Let us suppose that the proximate analysis of a rice hull sample is:<br>15.80% fixed carbon<br>63.60% volatile matter<br>20.60% ash.<br>If we remove all volatile matter, the remainder would be:<br>43.41% fixed carbon<br>56.59% ash<br>
Should this material not be called biochar?<br><br>Paul Olivier<br><br><div class="gmail_quote">On Thu, Oct 27, 2011 at 3:54 AM, Frank Shields <span dir="ltr"><<a href="mailto:frank@compostlab.com">frank@compostlab.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Dear Crispin, Tom,<br>
<br>
I think we need to define a minimum *carbon* content for a material to be<br>
called *biochar*. We can't call something a biochar if it has less than 1%<br>
carbon for example. So where do we draw the line? We need to include all<br>
natural biomass made into biochar like rice hulls. The material needs to<br>
have enough carbon to be useful. So I say 50% carbon a minimum to be<br>
'excellent' biochar knowing that most all natural, clean biomass will<br>
produce a biochar with greater than 70% carbon. But open to other values to<br>
make a scale. This makes it a product with enough value for a grower to<br>
purchase and spread.<br>
<br>
I think the product should have the carbon content defined for quality (not<br>
DAF). We should not include the oxygen and hydrogen and ash. We should<br>
calculate the percent carbon content on the biochar sample dry weight (200<br>
deg C). If we base quality on percent fixed matter (C-H-O) after subtracting<br>
the ash I think there is a mistake. Because we 'make' more ash when we<br>
change the cations into carbonates (increasing weight) during the process.<br>
More cations from vegetative matter the more the problem. And this quantity<br>
of ash is not what we are spreading on the field. Also the carbon trapped in<br>
the ash (as CO3) is not included in the fixed carbon fraction - it should be<br>
because it comes from the organic carbon in the raw sample. These are just<br>
details and perhaps not that important. To do what I think is needed we must<br>
determine the carbon using a Leco CHN analyzer. More work with expensive<br>
equipment. But if we want to get carbon credits in the future we need to<br>
start off accurately measuring the potential CO2 we are fixing. When money<br>
is involved these details need to be addressed. Now is the time or we will<br>
be back here again at a later time.<br>
<br>
Just because the carbon content is 0.1% and the ash is 99.9% doesn't mean<br>
the product is not beneficial for an ag field. But I don't think we should<br>
call it biochar even if someone did add a spoonful into a soil mix. This<br>
rating has nothing to do with benefit to a field. That is site specific. It<br>
has something to do with label on the bag (or may in the future).<br>
<br>
<br>
Regards<br>
Frank<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
Vegatative plant material is 10 to 20 percent. We test a lot for nutrients.<br>
It is very hard to get the customer to bring us a clean sample as it takes<br>
so very little dust and dirt to bring the ash concentration up. I think<br>
harvesting biomass for biofuel and one will not be careful to harvest clean<br>
samples.<br>
<br>
If you have 15% ash in a dry organic material. Loose 60% of the organic<br>
fraction during pyrolysis you have something like 20+ percent ash. And, as<br>
you point out, there can be biomass with much greater than 20% ash.<br>
<br>
I suggested the 50% thinking this would be high enough to include most all<br>
biomass that is made into biochar. Thinking we need some limit that if there<br>
is less than 50% carbon<br>
<div class="im"><br>
<br>
<br>
<br>
<br>
<br>
Frank Shields<br>
Control Laboratories, Inc.<br>
42 Hangar Way<br>
Watsonville, CA 95076<br>
(831) 724-5422 tel<br>
(831) 724-3188 fax<br>
<a href="mailto:frank@compostlab.com">frank@compostlab.com</a><br>
<a href="http://www.compostlab.com" target="_blank">www.compostlab.com</a><br>
<br>
<br>
<br>
</div>-----Original Message-----<br>
From: <a href="mailto:stoves-bounces@lists.bioenergylists.org">stoves-bounces@lists.bioenergylists.org</a><br>
[mailto:<a href="mailto:stoves-bounces@lists.bioenergylists.org">stoves-bounces@lists.bioenergylists.org</a>] On Behalf Of Crispin<br>
Pemberton-Pigott<br>
Sent: Wednesday, October 26, 2011 12:42 PM<br>
<div class="im">To: Discussion of biomass cooking stoves<br>
Subject: Re: [Stoves] [biochar-production] Re: Stoves Digest, Vol 14,Issue<br>
17<br>
<br>
</div><div><div></div><div class="h5">Dear Frank<br>
<br>
Apart from the special case of rice hull, how could you get a 50% ash level<br>
in char? Trees are about 0.5% ash. There is not much left of the fuel if<br>
the char is 1% of the initial mass.<br>
<br>
Regards<br>
Crispin<br>
<br>
Frank,<br>
<br>
I see the ash/carbon content as a sliding scale with relative changing<br>
benefits rather than a threshold level. If biochar has less carbon than ash<br>
is there still an agronomic benefit?<br>
<br>
It is not clear how the IBI guidelines will be used. The guidelines should<br>
list those components that should be measured. The recommended levels of<br>
those components for different purposes could be separate recommendations<br>
from IBI to a certification agency.<br>
<br>
If the purpose is stability and carbon sequestration why limit counting<br>
recalcitrant carbon even if it is 0.1% carbon or, 99.9% ash?<br>
<br>
Tom<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Paul A. Olivier PhD<br>27C Pham Hong Thai Street<br>Dalat<br>Vietnam<br><br>Louisiana telephone: 1-337-447-4124 (rings Vietnam)<br>Mobile: 090-694-1573 (in Vietnam)<br>
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