[Terrapreta] ? GHG emissions from Biomass Combustion ?

[Peter Read]

Yes, thanks Wayne
I think my rule of thumb is related mainly to woody residues and some 
modelling I did several years ago
Peter
----- Original Message ----- 
From: <teelws at jmu.edu>
To: "Tony Lovell" <tonyl at soilcarbon.com.au>; "'Peter Read'" 
<peter at read.org.nz>; <Shengar at aol.com>
Cc: <terrapreta at bioenergylists.org>
Sent: Monday, March 10, 2008 10:57 PM
Subject: Re: [Terrapreta] ? GHG emissions from Biomass Combustion ?


> Tony,
>
> Your questions is quite complicated because it is species dependent when 
> you get down to the actual numbers.  It even varies with soil type and 
> location.  The chemistry is relatively simple in a qualitative sense, but 
> quantitatively then it gets messy.
>
> Most carbon in plants is in the form of repeated sugar chains that make up 
> cellulose.  The basic formula is (CH2O)n, with n representing the total 
> number of repeated segments.  If your grass is naturally dried, like in 
> the late fall here is Virginia, then almost everything in the plant is 
> cellulose.  However, each dry species will have some levels of calcium, 
> magnesium, potassium, phosphorus, and in some species silica.  Some grass 
> species use silica as a repellent to grasshoppers.  (Some grasshoppers 
> have evolves aluminum-based mandibles to get around the silica - life is 
> complicated and fascinating).  When you burn most of the biomass is lost 
> as H20 and CO2 as long as oxygen is not a limiting factor.  Peter Read's 
> numbers are approximately correct, though I usually use 40%C for grass. 
> It is a little different with woody biomass because some of that is 
> lignin, which has a higher C percentage.  What remains after burning is 
> often a very light white powder, less than 1% of tot!
> !
> al weight, made up mainly of oxidized forms of the elements I listed 
> above.
>
> Green grass is different.  It is higher is nitrogen, phosphorus, and many 
> of the other elements as well.  The plant tends to withdraw these elements 
> into their root systems for next years growth if they dry naturally.  If 
> you cut them green they, of course, stay in the stalk or leaf.  Drying 
> these then burning could yield small amount of nitrogen oxides, including 
> some N2O, the worst of the plant-based greenhouse grasses, produced more 
> when composting or low oxygen pyrolysis to make biochar, which explains 
> why many of the list members want to make sure the off-gases from making 
> biochar are burned.  The C:N ratio is most green grasses is around 20:1. 
> In naturally dried grasses it is closer to 100:1, at least according to 
> the literature.  Different species will have slightly different ratios.
>
> I hope this helps some.  You should not produce any greenhouse gasses 
> other than CO2 and water with burning naturally dried grasses in open 
> flame.  Limited oxygen situations are the problem, and worse with cut and 
> dried grasses.
>
> Wayne
>
> ---- Original message ----
>>Date: Mon, 10 Mar 2008 14:12:22 +1000
>>From: "Tony Lovell" <tonyl at soilcarbon.com.au>
>>Subject: Re: [Terrapreta] ? GHG emissions from Biomass Combustion ?
>>To: "'Peter Read'" <peter at read.org.nz>, <Shengar at aol.com>
>>Cc: terrapreta at bioenergylists.org
>>
>>   Peter
>>
>>   Thanks for such a prompt response - which of course
>>   leads to more questions!!
>>
>>   What happens to the other 50% of material in the
>>   biomass that is not C? And if the combustion
>>   happened in a less than complete manner, eg in a
>>   bushfire or burn to clear land, what would the mix
>>   of GHG's be like?
>>
>>   Tony
>>
>>
>>
>>
>>
>>   ----------------------------------------------------
>>
>>   From: Peter Read [mailto:peter at read.org.nz]
>>   Sent: Monday, 10 March 2008 2:01 PM
>>   To: Shengar at aol.com; tonyl at soilcarbon.com.au
>>   Cc: terrapreta at bioenergylists.org
>>   Subject: Re: [Terrapreta] ? GHG emissions from
>>   Biomass Combustion ?
>>
>>
>>
>>   Hi
>>
>>   provided it is fully combusted there should be no
>>   CH4 or CO
>>
>>   how much CO2 depends on the particular biomass but a
>>   good rule of thumb is 50% C by weight in dry biomass
>>
>>   So 1 tonne Biomass contains ~500Kg C yielding
>>   500*44/12 Kg CO2 = ~1800Kg CO2
>>
>>   Peter
>>
>>     ----- Original Message -----
>>
>>     From: Shengar at aol.com
>>
>>     To: terrapreta at bioenergylists.org
>>
>>     Sent: Monday, March 10, 2008 4:38 PM
>>
>>     Subject: [Terrapreta] ? GHG emissions from Biomass
>>     Combustion ?
>>
>>
>>
>>     Hi All,
>>
>>     Could anyone provide the figures Tony Lovell is
>>     asking for below;
>>
>>
>>
>>     "Erich
>>
>>     Thanks you for sharing our work with your
>>     colleagues at TP.
>>
>>     Would you or any of your colleagues be able to
>>     assist me with finding some information?
>>
>>     I am looking for general parameters on how much of
>>     what GHG's are produced due to the combustion of
>>     biomass. In particular if we were to combust say
>>     1,000kgs dry matter of switchgrass or similar
>>     material how much CO2, CH4, CO, etc etc would be
>>     released.
>>
>>     Any assistance you can provide is greatly
>>     appreciated.
>>
>>     Take care,
>>
>>     Tony Lovell
>>
>>     Soil Carbon (Australia) Pty Ltd
>>
>>     PO Box 157, BOND UNIVERSITY QLD 4229
>>
>>     Suite 102, 20 Lake Orr Drive, VARSITY LAKES QLD
>>     4227
>>
>>     Ph: +61 (0)7 5553 7900 Fax: +61 (0)7 5553 7999
>>     Mob: +61 (0)418 730340
>>     Email: tonyl at soilcarbon.com.au
>>
>>
>>
>>
>>
>>
>>
>>     Thanks
>>
>>     Erich
>>
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> Wayne S. Teel
> MSC 4102 ISAT
> James Madison University
> Harrisonburg, VA 22807
> Tel: 540-568-2798
> Fax: 540-568-2761