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2014-01-31

The birth of a biochar stove


Finally after long time setting things up, I was able to invest some time to make a biochar stove here in PaiThailand with zero material cost of course, reusing and recycling as usual... This is another small Elsa stove prototype: it works nicely producing perfect biochar in about 20 minutes process with this size, probably enough to get your carbon-negative coffee going. 


Instructions and details follow in this post, in the perspective of more extensive demonstrations and workshops here in Thailand.


Step 1) get your tools ready
These are the basic tools needed: a pair of thin beak pliers, a hammer and a sharp nail (or a drill and drill bit in case) and a good pair of scissors to cut metal. That's it...
Step 2) get some steel cans and get them ready
These are two suitable cans to use... the rigged sizes ensure extra strength so look for those ziggy-zaggy patterns on steel cans which last way longer than aluminum. The first trick is to get rid of the rims around the mouth of the open side.


Just grind those rings off from the top side and get them out of the can: this way it's going to be much easier to proceed cutting. By the way, these rings end up usually nice and neat... ready for some other interesting "reusing" project.  
Step 3) punch holes in the bottom
Punch a lot of holes on the bottom of the can: try to be as even as possibly, getting a nice and even distribution along all the surface. You can drill or hammer them... but make sure to use some sort of wooden "anvil" on the back, supporting the hits or the pressure of the drill bit otherwise the bottom it may get warped and damaged.


Step 4) cut the slits along the mouth piece
First draw a guide line (the black line in the next picture) along the side of the mouth, then start cutting slits at about 45 degrees on that line, trying to be as regular as possible: the black line is going to guide you, not to be too deep or not enough...


At the end of the two previous steps, shape all the slits nice and even with the pliers and your can's mouth should look like this...


Step 5) get you calculations done 
Here on my sheet, also my son got some of his "projects" going... After getting the freely downloadable pdf of an Elsa model, you should adjust the dimensions in proportion with the sizes of the cans you're using... unless you're replicating an exact copy of an Elsa, you will always have to do this! You can download a blue print of the Elsa stove at this links.

Step 6) cut the cone 
Get a piece of metal sheet of the required size for you can and cut out the shape to make the cone: this is the most tricky cut so be safe when you do it, making sure to use gloves or to be extra careful...

A stone with the right shape may be very useful to grind out the sharp edges after cutting the metal sheet, so the bending and assembly of the cone will result much easier and safer. At the end it should look like something like this...
 Step 7) fire!
Yeah so now you're ready to put the cone on top of the can and start your stove... the flame will be tall and bright naturally spiraling like this. 
 

When you do this for cooking or heating purposes rather than just biochar production you'll need to consider wisely the correct positioning of the pot or the heating element, which it's going to be reasonably high from the top of the stove.
Considerations on these relevant details as well as safety procedures and handling will be provided during the upcoming workshops and demonstrations. Here's the first batch of biochar produced and deposited here in Pai... it all counts as a carbon-negative action... now let the re^Evolution start!


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