Best season of year to make biochar

I live in the coastal PNW, so it's pretty wet from November through about April.  It makes it hard to sustain a fire, and more importantly, the fire won't very efficiently create biochar from wood or other organic materials. I cut the wood from my food forest year round, but I only burn the stuff that has been seasoned and dried.   I have actually burned the wood to make the biochar exclusively in the drier months of summer through early fall, until now.  Last year, I tried to burn the wood in April, but I couldn't sustain the fire and it was spitting and smoking.  I waited until the summer and it worked.  This year, it was very dry for a patch in April, and we were bored from covid 19, so I decided to give it a try.  There are a couple of things that I did differently.  

Last year, I stored the wood for many months in the 55 gallon metal barrel. When the fire didn't burn very well, I quit, but I had to think about it. It's possible that the wood stored condensation from sitting in the barrel all that time.   This year, I stored it outside of the barrel even though it wasn't so tidy looking.  I also packed it more sparsely into the barrel. I knew I'd get less biochar, but good airflow and a good burn is worth it.  I was also very careful to have all my materials laid out carefully to start the TLUD. In addition, I started the fire in the afternoon instead of the morning, to avoid the morning dew.

I filled up the barrel first from the bottom with longer branches, then shorter ones. Outside of the barrel on the side,  I created a pile of cardboard scraps, a pile of small, skinny sticks, a pile of bigger sticks and made a scrunched up ball of newspaper.  I put the newspaper just below the top where I was starting the burn..  Then I lit it, put the scraps of cardboard over it, then the little sticks in a teepee, then bigger sticks on the teepee when it was really burning.  It worked perfectly.  I am guessing that all of the factors fit into the change in being able to burn the biochar efficiently in the spring.  Burning in the summer isn't the most comfortable. It just gets too hot.   I used to burn wood in the winter in an open fire, but I wasn't trying to create biochar in a TLUD, so it was easier.

I imagine that for many of you back East, the summer is rainy and humid and it's not the best time to burn.  Do the rest of you burn your biochar during a particular part of the year?
Thanks,
John S
PDX OR

I wonder if you could modify your barrel to act as a dehydrator to get that wood nice and dry? I'm thinking an alternative top with a length of pipe sticking as a solar chimney, and a wee intake vent, fed by more pipe, something you can seal during the burn..

Leave it in the sun and while it would still need some niceish days to do any drying it might be an improvement?


I make my char in late spring or early fall, burning in summer is A: banned, and B: risky. I am using open piles of moderately uniform materials, lit from the top, goosed with a cordless blower, then extinguished with absurd amounts of water when the time seems right.

Interesting perspective.  I am not doing an open burn, which would be banned. I live in the suburbs, and I burn in the driveway, with a barrel and a lid with a tall chimney.  We have to move our cars before we burn.  I am thinking about the possibilities of drying.  Good ideas.

John S
PDX OR

I used TLUD in the past but moved away from it for the reasons you describe. I much prefer the trench/cone kiln approach now and can burn even fairly green wood on it. Once the embers are established it can basically burn anything.

You might find that improving the draft on the tlud system helps - a second barrel mounted above as a chimney would do the trick.

Here is the link to my alternate drum design:

https://permies.com/t/137570/style-biochar-burner-typical-oil

John Suavecito wrote:Interesting perspective.  I am not doing an open burn, which would be banned. I live in the suburbs, and I burn in the driveway, with a barrel and a lid with a tall chimney.  We have to move our cars before we burn.  I am thinking about the possibilities of drying.  Good ideas.

John S
PDX OR

Yes, I understand TLUD is a very different animal; didn't mean to imply your method would be banned, just that mine is!

The impact of the blower on my very simply setup is amazing. It will produce an absurdly hot fire, super fast, while blasting the heat into the bulk of the pile to get a more uniform burn. I am not sure if TLUD would be amenable to this treatment.. but if it played nice it might be pretty nice.

I burn indoors during the winter, with small canisters that fit in the woodstove. Outdoors during the summer and fall I use a retort that sits on a rocket stove.

I don't do open burns. My area is windy enough I wouldn't feel safe.

I think it may be less a question of "which season is best", and more a question of "which method works best under which circumstances?"

Excellent point.  I like how we can broaden out the possibilities to make it work for more people.
John S
PDX OR