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Reworking the equation (was: Solar sham) - Page 5

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Posted by daestrom on February 15, 2008, 1:05 pm


The Al from some old infrastructure (say, an old airplane) is recycled into
something new.  Just as in the future some solar installation will be
recycled into something new.  The time between first use and recycle does
not completely disqualify solar for using recycled materials.

And just exactly what is wrong with a low-energy material?  Say, steel or
even wrought iron?  All you really need is a stiff substrate.

Sounds like an Australian oddity.  But considering that coal-fired power can
run in the 1.5 - 2 cents per kWh in the US, I don't see your point.

No, more like the high volume of sales in one locale means that many of the
T&D costs are avoided and the savings passed on to the consumer.

I guess you need to think about what 'realistic rates' are.  If you think
the price a homeowner pays is the price that a large industrial customer
pays, you need to learn some more about the electric industry and finance.

Funny, you make it sound like Australia's already doing just that.
Subsidizing Al smelting so it can export more Al.


Posted by Terryc on February 15, 2008, 4:39 am
Mauried wrote:

Yes, but discounted as the aluminium is recyclable.(?)

Posted by Anthony Matonak on February 15, 2008, 7:40 am
 Terryc wrote:

Aten Solar did away with the aluminum frame around the panel
and replaced it with four small mounting rails glued to the
back. It's conceivable that some other design would do away
with aluminum entirely.


Posted by daestrom on February 14, 2008, 11:56 pm

Hmm, no not really.  Suppose it takes 105 MJ to create 1 watt of solar.
Would you use electricity for all the heating processes, or would you use a
much cheaper fossil fuel?

For all stages of production that involve just thermal heating, you would
use the direct heat input, not electricity.  IIRC, that is a significant
portion of the energy used to produce the PV cell.  The energy from a solar
cell in the form of electricity is more valuable than an equivalent amount
of energy coming from natural gas (some would say that the exergy of a MJ of
electricity is higher than the exergy of a MJ of natural gas). (and yes, I
know that electricity *is* used in the final stages of refining to further
purify the Si)

So, while the government reports say solar cells can pay back the energy
required to produce them in just a few years, it still wouldn't be
economically smart to use solar electricity to produce them when thermal
energy from fossil is so much cheaper.


P.S.  Mind you, Dan Lancaster will still insist that all previous energy
used in all R&D everywhere, including the incandenscent light used to light
the drawing boards that scientists like Stefan and Boltzman used to work out
radiation theory and quantum mechanics be included in that payback.

Posted by Bill Ward on February 16, 2008, 8:29 am
 On Thu, 14 Feb 2008 18:56:55 -0500, daestrom wrote:

My impression is that most thermal energy in the final stages of
manufacture (after initial smelting) is electric, because of the
precision control and cleanliness needed.  I guess one could look at the
relative sizes of the gas and electric bills at a plant and get a better
idea of the breakdown.  I probably should have specified electrical
energy, rather than just "energy", as that's what I was thinking.  

That's pretty much my point.  Until and unless they get cheap enough to
compete with grid power, solar cells will be economically restricted to
those few areas where their advantages outweigh their drawbacks. If the
manufacturers can't use them to replace grid power, who can?

I wonder if nuclear could meet that test yet?

Thanks for your comments, as always.

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