Can solar panels in space help provide power to the Earth?

Robin Mills

Where can we go that is even sunnier than the Middle East and North Africa? Not many places on Earth, perhaps, but in space the sun shines eternally, unobstructed by clouds or dust. So it is understandable that a desert kingdom might team up with a foggy island nation in an effort to harness this energy source.
Saudi Arabia’s NEOM project, the futuristic new smart city being built in the country’s northwestern corner, is investing in British company Space Solar.
The UK’s business secretary met the chairman of the Saudi Space Commission in January to discuss collaboration in the space technology sector. The US, Japan and China have also shown serious interest in generating solar power in space.
Ground-based solar photovoltaic power has taken tremendous strides forward in recent years, with the Middle East hosting the cheapest and largest systems in the world.
Along with wind turbines, solar has emerged as the favored workhorse for the new, low-carbon energy economy that is essential for efforts to avoid disastrous climate change.
But even in the best locations, solar power’s capacity factor — the ratio of annual output to the maximum instantaneous generation — is only about 20 percent. Naysayers are fond of reminding us that the sun does not always shine, as if this is a new discovery.
There are partial solutions to this: Daytime solar energy can be used to charge batteries or generate hydrogen for storage, for example, or different time zones and latitudes can be connected through high-voltage cables thousands of kilometers long. One consortium is planning such a link between Morocco and the UK.
But “green” hydrogen technology is nascent and relatively expensive, and batteries have limited capacity to see a country through a long, sunless winter. Not all countries have readily-available land.
Long-distance cables could be surprisingly cost-effective but they present political and security vulnerabilities.
The off-world concept calls for an enormous system of mirrors and solar panels in geosynchronous orbit around the Earth, where the sun is visible almost all of the time.
The electricity this generates is converted into high-frequency radio waves, little of which are absorbed by the atmosphere, and beamed to a ground station that converts them back into electricity. The array can be easily redirected so it can serve several, widely-spaced receivers, switching from one to another as night falls or demand increases.
A report funded by the British government found that space-based solar power was technically feasible and affordable. Its potential viability has rocketed as a result of two major recent developments: The dramatic fall in the cost of solar panels, to the point of being the cheapest terrestrial source of electricity, and the declining cost of space launches, facilitated by reusable systems such as SpaceX.
When I wrote about the topic in 2014, the cost of lifting material into orbit was about $10,000 per kilogram, and photovoltaic panels cost about $0.70 per watt.
Now, the cost of a SpaceX launch is just over $1,000 per kilogram, and PV panels come in at about $0.20 per watt.
By 2035, Space Solar hopes to have a full-scale, operational, 2 gigawatt system.
For comparison, this is the same size as the Al-Dhafra solar plant under construction in Abu Dhabi that is set to be the world’s biggest and would generate about as much power as a large nuclear reactor.
The UK government report is more cautious and suggests 2040 as a start date. Based on conservative assumptions, it estimates an electricity cost of about 6 cents per kilowatt-hour.
This is significantly lower than new nuclear plants, hydrogen, or natural gas with carbon capture, which are the other main contenders for continuous, low-carbon electricity.
A development program designed to advance to the first operational system could cost about $20 billion and would probably need substantial government support in the early stages.
The basic components of the system are well-understood; the main technical challenge would seem to be mastering autonomous robotic assembly and maintenance in space.
The panels would need to be as lightweight as possible but modular, easy to assemble, robust and resilient to damage from micro-meteorites, and highly efficient. The launch rockets should use zero-carbon fuels.
It is not certain that space-based solar power can be made commercially viable. But it appears a rather easier prospect than other futuristic energy options, such as nuclear fusion.
It also seems a more practical candidate for the first large, cosmic industry than another popular idea, which is to mine asteroids for rare metals.
We might question why nations in the Middle East, which is set to be a leader in the deployment of terrestrial solar energy, should be looking to the skies as well.
But if other countries are going to launch such space-bound systems, it would be better to be on board.
Locations with plenty of open land close to the equator also make superior receiving sites. Ground-based solar, with its lower costs, could be a good complement to its orbital cousin.
The UAE has its own active space program, which has sent an orbiter to Mars, which entered orbit around the planet in February 2021, and a probe to the Moon, which should touch down in April.
The research and development required over the next two decades to make a space-based solar system a reality will have many technological spin-off benefits.
What was science fiction only a few years ago might soon help illuminate even the Earth’s sunniest regions.