Solar power keeps getting cheaper, but it still has a basic problem. The sun sets and output drops right when people get home and turn things on. What if your electric bill could be backed up by sunshine that does not care about nightfall?
A concept from Japan imagines building a huge ring of solar panels around the Moon. It aims to send electricity to Earth using energy beams, but it is still a proposal with no public funding plan. Big promise, bigger hurdles.
A ring of solar panels on the Moon
The “Luna Ring” concept would wrap the Moon’s equator with solar panels. The goal is to keep at least part of the system generating power as sunlight moves across the surface.
One outline describes a band that runs about 6,800 miles around the Moon and could be up to about 250 miles wide. It would build a base from lunar soil, cover it with panels, and send power to Earth using microwaves or lasers aimed at receiving stations.
Supporters have suggested construction might start as early as 2035 and have attached enormous output estimates. But building and maintaining a lunar power plant at this scale would require technologies and budgets that are not on the table today. This is why the idea reads like a blueprint from the future.
How the energy would get to Earth
Making electricity on the Moon is only half the story. The tougher part is delivering it to the grid you use every day without losing most of it along the way.
Microwaves can move through clouds better than lasers. Lasers can be tightly aimed, but that makes safety and reliability a bigger worry if anything goes wrong.
The idea fits under space-based solar power, which means collecting sunlight above Earth’s weather and sending it down wirelessly.
The Japan Aerospace Exploration Agency describes beaming energy to a receiving antenna called a “rectenna,” and it traces the concept back to Peter Glaser’s 1968 proposal and later NASA studies. It also notes that sunlight in space is stronger than what reaches the ground.
Why the Moon is tempting for clean power
On Earth, solar power is a bit like a great part-time job. It helps a lot, but it does not always match demand unless you add storage.
The Moon has no real atmosphere, which means no clouds and no storms to dim sunlight. If you can build panels there and keep them clean, you can collect energy without the weather surprises that frustrate solar operators on Earth.
Reliable clean power could reduce the pressure to burn fossil fuels when renewables dip. But it only matters if the electricity arrives cheaply and safely.
The Moon still has two-week nights
Here is the detail people miss when they hear “constant sunlight.” A single spot on the Moon goes through about 327.5 hours of daylight followed by about 327.5 hours of darkness, which works out to roughly two weeks of day and two weeks of night.
That is where the ring design is supposed to help. Even as one section turns into darkness, another is moving into sunlight, so the system is meant to stay partly productive. But that also means long power lines on the lunar surface and nonstop upkeep in a harsh environment.
The biggest hurdles are cost and scale
In 2011, CSP Japan president Tetsuji Yoshida said the project would need major funding and still lacked a firm price tag, arguing that Earth-based solar can produce “one-twentieth” of what it could in space. In the same ABC News report, Masanori Komori of the Institute of Energy Economics said lunar solar power is still too expensive compared with options available now.
Even if money appeared tomorrow, the construction challenge would remain. Robots would have to work for years in abrasive lunar dust and extreme temperatures, then keep fixing failures that are routine on Earth.
Any beamed-power system would need large receiving sites and strict rules to keep transmissions controlled. That is not trivial when weather, air traffic, and satellites all share the sky.
Space solar power is being tested right now
What makes the Luna Ring idea feel less far-fetched than it did a decade ago is that pieces of the puzzle are finally being tested. The California Institute of Technology says its Space Solar Power Demonstrator showed wireless power transmission in space, using a deployable structure about 6 feet by 6 feet.
In Europe, the European Space Agency is running an effort called SOLARIS to study whether space-based solar power could be practical and safe, including how radio waves behave in Earth’s atmosphere. The agency expects to weigh a next-step decision by the end of 2025, so for now the story is research, not Moon construction crews.
The main official concept has been published by Shimizu Corporation.
AloJapan.com