Nicole Simmons on wed 29 oct 97
This is in reference to Joseph Herbert's response to Marley about choosing a
kiln: He mentioned solar powered kilns. Is anyone out there using one? I
would love to hear more about this=21
Nikki Simmons
Russellville, MO
http://www.computerland.net CLand Page
http://nikki.ml.org My Page
nsimmons=40computerland.net
Joseph Herbert on fri 31 oct 97
Nicole Simmons is wondering about solar kilns. I had my tongue in my cheek
there but not entirely. There is a solar installation that reaches ceramic
firing temperatures and more at one of the National Laboratories - Sandia
maybe. The installation is composed of a tower that is the center of
attention for a hillside of mirrors. The surface area of the mirrors is Very
Large.
Here is a quote from my favorite pointed head reference -
"Solar Furnaces - One important high-temperature application of concentrators
is for solar furnaces. The largest of these, located at Odeillo in the
Pyrenees Mountains of France, uses 9600 reflectors with a total area of
approximately 1860 sq. m (about 20,000 sq. ft) to produce temperatures as
high as 40000 C (72000 F). Such furnaces are ideal for research requiring
high temperatures and contaminant-free environments for example, materials
research."
"Solar Energy," Microsoft (R) Encarta. Copyright (c) 1994 Microsoft
Corporation. Copyright (c) 1994 Funk & Wagnall's Corporation.
This is 20,000 square feet of actively tracking mirrors. Not a cheap
proposition. The tower is also necessarily high to give the mirrors a good
shot at it without having to build lots of towers for the mirrors - they keep
getting into each other s way. Even if you located a nice, almost cliff for
your mirrors, having the focal point of this array near ground level is just
asking for trouble. This is one mistake you only make once.
Private solar kilns, larger than 1 cubic inch, are only found among
government installations and the toys of the very rich.
Old tires is a much better energy source, really.
Joseph Herbert
JJHerb@aol.com
Bill Walker on sat 1 nov 97
Edmund Scientific Company sells Fesnel lenses and a book called
"Fun With Fesnel Lenses", and claim you can make a solar kiln with
them. 609-573-6879
These will probably not reach the 40000C temperatures that some
scientists have been able to obtain, but then most of us do not
need to vaporize our clay.
Bill Walker
Reid Harvey on sun 3 jan 99
I'd like to ask about the appropriateness of the technology of solar
kilns, particularly with respect to the cost of the kiln. Granted,
energy that does not pollute has wonderful appeal, but what is the cost
of the kiln? How does this cost compare with that of other kilns?
How would the kiln's price compare with that of a conventional kiln,
powered by a non-polluting energy source. For example, a conventional
electric kiln powered by a windmill.
I am not looking for price quotes but ballpark numbers. Perhaps the
books mentioned have these numbers, but I do not have ready access to
them.
Reid Harvey
LOWELL BAKER on tue 11 jul 00
Herriet Brisson in Rhode Island has done some work on solar kilns.
My feeling on the subject is it is not worth the effort, unless you
want to fire only one side of the piece at a time; and small pieces
at that. Of course this is impractical.
Solar is great for a lot of things, but I fear firing pots is not one of
them.
Lowell
Earl Brunner on fri 23 feb 01
Agreed.
There is a fascinating power plant that they built out of Yermo
California (near Barstow). Several acres of mirrors are focused on a
focal point to super heat water and create steam to generate
electricity. I could see this kind of operation, but still incredibly
expensive to set up.
vince pitelka wrote:
> Earl - Yep, that's about it. But the question of refractories in solar
> kilns is a completely different issue than what we are accustom to dealing
> with in conventional kilns. In a solar kiln, a very large amount of
> reflective concave mirror surface directs the suns energy onto a very small
> firing chamber, which must be dark in color in order to absorb the light
> energy and convert it to heat. The chamber walls must efficiently transmit
> the heat into the chamber, and must be capable of withstanding extremely
> high temperatures. Consider the fact that the firebox and/or flames of a
> gas, oil, or wood kiln must achieve a temperature far higher than the
> desired firing temperature in order to bring the kiln and the wares up to
> that firing temperature. The same would be true of the "kiln" structure on
> a solar kiln. It would have to achieve temperatures considerably hotter
> than the desired firing temperatures, and would have to transmit those
> temperatures inwards without suffering damage to the containment structure.
>
> And then you have the whole issure of "black body emissions." Once the dark
> surface of the "kiln" structure reaches red heat and starts emitting light
> itself, it does not absorb light nearly as efficiently. So there would be a
> serious drop-off in heat absorption just as the "kiln" approaches the point
> where it needs the most heat.
>
> I tend to be an optimist and an idealist, but alas, with the technology we
> have available today, the idea of a solar kiln does not seem workable. But
> someday . . .
> Best wishes -
> - Vince
>
> Vince Pitelka
> Appalachian Center for Crafts
> Tennessee Technological University
> 1560 Craft Center Drive, Smithville TN 37166
> Home - vpitelka@dtccom.net
> 615/597-5376
> Work - wpitelka@tntech.edu
> 615/597-6801 ext. 111, fax 615/597-6803
> http://www.craftcenter.tntech.edu/
>
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Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
vince pitelka on fri 23 feb 01
> And I think we are dreaming about solar kilns period. I recall some
> work done on this back in the 70's (during the so called energy crisis).
> The solar collector panels (mirrors) were large and bulky, the firing
> chamber small and relatively useless. May be fun to fiddle around with,
> but without some kind of breakthrough in technology not commercially
> practical. We've had some pretty good breakthroughs in refractories and I
> still don't think it's enough.
Earl - Yep, that's about it. But the question of refractories in solar
kilns is a completely different issue than what we are accustom to dealing
with in conventional kilns. In a solar kiln, a very large amount of
reflective concave mirror surface directs the suns energy onto a very small
firing chamber, which must be dark in color in order to absorb the light
energy and convert it to heat. The chamber walls must efficiently transmit
the heat into the chamber, and must be capable of withstanding extremely
high temperatures. Consider the fact that the firebox and/or flames of a
gas, oil, or wood kiln must achieve a temperature far higher than the
desired firing temperature in order to bring the kiln and the wares up to
that firing temperature. The same would be true of the "kiln" structure on
a solar kiln. It would have to achieve temperatures considerably hotter
than the desired firing temperatures, and would have to transmit those
temperatures inwards without suffering damage to the containment structure.
And then you have the whole issure of "black body emissions." Once the dark
surface of the "kiln" structure reaches red heat and starts emitting light
itself, it does not absorb light nearly as efficiently. So there would be a
serious drop-off in heat absorption just as the "kiln" approaches the point
where it needs the most heat.
I tend to be an optimist and an idealist, but alas, with the technology we
have available today, the idea of a solar kiln does not seem workable. But
someday . . .
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
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