Jason Lomberg, North American Editor, PSD
Space-based solar power (SBSP) is a noble idea that’s likely impractical for a number of reasons.
But first, let’s clear up what SBSP isn’t – it’s not, by any means, a new concept. Researchers have pondered the idea since the early 1970s, during the height of the Apollo program, and SBSP was first mentioned back in 1968.
And solar power and NASA have long been intertwined. Solar panels have helped power the International Space Station since the first arrays arrived in 2000, and they’ve been running continuously ever since, providing energy for the daily research and science investigations, plus the continued operations of the orbiting platform.
Technically, a SBSP-like concept – where a space station collects solar power and transmits it back to Earth via microwaves – was described all the way back in 1941 in the Isaac Asimov short story, “Reason.”
So when the European Space Agency (ESA) began exploring the feasibility of SBSP in 2022, it wasn’t exactly Earth-shattering.
It’s not even a novel idea in recent times. In 2014, the U.S. Department of Energy discussed the idea of SBSP in similar terms as the present.
Noting that every hour, more solar energy reaches the Earth than humans use in a year, the DOE mentions that the atmosphere reflects 30% of this solar energy back into space. And since SBSP wouldn’t be effected by clouds, the atmosphere, or nighttime, it could soak up substantially more power than terrestrial models.
Specially equipped satellites would gather high intensity, “uninterrupted solar radiation by using giant mirrors to reflect huge amounts of solar rays onto smaller solar collectors,” after which the radiation “is then wirelessly beamed to Earth in a safe and controlled way as either a microwave or laser beam.”
This is eerily similar to the ESA’s proposed methodology.
The logistics are daunting – we’d need dozens of sunlight-gathering satellites, each with a mass 10x larger than the International Space Station. And, oh yeah, we’d have to substantially increase our life capacity – a 200-fold increase, to be exact, according to British firm Frazer-Nash, which produced one of two reports commissioned by the ESA on the feasibility of SBSP.
Frazer-Nash estimates that we’d need 54 gigawatt-scale satellites to be in operation by 2050, and that – plus the logistics of beaming the solar energy back to Earth – could introduce prohibitable costs.
Remember that the International Space Station – which, remember, is 1/10 the mass of one of the 54 gigawatt-scale solar satellites we’d need in orbit – took 10 years to construct and more than 30 missions.
Current technologies could certainly expedite that timeline, and Frazer-Nash estimates that each satellite would take 4-6 years, with a final timeline (and budget) dependent on the annual launch capacity.
According to the firm, a European space-port and one reusable heavy launch vehicle could support around 77 SBSP launches per year, but virtually no space project on Earth, especially in the last 30-40 years, has ever been on-time or on-budget.
I think physicist Casey Handmer perfectly summarized the pitfalls of SBSP:
“I can relax assumptions all day," Handmer wrote. "I can grant 100 percent transmission efficiency, $10/kg orbital launch costs, complete development and procurement cost parity, and a crippling land shortage on Earth. Even then, space-based solar power still won’t be able to compete.”
By Handmer’s calculations, SBSP would be 3x more expensive than terrestrial versions. So space-based solar power isn’t looking exceptionally viable.