A Suntower space-based solar power plant envisaged by NASA. Photo: Handout

Chinese researchers are designing solar receptors that may be capable of harnessing the sun’s rays for the first time from an orbiting spaceship or satellite. They hope to be generating power within two decades, but first need to overcome formidable technical challenges.

Preliminary designs are being drawn up for a ground facility in the western city of Chongqing that will test the viability of the technology, according to the China Daily. Occupying 13.3 hectares, the facility will take two years to complete and will have an initial investment of 100 million yuan (US$15 million) that will be borne by a local government.

Local media said the center will look at space transmission technologies and the potential effects on humans of beaming microwaves back to earth. Engineers will use tethered balloons equipped with solar panels to collect solar energy which will be converted into microwaves. On ground the microwaves will be converted into electricity and distributed to the power grid.

The size of the orbiting platform that will carry the solar panels has not yet to be determined, as research is still in its very early stages.

Scientists have said the aim is for China to have receptors in an orbit about 36,000 kilometers above Earth for power generation in the 2040s.

Collecting solar rays in outer space is one of the holy grails of power grids, and scientists at the California Institute of Technology proved early last year that the technology is feasible when they managed to create a prototype that could capture and transmit the energy.

To establish a viable program, China will need to achieve three design elements: collect solar energy in space with reflectors or inflatable mirrors onto solar cells, transmit the energy to Earth via microwaves or lasers, and capture the power on Earth via a rectenna (an antenna that converts  electromagnetic energy into direct current electricity) or a microwave antenna.

It is thought that capturing solar energy in space would offer substantial advantages over ground-based receptors, including a higher collection rate  and a longer collection period due to the lack of a diffusing atmosphere: and there would be no nighttime period while the Earth rotated. As much as 60% of solar energy is currently lost on its journey through the atmosphere to the ground due to the effects of reflection and absorption.

On the downside, the costs of launching and assembling such a system are likely to be astronomical, while scientists still have to work out how to transmit solar rays to Earth without losing much of its energy during the conversion processes.

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