Lunar Solar Power: Three Frontiers of Energy

The Luna Ring concept is Shimizu Corporation’s design and proposal to satisfy the entire world's energy needs. The plan proposes to: (a) harness solar energy by building a solar cells belt around the Moon’s equator, thus spanning 6,800-mile (11,000-kilometer); (b) converting the electricity generated to microwaves and lasers which will be beamed to Earth; and (c) converting these received beams on Earth back to electricity at terrestrial power stations around the world.
Credit: Shimizu Corporation

Part 1/3: Moonlight to Earthlight — How Lunar Solar Power Could Deliver Clean Energy Back Home

The global energy transition is accelerating, yet decarbonisation efforts are still constrained by infrastructure inertia, fossil fuel lock‑in, the intermittency of terrestrial renewables, and political lobbying. In this context, space‑based solar power (SBSP) is re‑emerging as a viable strategic tool. The Moon, having no atmosphere to weaken sunlight and featuring regions of near‑constant polar illumination, presents a uniquely potent platform for harvesting solar energy and beaming it to Earth.

Unlike ground‑based solar arrays subject to weather, dust, and night cycles, lunar solar installations can generate power almost continuously. Estimates suggest that SBSP systems in space can produce 8–10 times more energy per unit area than Earth‑based panels, thanks to uninterrupted exposure and lack of atmospheric losses. The European Space Agency (ESA) envisions that a single large solar‑power satellite could generate on the order of 2 gigawatts—comparable to a major nuclear plant—and require significantly fewer resources than terrestrial installations.

For developed nations, lunar SBSP offers a compelling way to diversify clean energy sources—adding resiliency to grids dominated by wind, solar, and nuclear. For developing economies, it represents a potential leapfrog, bypassing infrastructure investments in coal or gas plants to import clean energy directly from space. Private enterprises also see opportunity: aerospace firms can construct and maintain lunar arrays; utilities can market “space‑derived renewable kilowatts”; and infrastructure developers can build Earth‑based rectenna farms to receive power.

Research and policy attention are ramping up. In 2024, NASA’s OTPS (Office of Technology, Policy, and Strategy) published an SBSP report that analysed lifecycle costs and emission reductions compared to terrestrial renewables. They highlighted that while SBSP remains costlier for now, closing capability gaps—such as autonomous in‑space construction and efficient power‑beaming—could make it competitive by mid‑century. ESA’s SOLARIS programme is similarly advancing SBSP mission concepts for deployment in the 2030s.

A grounded vignette helps illustrate plausibility: in the early 1970s, Peter Glaser proposed transmitting large‑scale solar energy from space via microwave beams—a concept that won him a patent in 1973 for a satellite power station and Earth‑based rectenna system. While ambitions then were curtailed by high launch costs, today’s falling launch prices and advanced robotics make the concept more economically viable.

However, challenges remain. Building and assembling facilities spanning kilometres on the Moon would require orders of magnitude more launches than the International Space Station—and still be costly. Other hurdles include beam safety (ensuring microwave or laser energy doesn’t pose risks), international regulations, and trust in cross‑border energy systems.

Yet, as global climate deadlines tighten, lunar SBSP may shift from being seen as speculative to being perceived as a strategic complement—a planetary hedge in the energy transition.