Wireless power transmission startup - Emrod

[AlbertL]

Opinions?
https://spectrum.ieee.org/energywise/energy/the-smarter-grid/emrod-chases-the-dream-of-utilityscale-wireless-power-transmission
https://emrod.energy/

[f4eru]

Everybody should install a wireless optical power receiver on their house. No need for a stinking startup for that.

[AlbertL]

My questions are first, of course, is this technology for real and can it deliver enough power over a sufficient distance to be useful for anything but a few very specialized applications?

One statement that makes me wonder is

Emrod’s systems by default would provide the power supply at the base station as a low voltage supply (eg 48VDC) – reduces health and safety issues which otherwise arise from using 400/230 VAC.

(from https://emrod.energy/powering-cellular-base-stations/ ).  I mean, once the power has been received, how is it relevant what voltage and frequency it's converted to at the receiving end?  Or maybe they're saying that the characteristics of the power being transmitted are retained across the RF link, which really makes me doubt the reality of the whole thing.   

And second, are there any commercially-viable use cases that can't be more economically fulfilled by conventional technology like fuel-powered generators, batteries or solar panels?

[nctnico]

If you Google around a bit you can find reports on scientific experiments where they use beamforming to transport electricity over distances of several meters using electric or magnetic field resonance. Converting these proof-of-concepts into an actual product is not easy. However it seems we'll be seeing the first wireless power transfer systems for indoor use in the next couple of years. Doing utility scale wireless power transmission is one step further. I'm not going to claim it is possible.

Unfortunately wireless power transfer reeks of 'mad scientist' Nikola Tesla but he didn't have access to hefty DSPs and blazingly fast RF transistors so his setups where terribly crude compared to what is possible with today's technology.

[f4eru]

Yeah, really, why use a cable, with 99.9% efficiency, when you could use bullshit bingo wireless technology to transmit a power over a few with meters with 10% efficiency. At best. And it doesn't scale. And you cannot extend it.

[nctnico]

Yeah, really, why use a cable, with 99.9% efficiency, when you could use bullshit bingo wireless technology to transmit a power over a few with meters with 10% efficiency. At best. And it doesn't scale. And you cannot extend it.

If you'd done some actual research you'd see that the efficiency obtained from tests with real hardware (not simulations) is way better than 10%. More in the 70% to 80% ballpark. According to your logic we should all have extension cords to our mobile phones. Did it ever occur to you that with continuous wireless power transfer a mobile phone would need a much smaller battery (which in turn means less material use and manufacturing costs)? That is where an opportunity lies besides the convenience of not having to plug in your phone all the time to get it charged.

The Emrod system seems interesting for powering remote locations where it is excessively expensive or impractical to bring a cable to. Think about wheater or avalanche monitoring stations on mountain tops. If they get it to work over such long distances.

[madires]

Won't get an approval anyway, because RF regulations limit the maximum power for ISM bands to quite low values. Choosing an ISM band for wireless power transmission deserves a .

[AlbertL]

I'm still not seeing a widespread commercial role - the kind Emrod is proposing - that couldn't be handled more practically by existing technologies.  Maybe a few specialized scientific or military applications, but heck, there's even a solar-powered weather station on Mount Everest!

[madires]

Another for ignoring the impact of weather, e.g fog, rain or snow.

[nctnico]

Won't get an approval anyway, because RF regulations limit the maximum power for ISM bands to quite low values. Choosing an ISM band for wireless power transmission deserves a .

Is that also true for systems which use strongly directional antenna's? A short search doesn't get me an answer. In the end the maximum power limit is to avoid disturbing neighbouring devices using the same band. I can imagine that the limits don't apply to a system which doesn't send signals in every direction.

[madires]

Yep, antenna gain matters for ISM bands. For example, when your WiFi router may transmit up to 20 dBm and you attach some flat-panel antenna with a gain of 6 dB you have the lower the router's output to 14 dBm.

[Marco]

Even a tiny bit of stray exposure for a human would easily take you over ICNIRP limits too ... only using it when there's no human in a room would limit the applications a bit.

PS. same for these power poles, limiting ground level exposure to ICNIRP limits for MW distribution seems a lost cause ... those beams ain't going to be that tight.

PPS. oh, they're only aiming at very low power densities ... well forget connecting power poles like on that artist impression then.

[f4eru]

More in the 70% to 80% ballpark. According to your logic we should all have extension cords to our mobile phones.

No, it i not.

[benbradley]

I'm here because Facebook showed me a paywalled Popular Mechanics article on this, and yes, FB posters are all saying "it was done 100 years ago with Tesla coils." <looking up emoticins - oh here> 
https://www.popularmechanics.com/science/a33522699/wireless-electricity-new-zealand/
A quick refresh-ctrl-a-ctrl-c copies the article text, but it's not worth pasting. At least the IEEE article has some real info: Just the transmitter is at 70% efficiency, that's already three times the loss of a large electric grid that I recall averages 90%. At a power density of a kilowatt per square meter, it's gonna take some big rectenna panels to power even one typical home.

It may not be quite as bad as Solar F'in Roadways, it might have some niche applications, but it appears it's being advertised as running Real Commercial Power, and no, it won't. It's "relatively" low power, and just the off-beam leakage will blow away any nearby use of the frequency band, and perhaps adjacent bands too.

[jonpaul]

If you read some classic electromagnetic theory texts, you can see that regardless of TX and RX antennas, the radiated power is far greater than the recieved.

Tesla used 50 KW at several MV to light a few 1/2 W lamps perhaps 300' distant!

See the BTL studies of the SBSP = Spaced Based Solar Power back to 1960s.

https://en.wikipedia.org/wiki/Space-based_solar_power

Side benefit! CAN BE USED AS A WEAPON!

ENjoy,

Jon

[tszaboo]

Won't get an approval anyway, because RF regulations limit the maximum power for ISM bands to quite low values. Choosing an ISM band for wireless power transmission deserves a .

Is that also true for systems which use strongly directional antenna's? A short search doesn't get me an answer. In the end the maximum power limit is to avoid disturbing neighbouring devices using the same band. I can imagine that the limits don't apply to a system which doesn't send signals in every direction.

Yes, when I was doing RED certification, we looked up the peak antenna gain from the datasheet (it was 2 dB, best would be 0),  and reduced the max TX power with that much. Also increased with the efficiency, but that's no the point. I wasn't doing it, the certification engineer from the NoBo was doing it, high confidence that he knows whats what.

[tautech]

Opinions?
https://spectrum.ieee.org/energywise/energy/the-smarter-grid/emrod-chases-the-dream-of-utilityscale-wireless-power-transmission
https://emrod.energy/

Dunno what they're smoking but when they run out of it it's gunna be a hard landing !

A client has done 10KW over 200mm and this wireless power transmission shit isn't easy !

[Circlotron]

Do kW size, GHz capable rectifier diodes even exist?

[madires]

Yes, when I was doing RED certification, we looked up the peak antenna gain from the datasheet (it was 2 dB, best would be 0),  and reduced the max TX power with that much. Also increased with the efficiency, but that's no the point. I wasn't doing it, the certification engineer from the NoBo was doing it, high confidence that he knows whats what.

BTW. the gain of 2 dB, actually 2.15 dB (theoretically), is the gain of a lambda/2 dipole (0 dBd = 2.15 dBi) over an isotropic radiator (0 dBi).

[madires]

Do kW size, GHz capable rectifier diodes even exist?

Maybe it was an oversized induction cooker.

[Marco]

Do kW size, GHz capable rectifier diodes even exist?

In a rectenna you have lots of little diodes, so that at least isn't the problem.