Researchers Beam Power From a Moving Airplane (ieee.org) 58
Researchers from the startup Overview Energy have successfully demonstrated beaming power from a moving airplane to the ground using near-infrared light. It marks the first step toward space-based solar power satellites that could someday transmit energy from orbit to existing solar farms on Earth. IEEE Spectrum reports: Overview's test transferred only a sprinkling of power, but it did it with the same components and techniques that the company plans to send to space. "Not only is it the first optical power beaming from a moving platform at any substantial range or power," says Overview CEO Marc Berte, "but also it's the first time anyone's really done a power beaming thing where it's all of the functional pieces all working together," he says. "It's the same methodology and function that we will take to space and scale up in the long term."
[...] Many researchers have settled on microwaves as their beam of choice for wireless power. But, in addition to the safety concerns about shooting such intense waves at the Earth, [Paul Jaffe, head of systems engineering] says there's another problem: microwaves are part of what he calls the "beachfront property" of the electromagnetic spectrum -- a range from 2 to 20 gigahertz that is set aside for many other applications, such as 5G cellular networks. "The fact is," Jaffe says, "if you somehow magically had a fully operational solar power satellite that used microwave power transmission in orbit today -- and a multi-kilometer-scale microwave power satellite receiver on the ground magically in place today -- you could not turn it on because the spectrum is not allocated to do this kind of transmission."
Instead, Overview plans to use less-dense, wide-field infrared waves. Existing utility-scale solar farms would be able to receive the beamed energy just like they receive the sun's energy during daylight hours. So "your receivers are already built," Berte says. The next major step is a prototype demonstrator for low Earth orbit, after which he hopes to have GEO satellites beaming megawatts of power by 2030 and gigawatts by later that decade. Plenty of doubts about the feasibility of space-based power abound. It is an exotic technology with much left to prove, including the ability to survive orbital debris and the exorbitant cost of launching the power stations. (Overview's satellite will be built on earth in a folded configuration and it will unfold after it's brought to orbit, according to the company). "Getting down the cost per unit mass for launch is a big deal," Jaffe says. "Then, it just becomes a question of increasing the specific power. A lot of the technologies we're working on at Overview are squarely focused on that."
[...] Many researchers have settled on microwaves as their beam of choice for wireless power. But, in addition to the safety concerns about shooting such intense waves at the Earth, [Paul Jaffe, head of systems engineering] says there's another problem: microwaves are part of what he calls the "beachfront property" of the electromagnetic spectrum -- a range from 2 to 20 gigahertz that is set aside for many other applications, such as 5G cellular networks. "The fact is," Jaffe says, "if you somehow magically had a fully operational solar power satellite that used microwave power transmission in orbit today -- and a multi-kilometer-scale microwave power satellite receiver on the ground magically in place today -- you could not turn it on because the spectrum is not allocated to do this kind of transmission."
Instead, Overview plans to use less-dense, wide-field infrared waves. Existing utility-scale solar farms would be able to receive the beamed energy just like they receive the sun's energy during daylight hours. So "your receivers are already built," Berte says. The next major step is a prototype demonstrator for low Earth orbit, after which he hopes to have GEO satellites beaming megawatts of power by 2030 and gigawatts by later that decade. Plenty of doubts about the feasibility of space-based power abound. It is an exotic technology with much left to prove, including the ability to survive orbital debris and the exorbitant cost of launching the power stations. (Overview's satellite will be built on earth in a folded configuration and it will unfold after it's brought to orbit, according to the company). "Getting down the cost per unit mass for launch is a big deal," Jaffe says. "Then, it just becomes a question of increasing the specific power. A lot of the technologies we're working on at Overview are squarely focused on that."
Very funny, Scotty... (Score:5, Funny)
Still... (Score:5, Funny)
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I'll be more impressed when they beam it from a still airplane.
Really? I didn't think the runway demonstration was impressive.
EEVBlog explaining why this is BS (Score:2)
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It may be BS and really inefficient, but it could also be an awesome weapon. I they manage to put up a solar power satellite that can do, say, 1GW of useful power (probably 5GW of total power), instead of beaming power to the ground-based power plant, you can also aim it to the enemy country and some spot there gets really hot...
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If it is designed correctly in the first place it cannot be a weapon because you can't focus the antennas.
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Or, to capture wasted energy, these things could be placed in strategic points to grab energy waste from sources.
This is essentially an extension of solar and wind and water energy capture, by capturing already converted "loose" power. There are many possibilities with this tech.
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To focus is the efficiency part, so they will get to that point.
What you want is for the beam to be focused on the entire rectenna field. That way if it gets pointed in the wrong direction it doesn't cook anything. You do NOT want to be focusing for efficiency. If the system is designed in such a way that you can do that, then it can be used as a weapon, and it's too dangerous to allow it to exist.
Re:EEVBlog explaining why this is BS (Score:4, Insightful)
I was expecting it to be inefficient, but after looking into the, the efficiencies are a lot higher than I expected them to be, esp. given that they have a choice about what solar farm to beam to, so can avoid adverse weather. Looks like they could probably get like 50% laser efficiency, 40% system, with a ~500m spot. And 1064-1070nm is 90% clear in good weather.
Solar power in space gets ~40% more W/m2 than on the surface, has zero blocking by clouds, no night, passive solar tracking, no land cost, only one-off permitting costs, low mount costs (minimal structural loading), no weather damage, no dust, and they can beam to wherever they can sell the power for the highest price. Historically it was right-out because of high launch costs, but launch costs are plunging, and could get very low indeed. Also, space solar tech has advanced dramatically in terms of W/kg in the past few decades, and is likely to advance a lot more if this is pursued at scale.
Of course you have radiation, no maintenance, micrometeoroids, launch packing/stress/deployment, beaming, thermal management, and a whole host of other things - one can absolutely not say it'll be cost effective. But at this point, I don't think we can assert any more that it won't be cost effective, either. It's probably about the right time to start working towards giving it a shot.
There's also some fun things you can do with this, like on-demand spot-warming of specific areas and the like. Not visible lighting, mind you, since this is IR (the Soviets once did a small-scale experiment with mirrors to light a town with something like 1% of the sun's light from space)
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Solar power in space [...] has [...] no night
It does when it gets shaded by astronomical bodies, like the Earth.
Still, this could make ground-based grid-scale PV arrays massively more effective, boosting their output by increasing their input during the day, and if the satellites are in very high orbits, extending the duration of the "day" by delivering power to farms that are in dawn/dusk from satellites that are in full sun but still have line of sight to them. For that matter, you could really increase PV output if you used a constellation of sa
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I guess if you had hundreds of full-size space power plants and decided to beam all the power to the same place at once, then maybe? But for a given one, think "the sun", not "a laser cutter". The beam is very wide and diffuse.
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Not as cool then. Though, if its summer and the enemy city is experiencing a heatwave, giving it "extra sun" could be useful.
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If it is designed correctly in the first place it cannot be a weapon because you can't focus the antennas.
There's no way it would be a singular beam though. It would be a compound system with hundreds or thousands or more elements. Elements that would almost certainly need to be aimed at many ground stations (the orbital station can't be in geosynchronous orbit, because beaming extra light at solar panels during the day makes little sense, so it would have to keep skipping from one solar plant to the next as the Earth revolves). Geography, local weather patterns, national borders, property rights, etc. would ma
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The power intensity just isn't there. It doesn't matter whether you transmit the power as one laser or 1000, every single one of them will have their beam spread out over much of a square kilometer (or more, depending on the design).
If you were supplying a good chunk of Earth's power from space, and pointed all of the ones on one side of Earth at the same place, then, yes, you could fry that good chunk of a square kilometer (or multiple square kilometers), but you simply cannot do it with a single power pl
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The power intensity just isn't there. It doesn't matter whether you transmit the power as one laser or 1000, every single one of them will have their beam spread out over much of a square kilometer (or more, depending on the design).
A thousand beams, each spreading its power over a square kilometer or so, spreading their power over a _single_ square kilometer? I mean, let's do some back of the envelope math here. Let's say this is a thousand square kilometer solar array in space getting 1 kW/m^2 with 20% efficiency in turning that into a beam headed for Earth and then 50% of that energy is lost before hitting the ground. So 1 square meter of the array would produce about 100 Watts per square meter on the ground (averaged out, of course
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So your scenario is a *million square kilometers of solar panels*?
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... each with the power output of 1/1000th of the power plant.
I don't think that I should need to tell you that 1000/1000=1 and the premise is a power plant in the range of at least hundreds of GigaWatts. Also, in my back of the envelope math, I assumed a 50% power loss getting the energy to Earth and a total 90% power loss from the original amount of sunlight striking the power station. So that was a power plant receiving a TeraWatt of sunlight and delivering 100 GigaWatts of EM radiation at the surface. Even then, over the covered ground area the intensity was 100X
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Beaming Gigawatts of IR (Score:2)
Would could possibly go wrong? Yes, I'm sure its spread out but I still wouldn't want to be standing under it. Also clouds do a damn fine job of blocking most IR so why not just use visible light anyway so at least the beam could be seen and people avoid it?
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You wouldn't be able to see a laser, it's too directional.
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Seriously? Clearly you've never been to any kind of gig or sporting event where lasers were used and they're low powered. There's more than enough dust in the air to make it visible.
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They add a great deal of dust specifically to make it visible (and safe). When beaming energy, you don't want scatter. You select a frequency where virtually nothing along the path is going to scatter the light.
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"They add a great deal of dust specifically to make it visible"
So no, you've never been to a gig or event where they're used. You seriously think they pump crap up thousands of feet all the way to the clouds to make the lasers visible?
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1. Lasers don't shine sideways, and laser light doesn't scatter on its own. Test it yourself, get a laser pointer and try to bounce off a building a thousand feet away. You will NOT see the light.
2. If you seriously think that searchlights are lasers, you've problems. Gigs aren't going to use lasers into the sky because that has a very nasty habit of blinding pilots.
3. You're an idiot.
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Yeah, they're used in combination with smoke machines.
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Why not? It's less damaging than standing out in the sun. Why are you afraid of IR?
You seem to be thinking that this is like some sort of point laser with incredible intensity. It's not. It's an extremely wide beam of "normal" levels of light intensity.
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Define normal. The sun at midday at the equator is damn hot. If you double that IR it'll be burns territory.
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Why not? It's less damaging than standing out in the sun. Why are you afraid of IR?
Because IR will blind you, and you won't even know it until you're blinded.
The system would need a keep-out zone around the receivers, and it would also need an automatic beam cut-off if the beam drifts off target. If anybody has to be in the beam when the beam is operating, they will need to be wearing eye protection. However, this is completely standard in laser testing-- it's not like nobody has thought of this before.
No, it's infrared; you can't see it.
You seem to be thinking that this is like some sort of point laser with incredible intensity. It's not. It's an extremely wide beam of "normal" levels of light intensity.
Won't be a problem as long as you're wearing your
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If you're staring into it. Ambient IR of normal solar intensity is perfectly fine. The sun kicks off a huge amount of IR on its own.
Laser safety [Re:Beaming Gigawatts of IR] (Score:2)
If you're staring into it. Ambient IR of normal solar intensity is perfectly fine. The sun kicks off a huge amount of IR on its own.
I take it that you've never worked with lasers, and have definitely never taken a laser safety course.
Brightness is defined as power density per steradian. Lasers are much brighter than sunlight. Much much brighter.
The sun also puts out a painful level of visible light, which kicks in the blink reflex if the sun enters your field of vision. IR is invisible. You don't know whether it's hitting your retina because you won't see it.
Ambient IR of normal solar intensity is not "perfectly fine" (don't stare in
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These aren't. That's the point you're missing. The beam divergence is so great from traveling nearly 36 thousand kilometers that by the time it hits the surface it's at typical solar intensities, spread out over a large area.
What you're freaking out about is that a space solar plant:
1) Aims in the wrong place
2) Keeps aiming in the wrong place
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Except what matters for retinal damage isn't the intensity (watts per square meter), but the intensity per sterradian.
I'm not freaking out about anything. How to implement laser safety is well known; we do it all the time. First, you cut the beam if the beam wanders or if anybody enters the keep-zone. And, second, everybody who might need to enter the keep out zone wears eye protection. This is not hard. But it is something that would have to be implemented.
I didn't think to add one more item, but apparent
Re: Beaming Gigawatts of IR (Score:1)
Near IR isn't useful (Score:2)
The higher the frequency, the more energy the photons have. You want shorter wavelengths, not longer. Ideally, as short as possible. Because you're wanting to do this as a tight beam, or as tight as you can get, other applications are irrelevant. This isn't a general broadcast in all directions, it's unidirectional and should only affect a very small area of ground. All of which you will have collectors on, so there won't be any people there for the beam to interfere with.
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So what would you use, gamma rays? https://xkcd.com/273/ [xkcd.com]
IR is higher frequency than microwaves.
First Time (Score:2)
This is the first time I've seen this particular xkcd.
This is also the first time that an xkcd made me blurt out laughter.
The absorption spectra of Tampax and Depends. Kosher Radio. Miller Light. So many gems in this one.
Re:Near IR isn't useful (Score:4, Informative)
The higher the frequency, the more energy the photons have.
This part is right...
You want shorter wavelengths, not longer.
This part is complicated. If the only criterion were diffraction-limited beam spread, and the only optimization parameter were minimizing the size of the beam director, that would be accurate. But it's not.
in this case, however, the wavelength choice is simple. You want the wavelength where the efficiency of conversion of electrical light to laser output is most efficient, in a wavelength band that photovoltaic cells respond to well, and simultaneously, you need a laser technology with high beam quality. With today's lasers, there's only one choice that does both, around 1.06 microns. Really, that's the end of story.
Ideally, as short as possible. Because you're wanting to do this as a tight beam, or as tight as you can get, other applications are irrelevant.
Nope. Other considerations are critical. UV light will get scattered by the atmosphere and, at shorter wavelengths, absorbed. Classic visible lasers aren't as efficient. Semiconductor diode lasers don't have the beam quality. Long wavelength IR lasers (like, say, CO2 lasers) have high power but aren't converted efficiently by photovoltaics.
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Longer wavelengths travel a lot easier through haze or clouds so there will be less losses due to dispersion.
Not easily enough. If there are clouds you're not going to get power unless you're going all the way to microwave wavelengths.
What could possibly go wrong? (Score:2)
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This sounds an awful lot like a directed energy weapon.
Like one yes, think “directed energy squirt gun”. Like the difference between standing outside with light cloud cover and standing outside with no cloud cover. Something you can measure but not really feel. If you hijack them all maybe you can give someone sunburn (except they are all IR not UV).
Why not use a mirror? (Score:2)
Re:Why not use a mirror? (Score:5, Informative)
Why convert sunlight into electricity and then into infrared light to beam it to earth where it is converted into electricity again? Very energy inefficient and expensive. All you need is a mirror. Just reflect sunlight to earth to the solar farms.
It's not impossible... many people (for that matter, including me [ieee.org]) have looked at it. However, keep in mind that the intrinsic beam spread of sunlight is about half a degree, so the spot size on the ground is a minimum of 10 kilometer diameter per thousand kilometers beaming distance from your satellite.
(That's a consequence of the law of conservation of etendue, by the way (part of the laws of thermodynamics not well known to people who don't work in optics) so don't think you can make a smaller spot size by clever focussing.)
Small mirrors that can rotate like a giant mims projector. Would need analog control not digital tracking speed would not have to be very large. Of course it would also be useable as a giant directed energy weapon so a little scary. Might also be useful for extending crop growing seasons or directing weather patterns. Pump a little extra sunlight and steer that hurricane out to sea or that thunderstorm to the drought stricken field.
The mirror size to do anything like those applications would have to be truly enormous, and keeping surface accuracy on mirrors hundreds of kilometers in extent is going to be... tricky.
Wrong way (Score:2)
It would be more useful to beam power TO a moving airplane.
The problem with electric flight is that batteries aren't energy-dense enough for anything but short flights. If you could recharge while in the air then transcontinental flights may still be possible.
how the loss in the air (Score:1)
Does not "mark" anything (Score:2)
It is a stunt, nothing else. I bet somebody is looking for "investor" money.
Heating Earth is Not Enviromentally Friendly (Score:3)
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There was an article in Washington Post a few weeks ago about the cost or running lights in a room when you're gone. The article said it was no more than a couple pennies per day, and the calculations work out.
Of course there soon won't be any pennies (in the US), and I turn off the lights anyway.
Let me explain.. (Score:2)
Aound 1980, I heard a presentation that said that the Environmental Impact Statement had ALREADY BEEN SUBMITTED. And no, it won't cook birds (or cattle). You're beaming to an array.
We thought we'd get it by the nineties.
Adding heat to Earth system (Score:2)
That is a positive global heating factor.
Someone needs to do the math to show that the fossil fuel GHG emissions avoided by using this system for energy outweighs the direct heating of Earth by this system.
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Oh shush! We're not interested in petty details - we have suckers to fleece and a planet-sized ecosystem to destroy!
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The greenhouse warming reduction (assuming it replaces the same amount of gas or coal-fired generators) is many orders of magnitude greater than the additional energy delivered by the beam.
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Too lazy to calculate final answer myself: Showing work:
e.g. degrees C atmospheric heating (eventually settled atmospheric surface temperature delta after accounting for temp buffered by oceanic heat capacity) per GWh energy added to Earth system at surface, assuming otherwise in equilibr
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The Earth receives an immense amount of solar energy, about 173,000 terawatts which is over 10,000 times the world's total human energy consumption. So even if *all* human energy consumption was beamed to the earth's surface, and was then absorbed and re-radiated the same as solar energy, it would add 1/10000 to the effect of global warming.
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Worth noting that the radiative forcing factor (global heating energy) of excess greenhouse gases is estimated at about 0.003 to 0.004 of the solar radiation incoming. (Source: leading answer sourced and/or calculated by Google Gemini lol).
So yeah, an order of magnitude or two difference in heating, if all human energy would be supplied this way.
Where I Wasn't Going (Score:2)
What could possibly go wrong? Well, that was anticipated in a 1963 SciFi story in Analog magazine (where else?): Walt and Leigh Richmond, "Where I Wasn't Going". Read it here:
https://www.gutenberg.org/cach... [gutenberg.org]