Orbiting solar power plants could provide the energy of the future

The world’s space agencies are already working on the technology that would move a significant part of energy production from Earth to space. The Kardashev Scale, created by Nikolai Kardashev in 1967, measures the development of a civilisation in two ways: technological development and energy production. The second is in fact a prerequisite for the first, because the more energy we have, the faster we can develop – and of course the faster we develop, the more energy we can produce. It is no wonder that physicists and mathematicians have long been experimenting with ideas to make much more efficient use of the energy resources we have, the most obvious of which is solar energy.

Perhaps the best known example is the Dyson Sphere, invented by Freeman Dyson, which could harness all the energy of a given star, and although we are not yet at the point of realising this, an idea that seemed like science fiction a few decades ago could become reality in the next few decades.

As early as the 1920s, Konstantin Eduardovich Tsiolkovsky, one of the fathers of modern rocket science, laid the theoretical foundations for solar power plants orbiting the Earth that could harness the potential of solar energy much more efficiently than power plants on the ground. While renewable energy technologies have undoubtedly made huge advances and are becoming more efficient and cheaper, wind and solar power will always have the disadvantage of not being able to produce energy continuously. One solution to this might be to generate solar power not on Earth but from solar power plants orbiting the Earth in space, which would immediately solve two problems: solar panels facing the sun continuously would be able to generate power 0-24, and since the Earth’s atmosphere would not be in the way, they would also be able to operate much more efficiently.

Tsiolkovsky’s idea has mainly fuelled science fiction writers throughout the 20th century, but as Dr Stefania Soldini and Amanda Jane Hughes of the University of Liverpool show in a paper in The Conversation, the time is not so far off when the technology could be a reality. The European Space Agency has just launched a programme to develop these technologies, and is looking for any ideas that could help make orbiting solar power a reality. If successful, the programme could be a real breakthrough in development, as there are still several elements of space-based solar power that are still more theoretical about how it should work.

One unsolved problem is how to put such a huge structure into orbit around the Earth. To be effective, the spacecraft would have to be up to ten square kilometres in size, so it would have to work with very lightweight materials, since the most expensive part of the whole project would be to put the device into orbit. One widely supported proposal is to build the solar power plant from thousands of small satellites with solar panels, which would be assembled into a large structure in space. In 2017, researchers at the California Institute of Technology (Caltech) developed a possible way to do this, and prototyped a solar panel weighing just 280 grams per square metre, which is barely heavier than a smartphone, for example.

Similar technology is being experimented with by researchers at the University of Liverpool, who are using 3D printing to create flexible “solar sails” that can convert sunlight into energy, making them as suitable for powering space devices as they are for building a solar power plant. 3D printing could be key to the new technology, as it could in future allow solar power plant components to be printed directly in space, on the International Space Station or the yet-to-be-designed Lunar Gateway space station, saving the cost of launching them. The next step would be not only to manufacture in space, but also to obtain the raw materials, as researchers have long been exploring ways of mining the materials needed to make the various devices from asteroids or even the surface of the Moon.

The other major technological challenge is getting the energy collected by the solar power plant back to Earth, as today’s technology uses wires, which is not feasible in space. The plans, which are still in their infancy, would convert the electricity from the solar panels into electromagnetic waves, microwaves or lasers and transmit it to terrestrial antennas, which would then convert the electromagnetic energy back into electricity. The Japanese space agency already demonstrated a device that could do this in theory in 2006, and let us not forget that wireless energy transfer has long been actively pursued outside the space sector.

What is certain, according to the authors, is that such orbiting solar power plants could be a reality within the next few decades. So far, only China has a concrete plan to do so, having unveiled plans in 2016 for a solar power plant capable of generating 2 gigawatts of energy. Named Omega, it is planned to be operational in 2050 and could replace the full capacity of more than six million ground-mounted solar panels at maximum capacity.

Source: https: sciencedirect