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Path: utzoo!utgpu!water!watmath!clyde!rutgers!gatech!bbn!bbn.com!eli
From: eli@bbn.com (Steve Elias)
Newsgroups: talk.politics.misc,sci.misc
Subject: Re: greenhouse effect
Message-ID: <22670@bbn.COM>
Date: 27 Mar 88 15:51:19 GMT
References: <34557@kestrel.ARPA> <2430@umd5.umd.edu> <2116@mit-amt.MEDIA.MIT.EDU> <22089@bbn.COM> <35092@kestrel.ARPA> <22285@bbn.COM> <2963@sfsup.UUCP>
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In article <2963@sfsup.UUCP> glg@/guest4/glgUUCP (xt1112-G.Gleason) writes:
>In article <22285@bbn.COM> eli@BBN.COM (Steve Elias) writes:

	(regarding solar power satellites)

!!	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).

	indeed something is bogus:  the very idea of Solar Power Satellites
	being a useful energy source.  they would be enormously expensive
	and enormously dangerous (thermally), if enough were built to 
	actually provide a decent amount of energy.

	energy put into building earthside collectors is not leaving the
	earth/atmosphere system, so it doesn't negate the energy sent down
	by the power satellites.  reflectivity changes due to the collectors
	would have to be considered, as well.  but, regardless of reflectivity
	changes, thermal equilibrium would be quite goofed up -- by waste heat
	from the microwave receivers...

	the greenhouse effect can theoretically be kicked off by both CO2
	buildup and by large thermal changes -- both factors are 'cause' and
	both factors are 'effect'.  that's Frank Drake's point...  i'm with
	him all the way on this one...  just call me "thermally correct".