[Stoves] [biochar-production] Re: Stoves Digest, Vol 14, Issue 17

rongretlarson at comcast.net rongretlarson at comcast.net
Wed Oct 26 20:31:49 PDT 2011


Tom and (now) 2 lists (adding biochar-policy): 

This may be the first time I have ever disagreed with you - so I look forward to further dialog, and apologize in advance should I be wrong here below. 

I think that there should be a lower limit cut-off - and 50% seems justifiable - based on the way we handle majority voting in a democracy. My main rationale is that, without such a limit, there could be a validity claim for a lot of material coming out of gasifiers that is mostly ash. This refuse will be attempted to be sold as biochar in order to get the maximum price for a product that might otherwise need to pay a tipping fee to get rid of. From a sequestration promotion perspective, I would rather see the gasifiers move towards pyrolysis. 

Your last point below on a sliding scale is (I think) going to be mandatory anyway. It will surely be (or at least should be) required to receive a carbon credit. If I am paying for carbon sequestration, I certainly don't want to pay for ash and dirt. In all likelihood that payment will even be low-balled to ensure that the labile component also does not get much/any reward. 

I can't think of any biomass input besides rice husks apt to have a problem satisfying a 50% minimum rule. To achieve 50% carbon should be pretty easy - even for rice husks - by merging different chars (if needed). I believe Paul Olivier has already reported that he had a superior flame when mixing rice and coffee husks as the input. 

Ron 
----- Original Message -----
From: "Tom Miles" <tmiles at trmiles.com> 
To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org>, crispinpigott at gmail.com 
Sent: Wednesday, October 26, 2011 8:43:11 PM 
Subject: Re: [Stoves] [biochar-production] Re: Stoves Digest, Vol 14, Issue 17 

Where is the evidence that a Minimum should be established at 50% ash? 

IBI guidelines for specification need to recognize that there are different 
qualities of biochar for different purposes. The draft guidelines do specify 
a method for analyzing carbon, determining H:C ration, and determining C in 
carbonates. I do not agree that a threshold should be established for 
calling a residue a biochar. When does wood ash become biochar? According to 
the draft guidelines it would not become IBI certified "biochar" until it 
had less than 50% ash regardless of the amount of stable carbon it would be 
contributing to the soil for sequestration purposes at more than 50% ash. 

I don’t think we need to draw a line to call it biochar. A sloped line might 
be drawn for the carbon sequestration benefit that you would get for 
decreasing amounts of stable carbon. 

Tom 

-----Original Message----- 
From: stoves-bounces at lists.bioenergylists.org 
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Frank Shields 
Sent: Wednesday, October 26, 2011 3:55 PM 
To: crispinpigott at gmail.com; 'Discussion of biomass cooking stoves' 
Subject: Re: [Stoves] [biochar-production] Re: Stoves Digest, Vol 14, Issue 
17 

Dear Crispin, Tom, 

I think we need to define a minimum *carbon* content for a material to be 
called *biochar*. We can't call something a biochar if it has less than 1% 
carbon for example. So where do we draw the line? We need to include all 
natural biomass made into biochar like rice hulls. The material needs to 
have enough carbon to be useful. So I say 50% carbon a minimum to be 
'excellent' biochar knowing that most all natural, clean biomass will 
produce a biochar with greater than 70% carbon. But open to other values to 
make a scale. This makes it a product with enough value for a grower to 
purchase and spread. 

I think the product should have the carbon content defined for quality (not 
DAF). We should not include the oxygen and hydrogen and ash. We should 
calculate the percent carbon content on the biochar sample dry weight (200 
deg C). If we base quality on percent fixed matter (C-H-O) after subtracting 
the ash I think there is a mistake. Because we 'make' more ash when we 
change the cations into carbonates (increasing weight) during the process. 
More cations from vegetative matter the more the problem. And this quantity 
of ash is not what we are spreading on the field. Also the carbon trapped in 
the ash (as CO3) is not included in the fixed carbon fraction - it should be 
because it comes from the organic carbon in the raw sample. These are just 
details and perhaps not that important. To do what I think is needed we must 
determine the carbon using a Leco CHN analyzer. More work with expensive 
equipment. But if we want to get carbon credits in the future we need to 
start off accurately measuring the potential CO2 we are fixing. When money 
is involved these details need to be addressed. Now is the time or we will 
be back here again at a later time. 

Just because the carbon content is 0.1% and the ash is 99.9% doesn't mean 
the product is not beneficial for an ag field. But I don't think we should 
call it biochar even if someone did add a spoonful into a soil mix. This 
rating has nothing to do with benefit to a field. That is site specific. It 
has something to do with label on the bag (or may in the future). 


Regards 
Frank 








Vegatative plant material is 10 to 20 percent. We test a lot for nutrients. 
It is very hard to get the customer to bring us a clean sample as it takes 
so very little dust and dirt to bring the ash concentration up. I think 
harvesting biomass for biofuel and one will not be careful to harvest clean 
samples. 

If you have 15% ash in a dry organic material. Loose 60% of the organic 
fraction during pyrolysis you have something like 20+ percent ash. And, as 
you point out, there can be biomass with much greater than 20% ash. 

I suggested the 50% thinking this would be high enough to include most all 
biomass that is made into biochar. Thinking we need some limit that if there 
is less than 50% carbon 






Frank Shields 
Control Laboratories, Inc. 
42 Hangar Way 
Watsonville, CA 95076 
(831) 724-5422 tel 
(831) 724-3188 fax 
frank at compostlab.com 
www.compostlab.com 



-----Original Message----- 
From: stoves-bounces at lists.bioenergylists.org 
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Crispin 
Pemberton-Pigott 
Sent: Wednesday, October 26, 2011 12:42 PM 
To: Discussion of biomass cooking stoves 
Subject: Re: [Stoves] [biochar-production] Re: Stoves Digest, Vol 14,Issue 
17 

Dear Frank 

Apart from the special case of rice hull, how could you get a 50% ash level 
in char? Trees are about 0.5% ash. There is not much left of the fuel if 
the char is 1% of the initial mass. 

Regards 
Crispin 

Frank, 

I see the ash/carbon content as a sliding scale with relative changing 
benefits rather than a threshold level. If biochar has less carbon than ash 
is there still an agronomic benefit? 

It is not clear how the IBI guidelines will be used. The guidelines should 
list those components that should be measured. The recommended levels of 
those components for different purposes could be separate recommendations 
from IBI to a certification agency. 

If the purpose is stability and carbon sequestration why limit counting 
recalcitrant carbon even if it is 0.1% carbon or, 99.9% ash? 

Tom 
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