Energy Blog: Space-Based Solar Power Takes a First Step

Energy Blog: Space-Based Solar Power Takes a First Step

Beaming solar energy from space to Earth looks more feasible after the first results of a Caltech experiment.
Solar energy has been on a tear in recent years, as the global installed capacity rose to 3,372 GW in 2022. The International Renewable Energy Agency reported 295 GW was installed in 2022 alone. It was the second largest generation growth of all renewable technologies, after wind, according to the International Energy Agency, but in order to reach the goals of net-zero emissions by 2050 solar generation must grow by an annual average of 25 percent from 2022-2030.

Solar and other renewable energy sources will continue to grow, but what could be the ultimate game-changer is development of space-based solar power (SBSP). For many, it still seems like pie in the sky, but the first efforts at launching a satellite into orbit and having it transmit energy back to Earth became a reality in June. A space solar power prototype launched earlier this year demonstrated the ability to wirelessly transmit power in space and beam detectable power back to Earth. For the first time.

There’s a long way to go before SBSP is viable, but every new technology starts somewhere and SBSP has the potential to radically change solar power from an intermittent power source to a stable generating option that could provide more energy than the world consumes. That’s a big claim, but the National Space Society claims SBSP has the potential to dwarf all other sources of energy combined.

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Satellites collecting and transmitting solar from space could work 24/7 without having to deal with the Earth’s rotation that divides day into night, when solar becomes dormant. Essentially, the concept uses solar panels to collect solar energy in space with reflectors that direct solar radiation onto solar panels, and then beaming it back to Earth using microwaves or lasers.

The Caltech satellite that stepped off development was designed and launched in January by the school’s Space Solar Power Project. It was developed by a team led by Ali Hajimiri, the Bren Professor Electrical Engineering and Medical Engineering who is the co-director of the project. Caltech research scientist Austin Fikes described the project in an ASME Techcast earlier this year.

Known as the Space Solar Power Demonstrator, it holds three technologies being tested in space. MAPLE, or Micorwoave Array of Power-transfer Low-orbit Experiment, is the system that successfully transferred power from space to Earth, specifically to Caltech. It consists of an array of flexible lightweight microwave power transmitters driven by custom electronic chips built using low-cost silicon technologies, according to the researchers.

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Success hinges on the equipment to be light enough to minimize the amount of fuel needed to launch into space, and flexible enough to fold into a package that can be fitted to a rocket. Keeping costs low is a big driver of the project.

“To the best of our knowledge, no one has ever demonstrated wireless energy transfer in space even with expensive rigid structures,” said Hajimiri in a statement. “We are doing it with flexible, lightweight structures and with our own integrated circuits. It is a first.”

Back on Earth, Rep. Kevin Mullin (D-Calif.) introduced an amendment that the House Science Committee passed that added SBSP to a list of areas for NASA and the Department of Energy to coordinate research and development. Jonathan Dagle, a policy manager for the National Space Society, said in an interview this was the first time since the 1970s that the idea of space-based solar power has been addressed in legislation.

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Mullin noted in committee that Japan, China, the European Space Agency, and the U.K. all are studying the technology and considering space demonstration.

“A lot of the technology that once made this source of energy the work of science fiction is now much cheaper and easier to deploy than ever, putting it within reach,” Mullin said. But it’s not inevitable that this promising research will become feasible at scale. There are still science and engineering hurdles to overcome.”

Advances in rocket technology are helping advance a renewed interest in the technology. It is much cheaper to install solar panels in deserts or on top of large flat roofs than to send them into space. But reusable rockets and more efficient payloads are bringing down launch costs, making it a bit cheaper to get up and into space.
John Kosowatz is senior editor.

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