Mitsubishi Completes SSPS Wireless Transmission Test
Mitsubishi wireless power transmission system. (Credit: Mitsubishi Heavy Industries)
TOKYO, March 12, 2015 (MHI PR) — 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.”
Mitsubishi wireless power transmission system. (Credit; Mitsubishi Heavy Industries)
Wireless power transmission technology aims to eliminate the cable connections conventionally necessary for transmitting electricity, and the newly successful test results lead the way to applying the technology in numerous terrestrial fields. The achievement of wireless power transmission over long distances will not only facilitate the transmission of power to locations where installation of power cables has been difficult or dangerous; it is also expected to contribute to transmission of power from offshore wind turbines and various other applications in the future. One readily conceivable application is wireless transmission of power to electric vehicles.
The wireless power transmission being developed for SSPS usage is referred to as a radio emission technology, and once the technology is achieved it will enable wireless transmission of power over unprecedented distances.
The SSPS is being developed as a system that will generate power on a geostationary satellite at 36,000 kilometers above the earth using solar cell panels; the generated power will be transmitted to earth by microwave/laser – i.e. without relying on cables – and the power received on the ground will be converted to electrical energy. As the power source is environmentally clean and inexhaustible, the SSPS is highly anticipated to become a mainstay energy source that will simultaneously solve both environmental and energy issues.
Going forward MHI aims to pursue expanded practical applications of this advanced aerospace technology in a quest to contribute to social progress, while simultaneously further advancing Japanese technology toward the realization of tomorrow’s SSPS’s.
12 responses to “Mitsubishi Completes SSPS Wireless Transmission Test”
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The only important thing about this is the efficiency. Ten kilowatts was transmitted. How many were received? I can light up an LED using a CB transmitter. I can make a small magnet spin in synchrony with another 100 feet apart. If the transmission power efficiency is not revealed, I certainly wouldn’t call this a “successful test”.
Given the beamspread of microwave frequencies, it is better to consider power transmission with high power lasers, which has also been demonstrated.
[UPDATE: From another article (which didn’t mention the transmit power!) we find that 1,800 watts were received, or an 18% efficiency overall, over a distance of 170 feet. At the 500 meters quoted in this article, that would probably be down to a very small number. A plot of received power versus distance would be nice to see, but they are probably keeping that a company secret. While not great, it is better than earlier attempts, so we can classify this as a step along a long road. When we see losses at only about 70% over 24,000 miles, then we can start talking about building satellites.]
With respect to efficiency, if the power source is free and inexhaustible, what difference does efficiency make unless you can’t scale it up to commercial quantities? The argument that we can’t afford to use non-polluting sources where clean alternatives exist is an argument in favor of planetary suicide. Props to MHI for continuing the research. Beamed solar power would be the best new use we’ve found for space yet.
Efficiency matters because it costs money to loft equipment. I am not opposed to space-based solar power (I have been a proponent of it since the notion was first seriously proposed in the 70s). The efficiency of the receiving system has always been the primary constraint.
The main motivation for solar power satellites supplying Earth is to achieve an efficiency gain by having the panels above weather and not attached to a plot of ground that spends most of its time facing away from the sun. If transmission losses mean you get the same or more delivered power by leaving them on the ground, there’s no benefit to putting them in space.
For space applications, the motivation is reduction in power system mass at the receiver end, and transmission efficiency is not nearly as big a problem. Lower efficiency means a larger, heavier transmitter, but if the transmitter is just sitting in orbit delivering power to VASIMR-based tugs or something, that’s a price that only has to be paid once.
Microwaves can be produced and converted back to electrical power with high efficiency, lasers can not. Beam spread can be reduced by using a larger transmitter, improving laser efficiency requires development of entirely new conversion technologies.
Another issue, the microwave systems proposed are generally phased arrays using a signal sent back from the target as their reference. This reference is not just used for steering the beam, it’s used for forming it in the first place, and a beam can not be formed without a reference at its focus. This provides an inherent safety feature that laser systems don’t have. Another safety factor is that lasers are an eye hazard even at fairly low powers, and the infrared ones that are more efficient for power transmission do not produce an aversion reflex that protects the eyes. A system that doesn’t blind birds, pilots, and random onlookers with invisible stray reflections is preferable.
Lasers do have an advantage in compactness, which is far from an insignificant advantage, especially for spacecraft. They just aren’t necessarily the best option in every case.
You are correct about the hazards of lasers, but the microwave spectrum has hazards of its own. I remember a technician who had the misfortune of not checking whether the open end of a waveguide he was looking down was alive or not. His clue was that his head was getting hot. He was never the same afterward.
The environment has to be considered also. These systems are also being considered for moving power around in space, where lasers have a great advantage. Downlinks to the surface should use distributed microwave arrays operating at relatively low power.
I maintain that if the efficiency was not published, it is embarrassingly low. They may be testing other aspects of the system.
Interesting, I had no idea that MHI was conducting research in this area.
I consider this as a very good sign if an industry giant like MHI is working on the technology, that certainly gives it some kind of credibility in my opinion.
I have worked with MHI. Keep watching – there is probably an entirely different driver for the research than simply moving power around.
Yes, it is for robotics, power assist suits, and heavy equipment.
Very likely. And/or (at a more practical power level) balloon- or drone-based internet delivery platforms.
I am a follower of Gerard K. O’Neill and as such I believe the Moon
is the first place to go and exploiting lunar resources to power
civilization on planet Earth- and eventually acquire new lebensraum in
space- is the prize.
The two central concepts of O’Neill’s vision were Solar Power
Satellites built with lunar resources and the conclusion there are no
bodies in the solar system suitable for colonization leaving artificial
hollow moons constructed from lunar resources as the answer.
Space Solar Power System supporters seem to be their own worst enemies. They do not have much more credibility than Space Elevator fans. That needs to change with clear descriptions and depictions of the size of a transmitting station in space and size of a receiving field on Earth- for starters.
The public should be made fully aware the main criticism of SSPS- lifting the components out of the Earth’s gravity well- does not apply if they come from the Moon.
Power generation over great distances will probably never make sense, except for ephimeral hook ups, such a military fob, a ship in distress, or a disaster area.
Beyond that, this tech is not intended for Spss, but for heavy equipment and robotics.
This is why I have suggested over and over that the DOD should do a cots for this.