By Jia Fengfeng, People’s Daily
China has achieved a significant breakthrough in wireless power transmission, bringing the long-term vision of a space-based solar power station (SSPS) closer to reality.
Researchers at Xidian University in northwest China’s Shaanxi province have successfully demonstrated the world’s first ground verification system capable of transmitting microwave power wirelessly from a single transmitter to multiple moving targets simultaneously.
This achievement addresses one of the most critical technical challenges facing future space-based solar power systems. In the future, a single orbital power station could supply electricity to multiple spacecraft — or even mobile ground equipment on the ground — at the same time.
The milestone was reached in early spring this year at Xidian University’s Chang’an Campus in Xi’an, capital of Shaanxi province.
At the test site, a 75-meter-tall steel tower rose above the experimental field, its transmitting antenna aimed at receivers more than 100 meters away.
“It’s on! It’s on! They’re charging!” shouted Li Xun, a professor at the university’s School of Electronic Engineering, as LEDs mounted on unmanned aerial vehicles gradually lit up in the air.
For the research team, the successful demonstration marked the culmination of years of work to overcome one of the most difficult obstacles in wireless energy transmission: delivering high-power, high-efficiency microwave energy over long distances to multiple moving targets with precise beam control.
The concept of SSPS was first proposed in 1968, when scientists suggested placing massive solar power facilities in Earth’s orbit. Unlike ground-based solar farms, orbital systems would collect solar energy continuously, unaffected by weather or the day-night cycle. The electricity generated would be converted into microwaves or laser beams and transmitted wirelessly to Earth, where it would be converted back into electricity.
If realized, such a system could provide an abundant, nearly carbon-free source of clean energy.
For decades, however, the vision remained largely theoretical due to formidable technical challenges.
Only in recent years have advances in high-efficiency energy conversion, wireless power transmission and the construction of ultra-large space structures brought the concept significantly closer to reality.
China began researching space-based solar power in 2006.
In 2014, a research team led by Duan Baoyan, professor from Xidian University and an academician of the Chinese Academy of Engineering, proposed the OMEGA-SSPS concept, an independently developed design with independent intellectual property rights. Four years later, on Dec. 23, 2018, the university officially launched the Zhuri project, a ground verification system for space-based solar power technologies.
After another four years of intensive research, the team completed the world’s first full-chain, system-wide ground verification for SSPS using the self-developed OMEGA-SSPS ground test verification system in 2022.
A “full-chain” system means that every stage of the process from solar energy collection and photovoltaic conversion to microwave transmission, wireless propagation, reception, and rectification back into electricity, was successfully demonstrated as an integrated system.
“The key performance indicators at that time included a transmission distance of 55 meters between the transmitting and receiving antennas, a transmission power of 2,081 watts, a beam collection efficiency of 87.3 percent, and an end-to-end DC-to-DC transmission efficiency of 15.05 percent,” said Duan Xuechao, deputy dean of the School of Electronic Engineering at Xidian University. Those results ranked among the world’s most advanced at the time.
But that achievement was only the beginning. Supplying electricity to a stationary receiver is comparable to stretching an invisible power cable between two fixed points. Once the receiving target moves, however, maintaining accurate beam alignment becomes vastly more difficult. Moving from powering stationary targets to moving ones became the team’s next major challenge.
By the end of May this year, after another four years of research, the team unveiled Zhuri project 2.0 — the world’s first ground verification system capable of wirelessly transmitting microwave power from a single transmitter to multiple moving targets.
This “one-to-many” capability allows a single transmitting system to direct its microwave beam with exceptional precision, supplying power almost simultaneously to several fast-moving targets.
Researchers explained that the technical difficulty is similar to using a single beam of light in complete darkness to repeatedly and accurately hit multiple moving targets.
After years of efforts, the team finally achieved this breakthrough. Tests conducted this summer showed that over distances exceeding 100 meters, the system achieved a DC-to-DC transmission efficiency of 20.8 percent and a beam collection efficiency of 88 percent.
At the same time, drone flight tests were also successful. A drone flying at 30 kilometers per hour, and 30 meters from the transmitter, continuously received 143 watts of electrical power. The demonstration suggested that small drones could one day remain airborne while being recharged wirelessly during flight, significantly extending their operating endurance.
Countries including the United States, Japan and the Republic of Korea are all pursuing space-based solar power technologies. So far, however, China is the only country to have successfully demonstrated both a full-chain system and wireless power transmission from one transmitter to multiple moving targets.
The successful ground demonstration marks only the first step. According to China’s roadmap for space-based solar power development, the country aims to build a megawatt-class experimental power station in orbit by 2030, followed by a gigawatt-class commercial space-based solar power station by 2050.
Duan Baoyan outlined the enormous long-term potential of the technology. “If space-based solar power stations were deployed every 0.1 degree along geostationary orbit — roughly every 73
China takes a major key step toward building space-based solar power station
