Mitsubishi Wirelessly Sends Electricity Across 500-Meter Gap

APR 18 2015 BY MARK KANE 14

Wireless Charging Display

Wireless Charging Display

Wireless charging isn’t the basic method of EV charging, although there are a lot of developments in this area and the first products for cars are already available (mostly through Plugless Power).

Typically, wireless charging is done over short distances, but special technology enables the sending of energy over long distances as well. Now for sure this is not directly related to EVs right now, but it does give us a broader perspective of what can be done.

Mitsubishi Heavy Industries recently announced that using microwaves it can wirelessly send 10 kW of power over 500 m.

The chance that equipping an EV with microwave oven will let you do the same is unlikely, Mitsubishi’s aim here is space solar power systems (SSPS) and is considering other industrial applications (wireless power transmission to locations where installation of power cables has been difficult or dangerous, offshore wind turbines).

“Mitsubishi Heavy Industries, Ltd. (MHI) has conducted ground demonstration testing of “wireless power transmission,” a new technology presently under development to serve as the core technology of the space solar power systems (SSPS) that are expected to be the power generation systems of the future.

With successful completion of the test at the company’s Kobe Shipyard & Machinery Works, MHI has now verified the viability of long-distance wireless power transmission. In the ground demonstration test, 10 kilowatts (kW) of power was sent from a transmitting unit by microwave. The reception of power was confirmed at a receiver unit located at a distance of 500 meters (m) away by the illumination of LED lights, using part of power transmitted.

The transmission distance and power load mark new milestones in Japan with respect to length and volume of wireless power transmission. The testing also confirmed the performance of the advanced control system technology used to regulate the direction of the microwave beam so that it does not veer from the targeted receiver unit. MHI conducted the ground demonstration testing based on an agreement with Japan Space Systems, the incorporated foundation that has been consigned by the Japanese Ministry of Economy, Trade and Industry to carry out the “2012 Solar Power Wireless Transmission Technology Development Project.”

In the comments on Green Car Congress we found that the record-breaking wireless transfer is pretty old – 34 kW over 1.5 km (almost a mile) at 82% efficiency in 1975!

“The June 5, 1975 NASA JPL Goldstone Demonstration of high power long distance wireless power transmission successfully transmitted 34kw of electrical power a distance of 1.5km at an efficiency of greater than 82%. At the time, it was the world record for high power long distance wireless power transmission, and it may remain the world record yet today.”

Categories: Charging, Mitsubishi


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14 Comments on "Mitsubishi Wirelessly Sends Electricity Across 500-Meter Gap"

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I have to wonder, would this be a health and environmental hazard? People worry about transmission lines, this seems to be far riskier.

At the Nike missile site museum in the Marin Headlands, they had this post WWII tracking radar that sent out a lot of power. It could kill a man at 10 feet distance, a bird at 200 feet (seem that would make it a target itself). Unless they can show this microwave energy doesn’t have have I’ll effects on biology, it’s a nonstarter.

Well, if you pump enough energy thru human tissue, it certainly will cause damage, regardless of what the energy is. However, despite a lot of fear-mongering and a lot of lawsuits, nobody has ever shown any statistical relationship between any chronic illness and living near power lines. Even the recent claims that excessive use of a cell phone pressed to your ear may cause an increased risk of brain cancer appears to lack clear evidence. The amount of radio energy put out by your cellphone is pretty small.

Regarding large, high-power radar dishes: I do recall an older tech guy plausibly saying that if you threw a ball of wadded-up aluminum foil into the focus point of a WW II era radar dish, you’d get a spectacular fireball. But the ability to “kill a man” at a distance of 10 feet… I’d like to see some documentation on that. More likely, it’s an earlier version of this urban myth:

It’s what the docent at the Marin Headlands said, who had worked in one of the stations many years ago. I’ve been a little skeptical of powerlines, but I know they can create surprising strong magnetic fields; I saw a six inch chain underneath one of them stand straight up.

Good luck to them. I can’t imagine making any business case for this in the long run though. Possibly for the offshore turbine thing. Even with all the benefits of having solar panels in space vs. on the Earth’s surface I can’t image the ROI ever working out over the panels’ 20-30 year lifetime. Would you really get that much more energy per panel in space to offset the cost of getting them up there? Think of the cost difference of installing 2,000 lbs. of PV panels on Earth vs. 2,000 lbs. of panels into a stable orbit. On Earth installation costs are about equal to the panel cost. In space at a cost of $10,000 per lb. to orbit, 1 ton of PV panels which would give you about 8 kW, would cost $20,000,000 just to launch into orbit. Even if companies like Space X can get that cost down to $1,000 per lb. in the future it would still cost $2,000,000 for 8 kW. That’s not including the cost of building the specialized space platform they would ride on with all the electronics and guidance and microwave beaming equipment on board and the added cost of launching that… Read more »

I agree, it looks like this tech is a solution looking for a problem.

I was an active member of the Liftport forum for awhile, when that company was touting itself as a project to build the Space Elevator. There was an intense discussion of the technical issues there, by a lot of well informed people. The consensus on solar power satellites was that even if the launch costs were free, a space-based system for beaming microwave power to Earth wouldn’t be cost-competitive with ground-based power generation. The cost/benefit ratio is too low, partly due to the inefficiency of beaming power over long distances.

The idea of beaming power to cars as they travel along the highway, eliminating the need for a large battery pack, is something that I see talked about in a lot of posts from people building castles in the sky. I suppose it’s not impossible that some future near-magical tech might lower costs sufficiently for that to become practical, but at least for the near-term it’s not going to happen.

In general terms I agree with the fact that it is more interesting to have the solar panels on Earth but there is a surprising exception on Mars. Indeed in that specific case the solar panels must be carried from Earth into space and from Earth orbit to the Mars orbit. Since they arrive on Mars orbit in the first place, why spend extra energy to bring them down on the surface. If they remain in orbit they will not need that extra energy and they will remain dust free. The Mars geostationary orbit at about 14000 km of altitude is also much close then on Earth, which means a short her distance to beam down the energy. Being in a Mars geostationary orbit also means that you don’t need relay stations on the ground to allow full time operation. An additional advantage on Mars is the possibility to avoid power transmission lines on the ground since a geostationary solar station could beam energy to multiple points on a same planetary hemisphere. Actually 2, preferably 3 Mars geostationary solar stations could provide power to anywhere on the planet. A serious advantage compared to installations on the ground and long power… Read more »

Somewhere, the ghost of Nikola Tesla is whispering “I told you so…” 😉


Except Tesla didn’t know what he was doing. Although he made a lot of stuff that threw off alot of sparks. His basic problem was the inverse-square ‘law’.

Westinghouse could get induction machines to work (likely using Edison’s motto: 1% inspiration (we’ll grant that to Tesla’s patents) and 99% persperation).

It wasn’t for lack of money either: JP Morgan finally realized he was being scammed and withdrew funding upon seeing repeated failures.

This is different technology. Its not here yet at a reasonable price, but presumably you could do the same thing with a Maser or Laser.

Now as far as this goes, I’d guess its because Mitsubishi is involved in everything remotely electrical, think Mitsubishi Heavy Industries. But its not that noteworthy since triple the power and triple the range were accomplished 40 years previously, as this article states.

Everyone thinks AC motors are such a big deal, when really, ALL motors are AC.

The armature windings in a DC motor have alternating current in them. So even Edison used AC, and yes, he knew that because he knew about Armature Reaction which can only exist because of alternating current in a DC motor or generator.

It is a great parlor trick but it is not really a great idea due to losses. If you don’t mind the losses and it provides an important need, then do it.

But most of the time, just running a conductor between the points is not too hard to do and will provide better results.

I’m more interested in Elon’s robotic snake idea.

I want a hot dog on a long stick to do some testing…

Don’t forget to bring some Marshmallows to your next neighborhood house-fire.

1.) They sent 10KW. That’s nice. How much was received? I’m more interested in the efficiency of the system. Yes I know the NASA Goldstone experiment achieved ~82%, but Mitsubishi isn’t NASA.

2.) Hello, Mr.Tesla, we’d like to finally give you credit for your work from nearly 100 years ago.