Xref: utzoo talk.politics.misc:8834 sci.misc:1279
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: <846@bucket.UUCP>
Date: 6 Apr 88 06:39:39 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> <774@spdcc.COM>
Reply-To: leonard@bucket.UUCP (Leonard Erickson)
Distribution: na
Organization: Rick's Home Grown Unix; Portland, OR
Lines: 54

In article <774@spdcc.COM> eli@spdcc.COM (Steve Elias) writes:
<my contention is that to meet a large increase in power demands with solar
<power satellites will add something on the order of one percent or so to 
<the total energy flux that the earth receives.  i believe i am accurately
<stating this theory as i learned it from Frank Drake.

As others have pointed out, this level of power demand is *totally*
unreasonable for a *long* time to come. And I rather expect that most
of the industry that would demand such levels of power would have moved
into space by then anyway...

<>You are missing the point: SPS will not be put up just for fun; no one
<>will say, "I want to launch a 500MW SPS, whether or not anyone will buy
<>the power."   We will only use SPS if there is a demand for the power.
<>When demand is predicted to exceed supply, there are only two choices:
<>increase supply or reduce demand.  Decreasing demand is not practical,
<>and may not be possible.  So, we are left with the decision, "How do we
<>generate the extra power?"   The amount of heat which will be generated
<>to produce this power is P/eff.  The power consumption sets a lower bound
<>on heat, but efficiency is important.  (Assuming there is agreement that
<>demand for power will increase) we must assume fixed generating capacity,
<>and argue the relative merits of different systems.  How are earth-based
<>systems better?  I believe that, considering only thermal and poluution
<>problems, they are not.  Building a heat engine on the earth will also
<>add heat to the environment that would not otherwise be present.
<
<	heat engines which use energy already present in the atmosphere
<	or elsewhere on earth would not add net heat to the environment...
<
<	agreed?  i'm not saying these power sources are necessarily the
<	'best' -- just that they do exist...

ANY heat engine has to work on a temperature *difference* at there are
rather strict limits on how much of that difference can be converted
to power. And if we need power at the levels you are worried about (1% of
the solar flux!!!), I fail to see where you will find the temperature
differences with out causing a *major* ecological disaster!

If you are talking geothermal, you *will* be adding heat not otherwise
present ON THE SURFACE OF THE EARTH (you'd be cooling down the lower
layers of the crust, but *that* won't affect climate, a 50 to 100 degree
Celsius rise in surface temperature of an area will!)

If you are thinking of the systems to use the temperature difference
between the surface of the ocean and the depths, at the power levels
you are thinking of you will quite likely cause a change in ocean
current patterns that will make El Nino look trivial.


-- 
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."