Science Forums 2

[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.