[Stoves] Fwd: Fwd: Simple Modifications to Traditional Wood Cookstoves - Rocks and Clay Grates

Sun Jun 23 20:00:32 CDT 2019

Dear Rogerio

I can't quite sort out which are your new replies but the details are interesting and helpful.

I do want to add something to the background on the related three stone fire.

++++++++

On May 27, 2019, at 11:09 AM, Rogerio carneiro de miranda <carneirodemiranda at gmail.com<mailto:carneirodemiranda at gmail.com>> wrote:

Hello Ron and stove colleagues:

Indeed, very interesting what Kevin is doing with three stone fire to improve efficiency. Clever, and boy, it took more than 10k years to figure out such simple solution…….

RWL:  Your store clearly uses a grate with a similar function to Kevin’s rocks.  Kevin started with a metal grate.

+++++++++

As I understand it Kevin started with three broadly bent U-shaped iron rods that were pushed into the ground to elevate the tips of the sticks as they were pushed into the burn area. These were not zero cost but were cheap and easy.

The metal char elevators (various types have been promoted) are more engineered and accomplish the same thing but for longer - holding up the smaller char.

There was a clay version proposed in Yogyakarta during the Indonesian CSI project made from local clay that had extruded T-sections standing on a clay plate. Very cheap. Very effective. It could be added under any fired served as the inspiration for the Karen Super.

The Pile'o'Rocks (PoR) is a free version of the Yogya model and works very well - for free. Any fire on a flat floor can be improved by elevating the char in a way that air gets underneath. The older "Clean Kitchens" campaign in Central Java was based on a built-in stove that had fired clay components including a circular clay grate at floor level with an excavated chamber below. This has the same effect as the PoR - it gets air under the fallen char.

The effect of all these on combustion is pretty dramatic. Elevating the burning tips has the same effect as the Rocket Stove with a fuel shelf - getting air under the fire rather than having it suffocate with air from the side. The question is how much control can be exercised over the excess air level so the combustion temperature remains high.

No doubt a conversation will emerge about whether to use pumice rocks like those sold on Lombok Island or dense ones like those found in Ontario rivers to hold (or not) some heat. I am betting on high thermal mass as the best answer because of preheating the primary air late in the fire.

Paul Anderson at one time advocated putting stones at the bottom of TLUDs for air distribution - right Paul? This time round we have some good test results from SeTAR and the Phnom Penh lab (SNV) to show the quantified results.

Congrats all round

Crispin

Hi Ron:

Sorry for the slow response.

This article you referred to is a very good one.  Transition to LPG has reached high levels in Brazil, nearly 95%, but to reach total and universal access is been difficult. There are still families fully dependent on fuelwood in isolated communities and the extreme poor, mostly in the north and northeastern regions of the country.  A recent set back to higher fuelwood usage has been observed due the deep economic crises, but the new government is apparently working on a new policy for LPG that will make it affordable again.  We are waiting to see it...

A minor portion of families in these regions also use charcoal stove, which could perhaps try TLUD stoves as alternative. Recently we saw a nice TLUD developed in Honduras by iDE (an development NGO) with the help of Paul Anderson, and professor Sergio Elarrat from the Federal University of Pará state is interested in adapting such TLUD to the Amazon region.

More answers below...

Em seg, 3 de jun de 2019 às 00:14, Ronal Larson <rongretlarson at comcast.net<mailto:rongretlarson at comcast.net>> escreveu:
To:   Rogerio cc stoves.   (Rogerio has a great history on stoves - and was one of the earliest stove list contributors (then in Nicaragua with Prolena))

Thanks for these additional thoughts on modifying a traditional rocket - with a similar “sideways flame”.

See a few questions below, but I also hope to get your reaction to apparently great changes (increases in wood stove use in Brazil - as subsidies have been greatly decreased for LPG.  )
This from reading: "The energy transition history of fuelwood replacement for liquefied petroleum gas in Brazilian households from 1920 to 2016”, available, non-fee, at a Kirk Smith site:   https://static1.squarespace.com/static/53856e1ee4b00c6f1fc1f602/t/5b8976edaa4a99b00191295c/1535735539528/Coehlo+LPG+history+EP+18.pdf<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fstatic1.squarespace.com%2Fstatic%2F53856e1ee4b00c6f1fc1f602%2Ft%2F5b8976edaa4a99b00191295c%2F1535735539528%2FCoehlo%2BLPG%2Bhistory%2BEP%2B18.pdf&data=02%7C01%7C%7Ceb2d18906b8042ad6caa08d6f83581e4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636969306030018976&sdata=ZkkQuVVezPiHFGy4AhEZa%2B0dmJqp1DpGUI7k1Cqn5io%3D&reserved=0>

This would seem to be a tremendous opportunity for TLUDs and char-making stoves - especially because of Brazil's Terra Preta history.  The above article emphasizes the importance of affordability - and charcoal-making stoves could have even negative costs.

Can you comment on this aspect of the usual stoves on this list (yours not being typical -  very handsome, but not apparently emphasizing minimum cost).

(More below)

On May 27, 2019, at 11:09 AM, Rogerio carneiro de miranda <carneirodemiranda at gmail.com<mailto:carneirodemiranda at gmail.com>> wrote:

Hello Ron and stove colleagues:

Indeed, very interesting what Kevin is doing with three stone fire to improve efficiency. Clever, and boy, it took more than 10k years to figure out such simple solution…….

RWL:  Your store clearly uses a grate with a similar function to Kevin’s rocks.  Kevin started with a metal grate.

Regarding the rocket stoves, what I have done is what a call an extended rocket stove chamber.   Usually an stand alone rocket stove supports only one pot under its combustion chamber, but if you add a griddle on top of it, you can use two or even three pots by channeling the hot gases under the griddle, before going to a chimney.

RWL:    Does “plancha” mean the same as “griddle”?   You are emphasizing no flame escape at each “pot-hole”.    Should Kevin strive for same in some cases?
RCM> Yes, plancha is a griddle, but usually in Central America planchas are solid made of  common sheet steel of 3 mm, with no holes on it.  Not sure if such approach would help Kevin, since he is working with open fires.

My extended rocket stove does support two pots under the same combustion chamber, which basically I make  a longer rocket stove ¨chimney¨, which does allow two pots above and on the same level. Of course, the fuel consumption is higher, 1.45 kg/hour in contrast with 0.9 kg/hour in a one pot stove.

[RWL.   Can you also discuss TDR = turn down ratio.
RCM>  a correction ¨ My extended rocket stove does support two pots above (not under) the same combustion chamber¨
The ratio in the Premium stove is 2.5 kg/hour at high power and about 0,5 kg at low power. The 1.45 kg/hour is a average.

I made this extended rocket stove in order to power a four burners Premium Ecostove, which has an one meter long griddle (4 pots holes), a 45 liters oven, and a water coil heater.   Basically, I get direct flames under the first two holes from the extended rocket chamber, and also flames onto the third hole by the suction from the chimney draft.  On the fourth hole I usually get flames only when the stove is operating at full power.

This new stove was developed in response to the Brazilian market, which liked the benefits of the rocket stove, but demanded a more powerful and useful stove.  Here a link for a photo of our Premium Ecostove https://ecofogao.com/wp-content/uploads/2018/08/WhatsApp-Image-2018-07-16-at-10.44.02.jpeg<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fecofogao.com%2Fwp-content%2Fuploads%2F2018%2F08%2FWhatsApp-Image-2018-07-16-at-10.44.02.jpeg&data=02%7C01%7C%7Ceb2d18906b8042ad6caa08d6f83581e4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636969306030038993&sdata=Mj03x8%2BgJsaviwrKJoQHqCpW7knJRbjt87TjMgD02k4%3D&reserved=0>

See also Rogerio here:  https://www.youtube.com/watch?v=8tNpSRhEeRI<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3D8tNpSRhEeRI&data=02%7C01%7C%7Ceb2d18906b8042ad6caa08d6f83581e4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636969306030059009&sdata=Z1ICLle9UYDKUhCRlc80PpcOclaPFIA0bS48o9IKQ%2BQ%3D&reserved=0>

I think this list would like to understand your market.  Is wood firing like yours competing now against LPG?  On a cost basis - or what basis?  Could char-making, if giving negative costs, be a plus?

RCM>  My market is mostly recreation, e.g. middle class families who wants to  gather family and friends during weekends and  cook on their woodstoves for fun and tradition.   I also attend NGOs who wants to donate improved woodstoves to the poorest in the northeast region, but it is a small market.

For char-making, such stoves would need to cook more than one pot at once, in order to be attractive here.

Thanks again.

Ron

Regards

Rogério

Em qui, 25 de abr de 2019 às 01:02, Ronal Larson <rongretlarson at comcast.net<mailto:rongretlarson at comcast.net>> escreveu:
List:   cc Kevin M

1.   This is to bring you up-to-date on Kevin McLean’s “zero cost” stove work - that I have learned in the last 4 weeks..  This today is on three (mainly one) new concepts (despite keeping the thread name).   It has applicability especially to those working with Rocket stoves - but I am pretty sure he/we can find ways to work also with TLUDs.

2.  After Kevin sent me 3 short videos a few days ago,  we agreed there could be great benefit to his and everybody’s stove research to get this early work out for discussion.  So this is to ask everyone to view Kevin’s annotated 2 minute video on an approach I have not previously seen:
https://drive.google.com/file/d/1EJQEKKkMTQbcKn3kBC1YZ50oqtZPsbym/view<https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F1EJQEKKkMTQbcKn3kBC1YZ50oqtZPsbym%2Fview&data=02%7C01%7C%7Ceb2d18906b8042ad6caa08d6f83581e4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636969306030069020&sdata=EAUeFrNVY5Rb%2Fszg7nagtLZshwOCbG5sc9Px41T6OxE%3D&reserved=0>.
  I am amazed that so much energy gets to the second pot (and he may develop a 3 pot design, that also looks well worth the relatively small added extra cost).  No metals anywhere.
Anyone seen this before?

  3.  I will try to report soon on two other new (to me) very low cost stove improvement areas on which Kevin has also been working - and which I am unaware of any others pursuing:
-   adding energy storage using movable hot rocks or bricks (headed to hay baskets maybe?)
-  making char while cooking (and NOT with TLUDs)
Can anyone give a lead to these storage and char-making areas?

4.   The 4th area of our discussions since the message below still seems brand new:
- improved air flow with 3-stones - using "rocks and clay grates” to elevate the fuel.

5.  Since Kevin is adamant on zero costs to users (and minimum costs allowable when payback time is short), these ideas are not amenable to most companies looking at the 3-stone-user market.  Accordingly, Kevin will not be patenting any of this - all 4 areas will be open source.

Anyone working on any of these 4 areas?  Or know of past results from anywhere?

Ron

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