Image credit: Department of Energy
A future in which solar panels in space beam continuous energy back to earth will require some major advancements in tech and manufacturing, a new study published yesterday by NASA found. The report examined the potential for a space-based solar power system to start operating in 2050.
Renewable energy resources on earth, though advancing and deploying rapidly, can’t yet serve as a direct replacement for the consistent, reliable power that fossil fuels can provide anywhere in the world (at least not without major leaps forward in storage deployment). That’s the biggest value add space-based solar brings — filling that gap to help wean the world off oil and gas.
And while the technology hasn’t yet garnered the attention of investors, space-based solar is in many ways a concept the renewable energy sectors are already familiar with, said Vijendran, who described it as “an advanced form of solar power.”
“Take your solar panels that you're well used to and think of putting it in a place where you can get the most pure form of solar energy, at the highest intensity, where it's always available and that's just simply not available on Earth,” Vijendran said. “And the best place and the only place you can do that is out in orbit in space.”
NASA’s report considered two types of space-based solar technologies — a heliostat swarm and a planar array — the most studied models, NASA said.
A heliostat swarm system generates power 99% of the year by autonomously redirecting heliostats to face a concentrator to focus sunlight. NASA estimates that a two-gigawatt capacity system would cost $276 billion.
A planar array uses flat panels, with solar cells that face away from Earth and microwave emitters that face towards it. This system generates power 60% of the year, and is estimated to cost $434 billion — but according to NASA the technology is closer to readiness than the swarm system.
For both systems, launch costs are immense. The process — which involves physically getting panels into orbit — eats up more than 70% of the total price. Launch is also the technology’s major source of greenhouse gas emissions (though the report found that a space-based solar system would likely emit roughly the same amount of emissions as its terrestrial counterparts).
Manufacturing is the next most expensive element, accounting for 22% of heliostat swarm costs and 18% of planar array costs. According to NASA’s calculations, the baseline lifecycle cost of electricity for a heliostat swarm system is around 60 cents per kilowatt hour. For a planar array, it’s $1.59/kwh.
Compared to present-day clean energy sources already up and running here on the ground, very, very expensive: up to 80 times more expensive for planar array systems, and 31 times more expensive for the more nascent heliostat swarm.
But, NASA said, there’s still the potential to decrease the cost of space-based solar so drastically that it could be on par with terrestrial solar, wind, hydropower, and concentrated solar power. Doing so will require improving hardware lifetimes, solar cell efficiency, and manufacturing capabilities, among other things.
For example, extending the baseline hardware lifetime from ten to 15 years could cut in half the number of necessary maintenance launches, thereby decreasing the cost of both systems by 25%. Based on NASA’s calculations, these changes alone could decrease greenhouse gas emissions by nearly 30%.
Then there’s cell efficiency. Increasing the efficiency of solar cells decreases the size of the system needed to get to 2 GW, and also decreases hardware development and assembly costs. Increasing efficiency from 35% to 50% (which is in line with the market’s most efficient cells on offer today) reduces the total cost of operation by around 25%.
Those conditions — plus reduced launch costs and an accelerated manufacturing learning curve — could result in cost decreases of up to a whopping 95%, the report concluded, bringing space-based solar power into financial parity.
As with other frontier technologies, how long it takes to get there, Vijendran said, depends on money.
“Peculiarly, space-based solar power is the only really promising form of clean energy, potential form of clean energy technology, that I would argue the world is not investing in significantly,” he said, pointing to the billions of dollars pouring into nuclear fusion research.
“If we carry on at this rate, it can be a very long time before we see anything.”
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