[Stoves] Bangladesh TLUD (was Re: No subsidies in TLUD char peoduction

Paul Anderson psanders at ilstu.edu
Thu Dec 7 06:51:02 MST 2017


About the concrete inner (fuel) cylinder.   Hard to be sure without 
actually observing it, but I suspect that:
1.  The thermal mass is estracting heat, meaning cooler gases inside the 
chamber, with risk of insufficient temperature for ignition at the top, 
especially when nearing the end of pyrolysis.

2.  Julien and Mahbubul can confirm about this:  The concrete (or 
ceramic) inner cylinder does not have any of the side holes (24 in the 
metal version).  Such holes allow for some "pilot light" effect after 
the char level is below a hole.    I imagine that small holes would be 
very difficult to put into a concrete cylinder.   However, maybe 3 or 6 
holes could be created at strategic locations (to be discussed).   They 
could be created in the following way:
      When the concrete is being poured (or soon after), place something 
like round toothpicks (about 2 mm size??) across the concrete, sticking 
out both sides.   (might be at a place in the mould with holes that 
would leak concrete/water except that they would soon be "plugged" with 
the toothpicks.   When the piece is dried, and used for the first time 
(or two or three times) the wood would burn out (or be drilled out or 
poked out), leaving the desired hole.
     Alternatively, do the same with larger diameter pieces like 
chopsticks.   If the holes are too large (to be determined by 
experimentation), then they might be plugges slightly (in a variety of 

First, let's get more understanding of the 24 "pilot light" holes in the 
metal version.

3.  How much supply of coconut shells (hard part) is there in your zone?


Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
Email:  psanders at ilstu.edu
Skype:   paultlud    Phone: +1-309-452-7072
Website:  www.drtlud.com

On 12/6/2017 11:55 PM, Ronal W. Larson wrote:
> Julien cc List
> Thanks for the answers below.  Good to hear that both users with and 
> without land see value in making char.  No new questions,  two comments
> 1.  Re a concrete inner cylinder,  you said below “../but their 
> smoke-free combustion was less reliable, and there were some gas 
> burner issues to solve. “/
> It is not obvious to me why either concern should occur,  so I hope 
> stovers everywhere could try this out.  Seems likely to be cheaper 
> (can even maybe cast in place) and hopefully longer lived.  We know 
> usual cheap steel has a limited life and the best steels are likely 
> both not readily available and expensive.
> I forgot to congratulate on the two metal swinging “doors” at the 
> bottom.  Nice solution.
> 2.  Re fuels, the biochar list has had quite a lot of recent 
> discussion of “blue biochar” - where the source material is kelp or 
> other seaweeds.  Bangladesh is possibly already in that business, 
> because of its ocean proximity.  This could be a source of employment 
> and a way to save forests while having a feedstock that should bring 
> back needed minerals and fertilizer value.  Beating the price of 
> wooden blocks seems possible.
> Ron
>> On Dec 6, 2017, at 10:05 PM, Julien Winter <winter.julien at gmail.com 
>> <mailto:winter.julien at gmail.com>> wrote:
>> Hello all;
>> Thanks for you comments on the Akha-Biochar Project in Bangladesh.
>> The cost and payback is not fully worked out, because it will take 
>> about a year for TLUD-biochar ecosystem to become established in 
>> community, and it will continue to evolve. The stove costs about $20 
>> to make, this could be brought down as numbers of stoves increase.  
>> Also, we are still at the stove-prototype stage, so we can expect 
>> some modifications and fine tuning.    Payback is developing, as 
>> farmers and gardeners discover the value of biochar for food 
>> production.  We have "Farmer Biochar User Groups" that are conducting 
>> field trials, so they can learn from first-hand experience what 
>> biochar can do for them. There are also graduate students involved in 
>> gathering evidence to make recommendations on optimum application 
>> rates.  It could take a couple of years at any one location for the 
>> local population to be able to place their own value on biochar, and 
>> what they are willing to pay for it.
>> Whether people use the char themselves or sell it depends on their 
>> personal opportunities.  There are many families that are landless. 
>> Presently, they see char sales as a way to earn cash or barter. They 
>> think that is a great idea; save fuel, cook faster, AND make 
>> biochar!  People with land, especially farmers, see biochar as a way 
>> of making permanent improvements to the quality of their land, so 
>> expect that using biochar could have very substantial impact on their 
>> family's economic well being.
>> I have been advocating using biochar in composting, or mixing it with 
>> manure before it goes onto the field.  We need work on using it in 
>> human waste management.
>> There is no shortage of good soil scientists and agronomists in 
>> Bangladesh to work on biochar technology.
>> The outer concrete cylinder of the Akha stove is cast.  We have made 
>> stoves with concrete reactors (lined with clay slip), but their 
>> smoke-free combustion was less reliable, and there were some gas 
>> burner issues to solve.  That is not to say that concrete reactors 
>> will not work, but they need quite a bit of research and development, 
>> and a laboratory. Metal TLUD reactors, on the other hand, are well 
>> understood.  About 24 small holes in the side wall of the metal 
>> reactor make the gasification of chunks of wood more reliable, and 
>> less prone loosing the gas flame.  We use cast concrete (rather than 
>> clay) because it is easy to get concrete rings with flat surfaces at 
>> the top and bottom. The concrete components are made specifically for 
>> the Akha.  There are many small business around who can cast concrete.
>> Mahbubul has been working with different ratios of Portand cement, 
>> sawdust and biochar dust in the concrete. The more organics, the 
>> lower the heat capacity and heat conductivity of the stove body. 
>> Micro porosity is supposed to make concrete more resistant heat by 
>> providing spaces for minerals to expand into. Obviously there is a 
>> trade-off between adding organics and strength of the concrete.  
>> Different recipes are being tested in the field.  It is all trial and 
>> error.
>> Mahbubul has also worked with local ceramic artisans to make the 
>> massive stove components from clay.  There very skilled people to 
>> work with, and kaolinitic clay, so ceramic components are possible. 
>> The more metal components on the stove that we can replace with 
>> ceramics the better, because all metal in Bangladesh is imported.
>> The Akha is about 25% more efficient than a traditional stove.  The 
>> Akha has gone through a water-boiling test at a laboratory in Dhaka, 
>> and was about 30% efficient at getting energy from wood into the 
>> water.  The main view that the Akha saves 25% of the wood comes from 
>> household feedback. That is what the women tell us.
>> The Akha-Biocahr Project has funding for its current intervention 
>> until 2019. It is enough to see if the TLUD-biochar technology will 
>> take root.  If it does, then the technology may spread all by itself 
>> as local entrepreneurs see an opportunity.  In fact, I think that if 
>> these technologies viable, then they will out of our control and 
>> unstoppable.  The 'market' is 25 million homes.  All the same, I am 
>> trying to raise money so that Mahbubul and crew remain as proponents 
>> and stakeholders in what they started.  There is work to be done in 
>> developing compressed fuels, because there is not enough wood in the 
>> country.  We need to monitor the impact on forest cover, and make 
>> sure that poorest households don't become energy-starved if the price 
>> of wood goes up.
>> One other thing that will push TLUD-biochar technology forward is 
>> that sea-level rise could flood a third of the country, so soil 
>> productivity needs to increase.
>> Cheers,
>> Julien.
>> -- 
>> Julien Winter
>> Cobourg, ON, CANADA
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