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From: gary@ke4zv.UUCP (Gary Coffman)
Newsgroups: sci.energy,sci.electronics,sci.physics,sci.space
Subject: Re: solar cells
Message-ID: <1928@ke4zv.UUCP>
Date: 4 Jan 91 21:07:16 GMT
References: <37448@cup.portal.com> <1991Jan2.015717.23554@amd.com> <37487@cup.portal.com> <88637@lll-winken.LLNL.GOV> <37550@cup.portal.com>
Reply-To: gary@ke4zv.UUCP (Gary Coffman)
Followup-To: sci.energy
Organization: Gannett Technologies Group
Lines: 95

In article <37550@cup.portal.com> Ordania-DM@cup.portal.com (Charles K Hughes) writes:
>
>  I don't think the "allergy" is irrational given 3-mile island, 
>Chernobyl, lists of missing nuclear fuel, 55 gallon drums of nuclear waste

Actually Three Mile Island showed that primary confinement works even in
an induced loss of cooling accident. Chernobyl showed that even the worst
scenario put up by the anti-nukes, core meltdown, *no* confinement,
and a core fire for God's sake, didn't result in the fearmongers predicted 
mega-deaths.

>>	As to chemical poisons being decomposable, that depends on
>>what kind of chemical poison. Heavy metals cannot be chemically
>>decomposed. And some chemical poisons are difficult to decompose, such
>
>  Heavy metals don't need to be decomposed - they can be refined and reused.

So can nuclear fuels, but we're soooo scared we don't.

>>	I keep on being amazed by the anti-RTG movement. They complain
>
>  What is RTG?

Radioisotope Thermoelectric Generator. A completely sealed, no moving
parts, no active control system, lump of radioactive material that
gives off enough heat through natural radioactive decay to heat a
thermopile enough to generate useful amounts of electrical power.

>>	So either solar cells or RTG's are the way to go for
>>spacecraft. I presume that this is the standard argument.
>
>  Hmmm...why not ground or space power generation for those satellites
>that orbit the earth & moon?  Deep space satellites are of little concern
>here because once they leave, they're gone for good.

Beamed power has been very strongly opposed by the enviornmentalists because
of the supposed danger of the microwave power beam used to transmit the
energy. Or were you planning to use a *really* long extension cord.

>
>  RTGs (assuming they are small nuclear plants) are dangerous in any orbit 
>that decays before the nuclear fuel becomes non-radioactive.

RTGs are designed to survive rentry without breaching their sealed shielding.
The designs used have been exhaustively tested by actually sending
dummy units up and causing them to renter. They work.

>>	And on the issue of safety, one should ask what kinds of
>>critical tests are possible. It is much easier to perform really tough
>>tests on an RTG than on a nuclear reactor, so one may feel more
>>confidence in their safety.
>
>  I still don't like the idea of a blob of nuclear goop falling from the 
>sky into my living room. :)

Hook a couple of leads to it and run your computer off of it for a few
years. Now that's a UPS!

>>	And another possible difficulty with solar cells -- how much
>>energy does it take to make them? They would not be too good if the
>>amount of energy needed to make them was only equal to their output
>>for several years of running. Has that question ever been addressed?
>
>  If the energy is free, who cares how much it took to make them?

If it takes more fossil fuel to manufacture them than they will produce
over their operating lifetime you care. And it does take more energy
to manufacture them than they produce over their lifetime. They are
net energy losers. Also the manufacture of solar cells requires some
very nasty chemicals that must be disposed of after manufacture. 

>  The real question (as I see it) is the *TRUE* cost.  Burning fossil fuels 
>is cheaper than solar, nuclear is cheaper then solar, almost everything
>is cheaper than solar if only the current fuel costs are looked at.  If the
>total cost of burning fossil fuels, using nuclear energy, etc is 
>totalled, solar will come out the clear winner.
>
>Charles_K_Hughes@cup.portal.com

For solar cells the answer is a clear no on an energy basis and an 
enviornmental basis. For solar boilers driving freon turbines the
energy cost is a net win. But the enviornmental costs are bad considering
what the inevitable freon leaks will do to the ozone layer. Maintence
costs in general are high since efficiency is very low and you need a
lot of them to produce useful power. Perhaps the worst effect of using
large scale solar energy to replace fossil fuels or nuclear plants is the 
effect on the climate. By placing large arrays of solar cells or solar 
turbines on the surface of the earth, you dramatically change the reflectivity 
of the earth in that area. A good solar collector absorbs almost all of the
solar energy striking it and reradiates very little thus creating a 
hotspot in the local enviornment. The effects on the weather of the several
hundred square miles of solar collectors needed to replace one nuclear
plant should be spectacular.

Gary