Dennis, Eric, Dale, Jim and Joe, (and other friends who know RoCC kilns)
I will be seeing all five of you either in Ohio or in North Carolina next week about biochar production with the RoCC kiln technology.
In preparation, I refer you to this major document. In particular, see section 4. Eligible technology (for low income countries, but still very relevant.)
https://www.carbon-standards.com/docs/transfer/36_400EN.pdf
From Page 12 is this quote, and then some calculations for food for thought.
“One run of a 2 m3 conical flame curtain kiln with an upper diameter of 2.4 m produces 500 kg of biochar (dry matter basis) and close to 2 MWh of heat from shrubs, husks, straw, prunings and other organic farm waste in about three hours
needing one worker to maintain and control the process.”
Comments:
A. weight and volume of biochar:
Therefore, 1 m3 is 250 kg of dry biochar. 1 m3 = 1.3 yd3 = 264 gallons which is 4.8 of 55-gallon barrels.
In Kenya with biochar from corn stalks, 25 kg fits into 1 of 55-gallon barrel, so that is 25 x 4.8 = 120 kg biochar in 1 m3. Which is roughly half of the weight of char from wood.
B. Labor and time:
2 m3 weighting 500 kg comes from about 2500 kg (20% char yield by dry weight). And accomplished within three hours. Allow some extra time at start up and when finishing the final pyrolysis, and that means about 2500 kg in 2.5 hours of
main work, which is 1000 kg (one tonne) per hour for one person, which could be done at 6 minute intervals, meaning 10 times per hour, or 100 kg (220 pounds) every 6 minutes, with moderate effort to distribute the biomass across the top to the bed of char
that started small but reaches 2.4 m diameter (almost 8 ft.) In the first hour that would be less mass, and in the final hour (of 3) that would be maybe double the weight. Close to a hot open-top flame-cap kiln. Do-able, but a noteworthy effort. And
repeat in the afternoon for an 8-hr day producing 1 tonne of biochar manually in one kiln.
To do 2 m3 in one RoCC kilns needs a cylinder that is 4 m3 (top half is for the flames and does not get filled with char in standard practice.) If the cylinder diameter is 1.3 m (about 43 inches) the surface area is 1 square meter.
So 4 m length (~13 ft) gives 4 m3 empty volume. Diameter can be bigger and length shorter.
3. On page 13, the document mentions “giant 15 m3 kilns….” That is 7.5 time larger volume of the Kon-Tiki-type kilns. I have doubts about that size being viable.
We can discuss this via email and for some of us in person next week.
Paul
Doc / Dr TLUD / Paul S. Anderson, PhD
Email:
psanders@ilstu.edu Skype: paultlud Mobile & WhatsApp: 309-531-4434
Website:
https://woodgas.com see Resources page for 2023 “Roadmap for Climate Intervention with Biochar” and 2020 white paper, 2) RoCC kilns, and 3) TLUD stove technology.