Let us suppose that the proximate analysis of a rice hull sample is: 15.80% fixed carbon 63.60% volatile matter 20.60% ash. If we remove all volatile matter, the remainder would be: 43.41% fixed carbon 56.59% ash Should this material not be called biochar?
Paul Olivier On Thu, Oct 27, 2011 at 3:54 AM, Frank Shields <[email protected]> wrote: > 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 > [email protected] > www.compostlab.com > > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] 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 > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists > .org > > for more Biomass Cooking Stoves, News and Information see our web site: > http://www.bioenergylists.org/ > > > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org > > for more Biomass Cooking Stoves, News and Information see our web site: > http://www.bioenergylists.org/ > > -- Paul A. Olivier PhD 27C Pham Hong Thai Street Dalat Vietnam Louisiana telephone: 1-337-447-4124 (rings Vietnam) Mobile: 090-694-1573 (in Vietnam) Skype address: Xpolivier http://www.esrla.com/
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