I'm highly skeptical of the 60% efficiency figure being any sort of end-to-end metric. I suspect that was poorly phrased, and the receiver/rectifier was operating at 60% efficiency (which is reasonable for RF rectifiers), of power incident. But the vast majority of power loss is happening along the path before reaching the receiver.
Some ballpark numbers: 1km at 10GHz is ~110dB of path loss. Those look like feasibly 40dBi antennas at both ends. That still leaves -30dB link budget, i.e. 0.1% of energy reaching the target.
From the YouTube comments:
Video carefully avoids to state that the overall efficiency of the system is 1.8%. Input power was 91.2kW at the TX antenna, out of which 1.65kW was produced at the receiving side.
https://ieeexplore.ieee.org/mediastore_new/IEEE/content/medi...
Putting 92kW in for a 47dBm over 1km is comedic levels of loss. It’d be more efficient to move a 2kW generator over and send several people on laps with pogo sticks carrying thimbles full of diesel to keep it running.
I all really tired of all the unicorn shit being shoveled in the wireless energy transfer research area.
If the receiver is compact enough and light enough then this for examples allows you to have a drone orbiting a surface warship pretty much indefinitely.
Just so you know there is far greater loss of power in extracting oil, transporting it, refining it and then transporting the refined fuel to its destination.
But it’s still better than not bothering with all of that just because the fuel allows you to power up thing that otherwise you won’t be able to do so.
I don't think I'm the one missing the point. Drones are usually required to have a low radar surface and loiter far from any associated targets. The launch and landing points need to be masked. Can anyone realistically throw 100kW out to power a <2kW drone with a 1km range without basically sticking a big electronic sign on the transmitter saying where to send the bombs?
With some of the wideband phased array sensors out there now you can probably use the incident reflections off the drone to track the location of it as well.
It pulses multiple times a second and even tho in search mode it’s average power is 1-2% in tracking mode it can be as much as 50%.
It still lights you up like an xmas tree.
You also assume that the power delivery will be continuous instead of essentially just being used for charging a small UAV.
Every modern system we have is usually completely inefficient but the price of that efficiency allows you to do other things.
Our food production is extremely energy inefficient but it frees up the majority of the population to do other things, it improves sanitation in cities by pushing animal husbandry further out and it allows most of us to enjoy a wide selection of foods that taste good which has enormous societal benefits.
The fact that something is inefficient doesn’t make it useless or ineffective.
Heck sail ships are also far more energy efficient than airplanes but we kinda benefit greatly from being able to take off and land at any point on the planet within 24 hours or less.
a warship could (and some do) have baloons for that already though, and there are also drones that can be fed power through tether
but if you could put a serious loitering drone over a section of urban terrain in a conflict zone or in high crime area, that could move around to get angles as required, that would be cool
Because you have to start somewhere, if these technologists took these armchair physicist internet comments to heart, then what progress would they make?
Having worked for defense technology contractors in the area, these people want ideas. They want brand-new, sci-fi level ideas. These militaries and defense companies will literally hire sci-fi writers for inspiration.
It's not like SV where the primary focus is profit. It's less limited than that, these researches are on the cutting edge, it's where we received the internet itself. Remember, researchers in this league led the use and development of radio in its early stages for military reasons.
The truth is, in order to attract defense funds, you have to oversell an idea way, way down the line. Imaginative people with bold ideas of the future. It's beyond market trends, publicly-funded technological development is pure and machine-like. Blows any selfish, boyhood fantasies of the world's richest men out of the water.
This is optimist fantasy hyperbole. You can’t imagine physics into existence. And also the military is well known for spending on ideas that don’t even have a hope of working out whatsoever. We can use goat staring as a fine example of military thinking.
Having also worked for clearly larger and more respectable defence contractors, one of whom had a big stake in early radio, in an RF engineering capacity, this stuff is laughed off the table. No one really wants or needs this capability nor believes it will work. It’s fringe garbage.
Defence projects start with capabilities and then work out what you can deliver within those capabilities and client expectations.
Knowing when to tell the client they are lunatics rather than taking the money and dragging a project out while paying subcontractors is where things are divided in the market.
I worked on a huge project to beam power into the body, wirelessly, for an implanted blood pump /artificial heart.
It works for small amounts of power, like for pacemakers or nerve stimulators. But for any kind of real power, the power needed to move motors and do real work, it's just not feasible.
No matter what fancy math or physics you do, no matter if you work with a fancy tech firm that has decades of IP in this field and was founded to make this technology specifically (like wiitricity). None of those things changes the fundamental underlying physics. Energy in the EM spectrum decreases with the square of the distance, period.
If you need to beam a tenth of a watt one foot, that's possible, if you want to beam 10 watts 2 or 3 feet, that's possible (both with very large losses, 50% or more). Anything beyond this in distance or power is just wasting energy. It's like heating up 500 gallons of water, carrying it one mile and using the last 2 degrees of delta temperature left to do something. Instead it's far smarter to just take the 50 gallons of fuel one mile, heat the water there, and use its full energy.
How about having N drones and taking turns?
Seems to be much cheaper and doable right now.
For instance, people cannot operate 100% of time. I know that there's been some research in eliminating the need for sleep, etc, but having watches worked for ages.
I'm also not convinced that they're even out of Far-field. That looks like a roughly 5m dish, which at 10GHz is still in the radiating near field at 1km. I wouldn't be surprised if the main lobe is entirely incident on receiving aperture. That's a neat demo but it does not demonstrate truly radiating power between two distant points. They've essentially built a fancy a wireless cellphone charger.
60% is also almost certainly not total system. A portable antenna like that by itself, with no path loss or other losses, would likely have an aperture efficiency of about 60%. A planar patch antenna like the one used to receive would be similar.
Lasers have much higher "antenna" gain. How about using an IR laser to remotely heat a steam engine which runs a generator... I bet overall efficiency is at least an order of magnitude higher.
Can we kill the "genius" trope already? In 15 years at the nation's best engineering schools and another 10 at companies and institutions that employ their graduates, I have yet to meet a nobel prize winner, CEO, professor, astronaut, politician, or other individual that is single-handedly "propelling global human advance." Perhaps these magical minds are hiding under some rock I haven't overturned yet, but it's much more likely that the "genius" model is just not a very good one. There are plenty of clever people around and there will always be a tail end of the bell curve, but the idea that these individuals are lifting up the rest of us is self-serving and ironically, demonstrably false. It's hero culture for intellectuals. There are plenty of humans with tail-end IQ, none of whom become anything without the rest of society getting up and going to work to support investment in their minds and the infrastructure that enables them to utilize their capacity.
Einstein would have been nothing without cooperation from a wide range of scientists, mathematicians, family members, and hell his garbage man.
/end rant
Thank you for sharing that link, though - the bit about reproduction has some meat to it. I've wondered whether innovation will slow as global population levels off. We'll get better at being efficient with the capacity we have, to be sure, but I wonder if eking out efficiencies will also asymptotically stall.
I think that we don't meet many geniuses because they are off doing their own thing in research labs. Look at MRNA vaccines, just a few people toiling for decades have saved millions of lives. But fret not, innovation should only continue as more people are brought up and educated than we've ever been able to in the past. Incremental change will get more helpers. Plus we aren't stunting generations with lead poisoning by and large anymore, which certainly reduced the amount of minds that can handle super specialized endeavors.
On paper this is already very inefficient and your proposal is definitely more efficient. I am wondering why they even built it. Test manufacturing process or there is just too much research money floating around.
1km through the atmosphere is probably all you need to verify that the approach would work for Space Based Solar. I know the military is interested in that. Imagine being able to deploy energy anywhere on Earth and not have to setup a logistics chain to facilitate it. That's priceless. The economics for SBS don't really make sense to me, for domestic energy consumption. But economics are irrelevant if it enables you to project power deeper into hostile territory.
"Imagine being able to deploy energy anywhere on Earth and not have to setup a logistics chain to facilitate it."
Logistics is quite a complex beast and you mention "the military". Out of POL (Petrol, Oil, Lubricants) you now have one item nearly sorted - "petrol" ie power source. Your machines also need a few other things to work. Then there is food and water - your army's people need a power source too. Oh and they need a few things to throw at the opposition - munitions.
There's a major war being fought in Ukraine right now. Ukraine is bloody huge and it's all about logistics. Russia cannot possibly "win", where win is take and hold all of Ukraine. There was a huge armoured convoy headed for Kyiv and it stalled because it could not possibly have had enough of anything to run for more than a few days.
As my dad always used to say (Col. (Retd) RAOC): "An army marches on its stomach". That means that Russia may continue to commit acts of barbarism but it cannot possibly achieve its original aims. They have not got the legs.
That's not much comfort for the peoples of Ukraine suffering massive indignity and savage brutality, day after day.
Logistics (fuel, food, tires etc) were definitely a contributor to the convoy’s stalled assault.
As it turns out, there were also a group of Ukrainian Special forces that pestered and attacked that column relentlessly. Kudos to them and their efforts.
> As it turns out, there were also a group of Ukrainian Special forces that pestered and attacked that column relentlessly.
I mean yeah? That is the nature of millitary offensives. The opposition tends to make your life harder every way they can.
When someone says that the attack stalled because the attacking force botched the logistics, that doesn’t mean that they forgot that tanks run on fuel. It means that they couldn’t deliver the supplies needed because their logistics were not resilient to enemy action.
In the very micro level this might mean that a particular Ukranian soldier shot dead a particular Russian fuel truck driver. (Or they blown up the truck, or trapped it, or misrouted it, or caused them enough fear the truck driver decided to run away instead of getting the supplies to the troops.) On the macro level the details don’t matter, there you can say that the logistic failed.
Similarly if during an excercise in your own country the fuel trucks show up a day late that’s not a problem. You spend the day camping next to your tank and the fuel arrives when it arrives. But if the same happens during a real invasion you are a sitting duck the enemy is trying to kill.
Logistics failing and the Ukrainan forces pestering and attacking the column are not two different things. They are one and the same, but on two different levels of abstraction.
Well I was more imagining light infantry operations or recon in forward positions in the early stages of a war. If you need vehicles, you can use EV, then you generally don't need oil and lubricants as well. At least you don't have to airdrop fuel anymore.
"Well I was more imagining light infantry operations"
People need fuel within 24 hours at a minimum. LI need more than most because they need to move fast. I was a once a Devon and Dorset Light Infantryman (cadet). The DnDs used to have a mad pace - 180 per minute. We could get there as required and then get cut down by a single machine gun. That's old school stuff and the world has moved on.
No, it really isn't. Even in peace time you'll need most of this:
You need safe food and safe water for yourself and a chance to consume it. You'll also need water for bathing etc if you can to maintain comfort. To be combat effective you need a lot of energy. You'll also want to be comfortable so let's say 2l water for drinking and 50l for washing if possible. Food - at least 4000 calories per day.
Now you need to do something and that will require munitions and weapons. A tankie will require a lot of fuel, bits of track, lubricants for all the funky stuff. They'll need shells of various types - AP (anti personnel - basically ball bearings to kill people) and APDS types (armour piercing discarding sabot) and the other more modern fancy types with nastier purposes. Anyway - quite complicated and expensive too.
A tank out of fuel and shells is just a quick kill for the enemy.
Logistics is not that simple and we see this in Ukraine.
If Space-Based Solar becomes a thing and starts being used in war zones, then it seems almost inevitable that warfare will move in to space... and that could lead to a catastrophic chain reaction of exploding satellites (aka the Kessler syndrome[1]) leading to an impenetrable field of space junk around Earth, which will prevent or at least greatly delay further use/exploration of space.
How would space-based solar increase the risk of warfare in space more than space-based communications and geolocation infrastructure already risks it? Knocking out GPS satellites seems like it’d be nearly as effective as knocking out power-supplying satellites.
I guess maybe the difference is there is redundancy in the GPS network – taking out one satellite wouldn’t do much damage, but with power supplying satellites I presume it would.
There's also a symmetry concern. All parties to any conflict would be using something like GPS. But if only one has access to SBS, the others have less to lose by taking the fight into space.
Of course, a country that can shoot down a satellite can probably already launch a nuke, if they have one. And they likely have a bunch of stuff in space as well.
There are a few counterexamples, but they wouldn't be, for instance, Russia or China or the US. They'd be mad to do that over a power delivery system that they can utilize or hack.
The US Military can degrade GPS performance of a selected area while keeping the military encrypted accuracy at standard levels which they did during the Kargil War IIRC.
Not all that difficult for a ground deployment to know where they are without GPS. You know (generally) where you started, what direction you’re headed, and how fast you’re going. Maps exist, and cartography is still taught. Not to mention things like astral analysis.
Much harder to generate power from nothing in the middle of nowhere.
Dead reckoning is not appropriate for modern warfare and may result in death. Recent example would be Russians getting lost in Ukraine because the locals changed all the road signs.
space based solar probably works fine outside the atmosphere, but any space based "power beaming" system would need to contend with the entire thickness of the atmosphere for path loss.
> Imagine being able to deploy energy anywhere on Earth and not have to setup a logistics chain to facilitate it.
theoretical setups for receiver arrays for space based solar power beamed over microwave are very large, if you're going to go to the trouble to erect a big receiving array somewhere in an empty piece of land, you might as well just build a large ground mount photovoltaic system based on commodity 72-cell monocrystalline Si 400W rated panels.
The atmosphere is fairly transparent to microwaves, so the loss shouldn't be much worse. The book The Case for Space Solar Panel cited net efficiency of 40% with the tech at the time it was written, with a theoretical maximum of 60%. It's a pretty good deal given that a panel in geostationary collects five times as much energy in 24 hours as the same panel on the ground, and the power flows 24/7 for most of the year with no need for storage.
I'd question whether anyone writing "the atmosphere is fairly transparent to microwaves" has calculated the link budget, then implemented in the real world an FCC part 101 licensed microwave radio system (example: 1024QAM modulation, 11 GHz standard FDD band plan, +16 Tx power, 80 MHz channels H&V dual linear, 35 km, 180 cm high performance dishes both ends) and seen the path loss in reality.
I think anyone that's done terrestrial point to point microwave telecom professionally will take a very skeptical view of things like 10 GHz band, 1 km power "beams".
the reality is that the atmosphere absolutely eats microwave, and when it's not eating it, you have temperature inversions, ducting and diffraction effects to take into account at long distances as well. this is why their demo only works at 1.0 km.
Indeed. Such a writer may, however, have read up on studies on expected losses for the frequencies proposed for SPS. The book I mentioned covers a lot, but a paper I just googled is available on scihub at your discretion. Here's the abstract: https://www.tandfonline.com/doi/abs/10.1080/00222739.1970.11...
The paper is published in the Journal of Microwave Power, proposes using a wavelength around 10 cm, and with a vertical beam calculates a loss of 1% in clear skies and up to 10% loss with rain.
There's an equation for that. The effective range of a Gaussian beam is roughly equal to (beam width)^2 / wavelength. I'm not sure what wavelength or beam width they used here, though.
In fact, SPS designs involve receivers measured in square kilometers. But they'd be mostly wire and would only contribute about 0.7 cents/kWh to the cost.
Why do you think it's a maser? High power microwave beams are a thing in radar. We don't use masers to make them. We don't use masers in microwave ovens, either, or in industrial applications requiring high power microwaves.
No, the ionosphere does weird things, including self-lensing at high enough power densities (frequency dependent too), so there's probably a bit more to test
It is. I guess I was extrapolating without explaining. Whatever results they get from this test at sea level, they should be able to predict the efficiency for a Space Based Solar System. I wasn't necessarily saying their test verifies that Space Based Solar would work, but just that they have the information to determine if it would.
- Build a massive fleet of power-shunting satellites
- Deliver all of that down to the ground
I think you may have watched too many James Bond movies.
What seems to be missing is consideration of what happens to all that 'lost' power.
In their test, they sent 91kW, and received 1.6kW, over a distance of 1km. That missing power doesn't just up and disappear, it's heating the air and water between it. You'd have to scale this up, massively -- I'm not good enough at the math or physics, but I can't imagine it gets any easier at longer distances.
So what you're really describing is a death-beam that even if you don't cook the people on the ground, is going to be dumping huge amounts of heat into the atmosphere.
I doubt it's never going to be practical enough to be useful, at all.
I might be wrong and someone can do the calculation to prove me wrong, but I don't think there is any way you're going to power an army or even a single regiment with that (or even more than a couple of toasters).
First, Low Earth Orbit is at least 160km above the Earth. You could do it at 100km but now you have to fight atmospheric drag on top of everything else and constantly need to readjust your orbit to avoid burning up.
Forming a beam tight enough that it stays focussed on your small target is the first challenge. Talk about fraction of a degree. You'll get much worse energy loss just there, because your target will always be smaller than the energy spot. If you have to build large targets, then there is a point where it would be more advantageous to just use solar panels on the ground.
Second, since you'd be using a low orbit, you'd still be in the dark at night, so no power for you.
Third, the lower the orbit, the faster the satellite is going to zoom past in the sky. You'd need a constellation of these to constantly reshape their beam to all their targets. As their distance from the target increases, the power received will also vary a lot. It also means the satellite will have to know the precise location of the target at all times. Might be workable for a static unit, but if you're talking drone/autonomous system, then they will need a way to transmit this information somewhere, very, very accurately too so the beam can find it.
It's not something you could deploy anywhere in an instant unless you have thousands of satellites covering all areas of interest.
The solar panel size you would need to ensure some decent minimum power received on Earth would be pretty big. Say you have a super efficient solar panel that can get you 30% efficiency, you'd get max of 300W/m2. So you would need very large arrays of panels just to get a few kW on the ground.
Now if instead of solar panels you want to beam up energy to bounce from the satellite back to the target, you'd double your problem space: need lots of large emitters that would need to target a constellation of fast moving satellites. Not great unless you know you can deploy them exactly where they are needed, which probably limits the use cases in foreign territories.
So, I'd say this will remain a niche application on Earth, where the size of the transmitting arrays depends on the distance to the target, and will probably never go beyond a trial in space if they manage to convince someone to get funding for it.
> First, Low Earth Orbit is at least 160km above the Earth. You could do it at 100km but now you have to fight atmospheric drag on top of everything else and constantly need to readjust your orbit to avoid burning up.
I am just thinking out loud but what if we went out further and added an array of satellites in the geostationary orbits, not to power anything on earth but rather to power each other. I was thinking if we had enough of these satellites and they were in line of sight between each other, could they kind of send power to each other in case one of them was in the dark? Just thinking out loud.
Geostationary orbit is 36000km. Imagine the amount of power you would need to concentrate to be able to create a beam of energy small enough to hit a target that is zipping by 36000km below.
And these geostationary satellites would still be in the earth's shadow. Even the moon gets in the earth's shadow, and it's more than 10x the distance. You would need to have a bunch of satellites that can bounce energy to the target at low angles (so longer distances) which makes losses a lot worse and the problem even more complex.
Others have also mentioned that the claim of achieving 60% efficiency at 1km looks dubious. Look at the pictures of the size of the antennae needed to basically run a couple of toasters... extrapolate even just a bit to compensate for the orders of magnitudes in range.
I agree we won't be powering individual vehicles from orbit, but geostationary satellites don't go in shadow for most of the year. The reason is that the Earth's axis is tilted with respect to its orbit around the sun. The only times the satellite is shadowed are around the equinoxes, for a total of 88 days per year with most of those days only shadowed a few minutes, and a maximum of 72 minutes on the equinoxes.
Here’s an out there scenario - a few power generating aircraft or satellites in high orbit sending power down to drones at lower altitudes, and vehicles on the ground that just have inverters and motors. No costly batteries, let alone the logistical supplies required for fuel and maintenance for combustion. You are no longer limited by the slow moving fuel vehicles; a blitz is a whole other thing now.
Generators and solar arrays are the backbone of most forward operating bases - no longer. You have so much more freedom and space as you are no longer restricted by your power / fuel requirements.
It will shift the balance of war, vehicles, infrastructure, logistics.
For less military uses - imagine doing away with power cables entirely. No more costly infrastructure built above or below the ground. Just a few towers (much like mobile phone towers) transmitting to households. Depending on where the technology goes, imagine not needing batteries in anything anymore. You’re just hooked up to the wireless grid for power too.
It’s still in its infancy, but this is pretty significant.
This sounds great, but extrapolating from what I see in the article, the setup required for moving any for of armor would be impractically large (not to mention fragile).
I’m fairly certain that even if this works you need battery or fuel based backup power.
Or you know, maybe we can strive for less wars and all that. Because this also means space warfare is going to become an important component of every major military power's defense system, and that's not good.
> Imagine being able to deploy energy anywhere on Earth and not have to setup a logistics chain to facilitate it.
I suppose. But on the other hand, let's say "anywhere on Earth" is a PCB inside an attacking enemy jet fighter. I haven't designed any PCBs for the military, so I don't know what their standards are, but I can say every low voltage circuit I've designed would not appreciate even 10W being dumped into any arbitrary net...
Isn't this more likely just the cover story for a space based death ray? Why pass energy to the ground for your troops, if you can just kill your targets from space?
Frankly, I'm a bit tired of these proposals transmit power by microwaves back to earth, especially so when frequencies such as 10GHz are either proposed or are used as test frequencies.
Do these people actually realize the likelihood of interference to RF and Microwave bands from potential intermodulation products that they'd cause? It would be an environmental disaster much worse than Musk's light-radiating satellites. I'd reckon that huge swathes of radio spectrum users includibg radio astronomers would be up in arms at such an outrageous proposal.
I've nothing in principle against such a proposal but it needs to be done in a part of the spectrum that will not cause interference to communications - and that will take considerable research and planning. For instance in the infrared or THz spectrum but even then we'd need to take great care for many reasons. (Recently, I've heard of experiments to detect neutrinos in the THz spectrum so that may also be ruled out).
I've strong thoughts about the inappropriate funding of this research in the 10GHz spectrum but I'll refrain from further comment for the moment.
Just let's say I've insufficient adjectives in my magazine to ensure a knockout.
> For context, 1.6 kW is about enough to power 1 home appliance: a dishwasher, refrigerator, or toaster.
Most (US) homes put outlets on a 15A breaker (sometimes 20A), which gives have 1.8 kW to play with. So this is less power than a typical home outlet.
> I think your A/C would be more - but I'm not certain
A/C definitely requires far more power—you have to deal a high peak load for motor start. Absolutely not happening with this setup.
The applications of this are rather curious, and definitely not for the any typical person. Probably defense, with a very short lead time, with the need for faster mobility?
> If you had Solar panels deliver this power [...]
Yes, definitely. And it can still be highly mobile: https://www.youtube.com/watch?v=VTiDklyEYaI (and once a setup is at a location, you could throw it on the back of a truck for some short-range transit. You'd just need to spread out the solar in each new place. FWIW, Solar and Microwave both have interesting yet different line of sight requirements.)
> Most (US) homes put outlets on a 15A breaker (sometimes 20A), which gives have 1.8 kW to play with. So this is less power than a typical home outlet.
US outlets run at 15A, but per the NEC [0] no single plug-in appliance can continuously pull more than 80% of the max rating, or 12A. Which is why space heaters all max out at 1500W instead of 1800W. But an intermittent appliance, like a hair dryer or toaster, can pull the full 1800W though.
My window-mount AC unit says to put it on a dedicated 15A circuit, which should mean it pulls a maximum of 1.8 kW, no? Otherwise it would trip the breaker every time it turned on.
Most breakers do not trip instantly. They are designed to protect the wiring insulation from melting. Because the wires have thermal mass, a brief pulse above rated power is fine. Your 15A A/C may pull 30A or even 45A for 100ms while starting, and that's okay because the wiring won't overheat that quickly. It does drag down the voltage on the wiring though, which is why some lights may flicker when it starts.
Residential breakers (in the US at least) have two trip modes -- a delayed trip thermal mechanism, and a fast trip magnetic mechanism. What it essentially does is trip faster if you overload it more. There are requirements for how long a breaker can take to trip at 135% of the rating, and a faster trip time required at 200% of the rating.
I think some people have probably experienced this first hand -- if you just barely overload a breaker, it might take a little while for it to break, and if you turn it back on, it might stay on a little bit before breaking again. And if you really overload it or short it out, it'll break right away. This is all by design.
> A/C definitely requires far more power—you have to deal a high peak load for motor start. Absolutely not happening with this setup.
It depends on what size A/C we're talking about. After all, window units run off a regular 15A wall plug.
I've also run an RV A/C unit manufactured around 2006 at about 13 amps continuous draw during duty cycle, insignificant surge at startup, with a 3 kW inverter (plenty of capacity left over) and LiFePO4 batteries.
Make that A/C 10+ years newer and it would draw a a few amps less, too.
And if the surge is too much, there's an extra gadget you can install in the A/C that's essentially a capacitor for smoothing the surge.
In the US this is almost exactly the maximum you'll find to not risk blowing fuses. Electric heaters are probably the most obvious continuous draw ones.
Those appliances nearly never have 100% duty cycle. It's important to note that this power can be transmitted when it is cloudy or nighttime and could potentially require less weight and setup.
I'm not saying line-of-sight transmission is a great solution, but this is an impressive engineering demonstration with some limited battlefield application.
Yeah, but only for fixed sites, or intermittently mobile sites.
Perovskites open the possibility of printing your solar cells on flexible films, so the panels can be unrolled like projector screens or greenhouse roofs, and rolled up again.[1]
10-15 kW of panels and suitable batteries would get you near 1.6 kW continuous.
This (microwave power beaming) is for battlefield applications, where mobility is primary.
Perfect application for this tech. Drones can fly back to the ship to recharge without landing, local aerial defence fleets can be lighter as they'd need a smaller capacity battery.
Moderately long distance wireless power transmission has a whole host of applications.
The key point here is that it has a 60% efficient.
The question is, why is it important?
Well in the later part of Afghanistan war, significant time, money, and lives were spend shipping diesel around. If you can avoid that, you can save a shit tonne on logistics.
From the YouTube comments:
Video carefully avoids to state that the overall efficiency of the system is 1.8%. Input power was 91.2kW at the TX antenna, out of which 1.65kW was produced at the receiving side.
https://ieeexplore.ieee.org/mediastore_new/IEEE/content/medi...
based on terrain and other logistical challenges in Afghanistan I bet you $5 that sending a 20' ISO container packed with solar panel/ground mounting/advanced battery system would accomplish a whole lot more kWh per month than a "power over microwave" system from some central point to regional FOBs.
1.0km and 60% efficient is not very impressive.
various parts of the DoD are very interested in things like hydrogen fuel cell generators, more advanced/efficient diesel generators, prepackaged photovoltaic power systems, etc. they fund and buy prototypes all the time. they're well aware of the problem in transporting liquid fuel around.
Plenty of applications at 1 km and 60 % are possible, many devices are small and becomes easier to operate around a outpost if powering them wasn’t impractical with wiring , or have short battery lives
Recharging drones is a good example, depending on how compact the receiver can be developed you could even integrate into the drone and keeping it up continuously .
There are bots like the stuff Boston dynamics builds that can work in say a minefield or other hostile environments for more time or continuously if you could be beam power to them.
You could use it to recharge cctv and other perimeter monitoring system sensors rapidly in a new output where you haven’t time to do wiring , or the outpost is temporary .
In a urban environment you could to keep you active EM emitting equipment like radar / satellite dishes equipment 1 km away and be safer from missile strikes.
Sure it would be nice to have 100s kW at 10s of km but a kW is plenty of power for a lot of devices and there are solid applications
Seems like it would introduce a single point of failure. Hit the transmitter and all drones, cctv, etc will shortly go down. Even if they had a handful of microwave stations that feels very vulnerable for powering the military effort.
Yea, seems like easier technology is out there for real battle zones. I think this wireless power idea would be best in disaster scenario areas on the US mainland after weather events.
They could pre-ship out the dishes to EMA agencies around the country. Quickly deploy in a few hours and re-power areas that have been destroyed by hurricanes/tornadoes/wildfires until the electrical grid is re-established or a ISO container can be sent.
That was my first thought as well, but, when you are able to deploy this transmitter, you are most likely also able to deploy a huge generator and some big generator trucks can deliver a thousand times more energy than this wireless thing.
I'm not sure how passive solar panels would be more covert than actively emitting radiation. Solar panels may be more visible from satellite imagery, but your base is going to be visible anyway. Militaries have been focused on pinpointing micro-wave emitters for decades, it's foundational to detecting radar stations.
Even the smallest sort of COP or FOB is very obvious where it is - you aren't going to disguise any concrete t-walls, rows of stacked HESCO bastion, perimeter guard towers, etc.
it's a whole construction project to erect one, anybody that lives in the area or has access to half-decent aerial photography is going to know fully where/what it is.
putting up a big-ass tower with a flat microwave receiver array aimed somewhere towards the horizon is going to be even more obvious than ground mount solar.
So like all technological achievements, things will improve so the amount of power that can be transmitted will increase and the distance will increase.
At some point in the future it might become feasible to beam the energy down from a Low Earth Orbiting Satellite, which would transfer logistical costs into the preemptive side of accountancy instead of reactionary accountancy, but if they could do this from a LEO, then perhaps its also become a bit of a non ballistics weapon which may not be covered/restrained by current international agreements.
Most solar power satellite designs put the sat in geostationary, which simplifies things dramatically. It makes the power density low enough at ground level that birds can fly through the beam without harm. The receiver has to be several square kilometers but it's mostly antenna wire.
The transmitter would be a phased array antenna, and getting even that much focus would require a reference signal transmitted from the ground station.
In my opinion by the time you're going to the trouble to clear a flat plot of land and get into the construction project of erecting a several square km sized receiver array, you might as well just go whole-hog on commodity ground mount photovoltaics on the same area of land. And totally eliminate the cost of the satellite.
There's plenty of contractors out there who specialize in building such things from existing COTS systems/subsystems and components. Look at the specifications and size of some of the large ground mount PV systems in China and India. Margins are very thin in this business and very competitive on $ per kWh feed-in tariff rates paid to contracted systems. The construction process has been optimized to nearly as good as it can get now. Labor is a major cost.
doesn't necessarily have to have batteries, as in many common installations, daytime PV is used to flatten the curve of fuel consumed by regional coal, gas, other fossil fuel power plants servicing the daytime peak of load demand. Conveniently enough in many places with hot weather when the peak of load demand is occurring mid afternoon with everybody's air conditioner running, the PV system is also performing at its best.
Or can be connected to something long distance similar in tech to the pacific HVDC inter-tie to move power long distances to where it's needed, or can be used to pump water uphill in a nearby pumped-storage hydroelectric system.
I mean yes, of course ground-based is cheaper if it's just part of a grid with lots of fossil power. I'm assuming we want to eliminate the fossil plants. For that, SPS at SpaceX Starship launch costs has a decent chance of being cheaper than ground-based solar plus the the various extra systems required to turn it into reliable power.
It was built but that’s not the real story. Ignore the TV documentaries.
The real story was the tower was built for information not power delivery. But Marconi got there first and made it irrelevant. Tesla decided to repurpose the thinking around some fanciful bullshit for power delivery to pay off all the money he’d borrowed to build it. This cycled into non delivery, because quite frankly it didn’t work, and he ended up bankrupt, living in a hotel for free after giving the hotel owner a “death ray” for security. This turned out to be some primitive measurement device.
Tesla did a lot of good work on AC power delivery however. But that was it. I’d rather remember him for this than the legendary bullshit.
Whilst 60% is efficient and it's an excellent figure don't be fooled by the hype. I reckon what they've said in the the video is outrageous in that much of it is deceptive and misleading in the extreme.
Let's briefly look at some of the issues:
1. We need to carefully look at where that efficiency happens and then examine every place where loss of energy can occur, especially those that aren't stated. Let's take a brief look at some of the more obvious ones:
2. Conversion of energy into power suitable for generating microwaves at the transmitter. On earth, and assuming direct connection from the power grid, we need to consider losses in the power transformers and power supply or switching power supply, these days efficiency can be very high perhaps even 90% or more. As this equipment will be used primarily for military use, it would likely couple with diesel motor/generators suitable for use in the field, if so then I'd be surprised if the combo was more than 35% efficient at best (someone who knows up-to-date specs on these units correct me if necessary). If the unit is ultimately used in space then the conversion efficiency of its solar panels must be taken into account. As far as I'm aware no solar cell has ever reached 60% or over—even the best GaAs ones (from memory, this 60% figure would exceed theoretical 'quantum efficiency' figures).
3. Assuming no other loss at the power supply end (such as offline batteries, which are a distinct possibility in the field in military use) then we have to take the efficiency of microwave sources into account. I've not up-to-date figures on the latest 10GHz generators so I'd be guessing these figures, suffice to say that until recently generating microwaves was comparatively inefficient (unless magnetrons are used and they have messy and inconvenient HV power requirements).
4. Next comes the waveguides, antenna horn and focusing unit and the antenna (these, if optimized, could be quite efficient).
5. Now comes the path loss between transmitter and receiver. Exactly what that is remains to be seen. I've worked with microwaves and I can assure you that it is dead easy for the antennas be slightly off alignment and you receive almost no signal. For this scheme to work efficiently there would have to be some kind of efficient control system (servo/feedback, etc.) that keeps the TX and RX antennas in precise alignment. Moreover, at 10GHz a storm or a heavy rainfall downpour could kill the circuit altogether (I've actually seen this happen to the extent that only over a path of a half dozens or so miles that not only the fade margin, normally >30dB, on microwave links was exceeded but also the signals fell so low that the circuit was actually lost. Moreover, for reliability, two microwave links were run in parallel and both circuits failed for some 5 or 6 minutes until the rain cleared).
5a. Now the killer bit: as mentioned, commercial microwave links have huge fade margins to protect against variations in atmospherics and objects—planes etc., blocking the way. These links have what is known as AGC—Automatic Gain Control—to keep signals level. That cannot apply in power transmission; in practice, even a temporary path loss of 6 - 12dB (which could easily be expected) would essentially be catastrophic, that is effectively kill all received power at the receiver (they'd want to have pretty good battery backup and often in military operations that's not always possible, extra weight etc.)!
6. Now comes the horror bit (this could also apply to the generation of the microwaves at the transmission end). That is, the rectification of microwaves at the receiving end will generate considerable RF hash and noise. To be efficient, the diodes rectifying the incoming RF would have to have an f(t) of well in excess of that frequency and heaven help anyone operating a microwave receiver within many miles of the receiver (radio astronomers for instance). As the rectification diodes have to be near or on the antenna for efficiency, screening them to stop them radiating locally generated crap everywhere would be a near impossibility—remember your Fourier lessons, you're chopping sine waves up to get DC and that means harmonics—the more efficient the process the more noise generated! Any attempt to filter the hash and noise generated by the diodes would further reduce efficiency. This is the sort of scenario that spectrum managers and planners have nightmares about.
Whilst this isn't quite the same, here's an example that illustrates what can happen. I had an Amateur Radio friend who used to do moonbounce on 432MHz and he'd often complain to me that various LED lights (i.e.: diodes) in his neighbors' possession would interfere with his incoming reception to the point where on occasions he'd have to abort the exercise. Now keep this in mind, he raised this matter with me over 10 years ago when LED lighting was far less common that it is today.
Face the facts, much of this pronouncement is little more than spin. Likely the principle reason the video was made was to keep their funding masters happy. Little of it will fool the technical cognoscenti.
Also keep in mind that all 'niceties' are off during military conflicts, interference to services other than to the military's own communications equipment would likely be irrelevant (as we saw in WWII, the military was the principal user of spectrum, what it wanted it got).
As for a permanent space port 'broadcasting' power to earth the idea is ludicrous—that is, until thousands of questions about likely problems have been asked and that genuine engineering solutions for them are actually found.
Seems to me their PR department has taken a leaf from the wordbook used by social media and politicians—that's the one that redefines the word 'fact'!
Is there some reason that this doesn't scale up to however high you want if you add more input power? I would have thought that 60% efficiency would be the interesting figure, not 1.6 kW.
I wonder if you could use this for "aerial refueling" of an electric drone - might be a cheaper way to make small long-endurance vehicles than trying to stick ICEs in them (though it has the downside of "tethering" them to a ground station).
google "microwave atmospheric path loss calculation" or "microwave free space path loss" - standard calculations for point to point microwave telecom systems, you lose quite a lot to the molecules in the air. probably would work a whole lot better in a vacuum.
Is there any chance that this could ever be reliable enough to act as the primary power source for a plane? (In other words, you'd keep just enough fuel/battery onboard for emergency landings, and otherwise rely almost entirely on space microwaves.)
If so, is there any possibility that it could also provide sufficient throughput to handle supersonic flight?
What if we spent most of the journey at a very high altitude, or even in/near LEO?
Some day, probably. But right now others have pointed out that this system is actually only 1.8% efficient as the 60% figure was just loss from antenna to antenna, but the initial input was almost 100kW!
And I don’t know much about this but it seems shooting high energy beams of radiation everywhere creates other issues.
I wonder about whether a big enough orbiting phased array, with all the elements carefully quantum-entangled, could achieve much better power delivery to a small receiver.
In this scenario, the phased array transmitters would be placed randomly in a swarm. The receiver would broadcast a pilot signal, and they would all adjust their phase by the received pilot-signal phase and, implicitly, their position in the swarm. (Maybe the pilot signal is at exactly half or twice the transmit frequency, and a maser, so all its photons are entangled.)
I don't know how you arrange to quantum-entangle the transmitting elements and their emitted photons to the pilot signal and (this) to one another. The goal is for all their quantum amplitudes to interfere constructively only at the rectenna, and so deliver all of their energy there. Is there any necessary or enforcible relationship between the photon wave phase and its quantum amplitude?
For a decoupled swarm to stay together, each would need to be in a slightly different almost-circular orbit, continually milling about a common center. Alternatively, they could have hair-thin fibers tying them to near neighbors, and all orbit as a unit.
Department of Energy studied the use of phased arrays to beam power (http://spaceflighthistory.blogspot.com/2016/12/energy-from-s...). The use of a pilot signal was useful because it prevented any 'death ray' scenarios. The transmitter would only be able to beam power to a receiver, even if it was knocked off target.
I am not sure what the benefit of a small receiver would be for power transmission. The DoE system used the same 2.45 GHz frequency as a microwave oven, so the receiver was more like chicken wire than the receivers we are familiar with. They would have been very large to prevent overflying aircraft or birds from being fried by the transmission, and could maybe be placed on pylons over otherwise useful land.
If you could use a small receiver, it could be mounted on an aircraft. The transmitters would have to know the velocity vector of the aircraft so as to adjust their focus to where its receiver will be when the waves get back to it, not where it was when its pilot wave was sent.
Without some (quantum) way to ensure that the energy is delivered exclusively to the rectenna, such a system would be hard to justify deploying.
No idea. I don't have a large enough maser to verify. I'm aware that plausibility != proof but certainly there is some level of energy delivered to moisture in the air that would move it. The arguing is about how much you need.
We already have clear evidence that human constructs change weather patterns. The next part is predicting it.
42% is RF to DC conversion efficiency, absolutely no way those omni antennas are end to end dc-rf-dc 42% wireless transmission efficiency at any distance, its going to be many orders of magnitude worse.
Had to do a double take for a minute, as in my days in the Army, we could max out our AN/TRC-170 on troposcatter mode at 2.0 kW, with a substantial range on a good atmosphere day.
The use case here, however, is incredibly different. We'd typically be towing 2x 10 kW diesel generators with us, so this is certainly an interesting POC to follow.
one of the fun things about "modern" troposcatter modems is they're pretty much the same as the more advanced SCPC satellite modems you might see in use for a dedicated piece of transponder kHz in the C or Ku bands, and a geostationary-based link between two locations. I've only done a tiny bit of troposcatter but it's my understanding that the extreme loss in the path generally results in using fairly rudimentary modulation (like QPSK 1/2) with a vast amount of FEC in the total percentage.
> The frequency was chosen because it was not only able to beam even in heavy rain with a loss of power of under five percent, it's also safe to use under international standards in the presence of birds, animals, and people.
What frequency is this specifically? I'm curious to know how people-safe it is in practice.
Let's hope we don't end up with the SimCity 2000 variant where the beam occasionally misses the dish and causes a fire. (The Internet tells me that in SimCity 3000 this never occurs.)
The headline makes me wonder - what ever became of Tesla's dream of an building a global atmospheric electric power network? Is it for commercial, physical or technical reasons that the idea seems to have been given up?
The only way this is in any way interesting is as a 1950s style death ray, and even then, it's only enough to warm porridge at that distance. A close-quarters vehicle mounted version at 100m might be a different proposition.
Wow, 60% is way higher efficiency than I thought these systems were getting. I was fully expecting “using 16kw of power 1.6kw was successfully transmitted”
Sure easily, as long as the ship stays within 1km of an active transmitter at all times and each transmitter has a power station on it to provide enough juice to push through the losses or is connected to a grid.
I think the end goal here is for the power to be delivered via satellite, which would be great for a ship out on the open ocean. Though you’re right that a nuclear powered ship would be better
No. “ The frequency was chosen because it was not only able to beam even in heavy rain with a loss of power of under five percent, it's also safe to use under international standards in the presence of birds, animals, and people. This means the system doesn't need the automatic cutouts developed for earlier laser-based systems.”
There's a pretty big spectrum between "safe" and "catastrophic".
Probably only a fraction of a percent of the transmission energy is getting absorbed by the body, but that doesn't mean I'd want to try it out.
I think the idea is that you'd take basic measures to try to avoid/discourage exposure, but you wouldn't have to worry about any extreme safety measures to guarantee it.
The beam is likely much wider than a person and at a precise frequency requiring a tuned antenna to convert it efficiently to electricity or heat. You might not want to stand in it for minutes, but passing through would be safe enough.
Theoretically, it should be equivalent to standing directly in front of a space heater in the worst case (if the human absorbs 100% of the microwaves).
Yeah but microwaves aren't exactly neutrinos, those don't really interact with much of anything at all. Like comparing a sound wave with a dump truck hitting you in the face. Water absorbs microwaves like a dry sponge, which is why microwave ovens are a thing and wifi over water sucks.
Not really, because the power is not super concentrated. The power is flowing through an area of a few m2, so it's less power per unit area than a sunny day, though on a similar order of magnitude, and that's assuming the microwaves are perfectly absorbed (the frequency of microwaves used is one where water is much more transparent than the one in microwave ovens). In the video they claim the beam is safe for people and animals to pass through (based on current standards for RF exposure).
This is comparison to e.g. lasers where even if the power density is the same the fact that it's concentrated in a few mm2 makes it a lot more dangerous.
Some ballpark numbers: 1km at 10GHz is ~110dB of path loss. Those look like feasibly 40dBi antennas at both ends. That still leaves -30dB link budget, i.e. 0.1% of energy reaching the target.