Indoor biochar kiln and heat source

I hope I've missed it, but is there a design for a char kiln that can be used indoors to also heat a greenhouse?

I'm imagining a device that that has a canister that you load with wood/scraps/bones/char-to-be that sits in a larger heater.  Then start a fire in the larger heater.  That fire heats the chamber and the driven off gasses burn and further heat the system.  All that heat is used to warm mass within a greenhouse.  The next morning you remove the canister and harvest 20 gallons of char.

You loose a lot of the efficiency if you want char.
Basically you will be burning ( mostly) only the gasses and the majority of the fuel you will take it out as char in wich case you will be burning more wood ,probably double the ammount or more ( im optimistic but i think its 3-4 times).
If you want to make biochar its not a bad idea and any gasification type of stove should do the trick.
Its also more dangerous to have such type of stove ( used for charcoal making,a normal gasification stove is safe if you dont strangle the air intake to make charcoal)because the combustion happens with verry low oxigen and you get a lot of CO instead of CO2.Needs to be sealed verry well.

This is the nicest wood stove i know that does what you wish.

I do realize that I will be leaving some of the energy from the feedstock inside the biochar.  But I figure it's better to make biochar and use the heat for heating instead of making biochar outside and wasting the heat.  I just keep seeing more reasons to make and use biochar so that's why I'm investigating the idea of stacking those functions.

That video shows a pretty stove but it doesn't really look like it produces much char....

Here's one version that I ran across:


This is nearly exactly what I'd be looking for only with more char capacity, some thermal mass and no casters

The drum makes me wonder if it could be combined with a RMH so that the riser of a rocket stove is next to the char stock container.  Then the gasses could be routed back to the burn chamber to further run the rocket.  And the heat would be stored in a bench.  But it probably wouldn't work.

Mihai Ilie wrote:You loose a lot of the efficiency if you want char.
Basically you will be burning ( mostly) only the gasses and the majority of the fuel you will take it out as char in wich case you will be burning more wood ,probably double the ammount or more ( im optimistic but i think its 3-4 times).
If you want to make biochar its not a bad idea and any gasification type of stove should do the trick.
Its also more dangerous to have such type of stove ( used for charcoal making,a normal gasification stove is safe if you dont strangle the air intake to make charcoal)because the combustion happens with verry low oxigen and you get a lot of CO instead of CO2.Needs to be sealed verry well.

The good news is that it turns out that you are not being optimistic Mihai.  When you make biochar you actually burn half the carbon and all the hydrogen.  If you look up the energy released for the wood versus the energy held up in the resulting biochar you'll find that you still get 2/3rds of the heat when you make biochar, and that's if you're perfectly efficient at making biochar.  If you are less efficient you'll burn up some of the biochar and get a higher percentage of heat.  While that 1/3rd loss is significant I think many of us will find that to be a bargain for the gain you get in generating all that fantastic biochar.

I make a lot of biochar.This year i made 3 cubic meters of char at home and ive burned probably 6.
This is how i make it,a simple fire ,then i collect the coals and i estinguish them with water.
It is the most efficient way to make char because you dont have to burn wood to heat the wood for charring.
But its time consuming,has its own disadvantages,the char its soaked in ash( witch i like),etc.
Im a biochar fan but i dont mix it in my heating sistem .With the ammount of wood i burned this year to make biochar i could have heated my greenhouse for 3 years or more.
It can be done successfull ,i know that.

Very nice Mihai!  I also make mine outside, but in a cubic meter volume pit.  I start with a small fire and then sequentially add wood so as to maintain a cap of fire over the biochar that forms.  It takes me about 4 hours to make a cubic meter, but I have no observable ash at all.  I'm sure there's some, but it's minimal as I end up with half the volume of biochar as the volume of starting wood, which is what I observe when I used a stainless steel kiln that separates the biochar chamber from the burn zone.  The pit shape really helps to minimize oxygen infiltration.  But again, you have made a beautiful pile of biochar....congratulations and thank you!!!  Also, you're gardens look wonderful!

Thank you Greg.The bigger pile on the right has exactly one cubic meter of charcoal( 100 buckets of 10 litters each,thats how i measure it).
In order to heat my greenhoouse in winter  i use one cubic meter of wood for the whole winter.

Mike,after i watccched the video you posted ,i say thats not a safe stove to have.I found 2 big flaws :
1 ,its not sealed well and could leak carbon monoxide .for instance after the fire is finished ,CO could leak through that hole in the box of char through the feeding chamber .

2 ,and biggest flaw its that the box of char could explode easily .The explosion wouldnt be big but enough to spew char bits all over the room.
It has the hole on the bottom and hot gasses rise on the top of the box with charcoal.If the box heated really well to the combustion point of those gasses ,is will explode.
The stove i posted does exactly the same thing as the one you posted but the hole of the char box is on top not on the bottom.

Thanks Mihai!  I thought that was a bit rough for what I'd be after.  But the concept was near to the one in my brain.  This would be for my greenhouse so the safety requirements are a bit lower than if it was in my house.  But I still don't want it to explode or kill me

If I have to heat with wood and make char some other way, that's fine.  I was just hoping to combine things a bit.

People obsess over process efficiency when it's actually system efficiency that matters. Thinking in terms of the whole system is one of the cornerstones of permaculture.

I like pyrolising solid fuel appliances. I would definitely heat my home with a pyrolising wood or pellet or biomass burner that yielded biochar for my compost, as long as I could fill it before bed and have it still be warm when I wake in the morning.

Basically, if the feedstock is carbon-neutral and I have closed the loop on my own property, I don't worry about how efficiently the appliance is heating my home. I would care about how efficiently it's producing biochar and heating my home, and about how much better the biochar makes my soil and increases productivity.

To put the efficiency argument on its head, 100% of that heat from an outdoor open pile burn, or even a pit burn as you describe, Greg, isn't benefitting anyone. It's literally just giving off its heat to the atmosphere. Theoretically, the most efficient way to make biochar would be to only do so when heat is needed for your home or as a by-product of another process.

One could also heat a retort with many sun-tracking mirrors, like they do for some solar thermal tower projects. I suppose geothermal energy could also be used if it is convenient, but work on the those scales usually requires corporate or national funding of some sort.

Losing sight of the forest for the trees is part of the overarching problems that have put humanity where we are at present. It is beneficial, I think, to pay attention to the health of the trees, to extend the metaphor, but only as it pertains to the health of the whole forest.

-CK

This movie is about a system a guy invented to create a biochar method like this thread: You use the heat to make a greenhouse, create the biochar, it uses solar and creates a profit.  The guy is a genius.  I would say that it's the best film I've seen on sustainability. I have no connection to them. I just like their system.

https://grow.foodrevolution.org/?orid=174172&opid=314

John S
PDX OR

Yes, that's quite a system!  A bit big for what I'm after.  I'm sure there's an industrial way to do what I'm after but I'm kind of looking for a hobby farmer sized arrangement...

Mihai Ilie wrote:This is the nicest wood stove i know that does what you wish.

Hi Mihai!

Have you been in contact with the sellers of that wood stove?  I sent them a question via their web site several months ago and got no answer.  It would be great to know if it's actually available.

Many thanks!

Morfydd St. Clair wrote:

Mihai Ilie wrote:This is the nicest wood stove i know that does what you wish.

Hi Mihai!

Have you been in contact with the sellers of that wood stove?  I sent them a question via their web site several months ago and got no answer.  It would be great to know if it's actually available.

Many thanks!

No,im not in contact with that stove manufacturer.I just seen it on youtube and i liked the design wich is perfect for making charcoal as people here desire.

Another thing i have to add is that a gasification stove its verry efficient basically like a rocket stove,has no smoke ,etc.
So if you mix a rocket stove with a gasification stove you didnt achieved nothing to gain more efficiency.

I use retorts inside my masonry heater. So easy to do. Unfortunately the steel cans burn out fairly quickly and definitely no 20 gallons at a time. But I am able to capture the heat so I accomplish everything that I am attempting all at once. I am looking to go bigger as my fish farm needs several cubic meters of the stuff. My cousin built an outdoor burner to heat household air (basically an outdoor forced air furnace) and I am hoping to retrofit it to make biochar and hopefully condensate. Reason for having an outdoor heater was size and insurance reasons. So if your worried about CO that would probably be the way to go.