- Luna Ring proposes continuous solar energy production from the orbit of the moon
- The lunar equator would host thousands of kilometers of solar infrastructure
- Energy transmission relies on microwave and laser beam systems
A Japanese construction company once proposed wrapping the moon’s equator in a belt of solar panels stretching nearly 11,000 km.
The Shimizu Corporation, a billion-dollar engineering giant, envisioned a structure ranging from several kilometers to 400 km in width at its widest point.
Assuming an average width of 100 km, the total surface area would reach approximately 1.1 million square kilometers – a territory roughly comparable to the combined land mass of Texas and California.
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How the lunar power plant would work
The concept, called the Luna ring, promised to generate 24 hours of continuous solar power without interference from weather or atmospheric conditions.
The solar cells along the moon’s 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 will rely on two types of wireless transmission: microwave technology and laser beam technology.
Every country on Earth would have rectenna arrays—antennas that convert microwaves back to direct current—to receive and distribute the power.
But building such a huge infrastructure would require the maximum use of materials found on the moon itself.
Moon sand consists of oxide compounds that can combine 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, doing most of the construction work remotely from Earth.
A self-propelled solar manufacturing facility would move along the moon’s equator, manufacturing and installing panels as it crawls forward.
Costs, timelines and validity remain a major 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 in 2011, Yoshida admitted that there was still no concrete estimate of the project’s total cost, leaving great uncertainty about its feasibility.
Masanori Komori of the Institute of Energy Economics noted that lunar solar power “sounds good in theory but costs too much,” and suggested that Japan should instead focus on geothermal energy.
At present, this proposal feels more like a futuristic marketing exercise than a viable energy solution for several reasons.
First, building a solar belt longer than Earth’s diameter across an airless landscape presents staggering engineering challenges.
Second, the robots required for such construction do not yet exist in any operational form, and Shimizu’s glossy brochure appears to understate these technical hurdles.
Whether investors will take this decade-old no-cost concept as a true technology roadmap remains to be seen.
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