Episode 50 | Space Solar | Naval Research Laboratory
It was a comment from my guest on Episode 43 that made me look into solar power in space. During our "Lightning Round," he said more solar energy strikes the earth on a single day than has been consumed in human history. If solar cells had a direct line of site to the sun from orbit, then the potential to harvest baseload, abundant energy would be closer to realization.
All searches for "Space Solar" turned up my guest, Dr. Paul Jaffe at the Naval Research Laboratory in Washington DC. He says NRL and the Naval Center for Space Technology have been developing versions of this technology for years, dating as far back as Vanguard 1, the first satellite equipped with solar cells.
Dr. Jaffe says most of the fundamentals of Space Solar are in place. They include:
- PV Cells designed for collection in orbit
- DC-to-RF Conversion Unit
- Transmitter for power Beaming
- Microwave or Laser
- Receiver on Earth
Most of Dr. Jaffe's research focuses on the first three components (all of which would be in orbit), which he refers to as a "Sandwich Module." The key is the power density, by which it would be possible to beam down potentially hundreds of megawatts of energy from a single orbiting satellite.
During our conversation it seemed to me the clear winner is lasers over microwaves. A 1-kilometer diameter Transmitter would require a 3.5 km Receiver on earth for approximately 250 megawatts of energy. However, a laser-beamed Transmitter would require a Receiver much smaller.
Dr. Jaffe reminded me that while the laser solution may be more ideal for a utility-based scenario, his employer, the Department of Defense, could find microwaves more cost effective in theater.
Before our interview I was led on a tour around the facility, where I got to see satellite fabrication and equipment for testing the rigors of space. One of the new technologies being developed is the Robotic Servicing of Geosynchronous Satellites (RSGS) system, which looked like a boxy unit with arms, propulsion, and cameras. Dr. Jaffe says this is key to the cost-effectiveness of any space solar program, because the alternative would be astronauts doing untold numbers of spacewalks to assemble solar satellites in space.
I am convinced that with lowering lift costs thanks to the work of SpaceX and Blue Origin, the RSGS system, and improved power beaming technology, Space Solar will play a strong role in our energy future...whether it be on Earth, the Moon, Mars, or beyond.
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