Ethanol From Waste Straw

>The minimum useful size for an SPS rectena is approximately 5 km
>diameter, or about a couple of Gigawatts.
>
True if you're transmitting by microwaves - but a laser system (which
admittedly might have some problems with weather) could beam to much
smaller locations. I've actually seen a detailed, though to my mind
rather far-fetched, proposal to beam power by laser from an SPS to
individual moving vehicles, at intensities sufficient to power them
(i.e. hundreds of kW per square meter). The information technology and
precision beaming requirements are not impossible; it's the liability
when you occasionally miss with your millions of beaming lasers that I
would worry about...