[Terrapreta] Low Temp Chars

[Tom Miles]

Sean, Allen,

 

References and testing of "high temperature" and "low temperature" chars are
pretty easy to find in the references that we link on the Terra Preta
website and in Danny Day's extensive (EPRIDA) library. Danny quotes
Christoph (as Michael Bailis did) in his summary of the 2004 UGA event:

"Low temperature woody charcoal (not grass or high cellulose) has an
interior layer of bio-oil condensates that microbes consume and is equal to
glucose in its effect on microbial growth (Christoph Steiner, EACU 2004).
High temp char loses this layer and does not promote soil fertility very
well." Danny presents a great description of char temperatures and char
qualities for his reactor. Harris and Gaskins (UGA) characterized high and
low temperature chars in more recent studies. 

http://terrapreta.bioenergylists.org/?q=harrispyrochar

There are others. Most of these studies characterize the properties
important to plant growth with the exception of volatile matter or bio-oils.
It will take some time to study what is available. 

 

The problem is that high and low temperature do not adequately describe the
char. Char making processes differ. Michael Antal has suggested that
volatile matter (VM) is a more accurate and simple test. Most char data I
have seen in my rather quick accumulation of references for the TP website
over the past few months are between 10% and 20% VM. The more direct
questions are, "what are the bio oils that microbes can consume and under
what conditions are they retained in the char?" Can we measure the content
of these oils in the char?

 

We will, in time, create a database of char properties on the Terra Preta
discussion website. 

http://terrapreta.bioenergylists.org/ Temperature also has an effect on the
retention of inorganic nutrients (P, K, S). These must be documented as
well. There are some Japanese studies using citric acid to measure the
release of these nutrients from chars. 

 

A caution is that concentrating pyroligneous acids (wood vinegar), tars and
creosotes in char products creates toxic substances. These same materials
were used as wood preservatives. Some former charcoal making plants are now
toxic waste sites. See "Biodegradation of Charcoal Production wastes":
http://terrapreta.bioenergylists.org/?q=usgspyrolig

Some small scale gasifiers in developing countries are cleaning the gas by
direct contact with water. The water is discharged into a pond. We have
measured levels of toxic compounds in these wastewaters that are many times
higher than our authorities allow in wastewater prior to treatment (TCLP).
One small scale gasifier site in Alaska became a superfund site. Recently
cancer has been studied in Brazilian charcoal makers. Antal has referred to
this as the "nastier side of the business."

 

We need to be able to measure the char qualities that are important,
including "bio-oil condensates that microbes consume."     

 

 

Tom Miles

 

    

 

From: terrapreta-bounces at bioenergylists.org
[mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Sean K. Barry
Sent: Wednesday, April 25, 2007 6:52 AM
To: terrapreta at bioenergylists.org; Allan Balliett
Subject: Re: [Terrapreta] Low Temp Chars

 

Hi Allen,

 

Welcome to the Terra Preta list.  You, know the only thing I ever read
outside the postings on this list about low temp. vs. high temp charcoal

has been, I think, mostly hypothetical.  It is hypothesized that charcoal
was made by the ancient Amazonians in a very simple way as a "slash and
char" operation performed right on the ground in the jungle.  Because of
this, is is assumed that the charcoal produced by such methods is low
temperature.  Additionally, I think it has been assumed that the longer
hydrocarbon strings left in low temp. char (known as the volatile matter,
pyroligneous acids, bio-oils, acetic acid, wood vinegar, and etc. various
other names) may represent food for soil microorganisms.

 

I do not doubt the possibility of these claims.  However, I have not as yet
seen any proof presented anywhere to support them.  It would be nice, if
this group had in it's membership, any microbiologists who could enlighten
us as to what the actual metabolic processes of soil micro flora are.  I
think we do a lot of guessing, otherwise, without that.  We could conduct
our own experimentation, but it may be a long haul before we could actually
make and experimentally supported theoretical statements.

 

Regards,

 

Sean K. Barry
Principal Engineer/Owner
Troposphere Energy, LLC
11170 142nd St. N.
Stillwater, MN 55082
(651) 351-0711 (Home/Fax)
(651) 285-0904 (Cell)
sean.barry at juno.com

 

----- Original Message ----- 

From: Allan Balliett <mailto:aballiett at frontiernet.net>  

To: terrapreta at bioenergylists.org 

Sent: Wednesday, April 25, 2007 5:00 AM

Subject: [Terrapreta] Low Temp Chars

 

Earlier, The Man from Videotron, Frank Teuton said:

>As I understand it the point of the New Green known as Black is to tap the
>biomass potential for fuels and return part of the materials to soils to
>achieve better soils and carbon negativity. The recommendations to char at
>relatively low temperatures and to not allow random offgassing of
byproducts
>are in the vein of environmental concerns...the low temps allows more oils
>and other materials to stay with the char with biological benefits to soil
>life, but also to allow the preservation of better char structure, ie, more
>complex habitat for the soil foodweb. The edible materials that stay in low
>temp char are relatively rapidly consumed, as I understand it...but the
>structure of low temp char should be its structure for hundreds of years or
>more.
>
>Adding high temp char to soil may be a nice thing to do for carbon
>sequestration reasons, but it doesn't have the 'win-win' character of
adding
>better quality char to soils, as I understand the argument.

As one who is very impressed by the archaeological record of terra 
preta, I'm wondering what the science is on high hardware char. Is 
there any or is this just a reasonable theory, an effort to 
differentiate by-products?


I know it's being said, but I haven't seen any proof. Has anyone?

Or were traditional charcoal making methods making this low temp char 
with smoldering banked fires?


I'm new to the list, hopefully, this there is an obvious answer to 
this question:

Has anyone found a reliable source of affordable charcoal fines? I'd 
appreciate a referral.

Thanks

-Allan Balliett
Fresh and Local CSA
www.freshandlocalcsa.com

PS You can find a copy of portions of my recent interview with 
Charles C. Mann at 
http://www.acresusa.com/magazines/archives/0407InterviewMann.htm

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