OMEGA-2.0: the butterfly-inspired design to cool China’s space solar power plant

Chinese scientists said they have solved a major challenge to generating powerful energy beams in space using a practical solution inspired by butterflies. China is developing a space solar power station that can collect solar energy and send it to Earth in the form of a microwave beam for producing electricity. The mega infrastructure will have a bowl-shaped body about 1km (0.62 miles) wide. The inner surface of the bowl is designed to face the sun and is made of reflective mirrors that could capture and concentrate sunlight on an electric generator. The rod-shape generator, which converts the solar energy to electricity, will use a number of large but lightweight structures mimicking the shape and structure of butterfly wings to dissipate heat, according to the plan known as OMEGA-2.0. The “wings” have tiny veins containing flowing fluids for heat exchange. Excessive heat has been one of the biggest headaches for the project’s engineers, but the bionic structure could effectively radiate the heat carried by the fluids to space and reduce the temperature of the generator by nearly half to just over 50 degrees Celsius (122 Fahrenheit), according to their calculation. “This is an innovative design,” Duan Baoyan, professor of mechatronics at Xidian University and a lead scientist in the Chinese space solar power plant programme, said in a paper published in the peer-reviewed journal Scientia Sinica Technologica on January 18. The butterfly wing structure “not only maximises the area of radiation heat dissipation but also achieves the lightest mass”, he added. In 2017, Duan’s team proposed the original OMEGA plan to send energy more than 30,000km to Earth. OMEGA is an abbreviation for Orb-shaped Membrane Energy Gathering Array. The design featured a full-spherical structure, like a ball. The sunlight would go through the ball’s semi-transparent membrane and reach the generator inside. The OMEGA plant can produce 8.4 kilowatts of electric power per kilogram of its weight, according to a computer modelling estimate. This was more efficient than any other design for proposed space solar plants, said Duan’s team. But the orb structure comes with big engineering challenges. The generator, for instance, could build up a large amount of heat inside the ball that could affect the operation of some critical components. The membrane structure also needs a special coating that lets sunlight in but prevents it from going out. Chinese scientists build hypersonic generator to power futuristic weapons Development of a new coating material to meet the project’s requirements proved to be difficult, according to Duan. But the bowl structure in the OMEGA-2.0 design put the electric generator in an open space that allowed the application of a butterfly-wing radiator. And it meant there was no longer a need for the special coating material, Duan said in the paper. The OMEGA-2.0 adopts some other new space technologies. It has replaced the giant microwave emitter of the earlier design with a pair of smaller, disk-shape antennas similar to the radar on an early warning aircraft. These antennas have no moving parts, but they can manipulate the microwave and direct the energy beam to almost any direction. The new solar plant will also be equipped with an ultra high-powered electric propulsion system, according to Duan. The megawatt ion thruster drive is under development in Shanghai and expected to consume significantly less fuel than a rocket engine and keep the station in its position for a long period. China plans to conduct the first space-to-Earth energy transmission experiment in about two years. The experiment will be carried out by an orbiting satellite at a much lower altitude than that used by the solar station to verify critical technologies for wireless energy transmission. The military is likely to be the first user of the technology, according to the plan. The microwave beam could power remote military outposts, drones or space-based weapons that require extra energy input. Some researchers say the microwave beam itself could also be used as a weapon. Computer modelling suggests the beam can increase air temperature and harmfully expose an unprotected area. Some other countries are developing similar technologies. China’s artificial sun project sparks discovery in fusion energy A Beijing-based researcher studying wireless energy transmission said the US military was the leader in this field. But a large-scale solar plant in space could be decades away because of the many scientific, technological and engineering challenges, said the researcher who asked not to be named because of sensitivity surrounding the technology. “The plant could weigh more than 10,000 tonnes. This is more than 20 times the size of the International Space Station,” he said. “Opinions will vary significantly on how to build and operate this mega project.”