How China's Space-Bound Solar Installation Will Beam Power Down to Earth

Researchers in China are planning a solar farm in space, an ambitious project that could deliver energy at six times the intensity of installations on Earth. The project, which made the front page of China’s Science and Technology Daily last week, would orbit in space and beam down energy to a receiver.

The station would reportedly orbit 22,000 miles above the Earth and benefit from harvesting energy without any complications from seasonal changes or atmospheric conditions, providing energy 99 percent of the time. It’s expected to weigh a staggering 1,000 tons, around 600 tons more than the International Space Station, so the researchers are exploring alternatives like using robots and 3D printers to build the construction in space. The idea is nothing new: NASA started researching the idea in the mid-1970s during the Arab oil embargo, and even devised bold concepts like the SunTower:

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Most concepts for space-based solar energy involve using either lasers or microwaves to beam the energy back to Earth. Laser satellites costs around $500 million to get started and orbit at a lower height of around 250 miles, with the added benefit of simple and cheap receiving stations on Earth. Unfortunately, they only beam around one to 10 megawatts per satellite, and the safety concerns around lasers could make it too risky.

An alternative approach is microwave-based installations. These satellites can send up to one gigawatt of energy to a receiver, with a steady stream of power through a safe beam that works through the rain and clouds. Unfortunately it also needs to sit around 22,000 miles away, and as the Chinese researchers note, that makes initial setups and repairs tricky. It would also require a giant receiver several miles wide. While the initial setup for both seems tricky, it could help capture the approximately 30 percent of solar energy that gets reflected back by the atmosphere.

China’s plan is to complete tests of the power transmission and wireless energy in the next 10 years, with the construction of an experimental plant already started in Chongqing. The team then plans to build a megawatt-level space solar test station in 2030. Researchers plan to build the final gigawatt-level station before 2050.

Pang Zhihao, a researcher from the China Academy of Space Technology Corporation, described it as “an inexhaustible source of clean energy for humans.” With China’s space agency also sending probes to the far side of the moon, it could also provide energy for its space-exploring robots.