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Best practical way of making biochar for soil improvement on commercial scale? Answered

I need help to build a cost effective biochar retort that will produce at least 500 kg biochar/day to use for soil improvement on my dairy farm. It must also be moveable to move to new sites. I've got access to a lot of forestry waste all over the district. Here is my initial idea: From 3mm sheet metal manufacture cylinders (drums of say 200 lt) one bigger than the other so that one fits into the other with a 100 mm play all round. Bigger cylinder has a lid with a chimney on top and close ended at the bottom with air inlet holes around the base and completely isolated with fire proof material.
Smaller cylinder (that goes inside) is open ended and stand on bigger cylinder baseplate with airtight lid that gets closed after filling with wood chips. It has 50mm outlet at the top that connects to a metal pipe (coming through the side of the outer cylinder) that leads woodgas to the bottom of the next retort and maybe have a drain to catch bio oil. The idea being that I can duplicate the retorts to increase production using woodgas from the previous to pyrolize the next. I then only have to burn wood in the first retort to get the process started. Please suggest improvements, or complete new more viable system. What can I use for isolation material? Can I collect other products off the woodgas instead of pyrolising the next batch?  What other byproducts might be valuable?


THE place to look is here:

There are teams there working on big and small biochar systems.

You don't need to waste your woodgas for pure pyrolysis of the next batch, you can run your engine on it !


Steve, thank you for your reference.  I've found a video by Peter Hirst and he's got exactly the type of retort I've got in mind.

You've been a great help.


I know some of the better connected people in that link I gave you - at least one of them might well be able to help you more directly. PM me if you need more help.

Half a tonne a day?
Do you have one of those slurry spreaders? I'm thinking that as a big steel thing on wheels it might be useful for a start.
You could feed the woodgas back-into the same retort rather than a second one, collecting & multiples sounds complicated.


Lemonie, thank you for your input. I am going to pursue Peter Hirst's retort. It looks like the answer to my querry.

Have a prosperous 2010