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From: lazarus@athena.mit.edu (Michael Friedman)
Newsgroups: talk.politics.misc,sci.misc
Subject: Re: greenhouse effect / solar power satellites
Message-ID: <4249@bloom-beacon.MIT.EDU>
Date: 1 Apr 88 23:12:37 GMT
References: <22678@bbn.COM> <5564@well.UUCP> <761@spdcc.COM> <4195@bloom-beacon.MIT.EDU> <763@spdcc.COM>
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Reply-To: lazarus@athena.mit.edu (Michael Friedman)
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Organization: Murder Inc.
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In article <763@spdcc.COM> eli@spdcc.COM (Steve Elias) writes:
>In article <4195@bloom-beacon.MIT.EDU> jfc@athena.mit.edu (John F Carr) writes:
>!In article <761@spdcc.COM> eli@spdcc.COM (Steve Elias) writes:

>!:     efficiency has nothing to do with the problem of thermal pollution.

>!Efficiency has everything to do with thermal pollution.  For a fixed power
>!consumption, efficiency determines the amount of heat generated relative to
>!useful power.  A system with a 50% efficient converter would produce twice 
>!as much heat as a 90% converter (including the rest of the system, and the 
>!consumer).

>      you are wrong, here.  both the 'useful power' and the 'waste heat'
>      end up in the environment as heat.  

Let's use an example to make this clear. Say I need a megawatt of
electricity. Assume I have two choices - a 50% efficient method (A)
and a 10% efficient method (B). 

To get a megawatt of electricity from A I must produce 2 megawatts of
energy. 1 megawatt will be wasted, and released as heat. The second
will be used, and later released as heat. Total energy released into
environment: 2 megawatts.

To get a megawatt of electricity from B I must produce 10 megawatts of
energy. 9 megawatts will be wasted, and released as heat. The tenth
will be used, and later released as heat. Total energy released into
environment: 10 megawatts.

See the difference?

>      SPS is the only power source
>      which uses energy which would not otherwise enter the earth's
>      atmosphere.  it is worse than most other power sources in this
>      respect. 

This is not important for reasonable power use. If we increase the
total energy flux reaching the earth's surface by .001 % we are
unlikely to do damage. Even an increase that insignificat is probably
well beyond the reach of technology either today or for the
foreseeable future.

On the other hand, we are quite capable of significantly increasing
the CO2 content of the atmosphere. That can prevent energy from
escaping and increase the net energy flux reaching the Earth by a
significant amount. 

>      yes!  my point is that hundreds of solar power satellites
>      WILL add energy on the order of the present solar flux!

Unless you plan to have millions of square kilometers of collecting
surface beaming more power down to Earth than we can possibly use you
are off by many orders of magnitude.

These are the official opinions			Mike Friedman
of my organization. So, TOUGH!!