Questions for Biochar Makers

[MTUbiochar]

Hi there,

 

I'm a 5th year student at Michigan Technological University. For one of my humanities classes, we're exploring biochar. We actually tried making some yesterday in a barrel. I would call it a partial success....meaning, we got black stuff. We've got a few questions on the process though. Any advice from experienced biochar makers would be much appreciated.

 

Our setup is the simplest one we could find. We have a barrel sitting off the ground on bricks. We cut holes in the bottom for air. It has a lid with a clamp seal. We started the fire in the barrel with newspaper and twigs. The barrel was about half full with branches. Once the fire was going, we waited about 15 minutes (until the fire was going strong) and then closed the lid tight, and piled dirt around the bottom to stop air from getting into the bottom holes. It stayed hot for about another 45 minutes. We were worried we cut it off too soon. When we looked at the contents, we had smaller sticks (1-2 cm thick) that were solid black, and some larger wood that was still...wood.

 

So with that long intro, here are my questions:

 

1. Is this method legitimate? I know most setups I've seen are more advanced than this.

 

2. How big should the fire get or how long should it burn before sealing the barrel?

 

3. For proper pyrolysis, should air be completely sealed out, or just mostly? Our bottom seal is just dirt, which probably lets a small amount of air into the barrel. Is that good oxygen control, or just a poor oxygen seal?

 

 

Thanks in advance to anyone who takes the time to help us out.

[freeztar]

1. Is this method legitimate? I know most setups I've seen are more advanced than this.

 

2. How big should the fire get or how long should it burn before sealing the barrel?

 

3. For proper pyrolysis, should air be completely sealed out, or just mostly? Our bottom seal is just dirt, which probably lets a small amount of air into the barrel. Is that good oxygen control, or just a poor oxygen seal?

 

 

Thanks in advance to anyone who takes the time to help us out.

 

The black is the char, so your setup seems to be working, at least partially.

I'd recommend trying what a member here does (I think it was phillip, but I can't remember for sure). It's the same setup except without holes on the bottom and an unsealed lid. He starts a big fire and then throws unburnt material on top of the fire, just like your group did, but he places the lid on top with a slight gap (about 1/2 to 1 inch). This should put out the flames as the fire will not get enough oxygen. According to his description (I haven't tried it myself yet), it will smoke for several hours, changing color along the way. Once there is no more smoke, remove the lid (after it cools!) and there is your char.

 

I believe that your setup is not working that well because you cut off the oxygen completely and did not have enough heat to continue the pyrolysis. Are you using a thermometer?

 

Commercial setups, or even advanced homemade ones, use sealed containers with no oxygen to do the pyrolysis. What they have that you do not have in your setup is a continuous heat source (usually a jet torch). Also, it's important to note that as the material chars, it releases gases. If you were to do this yourself, you would need to have some way to vent these gases without allowing oxygen in. I'll leave it as an experiment for the reader to figure out how to accomplish this, but the info is on this site. :shrug:

 

The really neat systems imo are those that feed the gases back to the burner (they're flammable!).

[Douglas]

G'day,

Next time use two drums, a 55 gal drum, remove both ends cut 4, 2 x 2 inch air inlets to light fire later, the top needs a cover and a chimney (I cut up a second 55 made a fitted top with 2 inch lip and chimney, cut remainder lengthwise roll compressed and tied and inserted now having a lined fire box) and inside a inverted smaller dimention container/bucket about 2 inches shorter than the 55 (robust construction)(I use a discarded electric hot water cylinder one end removed) tightly packed with material to charcoal stand inverted on the disgarded bottom of the first 55 no airspace required. This internal container/s should take up 1/2 to 2/3 of the 55 gal drum, now place 55 cylinder over the inverted container after putting some paper and deal on the bottom fully pack the drum with good hot burning wood, NOW place a crushed alluminum drink on top of the container, put on top with chimney (for safety you can place a disgarded paint tin over chimney as a spark arrester) and light the fire. I light mine at 7 am, the NEXT day 6 am dismantle, remove top check for aluminum can if melted temp was greater than 660 oC and the charcoal will have a high surface area, remove 55, clean away ash now harvest clean charcoal.

I make one a day (slow) but over a year I have sufficient to put below the soil surface as I consider this charcoal as ONLY microbial accomidation.

I demonstrate this to farmers, gardeners, landcare groups anybody interested, I call it "The Sunday Roast" system.

Trust it may be of interest,

Regards,

Douglas.

 

 

 

 

Hi there,

 

I'm a 5th year student at Michigan Technological University. For one of my humanities classes, we're exploring biochar. We actually tried making some yesterday in a barrel. I would call it a partial success....meaning, we got black stuff. We've got a few questions on the process though. Any advice from experienced biochar makers would be much appreciated.

 

Our setup is the simplest one we could find. We have a barrel sitting off the ground on bricks. We cut holes in the bottom for air. It has a lid with a clamp seal. We started the fire in the barrel with newspaper and twigs. The barrel was about half full with branches. Once the fire was going, we waited about 15 minutes (until the fire was going strong) and then closed the lid tight, and piled dirt around the bottom to stop air from getting into the bottom holes. It stayed hot for about another 45 minutes. We were worried we cut it off too soon. When we looked at the contents, we had smaller sticks (1-2 cm thick) that were solid black, and some larger wood that was still...wood.

 

So with that long intro, here are my questions:

 

1. Is this method legitimate? I know most setups I've seen are more advanced than this.

 

2. How big should the fire get or how long should it burn before sealing the barrel?

 

3. For proper pyrolysis, should air be completely sealed out, or just mostly? Our bottom seal is just dirt, which probably lets a small amount of air into the barrel. Is that good oxygen control, or just a poor oxygen seal?

 

 

Thanks in advance to anyone who takes the time to help us out.