Well, seems very expensive and hard to collect. Over short distances it is fairly efficient, but signal density falls off at 1/r^4. Even a MASER would have a very wide beam in geosynchronous orbit once hitting the earth, let alone a large microwave array. That's good news if you're flying through the beam (not sure I'd want to be a slow flying bird though), but after ~23,000 miles (~37,000km) the energy density would be so low, that you'd need a huge antenna on earth.
So unless I forgot my college physics...
For instance lets imagine I have a point source radiator in space putting out a fairly narrow 2 degree beam (I have no idea how narrow you can truly transmit this much energy, but let's keep it simple here):
Why are you using 37,000km for distance in your calculations? space starts bellow 100km above the earth, which is where the power station may be located...
The microwave probably wouldn't spread out like normal light, it would probably be focused and have a much lower spread angle. Also, geosync orbit is less than 23K miles, it around 22K miles.
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This has been planned (on paper at least) for a long time.
None of the problems or dangers seem that great - just expensive to build and get started.
Solar in space is VERY efficient and so is microwave transmitting/collecting.
For those of you afraid of microwaves frying everything up, many companies already use them to beam things around - way below dangerous levels.
In the long run, could be cheap energy, but can't imagine it being cheaper than nuclear energy.
http://en.wikipedia.org/wiki/Space_solar_power
Well, seems very expensive and hard to collect. Over short distances it is fairly efficient, but signal density falls off at 1/r^4. Even a MASER would have a very wide beam in geosynchronous orbit once hitting the earth, let alone a large microwave array. That's good news if you're flying through the beam (not sure I'd want to be a slow flying bird though), but after ~23,000 miles (~37,000km) the energy density would be so low, that you'd need a huge antenna on earth.
So unless I forgot my college physics...
For instance lets imagine I have a point source radiator in space putting out a fairly narrow 2 degree beam (I have no idea how narrow you can truly transmit this much energy, but let's keep it simple here):
Beam width = spread-angle * 0.18 * distance
= 2 * 0.018 * 36800km = 1324.8km
Lets assume the signal is 1.2gW as stated
Square area is 3.1416 * (r=662400m)^2 = 1378451644416m^2
energy density = 1148.7 W/m^2 (not counting transmission losses)
You need a BA'ed antenna to capture that energy (as a point of comparison the District of Columbia has a square area of 177 sq Km)
I don't think this'll work very well either. Maybe if they can float a 177mi^2 antenna on the ocean. =/
(And fry up some sea life. mmmmm....)
Why are you using 37,000km for distance in your calculations? space starts bellow 100km above the earth, which is where the power station may be located...
@TaBu
It's called geosynchronous orbit.
@ henry
The microwave probably wouldn't spread out like normal light, it would probably be focused and have a much lower spread angle. Also, geosync orbit is less than 23K miles, it around 22K miles.
I don't know... having it as non-geosynchronous would make things more exciting. And who doesn't like things exciting?