A new cost-benefit analysis based on current NASA designs for space-based solar panels shows they could remove the need for up to 80% of ground-based solar and wind in Europe.
The concept of space-based solar power was first proposed at the height of the space race in 1968 by Czech-American aerospace engineer Peter Glaser. Though published nearly 60 years ago, Glaser’s paper made the prescient observation: “Whether or not the human species will continue to expand could depend on our ability to develop alternative energy sources [to fossil fuels].”
Alternatives such as solar and wind power have become increasingly popular amid a need for net-zero carbon emissions to offset human-induced climate change.
Despite this growth of wind and solar, there remain problems.
Solar energy, rather obviously, can only be produced when the Sun is shining. Engineers are working to develop massive batteries which can store huge amounts of energy to compensate for periods when the Sun isn’t out like at night or in cloudy conditions.
Such issues could be alleviated by solar panels in orbit around Earth.
The new analysis, published in the Cell Press journal Joule, looked at 2 current proposals for space-based solar panel designs.
One is a “heliostat swarm” – a large group of mirrors which reflect sunlight to a central receiver transmitting energy to Earth. Such a design could provide power for up to 99.7% of the year whether it is day, night, sunny or cloudy on the ground.
The other design is known as a “mature planar array”. This is a more traditional design which has an array of flat solar panels facing away from Earth and radio wave emitters facing down toward the planet to transmit the solar energy. This design has a lower capacity, capturing solar energy about 60% of the time.
Either design would be a major advance on current Earth-based solar panels which have an efficiency of only 15–30%.
Both designs are detailed in a 2024 NASA report on the viability of space-based solar power.
“In space, you potentially have the ability to position solar panels to always face the sun, which means power generation can be nearly continuous compared to the daily pattern on Earth,” says senior author of the Joule paper Wei He, an engineer at King’s College London, UK. “And, because it’s in space, the solar radiation is higher than on the Earth’s surface.”
Space-based solar power is being researched around the world, including in China, India, Japan, Russia, the US and the UK. But how effective the concept would be in the push for net-zero emissions has yet to be quantified until now.
Space solar illustration. Credit: Wei He.
“This is the first paper to put space-based solar power into the energy system transition framework,” says He. “We’re currently at a stage to transfer this blue-sky idea into testing at a large scale, and to begin discussing regulation and policymaking.”
He and colleagues modelled scenarios with and without space-based solar power to see how the technology would compete with other sources of renewable energy in Europe.
Their findings showed that the heliostat design would outperform wind and solar power in Europe by the year 2050.
Heliostat power would reduce total system costs by 7–15% and offset up to 80% of ground-based wind and solar. The simulations also showed a 70% reduction in the need for large-scale batteries, though some colder regions would still require hydrogen storage in the winter months.
The heliostat design’s annual costs would need to fall to about 14 times the cost of Earth-based solar panels in 2050 to be cost effective. A planar design would be cost effective at 9 times the estimated cost for Earth-based solar panels in 2050.
“At present, space-based solar power’s costs are 1 to 2 orders of magnitude above these break-even points,” says He.
The team suggest developing both space-based technologies, despite the planar design’s relative inefficiency.
“We recommend a coordinated development strategy that combines and leverages both technologies to achieve better performance,” says He. “By first focusing on the more mature planar design, we can demonstrate and refine space-based solar power technologies while concurrently accelerating R&D for designs with more continuous power generation.”
“In the future, I also want to explore potential risks to space-based solar power, such as orbital debris and system degradation, and how we can minimise those risks,” says He.