[Stoves] Characteristics of biochar was Re: [biochar] grassifier & cedar chip char

Tue Feb 5 03:57:05 CST 2013

Stuart and all,

On 2/3/2013 10:21 PM, stuart mather wrote:
> That's great, thanks Paul,
> So the higher % yield of lower temp char is only extra weight from 
> ungasified volatiles, and not because less of the carbon structure is 
> being combusted? In a no oxygen environment, no carbon can combust, no 
> matter how high the pyrolysis temp can it?
> And I suppose there's also the issue of recalcitrance. Do you know the 
> figures for increased recalcitrance from a higher pyrolysis temp.?
> Stuart.
The chemistry is important here.  In the biomass are many carbohydrate 
(C & H & O) molecules.  They are NOT elemental carbon (C).   Char is 
produced by pyrolysis, which uses heat, whether with or without a flame 
present.  Carbonization/pyrolysis (2 sides of the same coin) is the only 
way to make char at the surface of the Earth.   Carbon that is called 
coal is by pressure and heat underground (or in a laboratory).

More than this, we need some chemists to fill in the picture to answer 
your questions.

Paul

>
> Paul S. Anderson, PhD  aka "Dr TLUD"
> Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
> Website:  www.drtlud.com
> ------------------------------------------------------------------------
> *From:* Paul Anderson <psanders at ilstu.edu>
> *To:* biochar at yahoogroups.com
> *Cc:* stuart mather <kneebraceboy at yahoo.com.au>; Hugh McLaughlin 
> <wastemin1 at verizon.net>
> *Sent:* Monday, 4 February 2013 2:00 AM
> *Subject:* Characteristics of biochar was Re: [biochar] grassifier & 
> cedar chip char
>
> Dear Stuart, Trent and all,
>
> On 2/3/2013 6:32 AM, stuart mather wrote:
>> Tom,
>> Isn't the most compelling reasons for keeping the temp low is that 
>> the yield is higher. If one of the motivations
>>  for making biochar is to sequester C, then minimizing the amount of 
>> CO2 you emit to the atmosphere in actually making the biochar would 
>> seem to be prudent, wouldn't it?
> Higher yields (as measured by weight) do not mean that more of the 
> "right kind of C" is created or put into the soil.  Higher weights are 
> usually associated with having more of the volatiles remaining in the 
> char structure. So,
>
> Charcoal at minimal temps (I think about 300 - 350 C) have a lot of 
> carbon remaining as  volatiles (mobile, can be leached in soils, 
> hurting plants), which is good if you are trying to ignite it in a 
> charcoal cooker.
>
> Charcoal at 450 C (in my opinion) is the bottom range of what is 
> decent to be used as biochar.
>
> Charcoal at 550 C to 800 C has less weight, but a larger percentage is 
> the desired carbon structures for good biochar.  Very few volatiles.   
> And has higher adsorption capacity.
>
> McLaughlin has a great chart showing this but I cannot find it right now.
>
> Please see the paper on the internet:    All biochars are not created 
> equal....    By McLaughlin, Anderson, Shields and Reed (2009)   Also 
> available at my website
> http://www.drtlud.com/resources/publications-and-multimedia/entire-catalogue/
>
>>  I understand that if you need to cook with biomass then  a Tlud is 
>> clearly the way to go. But can it be argued that people in the 
>> developed world would be doing the climate a favour by cooking food 
>> with a TLUD too, and leaving the fossil fuel gas or electric powered 
>> stove gathering dust.
> I certainly like to read comments like that!!!
>
> And there is certainly room for a lot more efforts by interested people.
>
> Paul
>> Paul S. Anderson, PhD  aka "Dr TLUD"
>> Email:psanders at ilstu.edu  <mailto:psanders at ilstu.edu>    Skype: paultlud  Phone: +1-309-452-7072
>> Website:www.drtlud.com  <http://www.drtlud.com/>
>> ------------------------------------------------------------------------
>> *From:* Tom Miles <tmiles at trmiles.com> <mailto:tmiles at trmiles.com>
>> *To:* biochar at yahoogroups.com <mailto:biochar at yahoogroups.com>
>> *Sent:* Sunday, 3 February 2013 2:58 PM
>> *Subject:* RE: [biochar] grassifier & cedar chip char
>>
>> David,
>> Nitrogen in wood and straw forms ammonia and ammonia like compounds 
>> during pyrolysis. That is what you are smelling. Collectively they 
>> are called NOx precursors. When burned they become Nitrogen oxide 
>> emissions (NOx). As you suggest the TLUD is a more oxidizing 
>> environment and so you don’t see the same ammonia formation.
>> The assumption that 450C is magic for all applications has to be 
>> further tested. We have anecdotally seen very good results with 
>> gasifier chars which are subjected to much higher (>600-800 C) 
>> temperatures. It is likely that TLUD chars are subjected to these 
>> higher temperatures.
>> Tom
>> *From:*biochar at yahoogroups.com <mailto:biochar at yahoogroups.com> 
>> [mailto:biochar at yahoogroups.com] *On Behalf Of *trent
>> *Sent:* Saturday, February 02, 2013 8:36 PM
>> *To:* biochar at yahoogroups.com <mailto:biochar at yahoogroups.com>
>> *Subject:* Re: [biochar] grassifier & cedar chip char
>> Well Don, the noose is just hanging there empty so I am going to put 
>> my head in it. Looking to scale up and have tried a couple different 
>> things including using */_propane/natural gas._/* Until proven 
>> otherwise, I don't see how you can achieve a steady, consistent burn 
>> to account for biomass variables in MC, density, etc. */_and_/* 
>> produce the volume needed to make a profit on industrial sizing.  
>> Steel went away from charcoal to reduce costs. There is a lesson 
>> there. If 450C (842f) is the number being bandied about for ideal 
>> commercial biochar, its going to take a lot of processed biomass 
>> burned or wasted, to keep a continous kiln at that temperature. 
>> Processing biomass as fuel isnt cheap. Using a combination of gas and 
>> the biogas, industrial ceramics and automation to create an oxygen 
>> free enviroment, opens up all kind of doors. I have a very simple 
>> design in mind which can run 24/7 with gas and was wondering if 
>> anyone could recommend someone with a little more engineering 
>> expertise than my UHK degree to fill in some blanks.
>> http://news.rice.edu/2012/03/22/cooking-better-biochar-study-improves-recipe-for-soil-additive/
>>
>> ------------------------------------------------------------------------
>> *From:*David Yarrow <dyarrow5 at gmail.com <mailto:dyarrow5 at gmail.com>>
>> *To:* biochar at yahoogroups.com <mailto:biochar at yahoogroups.com>
>> *Sent:* Saturday, February 2, 2013 12:02 AM
>> *Subject:* Re: [biochar] grassifier & cedar chip char
>> On Feb 1, 2013, at 9:12 PM, Trent Lund wrote:
>> > David
>> > Do you think you could char a bale of straw or is it pressed to tight?
>>
>> hi trent,
>>
>> i've thought about that. ideally, we can design a burner that can 
>> char an entire hay bale without extra handling. might require a fan 
>> to improve the air flow thru the feedstock. the round stalks of hay 
>> and straw may allow significant leeway in how tight they can be 
>> packed together and still allow air to flow up through the stalks. 
>> dust is a further issue that can shut down air flow.
>>
>> currently, i use a TLUD, which requires air to be sucked up through 
>> the biomass. experience is this device is finicky and temperamental, 
>> and particle size and feedstock density is a significant issue. often 
>> i have to screen wood chips through 1/4-inch hardware cloth to 
>> separate out the dust and finer particles, or the TLUD chokes, the 
>> gas flare goes out, and a smoky, stinky burn results. i'm concerned 
>> hay, straw, weeds, even cornstalks might similarly choke my TLUD, so 
>> my first test burn last weekend with hay for feedstock, i was careful 
>> to loosen the stalks of the tightly packed hay bale and pack it in 
>> the barrel loosely but firmly.
>>
>> in the next two months, i will do more test burns with a variety of 
>> weedy materials. i will experiment to see how tight i can pack hay or 
>> straw without choking the updraft.
>>
>> two years ago, i was using a 55/30-gallon kiln & retort to char 
>> sticks and limbs of applewood for saratoga apple orchard. apple is 
>> denser than oak or maple, and harder to ignite and burn. what worked 
>> well was to loosely pack straw with the applewood. straw gasifies 
>> faster that wood, and kickstarts pyrolysis until temperatures are 
>> intense enough to gasify the denser applewood. worked so well the 
>> applewood limbs would shatter into small chunks, making them easier 
>> to process into soil mixes.
>>
>> curiously, i discovered that a freshly opened retort with straw char 
>> emitted such strong ammonia odor it would knock my head back. never 
>> got to fully explore what that was, but it seemed certain the ammonia 
>> was coming from the straw. with a TLUD, i doubt ammonia will be 
>> created, or if so, it will be oxidized and burnt off in the gas flare.
>>
>> david
>>
>>
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