China Sets the Date for the Largest Engineering Project 22,370 Miles From Earth: Its Solar Space Station

The goal is to capture continuous solar power from space and help China reduce its reliance on fossil fuels.

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Matías S. Zavia

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Aerospace and energy industries journalist. LinkedIn

Engineers are still far from constructing a Dyson Sphere, but China is on track to develop the first large solar power station in orbit around Earth. This project represents a more feasible version of the concept that NASA scientists dismissed in the 1970s and 1980s as economically unviable.

Times have changed, and the world is currently undergoing an energy transition toward renewable sources. China is known for adopting advancements from other nations to further its own goals. It’s currently working on its own version of a Starship: a massive, fully reusable rocket called CZ-9. The Chinese Academy of Engineering (CAE) aims to leverage this rocket to establish a massive solar power plant in space, located 22,370 miles from Earth.

When China announced its investigation into space-based solar power stations a decade ago, many viewed it as just another theoretical study or a proof of concept, similar to projects still being explored by NASA, the Japan Aerospace Exploration Agency, and the European Space Agency. However, Chinese officials have laid out an ambitious roadmap that has caught other countries off guard.

The first prototype of a 500 kW Chinese space power plant is expected to be ready by 2030. A fully operational 20 MW version is planned for 2035, while the final version, capable of producing 2 GW, is scheduled for 2050.

This is no small undertaking for a technology that has never been deployed, especially on such a large scale. It’ll likely require hundreds of launches and the assembly of thousands of solar panels in geostationary orbit at an altitude of 22,370 miles. The cost-effectiveness of launching large quantities of cargo will largely depend on the CZ-9 rocket being fully reusable, which China promises it will be.

Long Lehao, a rocket scientist at the CAE, used a vivid comparison to emphasize the project’s significance. “We are working on this project now. It is as significant as moving the Three Gorges Dam to a geostationary orbit [22,370 miles] above the Earth,” he said during a conference hosted by the Chinese Academy of Sciences.

China will have to launch small demonstrators of what will eventually become a solar space station. The country has already conducted tests using hot air balloons and is currently building a receiving station in Chongqing in Southwestern China.

The China Academy of Space Technology (CAST) aims to deploy its first 10 kW solar panels in space by 2026 to demonstrate wireless power transmission. Engineers expect to transmit up to 1 kW using laser technology and up to 4 kW via microwave, both to the receiving station on Earth and to a nearby satellite. This suggests a future where satellite constellations could be integrated with solar stations.

How China’s Planned Solar Station in Space Will Work

Details about the technical specifications of China’s planned solar panel farm in geostationary orbit remain sparse. In fact, authorities haven’t officially selected any specific project. However, three concepts from different Chinese laboratories have gained attention:

  • In 2014, the CAST proposed a 7.3-mile-long station featuring a 0.6-mile-diameter circular transmit antenna. This concept was later updated to a modular design, which is easier to assemble but has the drawback of producing a rectangular beam.
  • Also in 2014, Xidian University in Western China published a study on a spherical station with a diameter of 5 to 6.2 miles. This station would utilize semi-reflective panels to concentrate light onto internal photovoltaic cells.

In 2016, Shenyang Aerospace University in Northeast China proposed a cylindrical design that refracts sunlight onto internal photovoltaic panels, simplifying the process of tracking the Sun.

These concepts have one thing in common: They rotate like sunflowers to always face the Sun, allowing their large solar panels to continuously capture solar energy. This energy is then transmitted to Earth by concentrating a laser or microwave beam onto large antennas at receiving stations, where it’s converted back into electricity. This electricity can then be stored in batteries or fed into the grid.

Wireless power transfer uses a physical phenomenon known as interference or superposition of waves. To understand this concept, imagine a pond where both your hands create waves that propagate simultaneously. In this scenario, there are areas where the waves combine and become stronger (in phase) and areas where they cancel each other out (out of phase).

When the waves work together, the energy isn’t lost. Instead, it’s concentrated in a specific direction. If multiple sources emit signals at the same time and in phase, the energy can be directed effectively. However, if each source operates slightly earlier or later than the others, the direction of the beam can be adjusted.

Similar to how a magnifying glass focuses light on a single point, the timing of these sources can be fine-tuned to concentrate energy on a smaller area, such as an antenna on the Earth’s surface. This adjustment can occur on a nanosecond scale, allowing for quick changes in energy direction or allocation to different locations (e.g., different antennas).

Solar panels in geostationary orbit can operate continuously and achieve higher conversion efficiencies than those on Earth, indicating the benefits of a photovoltaic station in space. However, the complexity of deployment and concerns about the safety and efficiency of wireless transmission have prevented this technology from being implemented since it was first researched in the 1970s and 1980s.

China aims to lead the new space solar power race, capitalizing on its success in terrestrial photovoltaics. However, it won’t face this challenge alone. Japan became the first country to successfully transmit 1.8 kW of power wirelessly using microwaves in 2015, albeit over a distance of 164 feet. Space solar power remains a topic of intense research in the U.S., Europe, and several private companies as well.

Image | Arthur Wang

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