Space Based Solar Power - Feasible in 1980, Economical Today

A satellite 37,000 km away can power a city even though my wirelessphone charger doesn't work from a few millimeters away.
 
Almost 45 years ago, NASA published a space based solar power satellite reference design [1]. Using the technology of the day (slide rules and mainframes) they showed that even the simplest satellite can beam power to Earth with more than 80% efficiency [2]. The catch was that the transmitter and receivers need to be large; kilometers across. But this is not too large. The reference NASA receiver, at 4.5km in diameter, would easily fit in a small corner of today's utility scale solar farms [3] while producing more energy than the rest of the farm.
 
And..... we can do a lot better today! The advances over the past few decades make it possible to create more efficient beams and much smaller ground receivers.
 
A lot has changed since 1979. Lighter, more compact, solid state electronics have replaced klystrons [4]. Power beams can be steered electronically rather than mechanically. Solar cell are far more efficient and lighter [5]. Robotics are enabling in-space assembly and manufacturing eliminating the need for astronauts [6]. And most importantly, launch costs have dropped dramatically while launch options have expanded [7][8][9]. All of this comes together to make it possible to, not only efficiently beam power from orbit, but to economically put the satellites up and deliver clean, firm, renewable power where ever and when ever it needed.

 
References
[1] - NASA - National Aeronautics and Space Administration - National
Aeronautics and Space Administration - LINK
[2] - NASA - National Aeronautics and Space Administration - National
Aeronautics and Space Administration - LINK
[3] - Wikipedia - Klystron
[4] - https://lnkd.in/d3xz2UKM
[5] - National Renewable Energy Laboratory - Solar Cell Efficiency Trend Chart
[6] - Orbital Composites
[7] - McKinsey & Company - Report Link
[8] - Wikipedia - Launch Costs
[9] - Deloitte - Report Link
 
Images
NASA - National Aeronautics and Space Administration - SPS Alpha Report
NASA - National Aeronautics and Space Administration - Microwave Generation and Transmission Report