Open Source; Low Cost In Field Biochar Ovens and Kilns

1. Open Source; Low Cost In Field Biochar Ovens and Kilns • These infield biochar ovens and kilns have been developed as a simple and low cost method of eliminating the large amount of pollution and greenhouse gas produced when crop residues and greenwaste from land clearing is burnt in the field. • A novel method of firing the ovens has been developed that ensures that maximum biochar yields and maximum nutrient availability. This method is based on traditional Nepali and African farmer practice.

2. Traditional Practice in Nepal • Soil in an area greater than 5 sq meters is dug up. Straw and grass is laid on top of the soil and smoldering dried cow/buffalo dung cakes mixed with straw are laid on top of these residues. More twigs and leaves are placed on top of the dung and then this is covered by soil, mounding up systematically from the outside. • The dung slowly smolders for 3 days at which time the soil has changed to a lighter reddish colour and the biomass to biochar. The charred material is worked into the ground and left for three weeks before the millet crop is planted. After this time the soil has a very slight smell of pyroligneous acids. Our informant said the millet may not germinate and the seeds may not set if the charred biomass is not incorporated into the soil. If germination is a little slow, a small amount of urea is added. After the millet is harvested either wheat or potatoes are grown.

3. Nepal Women make biochar Using a Simple Earth Kiln Laying biomass on soil; Smoldering dung in pot next to biomass Preparing Ground Laying smoldering dung on biomass Putting leaf litter on smoldering dung Loosely covering the smoldering dung and biomass and allow to smolder for 3 days. Temperature is low and a lot of smoke chemicals produced Biochar Organo-Mineral Complex incorporated into soil allow to stand in the ground for 15 days before planting

4. 50 socket screws into drum’s 2 inch BSP opening 50mm Insulatation 240mm 300mm 25mm square hollow section legs Flare shroud 240mm Small fan or Bellows 170mm Optional; Small LPG burner to burn smoke and ignite syngas 85mm thermocouple 50mm diameter air pipe for starting the pyrolysis process. 2 rows *14 6mm diameter holes spaced every 10mm air for tar cracking 750mm 50mm diameter air for starting the pyrolysis process. Mixed biomass, minerals and clay. Layer can extend into the ground 570mm 900mm 25 or 40 mm angle

6. Outline InstructionsEach biomass and soil is different so you will need to experiment. Here is a general procedure for firing the kiln • Mixed very dry biomass (a grass or straw is best), Minerals (e.g. dolomite, rock phosphate/basalt dust and clayey soil is put in a box as per the traditional practice shown. Put dry manure on top • Dry manure is ignited as per the last slide • More biomass is added and covered with a thin layer of soil • Kiln is placed over the box. If you have a thermocouple place in the bed of biomass • Air is allowed to enter to get a flame burning. It is recommended to use a gas burner ensures no smoke if there is access to LPG. If LPG is not available make a torch from a stick with a piece of cloth that is ignited can help stop the emission of smoke • Fan is turned on so air mixes with volatiles. If Fan and power is not available a hand bellows will do. • The bottom air holes at the front of the kiln can be fully or partly closed once the flame is self sustaining • When there is no flame air air at the top of the oven is shut off and kiln allowed to cool

7. LARGE INFIELD PYROLYSER CONCEPT • Reduce emissions when crop residues & greenwaste are field burned. • Covers 7m3, ~2 tons biomass • Carried and placed by tractor • External gasifier provides hot air for drying / torrefaction to ~ 200oC, <15% moisture • Small genset powers fan, sends flue gas into kiln • Top of biomass is ignited through lower airholes, later closed 700mm LPG burner to crack smoke, ignite syngas Flare shroud 150mm Secondary air pipes Rigidized refractory wool Heat shield with gas holes Water sprays 150mm holes for start-up air. Burner inserted to ignite top 1.8 m 40mm square tube Frame with sheet steel • Volatiles mix with air and burn at the top of kiln, radiating heat to drive pyrolysis, which progresses downwards Biomass with clay Baffle with hot air or exhaust from diesel engine flowing up the side 2.7 m

8. LARGE SHEET-METAL INFIELD PYROLYSER CONSTRUCTION DETAILS – PROTOTYPE Airpipes above shield Ledge to support shield Airpipes below shield • 2mm mild steel sheet bolted to 40mm square tube frame with expansion holes • Two 600x600mm flues, flare shrouds not shown • Secondary airpipes of 150mm SS exhaust pipe with graduated air holes for equal pressure • 2mm mild steel sacrificial shield with 0.6m2 of gas slots supported on ledges at tops of walls • Hot air pipes of 150mm heavy gauge steel with graduated air holes welded to 3mm baffle plate • Weighs 765kg + exterior pipes, fan, generator, controls • Cost: $20,000 2.7m 2.4m 3.0m Sacrificial shield Hot air/exhaust flow Hot air pipes & baffles

9. The BIG ROO INFIELD PYROLYSER

11. Demonstration of TLUD Oven at Binh Thanh Commune Place straw, then rice husks, then bamboo/wood in layers about 20cm high Prepare the feedstock Put a thin layer of slurry of clay and lime on the straw. Cut wood and Bamboo to fit across the drum Make sure steel skirt around bottom of drum is open to allow air to come in. Light fire.

12. Demonstration of TLUD Oven at Binh Thanh Commune Cutting air off Putting lid on Reducing Air Dry Biomass In = 23kg Dry Biochar Out= 8.6kg Yield = 37% High yield due to high ash content of the rice husk and aged bamboo and wood Reducing Temperature to about 450-550C with spray water Testing Quality of Char

13. My Design at Home With Hot Water