. (According to one model the current interglacial peaked at about the dawn of agriculture and we've been essentially regulating the earth's temperature as the "furnace" output has been curving down for the last 6,000 years or so, with a slight bump since industrialization. Stop the CO2 and we'd quickly crash back onto the steepening slope of the cooling curve.) But that takes decades to centuries. So we can decide what to do about it in a few generations, when we start to get below the old "regulated" temperature.
One nice thing: If we need to bring in more heat from space we'll have the infrastructure to do it. B-)
Parent
Re: (Score:3, Insightful)
Of course - it doesn't have to be a desert, just a place where it's seldom cloudy.
The transmission losses using microwave to transfer energy may make that setup unpractical anyway. And there is the health issue too. What if a solar array turns the radiation to downtown Los Angeles or other major city? Time for the greatest Darwin Award in history?
Slight Problem? (Score:3, Funny)
The downside of this, obviously, is that if the beam is made twenty times smaller, you would only need a half mile array of collector
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