[HN Gopher] US Navy wirelessly beams 1.6 kW of power a kilometer...
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US Navy wirelessly beams 1.6 kW of power a kilometer using
microwaves
Author : geox
Score : 105 points
Date : 2022-04-22 21:17 UTC (1 days ago)
(HTM) web link (newatlas.com)
(TXT) w3m dump (newatlas.com)
| awslattery wrote:
| 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.
| walrus01 wrote:
| 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.
| olliej wrote:
| 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"
| mikeweiss wrote:
| Anything in-between the beam would be badly burned or set on
| fire.... Correct?
| white_dragon88 wrote:
| Oh god yes.
| vernon99 wrote:
| 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."
| GordonS wrote:
| > it's also safe to use under international standards in the
| presence of birds, animals, and people
|
| Wow, is it really safe to beam 1.6kW of microwave energy
| through a person?
| skykooler wrote:
| 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).
| speed_spread wrote:
| 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.
| qgin wrote:
| Depends on how focused the energy is. The sun is beaming
| over 1MW per square meter and it doesn't vaporize people.
| DennisP wrote:
| Actually one kilowatt per square meter.
| nwiswell wrote:
| 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.
| freemint wrote:
| Well, apparently. For reference neutrinos from the Sun are
| around 30W 24/7 and does it harm us?
|
| https://www.quora.com/How-much-energy-is-in-the-neutrinos-
| pa...
| [deleted]
| rcxdude wrote:
| 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.
| silexia wrote:
| The most impressive note in the article is that they only had a
| power loss of five percent.
| BenjiWiebe wrote:
| It says they operated at an efficiency of 60%. 5% is the
| additional loss when it's raining. Some microwave frequencies
| are easily rained out.
| coenhyde wrote:
| 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.
| ghostly_s wrote:
| > 1km through the atmosphere is probably all you need to verify
| that the approach would work for Space Based Solar.
|
| How so? Wouldn't a space-based-solar facility need to transmit
| through the full height of the atmosphere which is much more
| than 1km?
| coenhyde wrote:
| 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.
| pmoriarty wrote:
| 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.
|
| [1] - https://en.wikipedia.org/wiki/Kessler_syndrome
| TechBro8615 wrote:
| 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.
| walrus01 wrote:
| 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.
| DennisP wrote:
| 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.
| scythe wrote:
| We're a long way from geostationary orbit with this tech,
| though. They got 1 km, now you need 35,000.
| giantg2 wrote:
| I guess it depends on how tight the maser beam stays.
| Most of that 35k km has little to no atmosphere, so that
| part is a little less important.
| walrus01 wrote:
| 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.
| DennisP wrote:
| 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.
| sillysaurusx wrote:
| My imagination is limited. Care to help me out?
|
| 1.6kW deployed to any area in the world. I'm not sure how to
| visualize that, or what the implications are.
|
| Could this power a drone indefinitely with no need to land?
| agumonkey wrote:
| 500W is enough to power a bike strong enough an adult will
| have to fight to stay on top at first. 1600W seems plenty for
| a lot of devices.
| _s wrote:
| Yes, any vehicle that can be drive with a motor.
|
| 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.
| imperio59 wrote:
| 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.
| Retric wrote:
| It might have value in a military setting, but it's got to
| be really really stupidly cheap to compete in the civilian
| space.
|
| Which seems extremely unlikely.
| reaperducer wrote:
| _No costly batteries, let alone the logistical supplies
| required for fuel and maintenance for combustion_
|
| And if the enemy captures your vehicles, you can simply
| deauthorize them and they won't work anymore.
| thinkmassive wrote:
| Sounds cool, but also like that satellite is a massive
| single point of failure
| micromacrofoot wrote:
| parachute is still way lighter than a battery
| kylehotchkiss wrote:
| it'd be really cool (and understandably unlikely) if this could
| be harnessed for cargo ships so they don't need to burn bunker
| fuel
| walrus01 wrote:
| the cassegrain reflector design dish aimed sideways like that
| looks remarkably similar to a 1970s era troposcatter data link
| system used by the DoD.
| nayuki wrote:
| Outside of SimCity games, I never heard of microwave power
| transmission in the real world...
| KaiserPro wrote:
| 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.
| Terry_Roll wrote:
| 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.
| DennisP wrote:
| 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.
| walrus01 wrote:
| 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.
| DennisP wrote:
| And add the cost of batteries.
| walrus01 wrote:
| 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.
| DennisP wrote:
| 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.
| FredPret wrote:
| There is a power plant in Sim City that operates on this
| principle. Would be cool to have a nuclear reactor in orbit!
| Terry_Roll wrote:
| Tesla built the means to transmit power in the early
| 1900's. https://en.wikipedia.org/wiki/Wardenclyffe_Tower ht
| tps://en.wikipedia.org/wiki/Wireless_power_transfer#Histor.
| ..
|
| I would imagine alot of Radio transmitting knowledge would
| be useful in this domain of knowledge.
| walrus01 wrote:
| 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.
| manquer wrote:
| 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
| bushbaba wrote:
| Those solar panels might disclose your location. This is
| likely substantially more covert.
|
| There's also a big benefit of refueling electric drones with
| this.
| walrus01 wrote:
| 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.
| Manuel_D wrote:
| 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.
| lallysingh wrote:
| This would help hide the receiver of the power, no?
| CyanLite2 wrote:
| 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.
| powersnail wrote:
| The article mentions rain. What about sandstorms or snow? Is
| microwave heavily hindered by any other climate adversities?
| cwillu wrote:
| The very latest in coerced wireless heating technology.
| jakedata wrote:
| Detune for death-ray mode.
| formvoltron wrote:
| Next stop, the Dyson sphere.
| jleyank wrote:
| A maser? Obviously tuned to avoid hitting the rotational
| frequencies of things like water vapour (think microwaves). Neat
| bit of engineering.
| R0b0t1 wrote:
| The microwave frequencies we use don't perfectly match water.
| If they did it would only heat the skin on top. They have some
| penetration.
|
| To do this they probably beamed far more than 1.6kW. You need
| to heat the vapor in the middle and either go through it or
| move it out of the way.
|
| Fun consequence of this, you can disperse clouds by pointing
| microwaves up. It doesn't take a massive amount of power
| either, but scales with power.
| ianai wrote:
| Could that trigger rain?
| R0b0t1 wrote:
| Somewhere else, yes, you're driving the clouds off, though
| admittedly the effects may not always be so direct.
| pfdietz wrote:
| Why would you think it's a maser?
| geoduck14 wrote:
| For context, 1.6 kW is about enough to power 1 home appliance: a
| dishwasher, refrigerator, or toaster.
|
| I think your A/C would be more - but I'm not certain
|
| If you had Solar panels deliver this power, you could get similar
| power if you spent ~$1.5k on a panel 6.5 ft X 16 ft
| cptcobalt wrote:
| > 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.)
| varenc wrote:
| > 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.
|
| NEC 210-23: https://arlweb.msha.gov/District/DIST_09/Electric
| al%20test%2...
| skykooler wrote:
| 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.
| willis936 wrote:
| 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.
| closeparen wrote:
| How much does a battery powered drone need to recharge?
| nannal wrote:
| 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.
| tapland wrote:
| 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.
| Neil44 wrote:
| My toaster is about 1kw, fridge and freezer a few hundred
| watts. 1.6 is touch and go for a dishwasher though.
| tuatoru wrote:
| 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.
|
| 1. Several groups are developing these. For example in
| Australia, https://www.csiro.au/en/research/technology-
| space/energy/Pho...
| gpm wrote:
| 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).
| walrus01 wrote:
| 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.
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(page generated 2022-04-23 23:00 UTC)