Biochar Burn Demonstration
It’s Gonna be Hot, Hot, Hot!
Ever wonder how to make your own biochar? Wanna learn?
In the beginning years of Hawaii Biochar Products there were no fancy machines, only wood and sweat, lots of sweat. With a large supply of clean dry wood from local sawmills to play with, I developed a technique that proved to be a very efficient way to transform wood into biochar. Many different approaches were attempted, those will be discussed as well, but the focus of the day will be the live demonstration of the winning technique – Open Pit or “Imu Style” Biochar Burn.
Mark your calendars for Wednesday, June 12. This biochar burn demonstration is sponsored by Kalani, Hawaii’s largest retreat center, based in Opihikao on the beautiful Puna Coastline. All that is needed for entry is a $12 dollar fee, which also gets you a meal ticket to their local-centric lunch buffet. Start time is at 10:00am, the fire will be done by 3pm, conversations will carry on for hours. Lodging is available. Call 808 965-7828 for more details.
Hawaii Biochar Products has far more advanced production facilities now (a story soon to be told), but this technique is still used for home production on my own farm and has been taught to many others for production on their farms. It is estimated that in the last 5 years more than 150 tons of biochar were produced and sold from my own backyard using this approach!
The concept is rather simple, but the details are important. I will cover the basic concept below, but if you are interested and available I highly suggest you make it to the demonstration for the first hand experience.
It all began on flat ground. It grew into a pit to gain greater air control. Wood burns twice, once from wood to char, then from char to ash. The second part can only happen with oxygen. On flat ground the char produced during burning is hard to protect from oxygen entering from the sides. In a pit, the char is covered as it is produced.
First, a fire is started in the bottom of a pit, then dry wood is then added as fast as the fire will allow – you must always push the fire near to the point of smothering it, yet without actually smothering it. It is important to always keep a clean burning fire – no smoke. If it becomes a bit smoky, back off, let the fire catch up. If it is raging, add more wood to choke it out a bit. In this way you are constantly covering the char that has been made with fresh layers of wood, which become char, which are soon covered with fresh layers of wood, which become char, and so on. When you near the top of the pit or the end of your wood supply, you finish with small diameter wood. This chars quickly. Let the flames die down a bit, then voila – a large bed of red hot glowing coals. By this point, if you have done it right, the entire pit has turned to char. You can either hos e it down immediately, or cover it with soil to snuff it out, then uncover it a few days later and hose it down. Look to the pictures below for a visual reference.
Harvesting and grinding the char is a job all unto itself. You must be very careful to make sure that all the embers have been extinguished or the entire pile can re-ignite. Always follow local fire safety regulations.
To cook in the pit, dig a hole in the embers, line the bottom with crushed banana stumps, place food wrapped in leaves, cover with embers, smother with soil, uncover later and enjoy.
Have Fun, Be Safe,
– Josiah Hunt
All Photos By Josiah Hunt