China aims to use space-based solar energy station to harvest sun’s rays to help meet power needs
- Support for the unconventional orbiting solar programme jumped after China announced its 2060 carbon neutral target
- Civilian and military researchers will look at applications for the technology amid concerns about radiation and the potential for beams misfired from space
After breaking ground in Heping village, Bishan district, three years ago, construction of the 100-million-yuan (US$15.4 million) ground testing facility for the national space solar-power programme stopped, in part because of debates about cost, feasibility and safety of the technology.
The project resumed in June, according to the district government’s website.
Zhong Yuanchang, an electrical engineering professor involved in the project with Chongqing University, was quoted in the Beijing-based China Science Daily on Monday saying construction of the facility would be finished by the end of this year, meeting a tight deadline.
An intensive energy beam would need to penetrate the cloud efficiently and hit a ground station directly and precisely. Researchers at the Bishan facility will work on these and other projects.
A solar energy plant is not efficient because it only operates during the day, and the atmosphere reflects or absorbs nearly half the energy in the sunlight.
Since the 1960s, some space scientists and engineers have been attracted to the idea of a solar station in space. From an altitude of 36,000km (22,400 miles) or above, a geo-stationary solar plant can avoid the Earth’s shadow and see the sun 24 hours a day.
The energy loss in the atmosphere could also be reduced to the minimum (about 2 per cent) by sending the energy in the form of high-frequency microwaves.
Over the last few decades, various forms of solar power stations have been proposed from around the world but they remained theoretical because of major technical challenges.
At Bishan, Chinese researchers would first need to prove that wireless power transfer worked over a long distance.
Although the engineer and inventor Nikola Tesla popularised the idea in the late 19th century, the technology has been limited to only a small number of short-range applications, such as the wireless charger for smartphones.
Tesla failed in part because he made the electricity travel in the air like waves in all directions. To increase the effective range, the energy must be concentrated into a highly focused beam.
The Chinese researchers received wireless energy emitted from a balloon 300 metres (980 feet) above the ground. When the Bishan facility is complete, they plan to increase the range to more than 20km with an airship collecting solar energy from the stratosphere, according to the China Science Daily.
In Bishan, researchers will also experiment with some alternative applications of the technology, such as using the energy beam to power drones.
The core experimental zone will be 2 hectares (4.9 acres) and surrounded by a clearance zone five times larger. Local residents are not allowed to enter the buffer zone for their own safety, according to the district government.
The safety risk of a space solar plant is not negligible, according to some recent studies in China.
When the huge solar panels turn to chase the sun, for instance, they could produce small but persistent vibrations in the microwave beaming gun that could cause a misfire. The “space farm” would therefore need an extremely sophisticated flight control system to maintain its aim at a tiny spot on Earth.
Another hazard would be radiation. According to one calculation by a research team with Beijing Jiaotong University last year, residents could not live within a 5km range of the ground receiving station for the 1GW Chinese solar plant in space.
Even a train more than 10km away could experience problems such as sudden loss of communication because the frequency of the energised microwave would affect Wi-Fi.
In an article posted on the website of the Chinese Academy of Sciences in May, professor Ge Changchun, a lead scientist in the national space solar plant programme, said the project had come up against much opposition.
If China did not do it, the United States and other Western countries would, he added.
There is no civilian space solar station programme in the US at the moment. But in recent years, the US military has shown a growing interest in the technology.
The US Air Force, for instance, plans to send satellites in two or three years to verify key technology to beam energy to Earth. The energy would be used to power drones or remote military posts.
Potential applications for the technology extend beyond power supply to military uses. The energy beam could aim at a moving threat, such as hypersonic missiles and aircraft, or cause a communication blackout over an entire city, according to some defence contractors.
The research team in Chongqing could not be reached for comment. According to openly available information, the Bishan testing site will be a dual-use facility for military and civilian researchers.
Despite the controversies, space solar power technology plays an important role in China’s space development plan because it will stimulate the development of a wide range of cutting-edge technologies, including a superheavy rocket, a hypersonic space plane for low-cost transport, construction of massive orbital infrastructure and directed energy weapons, according to some Chinese space scientists informed about the programme.
China lags behind the US in space technology at present, but the programme will put China in a lead position in the race, they said.