[justanassembler]

Can anyone point me to scientific data about the contents of wood kiln effluent? I know there was a presentation @ NCECA in '05 or '06 that touched on it, and I feel as though I read something in CM or Studio Potter at one point, but Im coming up blank when it comes to specifics....

[JBaymore]

justanassembler, on 16 February 2013 - 01:09 AM, said:

I know there was a presentation @ NCECA in '05 or '06 that touched on it, and I feel as though I read something in CM or Studio Potter at one point, but Im coming up blank when it comes to specifics....

The NCECA presentation you mention might have been one that I did.

What exactly do you want to know?

best,

....................john

[justanassembler]

JBaymore, on 16 February 2013 - 06:31 AM, said:

justanassembler, on 16 February 2013 - 01:09 AM, said:

I know there was a presentation @ NCECA in '05 or '06 that touched on it, and I feel as though I read something in CM or Studio Potter at one point, but Im coming up blank when it comes to specifics....

The NCECA presentation you mention might have been one that I did.

What exactly do you want to know?

best,

....................john

Holy thread resurrection--sorry.
I was looking for particulate information, as well as carbon emissions in comparison to a similarly sized gas kiln

[JBaymore]

This kind of analysis gets really complicated if you are asking this question in trying to do a "better or worse" kind of comparison. That was one of my key points in the NCECA presentation. Too many "green" statements are very narrowly focused....and often highly misleading. The "big picture" is the only real accurate answer when you take ALL factors into consideration. To do this requires experts to look at it all. And lots of time and study (and hence money).

First of all..... WHO is firing each type of kiln, and HOW are they firing it? Those two factors alone can have a huge impact on "the numbers".

For example, in teaching situations I have deliberately taken a specific gas kiln and set it up firing in what would be an "appropriate" amount of reduction. Then I measured the levels with an Oxyprobe. I then had other people come in and observe the kiln VISUALLY for a while to "learn" the level of reduction happening using all the usual visual, auditory, and olefactory markers that potters tend to use for this. They could even see the reading on the Oxyprobe for that part. I then had them leave the room, and I mis-adjusted the controls to put the kiln into oxidation. I asked them each to then come back in and adjust the kiln VISUALLY to match the prior original condition (but no Oxyprobe available to them this time).

When they SWORE the kiln was set "the exact same way"...... I'd check with the Oxyprobe. The readings were ALL OVER THE PLACE. Some of these people were students... and some were facutly with MFAs and YEARS of firing experience. Some people's settings would have produced less CO and less particulate C ...... and others produced more. (Yhis is also what people often get "surprises" when they open the kiln.)

WHAT is the kiln design? There is another HUGE factor. Some gas kilns have very really lousy combustion systems on them and very poor in-chamber mixing. Others are "state of the art". Each would provide different answers for you... and STILL would be tempered by WHO is firing then amd HOW.

Some wood kilns have very efficient aeration and mixing...and some are literally still 15th century technology. Each would priovide you with completely different answers. There is a noborigama in Japan that has full industrial scrubbing........ fires as clean as a whistle.


To generalize (which makes this answer wrong in 99 percent of cases), PM 2.5 and PM 10 for a wood kiln is significantly higher than for a gas kiln. But on the other hand if you look at a 30 year cycle period, wood kilns are carbon neutral if replacement trees are being grown while gas kilns are greenhous gas producers.

Periodic studio type electric kilns are HORRIBLY polluting when looked at in the "big picture". They are NIMBY units when people think of them as "clean". They have a chimney.... it is located at a centralized power plant. Centralized electric generation and transmission is very lossy.... inefficient use of fuel. Coal is contaminated with mercury. Those types of kilns are typically underinsulated. They are also small and have large surface to volume ratios... so the heat energy used to heat up the kiln structure as a ratio to the heat energy used to heat the wares is TERRIBLE. I could go on.

Name your poison.


best,

....................john

[justanassembler]

Thanks--that was actually the sort of answer I was looking for--I appreciate your candor and experience--you're an asset here, for certain.