>At this level, our 3.6 km diameter collecting area would generate about 40 GWh of energy in a day, at an assumed reception/conversion efficiency of 70%. By comparison, a flat array of 15%-efficient PV panels occupying the same area in the Mojave Desert would generate about a fourth as much energy averaged over the year. So these beaming hotspots are not terribly more concentrated than what the sunlight provides already. Again, I find myself scratching my head as to why we should go to so much trouble.

And the footprint of the rectenna array is enormous-- Tom assumes a 100GHz transmit antenna 30m wide, which means the downlink antenna has to be 3.6km wide! And this is the minor axis-- the solar array has to be geosynchronous orbit, which means any receiving antenna not on the equator has be an ellipse.