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  • James Lowry

Caltech’s Space Solar Power Project Getting Ready for Test Launch

Imagine a renewable energy source that runs reliably 24/7, supplying the world with a clean, uninterruptible energy source. That’s just what Donald Bren, chairman of Irvine Company and a lifetime member of the Caltech Board of Trustees, did back in 2011 when he read about space-based solar energy. His dream led to a $100 million donation to Caltech two years later to make it a reality.

Now Caltech’s Space-based Solar Power Project (SSPP) is getting ready for a test ride that will hopefully one day result in solar energy collected in space being beamed back wirelessly to Earth through microwaves. If it works, increased terrestrial power availability unaffected by weather or time of day could become a game-changer for renewable energy. It would mean solar power could be continuously available anywhere on Earth without the limitations of the day-night cycle or cloud cover interrupting the flow.

Generally, the primary hurdle for such projects is money; however, the donation from Bren has given SSPP a jump start. Bren was intrigued by the concept of space-based solar energy manufacturing from an article he read in Popular Science. In 2013, his wife, Brigitte, agreed to fund the project.

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The concept is indeed intriguing. Utilizing an ultralight modular assembly, Caltech's design uses 2D foldable elements. Integrating solar power with radio frequency electrical power avoids disruption in the power network throughout the structure. The integration also helps reduce weight and complexity, enabling the opportunity for scalability. In addition, the various systemic components have local elements to prevent failure on different parts of the system.

"Solar energy is the world's most abundant energy resource. However, sunlight is intermittent at the earth's surface. This ambitious project is a transformative approach to large-scale solar energy harvesting for the Earth that overcomes this intermittency and the need for energy storage since sunlight shines continuously in space," said Harry A. Atwater, an SSPP researcher, Otis Booth Leadership Chair of the Division of Engineering and Applied Science and the Howard Hughes Professor of Applied Physics and Materials Science, and director of the Liquid Sunlight Alliance.

Caltech recently demonstrated the lightest integrated multifunctional prototype. The prototype collects sunlight, converts it to RF electrical power, and then wirelessly transmits that energy in a steerable beam.

The Caltech team will launch the project's technological prototypes into space in early 2023, marking the SSPP's first space test. The solar power generators and RF wireless power transfer will include a deployable structure measuring approximately 6 feet by 6 feet. Thus, SSPP's aim to produce affordable, renewable, clean energy on a global scale may soon come to fruition. The main interest in harnessing solar power from space is the removal of weather constraints and intermittent darkness. The ability to access the sun all day, every day, would be a massive step forward for clean, renewable energy.


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