[Terrapreta] fast vs slow pyrolysis

Sat Feb 24 12:44:35 CST 2007

Doug,

Thanks. I'll look at the EPRIDA documentation. If there is an effect of
pyrolysis temperature then it should be measurable as a char
characteristic. The agronomic impact must also be measureable or at least
noticable. 

Fast pyrolysis systems have evolved in the last several years primarily for
getting a high oil yield from biomass pyrolysis rather than making char. In
these systems temperatures are typically in the 500C range but they use a
contact media like snad to rapidly heat the biomass. In that was they get
oil yields of above 70%. Correspondingly they get lower char and gas
yields. If you want to use the char in the soil then the porperties issue
is important. 10% Char byproduct is a low of char. The gas is consumed in
the process.

If you are primarily making gas then the biomass is exposed to temperatures
of 800C for a short period of time. Char production is lower- 2% to 5% -
but you must stil dispose of it. If it can be used in the soil all the
better.

So the usefulness of byproduct char from higher temeprature processes must
be determined. It will have some value. It just may be a different
application or expected result than for processes where char is the primary
product. 

Tom  

Original Message:
-----------------
From: Douglas Clayton dnclayton at wildblue.net
Date: Sat, 24 Feb 2007 02:05:18 -0500
To: terrapreta at bioenergylists.org, tmiles at trmiles.com
Subject: fast vs slow pyrolysis

Tom,

This is dangerous.  I am engaging in idle speculation here.  Please ,  
no one take this as the truth.  It would be better to read some  
scientific papers.  But, I think, lower temperatures produce more  
acetic charcoal.  I know completely combusted wood (ash) is very  
alkaline.

Sorry to be so ignorant.  does fast vs slow refer to anything beyond  
temperature?

In Danny Day's powerpoints on the Eprida site it looks like he is  
suggesting slightly less than 400C as a best pyrolysis temp, ballancing  
C sequestration liking less and microbial life liking char produced at  
higher temps. (I'm having some difficulty looking at this PowerPoint  
stuff because I don't have the right software so I'm seeing all the  
layers at once.  If anyone has a suggestion for a Mac user who doesn't  
want to buy Microsoft Word, I'd like to hear it.  icWord didn't work.)

This seems to contradict my understanding that the charcoal may greatly  
increase C in the soil by triggering/catalyzing the large increase in  
microbial life and the creation of glomalin associated with fungi. (it  
is my understanding that the charcoal-glomalin connection is unproven  
theory).

I understood Johannes Lehmann to be speculating 450C as a good temp.   
Maybe.

I'm going back to the reading now.

Doug Clayton
50 Bullard Rd
Jaffrey, NH  03452
603-532-7321

On Feb 23, 2007, at 8:57 PM, Tom Miles wrote:

>
> Doug,
>  
> I’m curious about the reason between the fast pyrolysis char vs slow  
> pyrolysis char. I’d like to see the research or the anecdotal  
> experience that supports this. Char can have different properties for  
> many reasons. It is probably in the Lehmann papers that we have linked  
> to the site.
>  
> Tom
>  
>  
>
> From: terrapreta-bounces at bioenergylists.org  
> [mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Douglas  
> Clayton
> Sent: Thursday, February 22, 2007 8:21 PM
> To: Jeff Davis
> Cc: terrapreta at bioenergylists.org
> Subject: Re: [Terrapreta] Terra Preta & Pigs
>  
>
> I spoke with Dr. Johannes Lehmann this morning and received the clear  
> message from him that it was a mistake to go fooling around  
> willy-nilly with charcoal at this time. Not that it is dangerous but  
> just that it is hard to learn anything definative. The science isn't  
> there yet to know what we are doing. This was a great disappointment  
> to me but I understand where he is coming from.
>
>  Dr. Lehman indicated that the temperature at which the charcoal is  
> produced is critical, the material being charred and the end use, the  
> soil type and conditions and the crop being grown are variables about  
> which we can not yet, say what is appropriate. Not knowing the source  
> material means something may work one time but not the next. He  
> indicated that it is definitely not a panacea and applying charcoal  
> can, in some circumstances, do harm to soils and crops.
>
>  Never the less, I plan to experiment a little bit in the garden this  
> summer myself!
>
>  How do we check the pH of the charcoal we purchase or produce?
>
>  Douglas Clayton
> 50 Bullard Road
> Jaffrey, NH  03452
>  H. 603-532-7321
>  W. 603-532-1120
>  Fax. 603-532-4581
>
>  On Feb 22, 2007, at 10:27 PM, Jeff Davis wrote:
> wrote:
> Jeff, charcoal is used for human consumption for certain conditions
>  including indigestion and some poisonings. I think that some of it in  
> the
>  soil would
>  be not so bad for the pigs.
>
>
>  Maybe the pigs would be helpful to the Terra Preta. They rot, eat  
> soil and
>  produce manure.
>
>
>  Jeff
>
>
>
>  --
>  Jeff Davis
>
>  Some where 20 miles south of Lake Erie, USA
>
>  _______________________________________________
>  Terrapreta mailing list
>  Terrapreta at bioenergylists.org
>   
> http://bioenergylists.org/mailman/listinfo/ 
> terrapreta_bioenergylists.org
>  
>

--------------------------------------------------------------------
mail2web.com – Enhanced email for the mobile individual based on Microsoft®
Exchange - http://link.mail2web.com/Personal/EnhancedEmail