
374 Engineering Response to Climate Change
provide electric power without the movement of mass through the biosphere,
without power plants, and with power that is independent of the biosphere.
The rectennas are safely illuminated at a maximum of approximately 230
W
e
/m
2
or approximately 20% of noon sunlight. They output approximately
200 W
e
/m
2
and approximately 30 W
t
/m
2
of waste heat. A rectenna can be
approximately 90% transparent to sunlight. Areas under a rectenna can be
whitened and can reect, averaged over a year, more solar power to space than
what the rectenna receives as microwaves. Thus, rectennas can be thermally
neutral. Only 100,00 ...