Xref: utzoo talk.politics.misc:8777 sci.misc:1270
Path: utzoo!mnetor!uunet!tektronix!reed!percival!bucket!leonard
From: leonard@bucket.UUCP (Leonard Erickson)
Newsgroups: talk.politics.misc,sci.misc
Subject: Re: efficiency / greenhouse effect / solar power satellites
Message-ID: <845@bucket.UUCP>
Date: 5 Apr 88 04:31:22 GMT
References: <22678@bbn.COM> <5564@well.UUCP> <761@spdcc.COM> <4195@bloom-beacon.MIT.EDU> <763@spdcc.COM> <2997@sfsup.UUCP> <768@spdcc.COM>
Reply-To: leonard@bucket.UUCP (Leonard Erickson)
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Organization: Rick's Home Grown Unix; Portland, OR
Lines: 49

In article <768@spdcc.COM> eli@spdcc.COM (Steve Elias) writes:
<sheesh.  you guys are missing my point regarding efficiency and solar
<power satellites.  pardon me for not being precise enough, and for 
<missing John's point regarding 'fixed power consumption.'  
<
<the point is that every joule sent down from the satellite will end
<up as waste heat on earth -- the efficiency of the ground based part
<of the system does not matter!  
<
<this is true not for 'fixed power consumption', of course.
<it is true for 'fixed power transmission from the satellite'.

The efficiency of the ground station matters because we'll be dealing with
the *useful* energy recieved. Thus a higher efficiency means a better
ratio of usable power to (initial) waste which means a smaller total
heat input.

Heres a list of power sources and whether or not they "add" heat that
would not otherwise be present.

coal			adds
oiil			adds
natural gas		adds
wood			does not add appreciably
nuclear	fission		adds
nuclear fusion		adds
ground based solar	adds
space based solar	adds
hydroelectric		does not add
wind			does not add
tide			does not add

We are near the limits for hydro power (unless you wish to totally mess up
river systems. Wind is far too undepenable. And tidal power on any large scale
will have massive ecological consquences.

Wood was singled out from the other fuels because the energy it releases 
was accumulated *recently* and thus probably won't have *too* great an effect.

So the *sole* issue for all the practical power sources is how to get the
most useful power with the least (initial) waste heat. For all the sources
that are listed as adding, space-based solar would appear to add the least
"extra" heat. (to my knowlegde none of the others even come close to a
9 to 1 ratoi (ie 90% of the heat is useful))
-- 
Leonard Erickson		...!tektronix!reed!percival!bucket!leonard
CIS: [70465,203]
"I used to be a hacker. Now I'm a 'microcomputer specialist'.
You know... I'd rather be a hacker."