[Stoves] SPAM Cooking Hole Modification to Three Stone Cookstove - Update

Wed Jun 22 15:21:04 CDT 2022

Dear Kevin

The TLUD restaurant stove may have been a response to local economic conditions. It was probably developed in 1984 and popularized in '85. In those days commercial cooking used electricity, wood, kerosene or charcoal. Maybe all of them became unobtainable.

A round hole is harder to dig but easier to line with a metal can.  I am not sure but I think standing fuel is faster than layering it.  Loading a pre-formed bundle is fastest.

The idea behind mixed fuels is to get a higher density fuel load. Low density fuels tend to burn rapidly. Denser twigs will tend to burn slower and make more char which can extend the usefulness of the fire.

A good point was made by another contributor: what about the heat transfer when the fire is so far below the pot?

Because the fire in the hole has no under-air supply, the excess air ratio in the fire, or above the fire, is much lower than a three stone fire. This means a higher temperature fire (flame) and a higher heat transfer efficiency. Yes, the fire is further away which can create a loss, but it has inherent advantages as well.  The proof is in the burning.

Regards
Crispin

From: kmclean56 at gmail.com
Sent: June 22, 2022 12:31 PM
To: stoves at lists.bioenergylists.org
Reply to: stoves at lists.bioenergylists.org
Subject: Re: [Stoves] ***SPAM*** Cooking Hole Modification to Three Stone Cookstove - Update

Dear Crispin,

Thanks for your observations.  I wonder why the cylinder method in Uganda is no longer being used.  It sounds much better than unmodified three stone.

A cylinder cooking hole should be more efficient.  We tried putting maize stalks upright in the cooking hole.  It worked but horizontal was easier.  And liner bricks bricks are easier to make for a square hole.

Why do you say mixed fuel will work better?  We will try it.  But if I know the reasoning, our testing will be more efficient.

Kevin

On Wed, Jun 22, 2022, 5:40 PM Crispin Pemberton-Pigott <crispinpigott at outlook.com<mailto:crispinpigott at outlook.com>> wrote:
Dear Kevin

This is another fine piece of work. I looked at all the videos and the techniques are clearly explained.

I suggest that it is possible to make a round hole and to bundle the fuel with string or grass such that it is prepared in advance and fills the hole completely.  This method of cooking with grass and reeds was in use in Ugandan restaurants in 1986 or perhaps 1985.  Fuel vendors prepared the fuel for sale in “cylinders” which were dropped into the stove and top-lit.  The difference is that the fuel was standing up, not cross-layered and horizontal.  I understand they tied the reeds into long bundles with multiple strings and then sliced then like a sausage so one string held one bundle.

You might try it to see if it is more convenient than hand-laying the pieces.

I am sure a mix of fuels would be better than one alone.  Twigs and stover, for example.

Realizing that this is potentially wasteful, but have you tried burying a bucket in the ground and using that? You can douse it and lift it out by the handle.  In some places buckets are hand made from roofing as a cylinder, not tapered.  That might be ideal.

Many thanks for your original ideas and extensive field work.

Best regards
Crispin

From: Stoves <stoves-bounces at lists.bioenergylists.org<mailto:stoves-bounces at lists.bioenergylists.org>> On Behalf Of K McLean
Sent: Tuesday, June 21, 2022 15:13
To: Stoves and Biofuels Network <stoves at lists.bioenergylists.org<mailto:stoves at lists.bioenergylists.org>>; Ronal Larson <rongretlarson at comcast.net<mailto:rongretlarson at comcast.net>>
Subject: [Stoves] ***SPAM*** Cooking Hole Modification to Three Stone Cookstove - Update

Adding a 25x25x25 cm hole to traditional open-fire cookstoves may end the collection of firewood from forests in many areas.  By piling fuel in the hole beneath the cookpot and lighting the pile on the top, the fuel burns long, hot, with no tending and with less smoke.  And by quenching the embers, cooks make biochar.

We found that most woody biomass bigger than thin twigs burns well in the cooking hole<https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fyoutu.be%2FDmzQFCp2kNI&data=05%7C01%7C%7Cd03ae001820d4003d6a708da547d689c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637915194870399245%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=HY8uScDFhxbkYEkSPamiS1X2qeAVJYsAKnMQQgVeMag%3D&reserved=0>.  Firewood the size that is typically burned in unmodified three stone cookstoves burns for three hours without tending.  Much less smoke is emitted than from an unmodified three stone cookstove.  A colleague estimates that the amount of wood in the cooking hole would burn for 30-40 minutes in an unmodified three stone cookstove.  Here's a video<https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F15V4vTJxO1Lcm0wFzB96pQT9jvgjaXkwh%2Fview%3Fusp%3Dsharing&data=05%7C01%7C%7Cd03ae001820d4003d6a708da547d689c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637915194870555500%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=309kxjNHFmYkismlcUAUSeaNbEqrsg1212ClSq33bp4%3D&reserved=0>.

Thick twigs burned without tending for 1.5 hours.  Thick twigs and small branches are abundant and unused in much of Africa.

The cooking hole also works with crop waste (maize stalks and cobs, cassava stems, banana peels, bean stems, ...), elephant grass, bamboo, large sawdust and wood shavings, sawdust briquettes, dung patties and more.  Depending on the fuel, the fire will burn without tending for 20 minutes to several hours.  Here's our training video<https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fyoutu.be%2FDmzQFCp2kNI&data=05%7C01%7C%7Cd03ae001820d4003d6a708da547d689c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637915194870555500%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=31vM9fsRvcg%2B590zfI9zx4N8jp7%2BIzLmCw8m%2BVt9vCA%3D&reserved=0>.

Women can:
- All but stop collecting firewood.
- Leave the kitchen to do other things once they start the fire.
- Make biochar.

And 8-12 common bricks can support two cookpots over one cooking hole allowing two meals to be cooked with the same amount of fuel and time it takes to cook one meal.  The time to boil is only a few minutes longer than for one pot.
[cid:image001.jpg at 01D88586.BA2EC9D0]

In much of Africa, most people know how to make bricks.  We show them how to make free custom bricks to line the cooking hole.  Here is a video<https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F1b2WvePKX_ofnELUWhexqQZR4NyCrXxnH%2Fview%3Fusp%3Dsharing&data=05%7C01%7C%7Cd03ae001820d4003d6a708da547d689c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637915194870711716%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=MKX4SEd2BynwMQrzsftdQ0uevOgty73pmmkfY7qiY4g%3D&reserved=0>.

Kevin McLean
Sun24
_______________________________________________
Stoves mailing list

to Send a Message to the list, use the email address
stoves at lists.bioenergylists.org<mailto:stoves at lists.bioenergylists.org>

to UNSUBSCRIBE or Change your List Settings use the web page
http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org<https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.bioenergylists.org%2Fmailman%2Flistinfo%2Fstoves_lists.bioenergylists.org&data=05%7C01%7C%7Cd03ae001820d4003d6a708da547d689c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637915194870711716%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=eQJilz7fSYNnGvzVqpz02NyU5HAKGBXaDV4ROZ5hBMY%3D&reserved=0>

for more Biomass Cooking Stoves,  News and Information see our web site:
http://stoves.bioenergylists.org/<https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fstoves.bioenergylists.org%2F&data=05%7C01%7C%7Cd03ae001820d4003d6a708da547d689c%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637915194870711716%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=1Ktr1lj%2FJjFb49n9Nwa346PlI2QUDZUhcHnMOYpmERQ%3D&reserved=0>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20220622/b941847e/attachment.html>