Shimizu's Luna Ring to beam solar energy from the Moon


December 2, 2013

Shimizu's Luna Ring proposes an  an array of solar cells around the moon's equator to harvest solar energy and beam it back to Earth (Image: Shimizu Corporation)

Shimizu's Luna Ring proposes an an array of solar cells around the moon's equator to harvest solar energy and beam it back to Earth (Image: Shimizu Corporation)

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A Japanese firm has come up with the idea of constructing an array of solar cells around the Moon's equator to harvest solar energy and beam it back to Earth. The Shimizu Corporation proposes creating a "Luna Ring" using materials derived from lunar soil along its 11,000-km (6,800-mile) equator. The plan involves starting with an array that's a few kilometers wide and eventually increasing that to around 400 km (250 miles).

The goal is to generate a continuous stream of power from the Moon's lunar equator, which receives a steady amount of exposure to the Sun, and beam it down to Earth from the near side of the Moon. It's an ambitious idea that calls for assembling machinery transported from Earth and using tele-operated robots to do the actual construction on the Moon's surface, once it arrives.

The multi-phase project, to be spread out over a period of 30 years, envisions creating construction materials using a combination of strategies. Water, the firm claims, could be produced by reducing lunar soil with hydrogen imported from Earth. The company also proposes making lunar concrete by extracting cementing material, and utilizing solar-heat treatment processes to create bricks, ceramics, and glass fibers.

The concept also calls for remotely-controlled robots to undertake tasks such as excavating the surroundings, leveling the ground and laying out solar panel-studded concrete. Embedded cables could transfer the collected solar energy and send it to transmission stations that are located on the near side of the Moon.

Power could be beamed to the Earth through microwave power transmission antennas, about 20 m (65 ft) in diameter, and high density lasers, both guided by radio beacons. Microwave power receiving rectennas on Earth, located offshore or in areas with little cloud cover, could convert the received microwave power into DC electricity.

The company claims that its system could beam up to 13,000 terawatts of power around-the-clock. The proposed timeline has actual construction beginning as soon as 2035.

Check out a video on the Luna Ring from Shimizu below.

Source: Shimizu Corporation

Update (Dec 3, 2013): This article originally stated that the project would "generate a continuous stream of power from the side of the Moon that's always facing the Sun, and beam it down to Earth from the side that's in shadow." Our apologies for this error, and our thanks to Gizmag reader David Evans for pointing it out. The error has now been corrected to reflect the fact that there is no such place. Ed.

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Lakshmi Sandhana When Lakshmi first encountered pig's wings in a petri dish, she realized that writing about scientists and imagineers was the perfect way to live in an expanding mind bubble. Articles for Wired, BBC Online, New Scientist, The Economist and Fast Company soon followed. She's currently pursuing her dream of traveling from country to country to not only ferret out cool stories but also indulge outrageously in local street foods. When not working, you'll find her either buried nose deep in a fantasy novel or trying her hand at improvisational comedy. All articles by Lakshmi Sandhana

Would Dr. Evil be getting residuals for coming up with the idea first?


orbit some mirrors around the moon as well? but heavens! a terrorist could fry the earth!


I love 30 year projects... we can't sustain anything that transcends one administration. Perhaps Japan is better at this, but imagine going to the bank and asking for a 100 year loan for a trillion dollars.

Matthew Bailey

in 2 weeks china will land a rover on the moon and begin transmitting images. maybe video.

china wins. japan loses.


Here's an idea: why not put solar panels on the face of the earth? Let the sun do the beaming (remember sunlight is wireless), plus it saves us the trouble of transporting millions of tons of manufacturing equipment to the moon, and the billions of tons of fuel to get it there!

Joris van den Heuvel

"the side of the Moon that's always facing the Sun,"

There is no such place. A solar cell on the Moon's equator will be in shadow half the time. There are plenty of good locations for solar power here on Earth.

David Evans

Of course it's not hyperbole to say the costs will be astronomical. Investors must be really sure nobody will make a fusion generator or other big breakthrough on earth for at least 50 years.

Legal questions: (1) why is that huge area of Luna your property? (2) Congratulations: you have just built a 13 petabyte weapon. Did you really think Russia, China, the U.S., and others would just still still for that?


Imagine losing control over one of these beams of death. Very ambitious plan to say the least.

Fretting Freddy the Ferret pressing the Fret

So this is the answer to the question "How do I power my giant Gundam when I shut down all of my nuclear reactors?"

The Japanese are so cool!!!


This is a highly economical solution if they made a Hollywood movie out of it that grosses $10T. What's wrong with a terrestrial energy mix and better insulation?


The luna ring gets a big LUNA TICK from me!


Now if they can focus the power beam tightly enough, it might be suitable to deflect one of those Earth-killer comets or asteroids we keep reading about. The main risk is control - if you control the whole thing from Earth, it can be 'hacked', if controlled on the Moon, then you get the problems and extra costs of habitat housing etc.

The Skud

This idea is stupid. The array could only ever work at 50% capacity with half the moon being dark.

The moon spins so you would need several stations all over the moon to beam the energy back.

The moon moves, meaning there wont always be a direct line of sight between you and the moon and you might not be able to use it.

Add all these together and you have a situation where complicated tracking and aiming systems are needed to work a 50% capacity power plant that might be on the other side of the planet when you need it most and might appear at night when you have no need for it at all, considering we use more power in the day.

Wouldn't it be far more cost efficient to just build an array and put it in orbit over your country very far out. Half the size it would have to be, it would be easier to aim, it would run at 100% capacity, and you could tap it all of the time except when its in the earths shadow. Which would normally be at night when you don't need it anyway, If you put it far enough out it would only be in the earths shadow for short periods. it would also be far less likely to be hit by an asteroid than the moon would be.


junk, dumb concept that will NEVER see the light of day (pun intended).

Derek Howe

the poor mans deathstar.


Also.. i seriously don't like the idea of shipping the earth's precious atmospheric gasses out on an industrial scale.. think about it.. yes yes, drop in the ocean and all that... but that's how it all starts.

Simon Sammut

@fenshwey The moon does rotate at the speed of one rotation per month, so It has the same 50% face to the earth. due to wobbling the actual % is a bit more (55-60%) don't know the exact number.

A bigger concern is that the moon is every month partly or complete in the shadow of the earth. So the power output has at least a dip. This can be solved by adding several batteries.

Major concern is that the energy harvested on the Moon can be used for better things than reflecting it to Earth. Support the Moon colony for instance. I agree with Joris van den Heuvel on that point.

Instead of solar cells everywhere I think concentrating sunlight with mirrors is much cheaper to make (and use only e.g. 10% solar cells). Might even be more optimal to fill the craters ...

Rob Tillaart

They should spend all that money and time for development of something else than solar energy.

Peter Pavelka

Dumbest idea (not) on the planet.

Jeff Michelson

As if we didn't have enough deadly microwave pollution already...


It would be more cost effective to put the solar collectors into a polar orbit above geostationary. including the cost of the catapult on the moon to launch the collectors.

@ Simon Sammut The amount of hydrogen is trivial. after the hydrogen has stripped the oxygen from the ore the water can be broken back into its component parts so the hydrogen can be reused.


Love the concept; hate the timeline. NASA proposed such a system over 20 years ago.

Robert Fallin

To earlier questions. They want to put it on the Moon instead of having a GEO solar array because you don't have to carry much mass to the moon. You just use resources already on the Moon to build it.

The biggest problem I can see with this project is the fact that the most important thing to build on the moon is rail gun going around the entire moon and this will get in the way of the rail gun.


Better than the moon or polar orbit would be to place the collectors in the balance point between the earth and the sun. Unless the Solar Output climate model is correct and we are looking at a repeat of the Little Ice Age which is a far worse problem than AGW.


The molten salt reactor is FAR easier to build and maintain. less than 20% enriched uranium (or accelerated neutrons) is needed to start the reaction. From there, thorium or spent fuel (waste) is all that's needed to power the world ten times over for thousands of years. No potential death beams, no 12 hour storage requirements (for the side of Earth not facing the moon), and most importantly, no ugly lunatic black belt!

Angel Bernal

It’s NEARLY as dumb as the “Solar Roads” idea of putting fragile solar panels under transparent paving.

This would essentially create a lethal microwave Cannon.

Even the previous idea of putting solar satellites in orbit and beaming the power down is stupid.

The losses from satellite transmission over 26,000 miles, the column of deadly microwaves pouring down to the receiving antennas, frying passing aircraft... that was bad enough.

But doing this from THE MOON ?

Hey, here’s an idea.

Put the Solar Cells in the DAMNED DESERT !

We even have robots to wash the dust off the panels now !

William Carr

While I applaud the efforts and passion of The Shimizu Corporation , all of this research was done about thirty years ago. And the conclusion then was that the most efficient way to go about this is to place space based solar power satellites in geosynchronous orbit. The advantages to this approach are to numerous to mention here but a short list would have to include: a geosynchronous orbit is only 22,200 miles away while the moon is 238,000 miles or over ten times the distance. A geosynchronous orbit stays over the same place on Earth making tracking much easier. Space based satellites can be optimally positioned to the sun and placed in high angle orbits to provide virtually uninterrupted electricity-at least 364 days a year. See Gerard k. O'Neill "The High frontier" and G. Harry Stine "The Space Enterprise".

Russell Poley

The proposed size of the array would provide enough power for the entire planet. This is a long term endeavour, meant to be used for centuries.

@ezeflyer: The beam is tightly focused so there is no 'microwave pollution'.

@fenshwey: The article states that only one beaming location is needed, and it collects power from all panels at once. The power is beamed to multiple arrays on earth because the moon moves in relation to us. This would have to be an international effort, or at least cooperation.


This idea is worthless as proposed. Beaming power from LEO to Earth based rectenna's is lossy and tricky enough that the idea is marginal. Beaming from the moon would be infinitely more lossy and tricky to target. The only advantage this would have would be in situ materials. It would probably be better to launch the material from the moon to LEO/GEO and build there.

As to the "beam of death" comments. The beam would not be strong enough to "fry" anything. It would produce at most a slight warming over the target area.


Lift all of it off Earth. Ship it all to the moon, install it on the moon, maintain it on the moon, send maintainance supply, tools, habitats, consumables and personnel to the moon to travel the circumlunar roadway system built to give them access. Only half of the PV will be used at any time. How does this effeciency and cost stack up against the effeciency of photovoltaics promise of "free electricity"? Perhaps they will build a cavernous storeage facility on the moon for the legions of cryo-sleeping clones of the lonliest repairman on the moon, work them one at a time till they go crazy.

John Hagen-Brenner

@ John Hagen-Brenner Almost all of the stuff on the moon will be built on the moon from lunar material.

I would not be surprised if they used solar thermal using Stirling Cycle engines rather than photovoltaic because of the ease of manufacture.


Aren't there asteroids and meteors running into the moon all the time? Wouldn't this enormous array get smashed all the time? Seems a little hokey not to mention ugly. I think the japanese should stick to anime, robots and runaway nuclear reactors all that have the single purpose of destroying the planet...

Nathan Tessier

The concept of generating in space and beaming back using Microwaves was first thought of in 1938. It was quickly dispelled because the unit that were to receive the transmission simply burnt up. Micro Waves way to hot to handle and is still true today...What happens to anything you put in a Micro-wave oven it heats up from within then spreads out.

Now it is not to much to think that DC power can not be generated on Satellites in Geosynchronous flight. this was done by a colleague of mine in 2006. When they proved the theory of wireless transmission of power generation was possible from one Island in Hawaii to another.

It is very elementary to think that the next step in transmission of generation will be wireless. This is simply the the obvious choice and will happen, making the grid as we know it obsolete.

I envision giant off shore generation stations using capped thermal vents as a heat source for generation with hybrid Wind, Solar and Wave action and tidal flow as a power house generator on platforms like drilling platforms and beaming to satellites that relay it to what ever grid needs it on demand worldwide.

Now to most who think this is just a pipe dream...the same was said of Kennedy's Idea of a "Man on the Moon by End of the Decade".


Way too radical Joris, it'd never work. It'd wouldn't even make it out of a committee vote. Think of all the trillions your saving & the pork money your throwing away. And think of the few astronaut jobs your loosing. A guy who thinks like you is looking to be blacklisted........

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