Building satellite-based solar panels could be hugely effective − once we get the technology right.
Building satellite-based solar panels could be hugely effective − once we get the technology right
Solar power is becoming commonplace, but it has limits to its effectiveness − it's interrupted by clouds and it doesn't work at night. To overcome these obstacles, engineers have for more than 40 years been looking at harnessing the sun's power using satellites.
Once considered too expensive and complicated, space-based solar power may soon be within reach.
The idea is to build solar panels in space, which would bathe in sunlight all the time. The energy they collect could be beamed to Earth as microwaves. Ground antennas would collect the waves, converting the energy, which arrives as a radio frequency, into electricity for the grid.
There are lots of challenges to achieving this, but the technology is moving forward fast. In 2008, researchers in Maui, Hawaii beamed solar-generated electricity using this method from a mountain top to the state's main island nearly 150 kilometres away. (The atmosphere is some 500 km thick, but about 80 per cent of it is within 16 km of Earth's surface.)
Cost is still one of the major hurdles. To build a 1,000 megawatt solar satellite station, it would take a solar station of about 52 square km. Until asteroid mining becomes viable, still decades away, all of this would have to be launched from Earth. Even as the cost of space travel comes down, this still would cost some $2,000 per kilogram.
The size of the microwave receivers on Earth is another challenge. To be effective, they would need to be as big as 8 km. in diameter, suspended 10 metres off the ground.
Nevertheless, John Mankins, a NASA veteran, thinks a solar satellite plant can be launched by 2025. He has designed one called SPS-ALPHA − it stands for Solar Power Satellite via Arbitrarily Large Phased Array.
The satellite solar power collector looks like a giant margarita glass. Using improved, more efficient solar panels and lighter, carbon composite construction materials, he believes solar power from space can become an affordable reality.
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