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From: glg@sfsup.UUCP (G.Gleason)
Newsgroups: talk.politics.misc,sci.misc
Subject: Re: greenhouse effect
Message-ID: <2963@sfsup.UUCP>
Date: 26 Mar 88 22:28:18 GMT
References: <34557@kestrel.ARPA> <2430@umd5.umd.edu> <2116@mit-amt.MEDIA.MIT.EDU> <22089@bbn.COM> <35092@kestrel.ARPA> <22285@bbn.COM>
Reply-To: glg@/guest4/glgUUCP (xt1112-G.Gleason)
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In article <22285@bbn.COM> eli@BBN.COM (Steve Elias) writes:
>In article <35092@kestrel.ARPA> king@kestrel.ARPA (Dick King) writes:
>>In article <22089@bbn.COM>, eli@bbn.com (Steve Elias) writes:
>! !  	and solar power satellites would be even bigger thermal
>! !  	offenders than solar cells on the ground.  
 
>! Actually no becuase the waste heat would be dissipated in space.

>	actually yes!  waste heat would be dissipated both 
>	in the atmosphere and on the ground.  (microwave transmission).

Actually, it is quite a bit more complicated than this.  First,
conversion effeciency for microwave transmission is considerably
higher (>50% (?75-85) vs 10-20% for solar cells).  Of course this
doesn't matter because the energy a satalite collects is in addition
to the sunlight already hitting the earth, and then we have to consider
the change in reflectivity by putting out solar panels (is it + or - ?).
Don't forget to count the energy you put into building your earthbound
collectors, which could be more than you get out in a lifetime (in space
the energy is free for all practical purposes).

In any case something seems bogus here, because in order to be significant
we would have to be considering SPS's with a total area that is *very*
large (significant relative to the earths total collection are).

Gerry Gleason