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Wireless Electricity Set to Power Village
freedommatters writes "The UK Sunday Times has a story today about how "Scientists have successfully applied the technology used in microwave ovens to beam electricity without the need for unsightly pylons and overhead cables." A prototype has illuminated a handful of light bulbs and they expect to be able to power a remote village within three years."
Call me an alarmist, but I want to see the 50-year health studies before I go to something this, er, extreme. I mean, it could be completely harmless, but it just *seems* like something so potentially fraught with problems that my instinct is to avoid it.
Every year during my review, I just pray the words "slashdot.org" aren't mentioned.
Instead of having plentiful places for birds to rest in urbanized areas, we get partially cooked ones occasionally falling from the sky! Allright, not really - but it would be oddly funny to see a bird or insect perch in one area up high, enjoying unexpected warmth, then suddenly move away due to sudden discomfort or unexpected smell.
I can't imagine that microwaves would end up anywhere near as efficient as wire transmission, but it is a nice idea for when you have a source of energy you otherwise couldn't capitalize on (like extra-planetory solar radiation in the recent Sim City games), and just want to siphon as much in a direction where you can't use more efficent methods.
Ryan Fenton
What we need is not another way to get energy from power plants to towns and houses but small clean power generators in every buiding.
Then again, the oil lobby blocked every innovation for cars, so this is not gonna happen soon.
(And that comment was NOT a flamebait, just my opinion)
Well, the server appears to be down, but it a most Slashdot way, I'd like to comment on the article without even having read it!
Nikola Tesla himself was known for doing stuff like this . But I don't believe the 95% efficiency for a second...You can't even get that though wires if they are long enough.
Practically, "Wireless Electricity" already exists; it's called radio. The difference is only a very tiny current is induced in an antenna, whereas these folks in the article are trying to power a light bulb.
The biggest problem with trying to do this is that electromagnetic waves drop off very, very rapidly as they propagate through space, and to counter this you need a huge generator. If you had such a thing you'd need to direct beam it to this village and you can bet the stream would barbeque everything in its path. Also, radio waves are not lasers...It is very difficult to control where they go, so you could expect a certain spread as it propagated form the power source. I would bet that a lot of the people in the source, destination, and everything in between would be exposed to these amounts of insane EM radiation constantly, and that can't be good.
In short, my take on it is that while this has a certain coolness factor, it's way too impractical. If they don't want to mess with running wire, they should just construct a fuel cell generator and leave them with a hell of a lot of hydrogen. And they can do this now, not wait three years.
-R
That much power focused into a beam will probably be enough to boil water. It'll be interesting to see if this has any side-effects during a rain shower!
Maybe we'll have the 'beams of steam' going across the various valleys in France!
Infrastructure is an evolutionary process. It's the fact that we have cheaply available power that sets up the conditions by which we produce cool power hungry gadgets. It's the fact that it can be delivered in large amperages to densely packed locations that makes it so everyone in your apartment building can watch a separate big-screen T.V. at the same time.
:)
Thus, it is completely unfair to knock this technology because it will never be a match for a burly copper cable.
Imagine what it's like to live in a remote village that has no power available. First off, this almost always means no phones, land-line or cell. It also usually means that the families that are better off run their generators during certain hours of the day, producing noise and fumes, and enough power to get some work done, but they don't run them day and night. Four hours a day at a few hundred watts of power and no phones would significantly change most of our lives.
The most important thing microwave power could provide would be to enable a low power cell-site to give continuous operation at low cost. Unobstructed, 10 five watt channels would provide good communication for a few thousand people if used frugally (the way everybody did when roaming was $2 per minute). The people in the town could set up cellular fixed station adapters and wire their homes with copper and have a cheap phone in every room. With rechargeable batteries that charging up during the generator "power hours" they could have hours worth of night of phone calls to everyone else in the village, and more importantly to people outside the village with which they might want to do business. Even people without generator access could buy a pocket phone with two batteries and leave one at the neighbor's house charging while the other stayed in their pocket to give them emergency contact capability.
In regularly overcast areas (I live in one) the day often has enough light to see by, but not enough to read by. Just one 30 halogen bulb produces better reading light than any oil lamp I've ever used. Without light to read by, or TV of course, nights around here could get pretty boring, and homework pretty hard to do.
Since this is "a remote village" that means it's likely there are some uninhabited outskirts between it and the nearest big city. So between your microwave distribution points there wouldn't have to be any people at all. They could also aim the beam such that overspill wasn't directed toward the town.
I don't like the idea of radiation burns any more than the next person, but if done correctly there would be little danger. This could be a tremendous asset to people living off the grid, and to tower-climbing children wanting to roast hot dogs.
In order for this to work, they would have to make the beam extremely focused from transmitted to receiver.
If they don't do this, not only do they get the heatlh issues you point out, but the system simply won't work in practice.
All energy that is not captured by the receiver is lost.
Tor
What the hell is "the technology used in microwave ovens?!?" Buttons? Electricity? Light bulbs? Microwaves?? Do journalists even read their own inane statements? Hey, I just harnessed the technology used in keyboards to send an e-mail, it's revolutionary...
A 'village'...how many people is that? Two or three hundred? 'Significantly'--what is meant by that? Here's a hypothetical case. Question: If between 1980 and 1990 there are four cases of cancer, and between 1990 and 2000 there are eight cases in this little village, what does that tell us?
Answer: Nothing. The newsmedia will be on their hind legs shouting that the cancer rate has doubled! The village statistician might tell you that the sample is too small--it's just as likely that there will only be two more cases between 2000 and 2010. The epidemiologist down the street will note that a lot of people have moved into the new retirement community, and that older people are more likely to develop cancers. The local toxicologist (it's a village full of professionals) could observe that a refinery closed upstream about twenty years ago, and is probably leaching mutagenic nasties into the creek. The town dietitian sees that McDonald's opened a new restaurant in the village about fifteen years ago, and wonders.
So what's the solution? Blame the cell tower. Why? Because you can see it. It sticks up. It's obvious. It's easy. The drunk drops his keys in a dark alley. He immediately steps out of the alley and begins to carefully scrutinize the gound around a nearby street light. Why? Because they light is better over there.
You've supplied us with an anecdotal report of an anecdotal report. Recent large-scale studies of EMFs show no link between moderate electric or magnetic fields (comparable to those associated with living near power lines or the use of cellular phones) and cancer. Gee.
~Idarubicin
The microwave systems that SSI have studied are basically like a UHF tv station transmitter (sans Weird Al).
Birds don't cook, people don't mutate, airplanes won't crash from this. Since this is a line of sight system, the range is probably less than 20 miles. Even so, it will make a terrific demo that proves the practicality of powering cities from SPS.
It has to be somewhat focused, but it can be focused over a very wide area using large dishes, on the order of 10s of meters. Remember, the power density will decrease at the square of the radius (area=pi*r^2). The end result is an energy level that's only slightly above that of what you get during the day by being outside, but when it gets concentrated by the dish on the receiving end, the power is all there. This was the same idea behind that orbital solar to microwave array -- the receiving dish would be a few hundred meters across so stuff that gets in the way of the beam won't be instantly cooked.
.2 watts/square foot, so it's still dangerous, but not to the point of instant death anymore.
Say you want to beam 10,000 watts of power somewhere. If you have a 1-foot radius dish, your power per square foot is ~3100 watts. Your typical microwave is somewhere in the order of 500-1000 watts per square foot. You'd get fried if you touch that beam. However, increase your dish size to 25 feet in radius. You're down to 5 watts per square foot. The OSHA safe level of exposure is about
The idea is that converting microwave energy is more efficent than converting solar energy (I forget why, but theoretically solar panels can not be more than 30-50% efficent, no matter what), so this would be quite interesting if it worked out well.
Besides wondering what marketing genius came up with that name, just what kind of efficiency can you get with this principle. The losses are at:
a) conversion from AC to DC
b) conversion for transmission
c) losses due to Tx antenna efficiency
d) losses during transmission incl. energy lost toasting birds and folk getting in the way of the Tx beam
e) losses due to Rx antenna efficiency
f) losses during rectification to DC
g) losses during conversion to work (here light), more if you go to storage (battery) and back again.
Those add up pretty darn quick. Plus power received varies as an inverse square law of the distance from the transmitting site. Not very efficient. Seems like strictly a niche application.
"Consensus" in science is _always_ a political construct.
Well, provided it is in the right part of the spectrum, the human body might have a relatively low absorbtion rate. Certainly, when we think microwaves, we think microwave oven, but that's only a small part of the microwave spectrum.
The more important point, though is that this may actually cause far less ambient electromagnetic radiation than normal power lines. Ordinary power lines carrying AC current are basically like large antennae (though if properly designed, they are hopefully not very good antennae). They generate radio frequency signals that go off in every direction (actually primarily perpendicular to the lines), which you know if you try to listen to AM radio underneath them. Depending on how they do it, a microwave beam could actually be quite well columnated, so that virtually all energy is sent directly toward the reciever. Certainly, if they used a maser this would be the case, but they probably won't. Remember, too, that they have an interest it making it very well columnated, because that increases the efficienty of the mechanism.
Since you should be able to columnate the beam pretty well, the main issue would seem to be stuff that might get in the way and scatter the beam: air (obviously), dust, flying animals (like cows from a catapult), and perhaps most importantly, water vapor. If you're worried about getting cooked, think about this: The human body is mostly water, as are most other animal bodies. In order to cook well, a microwave oven must be in the right range of the spectrum to heat water efficiently, which they do (efficient being a relative term). This beam must go through air that has water vapor in it and even rain. It must be designed so all that water is not a problem, meaning it probably must be designed so that it would not really "cook" an animal very well.
So, really, this beam shouldn't cook things and anyway there should really be very little leakage if designed correctly. I mean, I wouldn't go and stand in it, but it's probably not so dangerous for the reason you bring up. On the other hand, I'm not sure it's really a good idea from an engineering standpoint, and there's the other question of what happens if it gets misalligned or if somehow something does get in the beam that deflects a significant amount of it (like something metal). Anybody ever play SimCity 2000? :) I'm not saying it's not dangerous, just that this EMF stuff is probably not the main problem.
BTW, as far as I know there is no credible scientific evidence that electromagnetic radiation from power lines causes cancer (or other health effects). There were some studies that suggested it years ago, but last I heard they had all been refuted by newer, more extensive studies. I'm not aware of the scientific credentials of your "science fair experiments", nor am I a biologist, so I can't evaluate that evidence.
"You call it a new way of thinking; I call it regression to ignorance!" -- Operation Ivy
Efficiencies of over 60% have been shown in DC-DC transmission of power (look up microwave power beaming in google some time). Your "a" and "f" are the same issue, and the "rectenna" also adds "e" into the same process, so whatever loss there is in "rectennafying" it's one step. I've read 90+% is possible there; don't know if it's ever been done in practice. Your "g" is there no matter what you do with the power at the end, so that's a wash. "d" one hopes will be kept low - in any case, losses with traditional power lines are often 50% or more...
So that basically leaves "b", "c", and your final comment on the inverse square law as problems. The first two of these are a question of conversion efficiency which somewhat favors low frequencies. The inverse-square law problem is basically an antenna-focusing issue: obviously you want a high-gain antenna on the transmitting end, and a "rectenna" on the receiving end that is big enough to catch the main lobe of radiated power. Diffraction limits impose a minimum size on the two antennas; to keep those sizes down for a given transmission distance, you end up favoring high frequencies. The balance between antenna size and component efficiencies favors different configurations depending on total power, distance, etc, but end-to-end efficiencies of at least 60% have been proven, and 90+% is thought to be theoretically possible.
I believe the origin of this idea is Glaser's 1960's proposal for solar power satellites, which would beam power to earth via microwaves in the same manner. Not sure if Glaser used the term "rectenna", but O'Neill certainly did in "The High Frontier".
Energy: time to change the picture.