UBI 350 BLACK is the new GREEN Spring Green
Alex and Rebecca bring UBI 350 to North America and the United States with a learning effort at a 10 gallon biochar oven made from a garbage pale. Holes were drilled in the bottom and the oven was fired on a grill above an open fire. As we can see from the picture, the wind was blowing the flames away from the oven. At this point the oven is likely flaring hot gases from the heated biomass into the fire, producing an abundance of clean flame. Unfortunately, because of the wind, this and most of the heat from the wood fire as well as the gasses leaking from around the lid are not contributing to the conversion of biomass to biochar. While this is carbon neutral (the CO2 from the burning was recently removed from the atmosphere by the plants creating the biomass), it is inefficient in that the extra wood needed in the fire could be converted to biochar. Also, the leakage from around the lid at the top together with the holes at the bottom created an updraft in the oven that brought enough oxygen into the oven to cause some of the hot biochar to ignite and smolder as the oven was left to cool overnight.
Alex wishes us to take away the following lessons from this effort:
1. Ovens with loose lids should be made with the venting holes in the lids so that the ovens are fired with the lids at the bottom over the fire so that the leaking gases ignite and contribute heat to the conversion process. Also, this would create an air pocket within the oven that would lessen the chances of bringing oxygen into the oven.
2. A firebox with a cowling or heat retention housing around the oven are desirable for efficiency.
3. If this is impractical, use lengths of wood leaning against the oven, especially on the windward side to also create a tipi fire with flames rapping around the oven.
4. Monitor the flaring process and extinguish the fire when all flaring ceases so as not to over heat the biochar.
5. Immediately cool and seal the oven (wet rags over the lid) or open and extinguish any smoldering biochar.