Will space-based solar power ever make sense?

Space-based safety

These plans involve large fluxes of microwave or radio radiation. But space-based solar power is relatively safe. For microwave radiation from a space-based solar power installation, “the only known effect of those frequencies on humans or living things is tissue heating,” Vijendran said. “If you were to stand in such a beam at that power level, it would be like standing in the… evening sun.” Still, Caplin said that more research is needed to study the effects of these microwaves on humans, animals, plants, satellites, infrastructure, and the ionosphere.

Getting that across to the public may remain a challenge, however. “There’s still a public perception issue to work through, and it’s going to need strong engagement to bring this to market successfully,” Adlen said.

Military attacks using space-based solar power might also raise concerns. But even if a space-based solar power station was hijacked for military reasons, the hardware would limit the beam to a safe intensity so that it could not be used to harm people or ecosystems on Earth, Ceriotti said.

Beyond the environmental issues, there are additional concerns that will need to be sorted out before deployment. Interference with communications signals is another potential risk, although Gibney wrote that the beam’s frequency would not disrupt aircraft communication. Some other physical risks are important to take into account.

Orbiting debris such as meteorites or space junk could strike the station and damage it, Vijendran said. If the impacts on the solar power station generate debris, that could cause problems as well. Plus the hardware itself will have to be deorbited when it reaches end-of-life. “ESA has a Clean Space Initiative. Anything that we’re sending to space, we have to think about the whole lifecycle, cradle to grave,” Caplin said.

Finally, the project would still have an environmental impact. Putting the solar power station hardware in orbit, constructing it, and controlling it would generate pollution and use a substantial amount of fuel, Ceriotti wrote. Hundreds of launches might be required.

Launch economics

Beyond their environmental impact, those launches will cost money. Cost has usually been the main barrier to building a space solar power station so far, Caplin said. “As that landscape is changing and things are generally becoming cheaper to send to space, we can put it on the table again. Money talks. We have the advice of two independent studies on cost-benefit analyses, and they both determined that this could be viable.”

The expense of space-based solar power would include manufacturing costs, maintenance costs, and launch costs, Ceriotti said.

“We expect [the] cost to fall in future,” Vijendran said. “We can start with a power that is competitive with what we pay for nuclear today… between $100 and $200 per megawatt-hour… which is higher than intermittent renewables like solar and wind, but has a role to play because it is reliable and available 24/7.”

Vijendran said he expects the cost of space-based solar power will eventually fall to a point where it is competitive with solar and wind power on Earth, which is below $50 per megawatt-hour. According to the Energy Information Administration’s 2022 publication on this subject, both solar power and onshore wind cost around $20–$45 per megawatt-hour in 2021.

Adlen’s cost estimate is much lower—around a quarter of the cost of nuclear power.

SpaceX and Blue Origin are designing launch vehicles that can handle heavy lifts, Ceriotti wrote. These vehicles’ parts can be reused, and their high capacity and reusability can drop the cost of some aspects of construction by 90 percent.

Looking toward the future, what are the next steps in the development of space-based solar power? The ESA plans to make a decision next year about its goals in developing an uncrewed space station, Vijendran said. The process has been slowed by a shortage of financial support from some European countries.

“The first major decision point would be to implement a… small-scale in-space demo mission for launch sometime around 2030,” Vijendran said.

Outside of the ESA, Caltech has demonstrated a lightweight prototype that converts sunlight to radio-frequency electrical power and transmits it as a beam. The university has been researching modular, foldable, ultralight space-based solar power equipment.

“My view is that much like the world of connectivity went from wired to wireless, so we're going to see the world of power move in a similar direction,” Adlen said. International cooperation will be key to creating space-based solar power stations if projects like these move forward.

Kat Friedrich is a former mechanical engineer who started out as an applied mathematics, engineering, and physics major at the University of Wisconsin-Madison. She has completed a graduate degree focusing on science and environmental journalism and has edited seven news publications, two of which she co-founded. She is the editor-in-chief of the energy magazine Solar Today.