[Stoves] Personal history on charcoal-making stoves.(not necessarily same as TLUD)

[Ron Larson]

Stovers -  This message mainly trying to interest Crispin further in charcoal making.

     But first say with others that it was good to hear again at same time from Alex English - one of this list's best experts on larger scale clean charcoal making - especially doing so with bales of "hay" and the initial design and construction of the AD. Karve field charcoal-making system.

 Crispin said today (picking and choosing (newly numbered) topics):

    "1.  In the Vesto ...... produces wood charcoal if you were to dump out the fuel when the volatiles are gone. [RWL:  Unfortunately, "dumping" is still a design deficiency of the TLUD's I have seen.  (change your "fuel" to "char")]

    <snip>

    "2.  The TLUD, if it is working well, is producing a different gas profile and 
that is very interesting.  I am not sure if it matters much though.  Suppose 
it produced the same gas profile as a BLUD.  What difference would it make 
to the cook?"  [RWL:  I don't believe the BLUD can ever produce the "same gas profile".  A BLDD could - and I have been recently talking with Piet Verhaart on this topic.  I have seen no BL designs that make charcoal as its main intent and think this void should be filled by someone on this list.]

     "3.  I expect it makes a difference to the stove designer because the 
primary/secondary air split will (or might) be different.  Agreed? Otherwise 
they both provide burnable gas and use biomass.  [RWL:  Agreed (to the idea that air splits are of importance to stove designers.  But Charcoal Making Stoves (CMSs) are quite different from most stoves during the charcoal producing phase because there is necessarily a separate and small, controllable primary air supply.]

    "4.  A significant difference I can see with the Vesto approach is that it can 
use fuel that is not chopped into particles of a certain size and density. 
It can use regular wood chopped to fit inside.  There is a lighting 
technique required which I feel is more work: you should start a small fire 
in the bottom of hte combustion chamber and then put in the larger wood. 
After it is lit, you close the air and presto - a gasifier.  The TLUD is 
easier to light with a splash of alcohol a-la-Dr T's Campstove.  That's 
pretty cool. "  [RWL:  With practice, alcohol is not needed - I had luck with a handful of pine needles - above a small bed of char - above the fuel.  Re fuel supply, see my recent message on using "twig/branches".  I think if one thought in terms of some dedicated nearby trees to be coppiced as needed, this is by far the easiest fuel to use and requires only cutting (snipping) to length - not splitting, etc]

    "5.  But I don't want to chop wood into little pieces.  [RWL:  Agreed. See above.  Chopping or pelletizing is not a pre-requisite for CMSs.]

    "6. Apart from that the Vesto is not at all constructed to get the charcoal out, 
or even to extinguish it.  It just burn everything put into it.  Hmmm.... 
What exactly are we gaining with the TLUD?  [RWL:  Aha - my chance to proselytize.  Emphasis added in yours.

     RWL Reason 1 - Slowing down desertification and deforestation.   I started in this about a dozen years ago with the intent of stopping the southern movement of the Sahara in Sudan (where I lived for several years - seeing hundreds of big trucks entering the southern gates of Khartoum every day).  Instead of wasting more than half of the available energy out in the boonies (I wasn't placing high emphasis then on global warming), I felt that a CMS with rural users could supply the charcoal demand of urban users - and cut about half as many trees.  I think this can still be a valid "gain" for CMSs - but this no longer #1.

    RWL Reason #2 - Efficiency   As this list developed, much (maybe most) emphasis was on efficiency (saving the users' scarce funds for fuel).  The ability to control (and keep constant) power level is a big part of efficiency - and these CMSs do that - but few other stoves (your Vesto is a fine exception) can do that.  This also has dropped from the #1 slot

    RWL Reason #3 - IAQ - Considerable emphasis in the early days of this list soon turned to Indoor Air Quality - with much reference to the great work of Kirk Smith (later Dan Kammen) showing how bad most stoves are.  I came to believe (after some limited testing I have recently described) that this also is a valid aspect of CMSs - which Dean Still has also affirmed at Approvecho.  This also dropped out of #1 position.

    Reason #4 - Ease of operation -  For awhile, I thought that CMSs might have their best selling point in being able to set a desired power level (primary air flow quantity) - and then walk away for quite a time.  Those attending the Apprevecho stove competitions will agree that it is a little wierd to watch contestants tending a "standard stove" fire every few seconds and no-one tending the CMSs.

   Reason 5.  Income generation   As time went on - I felt the main selling point for CMSs should be the fact that the rural cook could a make a small income from selling the produced charcoal for later combustion.  The cost of a high class stove could be recouped in a few months - and that cost need not be high.  I always used low cost "throw-away" cans.  Both Drs. Karve and Reddy are talking of low-cost sales.   Burning the char after its production within a CMS, as you have recently discussed, fails to achieve this income generation advantage.   Most stoves cannot hope for this favorable factor.  Income generation still remains a major advantage - but no longer #1.

    Reason #6 - Climate mitigation   In a google search on this topic, I found a more complete description (Stoves archives, September 28, 2002) of my "religious" conversion  to my (hopefully final) main justification for CMSs - now being covered on a sister list: "terra preta".  Its going to take a while, but I believe CMSs can be a strong part of taking CO2 out of the atmosphere - which I think may be the world's most serious problem.  I believe this to be especially valuable in the areas of Southern Africa where you have concentrated your efforts (all should visit Crispin's website if you have not).

    7.   "It is possible to make one with low tech materials. That's cool."    [RWL  agreed.  See reason #5 above.   I am mad at myself today for never having tried to make a CMS out of concrete as you have recently complimented Dr. Reddy on.  I have had considerable luck with two concrete blocks - but left many unsolved problems with that approach.  Woring with wet concrete should be a great approach.

    8.  "Most seem to need a fan which is definitely a problem where I am."  [RWL -
I have only worked with natural draft - and am still undecided on the need and merits of fans.  I understand your concern - but believe this need not be a major drawback as CMSs continue to develop.

    9.   "They produce char (not really 'charcoal') which is not interesting, frankly.  It they made charcoal that looked like regular wood charcoal that would be more saleable."   [RWL:  You are correct probably if you are trying  only to sell into the normal charcoal markets - but I have made some from pretty large pieces of wood.  But also Elsen Karstad has shown that he can sell charcoal briquettes made from small char scraps (in his case from bagasse mostly these days in a down draft design).  Fortunately perhaps, I think (we haven't yet proved) that charcoal from CMSs may have pretty good properties for placement into terra preta soil (easier to make into the desired even smaller charcoal particles for TP).

    "10.  I am coming to the conclusion that the domestic TLUD will be interesting if it can gasify the whole fuel load and do so without having to change the air 
split part-way through the burn.  With or without a fan.
    Has that been done yet?    [RWL:  I think it hasn't and cannot will not be done.  But I hope I've given above a few more things to consider in CMS use in your and other parts of the world.  It is virtually useless where I live.]

    RWL:  In the interest of full disclosure and intellectual honesty, I need to give my own remaining concerns about CMSs. Using my 7-item positive list from above:
    #1.  Desertification:  we need to get a system of wood lots and coppicing in place simultaneously to help all kinds of stoves - but especially for CMSs.  It is criminal to cut down a living producing tree for firewood - and then dig up the roots as well for a bit more charcoal.  
    #2.   Efficiency:  Lots of room left for improvements.  Outer shields to the pot help a lot - but  we need to design and sell a CMS-pot combination - that takes a lot more of the energy out of the up-traveling gases.  And we need development of a CMS design that works with the "plancha" type of cooking used in much of the world.  I don't think we have seen the end of needed work on heat recovery for both the primary and secondary air.  
    #3.  IAQ -  I always worked with a "no-chimney" design - but am sure that a chimney or hood combination will be needed in many places.
    #4.  Ease of operation -  I never found a good way to take the produced char out gracefully.  Dr. Reddy has shown a small "basket" with handle that looks good.  Having an automatic trip method might work.  Loading the right fuel in the right way needs work at the front end - small pre-packaged bundles?
    #5.  Income generation -  We need to show that people are willing to "hire" rural cooks to make charcoal - at a price attractive to all in the chain.  This has to involve the present charcoal makers - the husbands of the cooks.  Continuing to make charcoal in rural areas as has been done badly in the past has to be outlawed.  Such outlawing might be the right incentive.
    #6.  Climate mitigation - We may have opposition to CMSs at high UN levels.  It is not yet clear to me how to make CMSs eligible for carbon credits - or even what the hurdles are.  This is where I intend to spend the largest portion of my time.

Apologies for the length - always fun to hear from Crispin - who is doing some great stove and other development work.

Ron



Thanks
Crispin