Last Gasp For Fossil Fuels

The idea of beaming solar power down to Earth from orbiting solar farms is an alluring one. Space solar projects could deliver clean kilowatts 24/7, anywhere on Earth, any time, regardless of the weather — if they happen. Nevertheless, the technology pieces are beginning to fall into place, and the economic case is beginning to materialize, too.

Reducing The Cost Of Space Solar Panels

Solar cells are nothing new to the space field, of course. NASA launched the first solar-powered satellite back in 1958, and solar power has been a fixture in space exploration ever since.

The key issue for orbiting photovoltaic systems is the cost of the solar panels. The high tech solar panels used in space applications are costly, and launching them up into space is also costly. Those costs have to come down before orbiting photovoltaic arrays can compete with their Earth-bound counterparts.

The cost barrier is beginning to fall as researchers develop new solar cells for space applications. One new development came across the CleanTechnica radar on October 24, when the Universities of Surrey and Swansea reported on a first-of-its-kind, long term study of a solar array on a satellite.

“The findings could pave the way for commercially viable solar farms in space,” the University of Surrey noted.

The array was built by a team based at Swansea’s Centre for Solar Energy Research, assisted by engineers-in-training from the Algerian Space Agency. It was designed specifically for the purpose of assessing the economic case for orbiting PV arrays.

The work included developing a new thin-film cadmium telluride (CdTe) solar cell deposited on a thin layer of glass. Thin-film solar cells are lighter, more flexible, and less expensive to manufacture than conventional silicon solar cells.

In addition, the ultra-thin glass panels can be deployed with a relatively uncomplicated “roll-out” maneuver.

The study gathered five years of flight data for four prototype cells. The thinly layered cells showed no signs of peeling or delaminating throughout the 30,000-orbit flight, which was a key test. Electrical systems also held up well.

“The results help to strengthen the argument for further development of this technology for space application,” the team concluded.

Next steps include creating new back contact materials to help ensure against loss of solar conversion efficiency over time, which was apparently the only major challenge to crop up during the flight.

Reducing The Cost Of Rocket Launches

Meanwhile, the European Space Agency has been conducting cost-benefit analyses through its SOLARIS space solar program.

The payoff could be huge. “Sunlight is on average more than ten times as intense at the top of the atmosphere as it is down at the surface of the Earth,” ESA explains, “And up at a sufficiently high orbit sunlight would be available on a continuous basis, to capture all the sunlight available, able to be beamed to receiving stations across the planet, wherever it is needed.”

Getting all that equipment up into space is a challenge, though. ESA estimates that an economical solar farm in space would have to reach a size of at least one kilometer across. That would involve a lot of rocket launches.

ESA notes that the International Space Station required dozens of launches to construct, and a space solar station would require “an order of magnitude more.”

That’s the bad news. The good news is that launch costs have come down since construction on the International Space Station began in earnest, back in 1998. Last summer NASA also teased the idea of manufacturing solar cells on the Moon, which could also somehow come into play. If you have any thoughts about that, drop us a note on the comment thread.

Bad News For Nukes

Another aspect of the economic case for space-based solar is the attraction of avoiding the cost of major new electricity transmission projects on Earth. As demonstrated by recent experience in the US, new interstate transmission projects can take years to get off the ground, if ever.

ESA also bolsters the economic case by positioning space-based solar farms as an alternative to another 24/7 zero-emission resource, nuclear energy.

“A single solar power satellite of the planned scale would generate around 2 gigawatts of power, equivalent to a conventional nuclear power station, able to power more than one million homes,” ESA notes.

That’s not such great news for nuclear energy fans here in the US, where nuclear technology still gets the side-eye on account of the 1979 Three Mile Island nuclear power plant disaster in Pennsylvania. A new 2-gigawatt facility would have a tough time finding a home anywhere in the US without a long, costly slog through permitting obstacles and court challenges.

Despite its popularity in other parts of the world, nuclear energy has struggled to compete against the copious renewable energy resources of the US (see more CleanTechnica nuclear energy coverage here). Now here comes space solar with another twist of the knife.

Only three new nuclear reactors are at or near completion in the US since the turn of the century. One of them began construction back in 1972. The other two started in 2009 and lurched over the finish line dragging billions in cost overruns. All three are add-ons to existing nuclear power plants.

Space Solar: How To Get It From There To Here

As for how to get electricity from a space solar array down to Earth, that’s easy. As described by ESA, the basic technology for wireless transmission is already in place.

The devil is in the details, though. CleanTechnica has been keeping tabs on space solar research in the US since 2013, when we took note of a pitch organized by the National Space Society. The idea sounded far-fetched back then, but in 2014 we noted that the US Navy was eyeballing space solar in its efforts to cut down on fossil fuels.

By 2015, Northrop Grumman also had an interest in developing technology for space-based solar farms. They engaged in a partnership with NASA’s Jet Propulsion Laboratory through CalTech, which runs the facility. The Air Force has also identified space solar as a key energy technology for the warfighter of the future, so it’s no surprise to find Northrup Grumman partnering with the US Air Force Research Laboratory to accelerate the space solar industry.

Another piece of the puzzle came from the US Naval Research Laboratory in 2020, with an update on a solution to trim down the size and weight of solar cells for space-based solar farms. The new cells would be integrated with a solar conversion system and an antennae, enabling them to transfer solar energy to a radio signal and beam it down to earth.

The latest news from CalTech involves a successful test of wireless transmission from a space-based solar array to Earth earlier this year. Last week, reports also surfaced that CalTech scientists are working on a self-assembling system for solar farms in space, so stay tuned for more on that.

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Image: Europe’s SOLARIS space solar research program is building an economic case for sending solar farms in orbit around the Earth (image courtesy of ESA).