Design [2 Attachments] #technology #stoves

Edward Revill

Hi Daniel,

That looks very similar to one of my early prototype biochar rocket stoves. (Not wishing to sound too smug but I have to point out for the record that I was experimenting with catering on such stoves at festivals and events whilst running workshops back in 2009, the first video of such an event dates back to May 2010. James Hookway did not design this stove until some time after.)

I have also used a varation of tlud stoves indoors, connected to a flue outlet and capable of heating a 200 litre water cylinder to over 60°C in one 40 minute burn on willow wood chip. These stoves are certainly much easier to build. I put up a YouTube video a few years back entitled "pipe tlud" showing a forced air tlud variation which is easy to build and lighter, allowing greater volume, because it uses a central pipe instead of a double skinned wall. 

I suspect, looking at your photos, that your stove will burn on woodchip better than sawdust. To get it to burn on sawdust it might help to get more air into the retort chamber. Insulation surrounding the retort will also help. 

An easy way to seal the inlet is to buy a 6" (or greater) diameter barrel nipple and a 6"socket from an engineer supplier, cut the nipple in half and weld that on as the inlet hatch and cut the socket down and weld a disc on to make it a blank. Weld a strong handle onto the blanked off socket and use it as a screw on lid.

I build these stoves on legs with removable floors and make a correct size metal container which sits under the stove so the stove can remain in place under heat sources (oven/water heater) and the biochar can simply be dropped out into the container for removal. Sorry you probably made your stove from an old drawing.

I tend not to use mild steel, it does not last long. 304 grade stainless 1.5 to 2mm wall thickness is good for the elbow and much lighter than mild steel. (Be careful of legal + safety issues + fumes from paint and galv if using old gas bottles.)

Since about 2010 all of my domestic heat (cooking and hot water) has come from indoor biochar stove systems. (With exception of occasional use of an electric kettle). For most of my life I have worked as a market gardener, growing crops in an alley cropping system with a lot of viminalis willow, giant miscanthus and other copice wood grown in rows between alleys of annual crops. The biochar is incorporated into the annual cropping area. This way my needs and my income are met in ways that build soil carbon. Working towards boycotting extractive economic processes is my driving motivation behind growing crops and playing with biochar stoves.

I bring into this system other soil carbon influencing practises. I personally do not see much use for biochar or biochar stoves outside of a closed system involiving some element of copice based agroforestry. This I term "full cycle biochar". 

Unfortunately I can no longer compete with the recent surge in "green" grant subsidies (a farmer a week commits suicide in Wales and loss of sovereignty is a key factor in this. I would rather see appropriate tech as a means by which producers can compete with environmentally or socially unaccountable/subsidised produce than see appropriate tech as a means by which people can tap into grant subsidies.)

Anyway as from this year my fields sit idle and I have started to take my income as a building labourer. I pray for some economic shift/accountability in which case it will be possible to go back to taking an income from growing using truly regenerative systems. I hope that our extraction based economy takes a steady downturn in order that common sense can surpass the recent rise in hypocriticall and dangerous "green grant" subsidised growers who are displacing experienced producers.

I admire your determination and persistence in playing with stove designs and your work towards bringing these stoves into full cycle production systems. 

Best of luck, Ed.

On Mon, 21 Oct 2019 at 4:34, daniel.pidgeon@... [biochar]
[Attachment(s) from daniel.pidgeon@... [biochar] included below]

Trent, Ed and Paul,

Sorry for the typos and grammar errors in that last past! I was getting carried away. Attached are some pictures of my build, a cross between Ed's hybrid rocket, and James Hookway's retort. These pictures are from the first trial burn. You can see the sawdust loaded and the unit before being closed up and insulated in one photo. And the other shows the first test burn. You can see where gas is leaking from one of my welds on the top, and catching alight. As I said, I learned to weld in order to make this, so it is far from perfect. I have since touched up some leaks. Still trying to figure the rope seal at the bottom end, for it simply rips off when I open it up to unload. Ed, do you have a slot for the rope seal on the bottom, like you have for the doors in the pictures? I have flat plate against flat, and the glue that came with it simply does not hold.