(ORDO NEWS) — China has made important progress in its efforts to build a solar power plant in space, to convert sunlight in outer space into electricity to control satellites in orbit or transmit power back to Earth.
This month, a research team from Xidian University completed the world’s first full ground-based test of a space-based solar power plant, demonstrating a host of key know-how for the futuristic project known as Zhuri, or chasing the sun.
Space Solar Power Plant (SSPS), a hotspot technology, is a space-based power generation system used to harvest solar energy before converting it into electricity and then into microwaves. Outside the atmosphere, sunlight is brighter and shines most of the day.
The energy in microwaves is then transmitted to and collected by a receiving antenna in space or on the Earth’s surface, which converts the microwaves back into electricity.
Key technologies proven include high-efficiency light-concentrating and photoelectric conversion, microwave conversion, 55-meter microwave radiation and waveform optimization, microwave beam pointing measurement and control, microwave reception and rectification, and intelligent mechanical design.
Chasing the Sun
A 75-meter-high steel structure rises on the southern campus of Xi’an University. This is Zhuri’s ground-based verification complex.
A team led by Duan Baoyang, a 67-year-old antenna expert at Xidian University, is tasked with simulating the production and transmission of energy on earth. The main technical task is to minimize energy losses when changing the energy of various forms.
First of all, the researchers worked on adjusting the angles of the huge converging lens depending on the height of the sun. In the center of the lens are arrays of solar panels connected to transmitting antennas. They tested those antennas that remotely transmit microwaves to receivers.
The experiments were both exploratory and hard physical work. To move the 200 kg antenna, Duan had to hire college students as temporary porters.
“You have to try again and again on the spot,” says Duan. “Computer simulation doesn’t work.”
More than 100 researchers and students took part in the project. Thanks to their hard work, the audit was successfully completed on June 5, about three years earlier than expected.
Hot Spot Technique
American scientist and aerospace engineer Peter Edward Glaser conceived the idea of using satellites to transmit solar energy from space to Earth in 1968.
John C. Mankins, a former NASA physicist, proposed an approach called SPS-ALPHA (Solar Power Satellite via Arbitrarily Large Phased Array) in 2012. In 2015, US Corporation Northrop Grumman sponsored a US$17.5 million study over three years to develop the Space Solar Power Initiative (SSPI).
At the end of 2013, Duan proposed to start China’s own initiative, after which his team put forward OMEGA’s Chinese technology approach.
“Compared to ALPHA, OMEGA’s power generation efficiency has increased by about 24 percent, it is easy to control and has better heat dissipation,” Duan said.
Japan has included space solar energy technology in its national space development plan. In 2015, the country’s scientists conducted tests on power transmission at a distance of 55 meters using a microwave oven, demonstrating their technical advantage in wireless power transmission.
However, the Japanese experiment is not complete because it lacks a light-to-electricity test, Duan says.
In addition, engineers at the China Academy of Space Technology, a state-owned spacecraft manufacturer, earlier this month presented a roadmap for advancing this groundbreaking technology in a study published in China Space Science and Technology.
According to the plan, in 2028, a space experiment on high voltage transmission and wireless power transmission will be carried out in low Earth orbit.
The satellite will be capable of generating 10 kilowatts and carrying a quarter solar array, a microwave transmit antenna, a low-power laser transmit payload, and a transmit array of several meters to test power transmission 400 kilometers from orbit.
By 2030, it is planned to expand the solar array to generate more than 100 kilowatts and test medium-power laser transmission over a distance of 36,000 kilometers.
By 2035, the microwave transmitting antenna is expected to grow to about 100 meters and generate 10 megawatts of power. In 2050, it is planned to build a two-gigawatt commercial solar power plant with an antenna about one kilometer in diameter and a complex array of solar panels to be assembled in space.
“Transferring energy from space to Earth is our ultimate goal, and it requires several years of work,” Duan said. “But we can achieve some immediate goals.”
Duan said solar power in space could be used to power medium and small satellites. “Now they have to be launched with a huge payload of solar panels, and the panels cannot collect energy in shaded areas,
According to him, in the near future, these satellites are planned to be equipped with foldable receiving antennas, while discarding solar panels.
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