When I was an undergraduate in electrical engineering at the University of Idaho I wrote a paper reviewing the use of microwaves to beam energy from space to the surface of earth. In 1973 Peter Glaser, vice president of Arthur D. Little, Inc was granted a patent for certain aspects of this concept.

I was quite enthralled by the concept. The critics claimed things like:

• Bird will be cooked by the microwave beams mid flight.
• Planes which accidently get in the path of the microwave beam will drop out of the sky.
• The losses will be so great that on earth you wouldn’t be able to power anything bigger than a toaster.

Most of the critics were, to electrical engineers, laughable wrong.

In regards to cooking the birds the frequency of the microwaves would different from your microwave oven. A frequency that was not absorbed by rain and water vapor would be chosen to decrease transmission losses.

The energy density of the microwave beam would be little different than a microwave communications tower. The beam width was quite large and hence large amounts of energy could be transmitted without frying the electronics of anything blocking a small portion of the beam.

There are few things more well known than how to calculate the power loss of electromagnetic radiation in free space. You could power small cities from a single satellite.

There was one problem which did not have a good response. That was the cost to get the materials into orbit and to assemble it in space. If I recall correctly, Little’s study claimed the cost to orbit needed to get down to $30/pound for it to match earth based systems. Again, IIRC, the price at the time was well over $100/pound.

When the Space Shuttle went operation I thought perhaps the costs would be low enough that the concept would be practical. Nope.

It turns out that people are working on the concept again:

Scientists working for the Pentagon have successfully tested a solar panel the size of a pizza box in space, designed as a prototype for a future system to send electricity from space back to any point on Earth.

The panel — known as a Photovoltaic Radiofrequency Antenna Module (PRAM) — was first launched in May 2020, attached to the Pentagon’s X-37B unmanned drone, to harness light from the sun to convert to electricity. The drone is looping Earth every 90 minutes.

An important difference from Little’s plan is that these satellites would be be in low orbit rather than in geosynchronous orbit. This allows a handoff from one satellite to another when a satellite goes into the earth’s shadow.

It’s clean power. And more importantly, in contrast to earth based solar power, it’s 24/7/365.

I wish them luck.