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Focused Microwaves Could Enable Wireless Power Transfer
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."
What is it with geeks and magnifying glasses?
The little guy just ain't getting it, is he?
I know what you mean, messing with wireless power is a seriously bad idea. Tesla tried it too, and look what happened to him. He's DEAD!
Sendou Wave Kick!!
While it's nifty that they can focus EM radiation to a smaller point now, I'm not following how this will enable wireless power transfer.
What I remember from studying this technology 15 years ago was that it was possible to create a beam sharper than the diffraction limit, but the result was diffuse spill-over. That is, one could create an extremely sharp main lobe in the beam pattern, but one had to suffer higher side-lobes. That's OK for imaging and lithography applications -- the spill-over is diffuse enough not to cause too many problems. But for power applications it means both inefficiency (power lost to the side lobes) and irradiation for people who think they aren't in the beam.
Two wrongs don't make a right, but three lefts do.
If the limits on a CD are because of conventional lenses, and this can get 10 times the best a lens can do, it follows that a superlens-based CD, DVD or Blu-Ray system could get 10 times the capacity per track and 10 times as many tracks (in other words, 100 times the capacity). That would be some serious storage space.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
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It's interesting to consider whether power beamed down from orbit even has much of a future. If space elevators ever become a reality, it seems much safer just to have power from orbital solar arrays wired back down the elevator than beam it, where anything passing through could be fried.
Current proposed methods for space-based power transmission mean you need a several mile wide area to collect the energy. OTOH, it would be fairly safe. Like a day at the beach. You might get a sunburn but not much else unless you lived right in the path of the beam. And any hard surface, glass, or sunblock would negate almost all of it. But you need a really large area.
The downside of this, obviously, is that if the beam is made twenty times smaller, you would only need a half mile array of collectors, but anything caught underneath it would be fried in a few minutes. (do the math - 20x smaller is several orders of magnitude more powerful - like using a magnifying glass pointed at the sun at half an inch diameter versus a small dot)
Let's hope the aim never gets off.
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.
Back in the 1960's. Diode grid to rectify the beamed power. Bad idea.
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.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
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.
The issue with wires is that you will have IR drop and I^2R power losses. If you make the wires thicker to cut the resistance and losses, you have now made the wires heavier. Plus, you have to somehow support the weight of all that wire which means the tensile strength must be huge.
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.
Didn't we try this in Sim City? Look how well that worked out.
I don't see how it is that different from burning carbon-based fuels or running nuclear power plants. Both of those release heat energy back into the atmosphere/biosphere as well.
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.
The energy in question is coming from the sun, and was going to enter the biosphere anyway.
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.
I don't know if he's correct, but even a small amount of thought should show you a lot of possible ways.
* 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.
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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
I don't care if it's 90,000 hectares. That lake was not my doing.
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.
I don't care if it's 90,000 hectares. That lake was not my doing.
I've had wireless wireless extension cords for YEARS. I can't believe you guys think this is new, here's the site i got mine from. BTW they work great! Wireless extension cords
Three points. :)
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 stations in third-world countries, since it's not like the power would be doing anything useful if it wasn't getting sold.)
Second, space is really really big. Even with the space junk we have up there already, impacts are spectacularly rare. It's a factor, but it's not a huge factor.
Third, why fix the broken panels? I highly suspect it would turn out to be cheaper to simply launch more satellites, at least until we have some kind of orbital repair bots. As long as the core electronics are reasonably redundant, the thing can stay up there as long as it's got a single working panel.
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Actually, wire losses fall off as 1/e^(decay*r); it's free space where losses go as 1/r^2 when you get to the antennas' far field, but your overall point is still valid.
For *any* wire, even if it was made out of a really good conductor like gold, there is always some distance where the losses become greater than that of wireless transmission at the same distance.
Are you serious? You're smarter than a Nasa study?
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:
- No clouds, rain, or snow.
- No atmospheric attenuation.
- No night.
- No seasons. ("It's always noon on midsummer's day.")
Those are good for about a factor of seven (depending on the earthbound site you're comparing).
More importantly:
- No gravity (except tides).
- No wind (except solar wind).
- No oxidizing atmosphere.
- No corroding water and waterborne ions.
This enormously reduces the structures required.
That would be an enormous reduction in the amount of material needed to make and mount solar panels. Most of their structure is to protect them from the elements and support them against gravity and wind.
But we're not talking photovoltaic solar panels here. We're talking a steam plant, with the steam generated in pipes and mirrors and condensed by pipes with black cooling fins in the mirrors' shade.
With no gravity, wind, and the like, building square miles of parabolic-cylinder solar mirrors is trivial. Making them of aluminized mylar "spaceblanket" material supported by glued-together toothpicks and cobwebs would be a massive overdesign. Virtually all of your mass is the boiler and condenser pipes and the wisp of structure that keeps them straight and properly arranged and oriented as they heat and cool unevenly.
Now it might prove even better to build some film solar panels - especially if you're doing it in space by vacuum deposition of films on some flimsy substrate with an unlimited supply of hard vacuum for free. But sending up bundles of pipe, rolls of wispy plastic, and a flimsy support structure to expand in space. wrap with the mirror film, and aluminize once it's in place is a well understood and (as space stuff goes) inexpensive process.
The power plant is a moderately small lump of machinery suitable for assembling in orbit and charging with a small amount of water.
The transmitter array gets deployed much like the mirrors - but more simply. (It doesn't have to be accurately, or even consistently, spaced. The transmitters are synchronized and the array is focussed by a pilot beam from the ground site, computing the complex-conjugate of the incoming carrier's waveform to focus the beam on the antenna surrounding the pilot transmitter. Lose the pilot and they go incoherent - spreading the energy about equally through the surrounding sky, of which the entire facing side of Earth is a small fraction. (And you can modulate the pilot with an encrypted spectrum-spreader so nobody can steal the power or redirect it to another target.)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
... replacing our entire energy consumption with external sources only increases the energy flux striking the Earth by about 0.01%.
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-)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
What I was referring to was current squared times resistance which equals power. The R was resistance and not radius. V = I * R, and W = I * V. Therefore, W = I * I * R.
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.
Here is their other paper (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.
So. What about beaming it down the elevator umbilical cord, using optic fibre?
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.
Don't forget military vulnerability. If your entire power supply is based on things that are really far away in space, you'll have a hell of a time protecting them from sabotage or outright war. In fact, in case of war, you'll need to have some kind of back-up power source that you can use to power your country for at least a few years, until you either lose and get taken over (in which case it's now someone else's problem) or the war ends peacefully and you can shoot another transmitter into space.
In that case, you have to decide which kind of terrestrial power to choose: coal, oil, solar, gas, wind, nuclear--all of which have their drawbacks. So, to an extent, you're back at square one.
Not just Tesla, think of all those poor birds, when they land on these wires it's instant fried sparrow.
Sorry about the writing. Robot fingers, you know? Cliff Steele in DOOM PATROL #23
He didn't say "died".
I make websites and stuff. Buy one.
Belden http://www.belden.com/ is selling wire.
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?
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
It's a factor because of transmission costs and because of the availability of good land for this. Good land for solar panels tends to be good land for other things as well, unless it's off in the middle of nowhere, in which case you get the giant-cable-maintenance problem again. Trying to build a solar farm next to the Bay Area, for example, would be pretty impractical, while two or three receiving stations would be a lot cheaper.
:)
My position is still that I, and most of the people in this thread, don't actually know enough to determine whether space solar makes sense
(I do agree that nuclear is hilariously underused though. Get these damn rabid Greenpeace members out of my energy generation, dammit)
Breaking Into the Industry - A development log about starting a game studio.
The name of Nikola Tesla has been mentioned a few times already in this thread.
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
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
The deal-killer for space-based power generation via Hertzian cables is the difficulty of putting it in geosynchronous orbit. Consider how long and how many flights it's taken to assemble the ISS. That's for low earth orbit, where the space shuttle and Souyuz can reach it. Getting a series of power generation satellites to the Clarke belt would make that task look simple.
- 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.
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It's a gun. Phaser, here we come.
Bruce Perens.