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tcbarbara's avatar

Barbara & Howard Zinn thank you Bill!

What we choose to emphasize in this complex history will determine our lives. If we see only the worst, it destroys our capacity to do something. If we remember those times and places—and there are so many—where people have behaved magnificently, this gives us the energy to act, and at least the possibility of sending this spinning top of a world in a different direction.

And if we do act, in however small a way, we don’t have to wait for some grand utopian future.

The future is an infinite succession of presents, and to live now as we think human beings should live, in defiance of all that is bad around us, is itself a marvelous victory.” ~ Howard Zinn, from book You Can't Be Neutral on a Moving Train

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Stephen Schiff's avatar

As someone who worked in microwave systems engineering for a couple of decades, I am highly skeptical about schemes involving collecting solar energy in space then beaming it back to earth via microwave radiation, followed by conversion to electricity on earth. Please permit me to elaborate. First, there is the cost on placing the huge solar arrays, associated attitude control systems, DC to RF converters, and antennas into orbit. Next is the matter of efficiency. While it is true that outside the atmosphere the solar irradiance is abou twice that on the ground, typical RF devices are much less than 50% efficient, leading to more than a 75% loss from those devices alone. Then there are the antennas, which also introduce losses, and the potential added problem of unacceptably dangerous RF field levels if sufficient sidelobe suppression is not achieved. The there is the problem of microwave attenuation by the atmosphere. The latter can be ameliorated by choosing a sufficiently low frequency, but then both the space- and earth- located antennas become commensurately larger.

It is not a matter of possibility but rather of practicability. Ask yourself, who makes money on this? How does it contribute to a distributed energy infrastructure? How much more renewable energy would be produced bif the money was spent on earth- bound solar and wind?

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