Monday, February 27 was another picture perfect spring day. Balmy, warm temperatures made shirt sleeves necessary to avoid sweating whiles breaking up brush.
Brad cut up a large number of sunflower stalks. These weedy, fibrous stalks were perhaps half the feedstock. We wanted to test "weedy, not woody" feedstocks for burnability, energy density and biochar character.
After Brad loaded the barrel, I gathered thicker pieces of woodÑup to 4-inch diameterÑand tucked these in under the lid. Our burn times and temperatures were high enough, I thought we should see if our TLUD can char larger chunks of hardwood.
Photo above is from burn #10. Nearly 3-inch thick limb completely charred through.
|VIDEO: Full Flame at Peak
1 min 56 sec; 4.3 Mbyte, .mov
The burn started very fast, and flames rapidly increased. Tremendous heat was rapidly released, most of it upward into the chimney. The sound of upward rushing gas was louder, more insistent than any previous burn. I wondered if our chimney could contain that many BTUs.
The intensity of flames was greatest we've witnessed yet. The flames danced with hyperactivity that suggested a slightly pressurized, high velocity release of pyrolysis gaes up the chimney. We think this increased energy is largely due to increased air intake under the biomass fire.
For all its intensity, the burn soon ran out of gasÑafter perhaps 30 minutesÑand ended quickly as the gas flare collapsed into the barrel. We believe the looser packed, less dense sunflower stalks contributed to this short burn time and added intensity.
twigs and stems
We again noticed a sudden shift in the fire's smell when wood fuel was exhausted and the burn shifted to burning charcoal at a higher temperature. A distinct, nose wrinkling stinky odor.
Brad now has a consistent routine to choke the fire by plugging air vents with fiberglass, then diassemble the chimney and spray short bursts of water into the red-hot barrel to quench the charcoal fire. I am impressed these two measures can give us good control of the fire.
Learn to burn carbon-negative
Learn to live in the 21st Century
Co-create a carbon accountable culture