SPG - Biochar Workshop

24 October - only 1 person came. Rather sad as this is such an important and much needed skill for everyone with access to land to regularly do. Anyhow, we did a tour of the garden instead as she hadn't been to have a look before.

I did give a brief description of how to make Biochar. Here is a brief description of how I make biochar regularly:

  1. Set up a 44 gallon steel drum somewhere safe - it needs holes around the bottom. Bottom can be cut out or left in.

  2. Fill a 20l metal bucket (with lid) with waste wood - sawdust self insulates a lot and so takes a very hot, longer burn to work. Pack in as much as possible. Put on lid. The lid needs holes drilled in it to let gasses from the heated wood to escape. My holes are about 9mm and there are 15-20.

  3. Put the bucket upside down in the centre of the barrel.

  4. Stack wood around the bucket. Allow gaps between the wood for airflow. Only go as high as the bucket and near the top put smaller wood and then twigs. Add some egg cartons around with a little newspaper.

  5. Light the newspaper - this is a TLUD technique - i.e. the fire burns from top to bottom with very little smoke.

  6. Once the twigs and sticks are burning, other tasks nearby can be done.

  7. The concept is that the burning wood around the bucket will heat the wood inside to make it offgas. These gases come out and burn around the bucket. Because the gases are pushing out, no oxygen is inside and the wood pyrolysises.

  8. Extinguish the wood around the bucket with water when there are no/minimal flames. Be aware of the steam generated!

  9. Take the bucket out, take lid off and fill with water. Once char is cool, empty water on some plants.

  10. Char needs to be broken up as small as possible. We put it through a mulcher a couple of times. If there is a lot of dust add a little moisture. Too wet and it may clog it up.

  11. Char has to be activated to become biochar - i.e. add biology to it - this can be done with worm tea, compost tea extract, EM, etc. Also, good to add a nitrogen source to it so the carbon drawdown when put into soil is minimised. We add urine, but one could use blood and bone too.

  12. Use biochar to amend soil. We put it into our potting mix for plants and trees. Also when planting out plants, a small handful is added to the bottom of the hole. Biochar provides loads of habitat for soil biology and holds almost as much water as its volume. Adding biochar to soil is actively sequestering carbon.

Another similar method:

Use same barrel, with or without bucket in the middle. Half fill with wood trash and light from top down. When it is burning well, continue slowly to add more wood trash. The idea is that one builds up more and more 'coals' so that the whole barrel is full with these coals. If it smokes alot then either you are adding new material too quickly or there is not enough air. As before, when there is minimal flame at the top, extinguish with water. Tip it over and keep watering until there is no smoke, spreading the char out helps. If it is not cooled completely, it can easily re-ignite. This method is good for reducing more fuel load than the method above, but it takes more time and one has to be there to keep adding wood.

And another similar method, but using a chimney, explained on youtube by an expert: