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

[Paul S. Anderson]

Dear Ron and all,

Your message was well presented.  I hope you find my comments 
encouraging.  I do
not make claims that I cannot support.  (much has been snipped from your
excellent message that others should go back to read if they missed it.)

Quoting Ron (RWL) with earlier comments by Crispin in "quotes".
>    "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.

A TLUD without dumping (tipping over the fuel canister) was done by Alexis
Belonio for rice husks.  He has a hinged bottom grate to let the char 
fall out.
I am currently refining my own variation of this, but with a bottom door
(solid, not for air to pass through).  I will have the design functional by
Stove Camp 2007 in July.  Unlike most other TLUDs, the stove body does not
move.  No changing of fuel canisters.  Allow perhaps a minute between char
removal before new fuel can be added into the hot-walled TLUD.  Also, there is
"no dumping" from my AVUD gasifier that is larger, has continuous fuel 
feeding,
and also has the option for an auger to remove the char or ash.  (AVUD is
"Another Variation Up-Draft" gasifier, and is described in the Boiling Point
Issue 53, article called:  "Micro-Gasification:  What it is and why it 
works." That article is also at
http://www.chipenergy.com/UDG%20Boilingpoint%20paper%202007-02-26%20CEweb.pdf
  This AVUD technolgy has been shown (including lighting it) in the Chip Energy
Biomass Grill that was at the ETHOS 2007 meeting. )
>
> [RWL:  I don't believe the BLUD can ever produce the "same gas 
> profile" [as a TLUD].  ...   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.]

Already accomplished.  The AVUD gasifier technology can EITHER burn up 
the char
or can have the char removed almost as fast as the char is made (only a small
amount of char must remain inside the AVUD gasifier for continual operation.)

Please respect that the identifier "AVUD" is a term we reserve for THIS 
specific
form of updraft gasification found in the Chip Energy Biomass Grill and 
Biomass
Furnace.  I dislike the expressiong BLUD or BLDD because there can be many
different variations of "bottom lit" gasifiers.  Just look at the
gasifier.bioenergylist.org   website to see many types, but nobody there uses
the acronmy of BLUD.  The name of TLUD is quite specific to what Tom Reed
devised (and called IDD initially) and should NOT be used for the top-lit char
makers.  Let them get their own name or always spell out the full words 
of what
they are describing.  TLUD and AVUD are specific names with specific 
meanings!!
>
>     "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.]

To Ron, can a CMS operate with ONLY primary air?  I doubt it, even if it takes
in a little amount of secondary air through the primary air inlet.  Can a CMS
make charcoal and not have any combustible exhaust gases?  The pyrolysis gases
must be released, and if they are in excess of what is burned inside to make
the heat to create the char, then those combustible gases must come out.  If
they are not combusted, you have "smoke" and pollution and greenhouse 
gases and
bad stuff.  So we want to combust them, and that requires secondary 
air.  Maybe
that secondary air is not controlled, but it is still needed.  If not
physically "split", then the primary and secondary air at least come from two
separate sources of air.


Ron's item #4 has two parts and goes into #5 as well:  Crispin wrote about
ignition of TLUDs and chopping of fuels.  These are among the most frequent
(but incorrect) complaints about TLUDs.  Ron is correct in both counts:  easy
lighting even with dry pine needles or other starter that can be locally found
or made.
> [RWL:   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]

When people can get away from their "large-wood-dominated" thinking of biomass
fuels, they will find that most biomass is small stuff that is either already
appropriate for the gasifiers and char-makers or can be made into 
briquettes or
pellets.  We need to stop thinking of "big wood" because that leads to cutting
the whole tree or major limbs.  The advantages of a "forest" of small
fast-growing trees with frequent harvest, regeneration growth from strong
roots, soil protection, and assured continuing renewable fuel should become a
"no-brainer."  But old-thinking has massive inertia with traditional 
societies,
and even among the educated readers of the Stoves list.
>  [RWL:   Chopping or pelletizing is not a pre-requisite for CMSs.]
>
>    "6. ....> What exactly are we gaining with the TLUD?  [RWL:  Aha - 
> my chance to proselytize.  Emphasis added in yours.
>
>     RWL Reason 1 - Desertification   ...   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 -
      PSA adds:    And this includes the TLUDs and AVUDs.
>
>    RWL Reason #2 - Efficiency    The ability to control (and keep 
> constant) power level is a big part of efficiency - and these CMSs 
> [including TLUDs] do that - but few other stoves (your Vesto is a 
> fine exception) can do that.

>    RWL Reason #3 - IAQ  [ Indoor Air Quality]  - .....  is a valid 
> aspect of >   CMSs - which Dean Still has also affirmed at Approvecho.

>    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 
> [including TLUDs].

AMEN, AMEN!!!!   At Stove Camp this year, user-issues are to be 
included in the
criteria for evaluation of the competing stoves.  With fan-driven TLUDs, light
it and soon after it stablizes, leave it for 10 or 20 minutes (or even 40
minutes if using pellets).  With natural draft TLUDs, a few minutes at the
beginning are needed to get the combustion stabilized (with hot component
parts) before you can leave it.  Ron, I am so glad that you wrote about this
issue.
>
>   Reason 5.  Income generation   As time went on - I felt the main 
> selling point for CMSs [including TLUDs] should be the fact that the 
> rural cook could make a small income from selling the produced 
> charcoal for later combustion.  ...    Most stoves cannot hope for 
> this favorable factor.

>    Reason #6 - Climate mitigation   ...  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.

My calculation is that a family that changes from an inefficient fire to a
CMS/TLUD can accumulate nearly 350 kg (or more) of char per year per 
household. That is about 1 kg per day, which is 20% of the 5 kg of fuel 
(or more) that they
were burning in their traditional fire.  Three households can make a tonne per
year.  Assuming we need 300 million improved cookstoves in the impoverished
wood-burning areas, that would be 100 million tonnes of char per year.  And
that translates into approximately 350 million tonnes of CO2 removed from the
atmosphere each and every year forever.    BUT only if that char is NEVER
burned.  And that is where the Terra Preta sequestration of char plays an
important part.
For more about this, see pages 8 to 11 of
http://www.bioenergylists.org/stovesdoc/Anderson/GasifierLAMNET.pdf
Tom Reed and I wrote this in 2004, and identified nine (9) WINs and no loses
that match up with some of Ron's other comments above.

>    7.   "It is possible to make one with low tech materials. That's 
> cool."    [RWL  agreed.
   PSA adds:  I have received so much "grief" because of my use of "tincanium"
that I must express my thanks now to Crispin for saying "That's cool." 
Although low-tech materials might be cool, better materials are also 
needed to
help sell TLUDs and CMSs and other stoves.  I still do prototypes with 
tin cans
and sheet-metal air ducts, but I am very interested in using a stack of
Crispin's compressed rings.  And I will try my most recent ideas using cement
blocks.

>    8.  "Most seem to need a fan which is definitely a problem where I am."
   Crispin's statement is misleading.  "Most" in relation to "TLUDs for 
sale" or
"most" for prototype designs that have been made, or what?  The reality 
is that
the improved combustion of the fan-driven TLUDs is spectacular, and that is
what gets the attention.  On the other hand, the Champion Stove (Cat Pee Award
Winner for clean combustion at Stove Camp 2005 ) is natural draft, and a
variation of it is manufactured in small quantities by ARTI in India.  
The next
generation of TLUDs and the AVUDs can and do work with natural draft.  
They will
be shown at Stove Camp 2007.
[RWL -  [fans] need not be a major drawback as CMSs continue to develop.]

>    9.   "They produce char (not really 'charcoal') which is not 
> interesting, frankly."     [RWL:  You are correct probably if you are 
> trying  only to sell into the normal charcoal markets - ... 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).

[ PSA:  Again I agree with Ron.  To Crispin and others, Do not let tradition
cloud your vision.  This world is changing, and small-particle waste biomass
will increasingly take the place of large-wood as a fuel for the 
impoverished. We Stovers need to be prepared, and to offer, and to lead 
if necessary, with the
stove technologies for the fuel-starved world.]

>    "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.

PSA says:  I believe you are referring to the change of air at the transition
from the pyrolysis stage to the char-gasification stage.  I am on the side of
"do not burn the char."  Therefore, there is no need to change the air supply,
you will just not burn the char very well.
But even more important, when referring to the AVUD technology, there is
continuous operation and the air flow remains the same unless the user 
wants to
increase or decrease the amount of heat generated.

> [RWL continued:  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.]

My company (Chip Energy, with my partner Paul Wever) is founded upon the AVUD
technology that is totally compatible with charcoal making or char 
burning. You can already order a Biomass Grill aimed for North American 
customers.  But
there is also the Biomass Furnace that is being positioned to heat American
homes in the cold climates.  And you could set it for making char or for
burning the char all the way to just ash.  The furnace is not yet on 
the market
because we are adding automation for thermostat control in the homes and
automated addition of fuel.  But the manual prototype is operational 
and can be
seen in Goodfield Illinois.  Ron, your home is a model of energy 
efficiency, so
you might want to be one of the first to have a biomass heated home with AVUD
gasification and produce char for making Terra Preta.  We can discuss AVUD
technology on this listserv, but Chip Energy is a business, so commercial
discussions should be off-list to me or to Paul Wever   pwever at pwce.com
>
>    RWL:  In the interest of full disclosure and intellectual honesty, 
> I need to give my own remaining concerns about CMSs....    #2.   
> Efficiency:  ...  And we need development of a CMS design that works 
> with the "plancha" type of cooking used in much of the world.

Already exists.  See the Chip Energy Biomass Grill at   www.chipenergy.com

>    #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.

You will be impressed with what the chimney contributes to the CMSs.  Not as
good as a fan, but far better than "no-chimney" designs.  Draft is crucial.

>    #4.  Ease of operation -  I never found a good way to take the 
> produced char out gracefully.

We have two good options now.  One is the bottom trap-door and the 
other is the
char/ash removal auger.

>    #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.

The charcoal making in CMSs or larger char-making gasifier units can be 
done by
more than just the cooks.  A rural cottage industry using an appropriate
variation of the Biomass Grill (AVUD gasification technology) could 
improve the
efficiency and lower the emissions from the cottage industry fires and 
also more
appropriately and cleanly produce charcoal without the associated 
deforestation.

> RWL wrote:  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.

In many countries it is already legally outlawed, but not enforced.  
The people
who support themselves by making charcoal need alternatives (excluding growing
narcotics).  Helping them make charcoal via better methods is a logical
alternative to present practices, if the technology is appropriate and
available.  But where is there any support for doing that task?

>    #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.

We are grateful that respected leaders like Ron will be working on this 
issue. Carbon credits are great but they still have a low monetary 
value.  Currently,
the cash value of a tonne of char (about 3.7 times the value of a ton of CO2
because the weight of the O2 is not in with the char) is still far less than
the cash value of that char in the fuels marketplace.  Until the price for
sequestered char is equal to or higher than that of char to burn, the char
makers (even without formal education) know it is economically better to sell
char to burn than to sell char to bury.
>
> Ron wrote:  Apologies for the length -

No apologies needed.  These are topics that are important to many of us.

Paul
-- 
Paul S. Anderson, Ph.D., Geography professor - Emeritus
Telephone:  USA-309-452-7072 (residence and office)
Internet site:  www.ilstu.edu/~psanders
For my gasifier stoves info, go to:
http://bioenergylists.org/contributors#Paul_Anderson



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