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- Luna Ring proposes continuous solar power generation from lunar orbit
- Moon equator would host thousands of kilometers of solar infrastructure
- Energy transmission relies on microwave and laser beam systems
A Japanese construction firm once proposed wrapping the moon's equator in a belt of solar panels stretching nearly 11,000km.
The Shimizu Corporation, a billion-dollar engineering giant, envisioned a structure ranging from several kilometers to 400km in width at its widest point.
Assuming an average width of 100km, the total surface area would reach approximately 1.1 million square kilometers — a territory roughly comparable to the combined landmass of Texas and California.
Article continues belowHow the lunar power station would operate
The concept, called the Luna Ring, promised to generate 24 hours of continuous solar power without any interference from weather or atmospheric conditions.
The solar cells lining the lunar equator would convert sunlight into electricity, which would then travel via transmission cable to the Earth-facing side of the moon.
At that location, the energy would be converted into microwave or laser beams and transmitted directly to receiving stations on Earth.
According to Shimizu's proposal, "the massive energy of the sun will give us a beautiful Earth and an abundant lifestyle in the future."
The system would rely on two types of wireless transmission: microwave technology and laser beam technology.
Each country on Earth would possess rectenna arrays — antennas that convert microwaves back into direct current electricity — to receive and distribute the power.
But building such immense infrastructure would require the maximum use of materials found on the moon itself.
Lunar sand consists of oxide compounds that could be combined with hydrogen brought from Earth to produce oxygen and water.
The same sand could be mixed into cement, ceramics, glass, and even solar cells manufactured directly on site.
Large robots would drill into the moon's hard inner layer and level the softer surface ground, performing most of the civil engineering work remotely from Earth.
A self-propelled solar cell production plant would move along the lunar equator, manufacturing and installing panels as it crawls forward.
Costs, timelines, and validity remain a huge debate
This discussion has often felt abstract and has struggled to gain the sustained attention needed to move it toward real-world implementation.
When the concept was first introduced in 2010, Tetsuji Yoshida, the president of Shimizu’s space consulting subsidiary, acknowledged that it received little attention or public interest at the time.
It was only after the Fukushima nuclear disaster in 2011 that the idea began to attract renewed attention as Japan reassessed its energy strategy.
However, even by 2011, Yoshida admitted that there was still no concrete estimate for the project’s total cost, leaving major uncertainty around its feasibility.
Masanori Komori from the Institute of Energy Economics noted that lunar solar energy "sounds good in theory, but costs too much," and suggested Japan focus instead on geothermal power.
At present, this proposal feels more like a futuristic marketing exercise than an actionable energy solution for several reasons.
Firstly, building a solar belt longer than Earth's diameter across an airless landscape presents staggering engineering challenges.
Secondly, the robots required for such construction do not yet exist in any operational form, and Shimizu's glossy brochure seems to understate these technical hurdles.
Whether investors will take this decade-old concept without cost estimates as a genuine technological roadmap remains to be seen.
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