Japan Will Try to Beam Solar Power from Space by 2025 (engadget.com) 111
An anonymous reader shared this report from Engadget:
Japan and JAXA, the country's space administration, have spent decades trying to make it possible to beam solar energy from space. In 2015, the nation made a breakthrough when JAXA scientists successfully beamed 1.8 kilowatts of power, enough energy to power an electric kettle, more than 50 meters to a wireless receiver. Now, Japan is poised to bring the technology one step closer to reality.
Nikkei reports a Japanese public-private partnership will attempt to beam solar energy from space as early as 2025. The project, led by Naoki Shinohara, a Kyoto University professor who has been working on space-based solar energy since 2009, will attempt to deploy a series of small satellites in orbit. Those will then try to beam the solar energy the arrays collect to ground-based receiving stations hundreds of miles away.
Orbital solar arrays "represent a potentially unlimited renewable energy supply," the article points out -- running 24 hours a day.
Nikkei reports a Japanese public-private partnership will attempt to beam solar energy from space as early as 2025. The project, led by Naoki Shinohara, a Kyoto University professor who has been working on space-based solar energy since 2009, will attempt to deploy a series of small satellites in orbit. Those will then try to beam the solar energy the arrays collect to ground-based receiving stations hundreds of miles away.
Orbital solar arrays "represent a potentially unlimited renewable energy supply," the article points out -- running 24 hours a day.
So they beamed power 50 metres (Score:3, Insightful)
Space is 2000 times further (at least)
Inverse square law means you would get 1 four millionth of the power...
Re:So they beamed power 50 metres (Score:5, Interesting)
This is, obviously, a from of focussed energy beaming. Probably some phased-array thing derived from radar tech.
Re: (Score:2)
Could be a Klystron.
Re: (Score:2)
Trying to get similar beam divergence from an antenna as a Klystron or Free Electron Maser seems pretty much impossible.
Having higher efficiency but spreading it around half the hemisphere isn't an useful alternative.
Re: So they beamed power 50 metres (Score:3)
The inverse square law is still in effect. Beam divergence at the receiver is inversely proportional to the square of distance, directly proprtional to the square of wavelength, and inversely proportional to the square of the size of the transmitting antenna.
Either you shrink the wavelength (and incur losses), or increase the transmitter size and incur huge cost increases.
There is such a thing as an "electromagnetic bullet" that is a solution to Maxwell's Equations that doesn't diverge as it propagates, but
Re: (Score:1)
Re: (Score:2)
In this case, the power source isn't the sun. At least not directly. The power source is your emitter.
Re: (Score:2)
Beam divergence at the receiver is inversely proportional to the square of distance, directly proprtional to the square of wavelength, and inversely proportional to the square of the size of the transmitting antenna.
Translation: a space-based solar power needs a *really*, *really* big transmitting antenna, especially at geostationary orbit.
Thanks for the insight. We were all wondering why it wasn't built already.
The test project in TFA will be low orbit, but still too small for practical purposes. It is a test platform.
Re: (Score:2)
The inverse square law uses the distance from the beam waist, not the distance from the antenna. Since you obviously put the focal point in the middle to earth the inverse square law isn't very relevant.
Beam quality is what's relevant.
Re: (Score:2)
Indeed.
Re: So they beamed power 50 metres (Score:2)
Focus is defined in angular coordinates, not cartesian coordinates.
So you can have focus out as far as you want, and the beam waist will be in the middle of the earth, but you're still going to have 1/r2 losses to contend with when you turn it from radians into kilometers.
Re: (Score:2)
But the r is still from the beam waist.
Following your logic you could never focus a laser in the far field. It's a coherent focused beam, not a radio signal from a x-db gain Yagi.
Re: (Score:2)
The diffraction limited spot size for a given size phased array is not the inverse square law either and a maser type is going to need different rules of thumb again.
Re: So they beamed power 50 metres (Score:2)
For goodness sake! The far field begins about 100 wavelengths away from the antenna. And a "focused" laser in the far field has a beam width (defined in angular coordinates) of roughly lamda/d.
None of those statements permits magic focused spots in the far field that aren't roughly proportional in linear size to distance from the antenna.
Re: (Score:2)
185db of path loss from geosync. (at 1GHz) Good luck with that!
Re: (Score:1)
Just need some bigger antennas, that's all. And lots, lots more money.
Re: (Score:1)
Something needs to live there. Nature abhors a vacuum.
Re: (Score:2)
Space is 2000 times further (at least)
Inverse square law means you would get 1 four millionth of the power...
I think you should contact them and express your concerns. You might save them a lot of money.
Re: (Score:3)
Space is 2000 times further (at least) Inverse square law means you would get 1 four millionth of the power...
Actually, inverse square law means that with the same aperture you will get a four million times larger spot size at the receiver... if the original beam were diffraction limited.
But at a distance of 50 meters, though, the original beam wouldn't have been diffraction limited, so no, that doesn't apply.
Re: (Score:3)
Don’t get me wrong - there are about a hundred OTHER things that I’m skeptical about in terms of making this work. At least, not until launch costs are reduc
Re: (Score:3)
What the Chinese are discussing is slightly different to what the West wants to do. Western groups want to beam from geosynchronous orbit so that their patch gets all the power, and also to avoid shadow.
China wants to beam from low orbit, and swap power from site to site as the satellites progress in orbit. Presumably they'll beam between satellites to transfer power into shaded bits. Lossy, but then so is beaming 36,000km.
Cool thing though is beaming power to spacecraft or lunar colonies.
Re: (Score:2)
Lossy, but then so is beaming 36,000km.
You can get a tighter beam by using a bigger antenna. Geosynchronous orbit makes more sense for a large production power station.
But if you are starting with smaller experimental generators, it is logical to have them in lowish orbit.
Phased array seems the way to go, but in theory a huge parabolic dish could also work. I think it needs to be something like 1km across at GEO distance with microwaves.
Twice the size of the biggest earth-based parabolic antenna, but much lighter without resisting that pesky g
Re: So they beamed power 50 metres (Score:2)
Giant frickin space lasers in China's hands, what could possibly go wrong!
Dual use - civilian / military (Score:2)
China wants to beam from low orbit, and swap power from site to site as the satellites progress in orbit.
And I am sure there is not intention to adjust output power to produce a dual use (power / weapon) capability
Re: (Score:2)
Re: (Score:2)
I ran the numbers years ago. Best case from geosync, 185db of path loss.
Why do people continue to want to do this? The physics are simple and the results suck.
Re: (Score:2)
Sucks even more for anything getting in the path of the beam. Like birds.
Re:So they beamed power 50 metres (Score:4, Informative)
That's an easy one to answer. 13 trillion dollars.
That's what we globally spend on energy every year.
You could build infrastructure to do that here on Earth.
It would require a surprisingly small percentage of the earth's surface to do it. The problem with that is a baseload generation issue. To completely displace carbon-based energy you have to massively overbuild generation and storage systems to cover overnights and days to weeks of poor generation due to weather. In geostationary orbital that doesn't happen. You get 1.3 killowatts per square meter on your panels (or concentrators) that is available 24/7 for 280 days per year with no cloudy days, rain, or nighttime to interrupt generation.
For the other 80 days, two roughly 40-day periods around the equinoxes, the satellites will be eclipsed by the earth between 1 and 70 minutes per day near midnight local time under the satellite. These outages are predictable, localized, and occur during periods of low usage. If you have a pair of satellites a few degrees apart, they can cover each other and there are no outages. ...But it's expensive!
Yes, but that's getting better. The big rock has always been the cost of getting to orbit. That's dropping. Projects that were implausible at 90K$/kg might be possible at 3K$/kg (F9 today). If Starship delivers that number could be under 1K$/kg. If the tech works out, and it very well may not, it's a no-brainer to put grid scale solar farms in space instead of sandwiched between the NIMBYs.
For scale, ignoring the new guys like TerraPower, a nuke plant cost about 15 billion bucks and takes a decade to build. That amount of money can cover a LOT of launches and flight hardware.
For space junkies, myself included, there is another draw.
The opportunity here is big enough to have real money conversation about bringing resources to orbit and manufacturing components there instead of on the surface. I want to see us build industries in space that require electricians and plumbers instead of PhDs. Orbital solar power could be the gateway to that.
Re: (Score:2)
https://slashdot.org/comments.... [slashdot.org]
Re: (Score:2)
Re: (Score:2)
Batteries are so much cheaper than launching stuff.
That's why you build stuff up there.
Hammer of Dawn (Score:2)
Also nice space-based weapon (Score:5, Interesting)
Presumably you can fry a power-grid or electronics with this. If it is a phased-array type of beam it can be focussed anywhere without visible preparation.
Re: (Score:2)
Re: (Score:1)
That's probably why they are looking at geo stationary. Then they only thing they could fry is their own country, unless they move the satellite, which would be impossible to hide.
Re: (Score:2)
At that point, why would you need to hide what you're doing?
Re: (Score:2)
Because their main concern is China, and China has anti satellite weapons.
Re: (Score:2)
It remains to be seen how well those "anti satellite" weapons work. They've probably tested them on some of their own decommissioned satellites, but not an active military installation. Plus you're talking about a what would probably be a massive emitter array. Huge target area. You wouldn't put it up there with the intent to fry people without some way of protecting it.
Re: (Score:2)
Not quite. The earth is almost a sphere, remember? Hence they can also target neighbours. And look, there are some that may be interesting.
Re: (Score:2)
Exactly. If this is "geostationary orbit" (which makes sense: you want to always be able to beam to your power station), the satellite has to be over the equator. And since Japan isn't on the equator, the beam needs to be able to point far enough afield to zap the Japanese power station. Which can obviously also zap things near Japan's longitude anywhere closer to the equator than Japan, like say, almost all of China.
retro back to the 1950s, here we come (Score:2)
Re: (Score:3)
There's no need for scaremongering; the systems proposed use rectenna arrays and additionally the amount of energy that would be absorbed by say, a bird flying over the rectenna farm, isn't enough to cook it.
A satellite would have to fail in multiple ways simultaneously to be a problem - aim would have to drift, the safeties would have to fail to kill the power transmitter, and the beam would have to somehow magically focus itself onto a much smaller area before it would be a problem.
Re: (Score:2)
Re: (Score:2)
That's clearly the solar ray weapon from Gundam, used by zeon and the titans.
Re: (Score:1)
If SimCity 2000 taught me anything, it will just be a localized swath of fire, but luckily, I never underfunded my fire departments.
The late Jerry Pournelle talked about this (Score:4, Interesting)
In Another Step Farther Out [amazon.com] the late Jerry Pournelle talks about this. Like many such grand plans it depends on a heavy lift vehicle to get materials into orbit. Pournelle assumed that only governments could fund the expense and they'd grown bored of such things.
Hello Starship.
I think that we'd still be better off getting serious about nuclear power but once Starship is debugged it could be done.
Re: (Score:2)
You could make it relatively light weight. Make the solar panels flexible and kept taught by centripetal force. Or in other words, the satellite should be a heliogyro with the solar panels as its blades.
Re: (Score:2)
Would that work? I think you'd need to includes an ion rocket for station=-keeping. Of course, you might have that problem with any large collection of solar panels in orbit, but using something designed as a solar sail makes that a bit obvious.
Re: (Score:2)
You don't use solar panels for collection. You use solar mirrors, such as micron-thick mylar film, with your microwave transmitter and generator at the focal point of your outstretched solar mirror. This is all well explained in the older solar power articles, and even the wikipedia article.
Re: (Score:2)
Simple Mylar won't focus without a dish shape, maintaining a segmented dish shape will explode the structural components beyond the mylar weight. PV film can simply be pulled taught from centripetal force, no rigid structure at all. It's going to beat rigid mounted reflectors on weight efficiency by orders of magnitude.
You might be able to use diffractive structures on the mylar so it can also use centripetal force, but I doubt it.
Re: (Score:2)
There are different proposals: I suspect, though I don't have a good citation in hand, that a very thin mylar based array could be kept distended simply by light pressure. The light pressure alone, ignoring solar wind, is 4.5 uPascals/square meter. It's not a lot by terrestrial standards, but it's the basis of solar sails. It can't be ignored in large solar mirror design, especially in space.
Even if that's insufficient, a mild electrostatic charge would be simpler than trying to control large spinning mirro
Archimedes Death Ray (Score:4, Insightful)
If you want electrical power at good value, nuclear is the way to go.
If you want an Archimedes Death Ray in space, this is a good start.
Re: (Score:2)
If you want electrical power at good value, nuclear is the way to go.
Especially since Japan has a bunch of those sitting dormant since Fukushima. Hopefully they've used the time to review the safety and repair and upgrade everything that's needed.
China & NZ slightly beat them to it... (Score:2)
China did this in, I think, 2019. NZ's Emrod did 2kW a couple of years back. One of the purposes of China's Tiangong is to test it from orbit. So great technology, great idea, somewhat overstated in the cutting edge department.
Re: (Score:2)
FWIW, I think it ought to be developed as a way to power probes to parts of the solar system distant from the sun. After it's been developed, then think about more local uses. It could solve the "there's not enough Plutonium" problem without enabling bomb factories.
Re: (Score:3)
Typical China. You offer free energy and they complain.
Hard to express how stupid this idea is (Score:1)
Re: (Score:1)
Were those capitalised words meant to spell out a hidden message or something?
Nuclear? (Score:2)
By that logic we should also keep all that nuclear energy trapped inside those atoms where it belongs.
Re: (Score:1)
By that logic we should also keep all that nuclear energy trapped inside those atoms where it belongs.
It's not bad logic and is to the point. We have a solution to our energy demands. FEWER HUMANS. We just don't want to do anything about it.
Instead we wil do everything we can to make our situation worse... as long as it's only killing those faceless suckers in the future, we're all good.... right?
Re: (Score:3)
You see anyone volunteering? Aside from the "first world"ers who are not having many children?
Re: (Score:2)
Ummm yeah okay, I guess they count too. Though I wonder how many of those actually exist.
Re: Nuclear? (Score:2)
You can't have fewer humans without first having better humans. Unfortunately, it only takes a tiny subset of thoughtless selfish bastards to shit it up for everyone.
Re: (Score:1)
houghtless selfish bastards
You're describing humans.....
I played SimCity (Score:3)
Re: I played SimCity (Score:2)
Damn you beat me to this very point!
Re: (Score:2)
WMD (Score:2)
Re: (Score:2)
The comment above sounds like it's trying to be funny; but actually these would be the ultimate WMD. At 23,000 miles arrays of space based solar panels that beam back to earth with microwaves or lasers would be far worse that nuclear weapons. At least with ballistic missiles, you get a 5-20 minute warning and might be able to shoot it down. With these things, you could redirect the beam in maybe seconds or less depending on the technology and satelites beaming to Japan could strike much of Asia or the w
Elon Musk is not a fan. (Score:3, Interesting)
The one person on Earth that should love space based solar is Elon Musk. Mr. Musk runs a company selling solar panels, and another company selling rockets. Both companies need customers to prove their technologies in order to be viable long term, therefore getting more customers. It is proving this long term viability of his rockets is why Musk got in the business of internet by low Earth orbit satellites. It is not the only reason but it certainly didn't hurt that he could use his own satellites as payload on test flights of his rockets.
The problem with space based solar is the number of energy conversion steps, each sucking up a portion of the power. Sunlight has to become electricity. The electricity has to become radio waves to be directed to Earth. The radio waves are received then converted back to electricity. That electricity isn't likely to be in the form useful for battery storage or put on an electrical grid so there's another conversion step.
This next bit is not part of Musk's complaint about space based power but still an issue. The mass of solar PV panels and all the other bits that would need to be launched is huge. An individual solar panel is quite light but the power each produces is relatively small. There's going to be a boost in power from being outside the Earth's atmosphere (no air and dust in the way to diminish the sunlight) and with the right orbits the panels can be in sunlight nearly 100% of the time but that's like maybe a ten times increase in output, which isn't even close to making up for all the losses elsewhere. Assume no energy conversion losses and there is still the energy requirements to get this mass of satellites into space. The energy return over the life of the satellites is not likely to cover the energy invested. Even if the energy return on energy invested is positive it still has to be high enough when compared to alternatives to be worth the effort. Fossil fuels, onshore wind, hydro, and nuclear fission all get an EROEI close to 100. EROEI of Earth based solar is typically in the single digits. If we assume a 10X improvement in sunlight hitting solar panels because they are in orbit, and an EROEI of 9 for Earth based solar, then that's an EROEI of 90 but only to the point it gets to the radio transmitters on the satellites, there's still all the losses to be considered in getting that to Earth. Take that into account and the EROEI is not likely to get what Earth based solar could get, and Earth based solar has a poor EROEI compared to other options.
I wish JAXA luck on their endeavors but this sounds like a bad idea. What I expect to come from this is a lot more people getting more experience in space exploration, and a definitive demonstration that space based solar is a bad idea. That should make people pause to review their calculations before trying again. This won't be a total waste of time and money, it is simply not likely to aid Japan in reaching energy independence.
Re: (Score:2)
I've seen the clip. Musk rightly says that earth-based solar is more efficient, but does not address the real reason for space-based power, that it is reliable continuous power, unaffected by weather or day/night cycles. It does not matter if space-based panels have only half the efficiency, as storage, the conversion of intermittant solar power to a reliable continuous source, costs far more than the solar generation itself.
Presumbly Musk thinks that it will be easier to develop earth-base
Re: (Score:2)
Well, no harm experimenting with it and getting some hard data. Who knows, maybe we will get to the point that we can do space based manufacturing with resources sourced from the moon or asteriods in the future, which may eventually change the economics of beaming solar power down.
Probably not in the next couple of decades at least, but maybe for the next generation.
Re: (Score:2)
Well, no harm experimenting with it and getting some hard data.
The harm is in spending a lot of time and effort on a project that calculations show will not turn a profit when there's already known options that are profitable and are in need of these same resources. It would be like trying to build a dam across a river (a specifically troublesome river, not just any river) to produce electricity when all the calculations show that it would take more energy in moving in all the rock, steel, and cement than could be recovered from the dam once completed. So, we go try
Re: (Score:2)
I think pretty much everyone knows that solar energy being beamed to earth will not be profitable in the near future.
And I doubt whatever simulations we can perform to get some baselines on how much energy actually can be beamed is probably not that accurate anyway. Will it accurately factor in water vapour? What about cloud formations? Temperature gradients within the atmosphere?
Hard data always beats whatever simulation we can provide.
Not everything has to be for profit - I doubt the billions spent on th
Re: (Score:2)
The rough numbers are pretty easy. Solar power is on the order of 2 Watts/cm^2 of exposed area, or roughly 20 kWatts/square meter. The energy to get a kilogram to low earth orbit is roughly 450 megaJoules. So, for a one kilogram payload tapping roughly one square meter for solar power, it's 450 megaJoules / 20 kWatts, = 22500 seconds, or roughly 6 hours power accumulated to very roughly pay back the energy used to launch that small, not very efficient payload. Use the first few satellites to fuel the elect
Re: (Score:1)
Re: (Score:2)
People might want to know what Elon Musk thinks of space based solar power because of his background. He has bachelor degrees in physics and economics, that alone should mean he has some background to make an educated statement on the economic viability of space based solar power. He runs a company that launches things to orbit, runs a company that makes solar PV panels, and has enough of his own money to fund most any project he believes would make money. If there is one person that would know the capab
Re: (Score:2)
He has bachelor degrees in physics
Is that why all the companies that Musk works at has people to keep him away from the engineering departments?
Astronauts with freakin lasers! (Score:2)
Dr Evil was such a visionary!
He should have gone for astronauts instead of sharks.
receiver on my roof (Score:2)
I'm willing to test this can I put a receiver on my roof?
Global Warming. (Score:1)
Let's focus more heat to the planets surface.
Re: (Score:2)
Can someone explain to those that make comments like the parent post how global warming works and how space based solar would help, not hurt? I'm not in the mood right now to go into it.
Space based solar is a bad idea but not because it would focus more solar energy on the planet. It is a bad idea because the energy needed to launch everything into orbit is not likely to be paid back by the solar energy it collects and converts to useful energy. Even if we could improve the efficiency of the various step
Re: (Score:2)
Look slightly earlier. The energy cost of LEO is roughly 450 megaJoules / kilo, or 30 kilometers/second * 30 kilometers/second * kilogram / (2 * kilogram) The power of solar radiation is roughly 2 watts/square centimeter, or roughly 20 kWatts/square meter. If the design is *at all* efficient, say one kilogram / square meter of collecting array, the energy output is returned in roughly 6 hours (450,000,000 / 20,000 =
The rough numbers are pretty easy. Solar power is on the order of 2 Watts/cm^2 of exposed are
I've seen... (Score:2)
The sun (Score:2)
Re: (Score:2)
Yeah. But they turn it off at night.
QT-1 (Score:2)
There is no master but the Master and QT-1 is his prophet.
Have they never played SimCity (Score:2)
They had better be prepared for adjacent neighborhoods to be randomly set on fire.
Its all about economics (Score:2)
The problem is costs. Right now a KW of solar power in orbit is far more expensive than the same (daily average) power on the ground, even including batteries. Space is likely
Re: (Score:2)
That's true today. This kind of facility can scale _very well_., vastly lowering the price per kilowatt.
I can see the future headline already: (Score:1)
This is a stupid, desperate idea they've had. Since it's just based on a 50-meter distant experiment, I wonder if it's just clickbait and/or a way to attract idiots with money to invest.
At the very least they could try to develop a solar-pumped laser system instead, and collect it at a ground station consisting of solar panels tuned to the specific laser wavelength, for maximum efficiency -- but then you'd have countries all over the world wo
This is really dangerous (Score:2)
Re: (Score:2)
Mishandled, there's a risk. So is there one for oil pipelines and coal storage. Part of NASA's proposals has been deliberately limiting the intensity of the transmitted power to be collected by wide, lower power density, ground based microwave arrays and reduce the risk and even the ability to focus the transmission tightly. Most if not all failure modes would spread, not focus the power more tightly. It's fascinating work, and it does need close attention paid to avoid military misuse of the transmission a
Well, at least it's not (Score:1)
... in somebody's back yard.
But the Targeted Individuals will be going crazy. Uhm, craziER.