[Terrapreta] biochar and sugarcane growth (reply to AD Karve)

[Ron Larson]

Tom  (cc AD, terrapreta list members):

    Thanks.  Below, I add a few more comments to your message of last night on sugar cane.  You said:
  The inorganic salts in the cane tops and leave melt and vaporize at low temperatures. Even in pyrolysis there is some loss as these elements volatilize at low temperatures. But since pyrolysis occurs at lower temperatures (300-500C) than combustion (750-800C) more of these elements, particularly sodium and potassium, stay with the char.  In Japan the raku glaze is made on pottery by simply subjecting rice straw to temperatures above 750C which is the melting point of the naturally occurring mixture of potassium and silica (2:3) in rice straw. Other glazes like the ones you describe are simply combinations of these salts. In gasification sometimes we can gasify the carbon in a crop residue by gasifying it inefficiently, i.e. leave more carbon, which offsets the tendency for the melted components of the ash to agglomerate.

     [Tom:  Thanks for the added information.  I take this to mean thatyou believe pyrolysis is a simpler (therefore cheaper?) means of obtaining char than is gasification.  Do we have any data on whether gasification removes nutrients that we would rather not remove?  Or is our need for liquid fuels so great also - that we should be emphasizing fast pyrolysis and gasification?]
   

  Bagasse is generated at the mill as a result of crushing the cane. It has to be delivered back out to the rural smallholder for him to use it. Trash, on the other hand, is left in the field where it must be harvested separately from the cane for use. Harvesters like you'll see in Australia make billets, or short chunks, of cane and strip the leaves. There is increasing environmental pressure to stop burning all over the world so if the trash has a use that will justify collecting it then it will be used.   There still is a "cane energy network" of sugar mills around the world who have been either using or experimenting with combination s of bagasse and trash, or bagasse and wood, that can be used to generate power when the mill is not crushing. This is the basis of the growth of [power generations from bagasse in India. In South and Central America the mills are also modernizing to use less energy and to use their residues. You don't change an industry overnight. We've been working on this with some mills for about 20 years. 

   

     [Tom -  I had not heard of the "network".  This is very encouraging.  Is there a web location for that dialog?

      Are these mills thinking of CHP - so that "waste" heat is available to other types of factories that can then be encouraged to locate near by - and further improve the economics (and further reduce overall energy consumption and CO2 production)?  

      What is the ratio of sugar mills "using" vs "experimenting"?

      Any other biomass residue-using industries that are moving from part-year to full-year operation?

      Agreed this will take time - but do you see a new sense of urgency within the network?

      Will or could the transition be speeded up or slowed down by consideration of Terra Preta ideas?]

      

  Sugar mills making alcohol are still using molasses. Cellulosic ethanol (from bagasse) is still in development which is why it has gotten such a large subsidy.  I don't think we will see pyrolysis of bagasse or trash until a market value is apparent for the charcoal. It is my understanding that oil yields from pyrolysis of grasses and agricultural residues are very low which is why woods are preferred.  



      [RWL:  Interesting.  At the IAI meeting, one person emphasized that the word "agrichar" should be replaced by "biochar" - perhaps for the reason you suggest - that wood will be big for TP purposes.  I think we also need more data on whether the char from leaves and trash is as soil-effective as that from wood (thinking of surface area issues).

      The market value question is indeed critical and badly needs the much-increased involvement of soil scientists - and I have been amazed at how many of them there are.  They need funding.]

   

  I agree that an important objective of this group should be to demonstrate the value and use of charcoal. Then let the open market or the policy makers make it attractive for industrial interests to produce charcoal with qualities that are useful. We have already seen Kingsford/Chlorox ready to deliver charcoal by the truckload and that's not the barbecue quality charcoal.    

   

     [RWL:  We on this list can and must do a lot - but we need a much increased world-wide governmental involvement as well (providing $ and interest in the topic).  We are seeing amazing growth in literature on TP - but we are still mostly unknown.  

      Thanks very much for the added education - where I know you have been involved for many years.



  Ron]

      



  Tom Miles

   

   

   

  From: Ron Larson [mailto:rongretlarson at comcast.net] 
  Sent: Saturday, May 19, 2007 5:46 PM
  To: Tom Miles; 'adkarve'; terrapreta at bioenergylists.org
  Subject: Re: [Terrapreta] biochar and sugarcane growth (reply to AD Karve)

   

  Tom, AD,  terrapreta list members:

   

      I add a few questions to your message of last night:

     

    As others have remarked the trash (leaves) contain high concentrations of nutrients that make it difficult to burn in industrial boilers. These are appropriately retained in the char in the ARTI process, which would make a good agricultural char.       [Tom -  This is possibly the first time I have heard this - or are we talking about the presence of some components of ash that can generate a "glassy" residue?   Is the problem avoided in all pyrolysis approaches?   

        This is way off topic - but I saw a "kiln" (right word?) once in Uzbekistan solely dedicated to combusting (not pyrolyzing) a particular difficult-to-harvest mountain-top plant, whose composition led to "pockets" of a ceramics glaze (with very nice properties - with almost no further processing).  What is a combustion problem for many was the whole point of their operation.  (They are doing it now only to honor their village traditions  better glazes are available at much lower cost.)]

     

    We need to think on two levels in this discussion: (1) the rural smallholder, and (2) industrial production.

     

    Charcoal made from leaves and applied directly by the rural smallholder is one economy. The example is the ARTI kiln.   [RWL:  I have been thinking also of some rural small-holder pyrolysis of bagasse - perhaps in charcoal-making stoves - but perhaps even without that logical by-product use.  I don't believe we have to assume leaves only at the household level.]

     

    Charcoal made by processing the bagasse residue after processing the cane at the mill is another economy. Or, collecting the trash for conversion to charcoal at the sugar mill is an industrial economy distinct from the smallholder. The examples are the processes converting 100 tpd or more like Dynamotive, Renewable Oil Corporation, Ensyn, EPRIDA, and Carbon Diversion Technologies (Antal). [RWL:  Agree mostly.  But this large-scale conversion may prove to be best with both bagasse and the leaves.  I think it probably sub-optimum to leave the leaves (no pun intended) in the field for burning (as seems to be practiced worldwide).  The mill I visited a few weeks ago in Australia will for the first time ever be leaving no leaves in the field (I think in large part because of objections to the uncontrolled combustion there)!

     

    In recent years large gains have been made in India in converting bagasse to heat and power at the sugar mills. And there is pressure at all (900?) mills around the world to process the trash. There are also pressures and incentive to convert the bagasse and/or trash to liquid fuels. We have worked on industrial projects involving both those processes.  [RWL:  Tom - do you know of ANY of those (besides the two I learned of in Australia about to start), who are operating the electrical side of the sugar mill operation year-around?  I think the mill economics should much improve with that mode of operaton - and experts I have talked to say this is not being done to their knowledge - and of course have confirmed by experience that no-one in the mill business is pyrolyzing anything.

        I like the alternative conversion of the bagasse to liquids (either cellulosic ethanol or fast pyrolysis) and know of companies doing both with bagasse.  But I know of none who are emphasizing charcoal - except as a minor byproduct.  Have you worked with any along those lines?  (For anyone wanting to try it, I recommend Tom as the best person to start with this discussion.)

     

    Initially there may be more incentive for a sugar mill to make heat and power from bagasse than to make charcoal. There may not be enough value for the mill to bring in the trash from the fields for converting it to charcoal. That is where there should be an opportunity for small producers like JFBiocarbon, BEST Technologies, or char from the modular oil producers like Advanced Bio Refinery, Renewable Oil International or Agritherm.  [RWL:  Yep - the incentive is not there yet - but to prove there might be an appropriate incentive is the reason you started this list.  

        I think/hope that the world will soon discover (with the help of people in the field like AD and yourself) that the climate and soils benefits (neither now being considered in the sugar business apparently) of charcoal will exceed the value of any other form of their waste conversion, and especially of combusting leaves in the field.  I agree there is a role for pyrolyzers at all scales.  Fortunately, AD is an expert on this at the family level as well.]

     

    See: http://terrapreta.bioenergylists.org/company

     

       Tom - you are doing a great service by advertizing the existence of these pioneering firms!      Ron]

     

    Tom

      

     

       
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