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Biochar Kilns

Lesson Plans
  1. A Simple Backyard Biochar Kiln Design (
      "This 30.5 inch wide by 11 inch deep kiln, made of sturdy 20 gauge steel, is by far the easiest, affordable, and fastest way to make biochar at home."

  2. Lessons and Projects on Biochar for K-12 Students and Teachers (International Biochar Initiative)
      Provides projects and lessons with a focus on biochar for sequestering carbon, biochar for improving soil, and biochar kilns

  3. Simple Backyard Biochar Kiln Designs and Scaling Up (
      "I am working with a group of innovators in Oregon called the Umpqua Biochar Education Team. They have come up with some super simple, very productive biochar kilns."

  1. -Industrial Level Biochar Kiln (
      Describes the biochar kiln, made in Europe. 02-15

  2. Biochar Maker (
      Peter Hirst shows how to make biochar in 30 pound batches with minimal complex carbons released into the air. 08-09

  3. Biochar Production (
      Discusses the steps needed in making consistently good biochar with minimal pollution. Also discusses strengths and weaknesses of different gasifiers. 12-10

  4. Estufa Finca Cookstove Gasifier (
      Describes how to build and use a simple cookstove designed to reduce black carbon in the atmosphere. States that 3 billion people now cook their food using open fires fueled by wood. 12-11

  1. -Air Curtain Destructors for Generating Biochar (
      "Air Curtain Burners, also called FireBoxes, were designed principally as a pollution control device. The primary objective of an air curtain machine is to reduce the particulate matter (PM) or smoke, which results from burning clean wood waste. It is sometimes hard to visualize without seeing a machine in operation, but the machines do not burn anything, rather they control the results of something burning."

      "You could look at it as a pollution control device for open burning."

      Editor's Note: An air curtain destructor can be modified to produce primarily biochar or biochar and electricity. Since air curtain destructors are designed to produce ash, not biochar, it should be noted that spreading ash on agricultural or forest land may be a problem as it increases the soil's pH and potassium. 02-16

  2. -Basic Biochar Kiln Designs and Efficiencies (
      Provides designs. 12-14

  3. -Biochar (
      Karr Group makes biochar meeting International Biochar Initiative standards. Karr Group sells a wholesale product to business and forestry services. 04-15

  4. -Biochar Companies and Organizations (
      Provides a list, current in 2012. 12-14

  5. -Biochar Kilns (
      Karr group makes biochar kilns with a capacity of up to 6 dry tons per hour. 04-15

  6. -Efficiency of Different Types of Kilns (
      Provides information on yields and air emissions from different types of kilns and similar information. For example, pyrolytic char produces over 1600 pounds of stored carbon per acre per year compared to 1200 pounds of carbon storage from no-till switchgrass and less than 100 pounds from plow-tilled corn. 05-11

  7. -How to Make Biochar from a Pile of Wood and Brush (
      "The process is simple. Start a fire in the big fire ring and keep adding brush. As the wood burns, it turns to charcoal which falls to the bottom. More wood is added over this to prevent oxygen from getting to the hot coals. After several hours of adding brush, the fire ring is full of charcoal which is extinguished with water." 12-14

  8. -How to Make a Biochar Kiln (
      "There is a chimney built into the lid. The lid does not sit flush on the kiln, but there is a gap between the lid and the kiln. The draft created by the chimney sucks secondary air into the chimney, where it gets mixed with the pyrolysis gas to burn it." 05-09

  9. -Industrial Level Biochar Production (
      "Cool Planet is commercializing a technology to create green fuels and an advanced soil amendment that can change the world for good. The company’s green fuels are chemically identical to fossil fuels, and its CoolTerra™ advanced soil amendment product increases crop productivity and promotes more robust plant health while reducing water and fertilizer requirements. The process is capable of being carbonnegative, reversing the consequences of CO2 build-up from fossil fuels. Cool Planet’s technology has a broad portfolio of pending and granted patents. Strategic investors include BP, Google Ventures, GE, ConocoPhillips, NRG Energy, the Constellation division of Exelon, and leading venture capital investors, including North Bridge Venture Partners." 02-15

  10. -Kon-Tiki Top Lit Open Burn (TLOB) Biochar Kilns (
      The Kon-Tiki design, a cone design, dries the feedstock as well as pyrolyzes. "Another five to ten minutes later, a sufficiently hot bed of embers has been formed and the surface layer begins to be covered with white ash. This is the moment to add the first regular layer of biomass. Cover the zone of glowing coals evenly but not too thickly. Once this new biomass layer also becomes coated with white ash, this is the sign that the feedstock has solidly reached pyrolysis temperature and exothermic pyrolysis will continue even in the absence of flaming combustion. It is time now to add the next layer of biomass."

      "About 20 minutes before the last layer is pyrolyzed, the water tap at the bottom of the Kon-Tiki is opened. Water flows slowly in from the bottom of the kiln. When the water meets the hot coals, it evaporates. The heated 600-700°C water vapor rises through the char bed, and not only makes for a slow quench, but partially activates the biochar at the same time. The hot steam serves to expel and react with condensates from the pores of the biochar. The biochar is thus cleaned, increasing the pore volume and the inner surfaces of the biochar. In this way, partially activated biochar is produced." 02-15

  11. -Large Scale Biochar Production: Air Curtain Destructors (U.S. Forest Service) star
      "They are used in forest fuel management and wildfire mitigation efforts, in the construction industry to reduce debris from land clearing and demolition operations, and at landfill sites to maximize costly space by reducing wood waste and similar burnable waste streams."

      Editor's Note: Air curtain destructors may be configured to pyrolyze wood waste inexpensively to create biochar with minimal smoke (particulates) and emissions. Instead of incinerating the waste to ash by blowing air into the wood, the blowers will need to be repositioned to blow over the wood and the process will need to be ended, possibly by spraying water, to leave biochar instead of ash. Since air curtain destructors are designed to produce ash, not biochar, it should be noted that spreading ash on agricultural or forest land may be a problem as it increases the soil's pH and potassium. 02-16

  12. -Large Scale Biochar: Air Curtain Destructors Costs Compared to Chipping Waste (
      "For a comparison of the commercial or cost related aspects of the two methods (next section), the most important single distinction is the fact that the air curtain burner offers an end solution for wood waste disposal whereas the grinder offers only an interim process facilitating the transport of the woody debris. This process does not eliminate the waste, as the air curtain burner does."

      "You could look at it as a pollution control device for open burning."

      A chart suggests that processing 100 tons of woody waste with an air curtain destructor will cost a little over $150 compared to $5,600 for chipping the waste and then hauling it to a landfill.

      Editor's Note: An air curtain destructor can be modified to produce primarily biochar or biochar and electricity. Since air curtain destructors are designed to produce ash, not biochar, it should be noted that spreading ash on agricultural or forest land may be a problem as it increases the soil's pH and potassium. 02-16

  13. -Large-Scale Biochar Production (
      "We currently are offering pre-manufactured small to medium scale biochar kilns, as well as customized engineering plans that can be used to manufacture larger capacity biochar production facilities." 02-15

  14. -Larger-Scale Biochar Production (
      Provides a list. 02-15

  15. -Pyramid Pile Open Burn Biochar Kilns (
      "Open burning is often the only economically viable way to dipose of this woody debris, but nobody likes all the smoke it generates"

      "The essence of the clean biochar burn technique is this: contrary to what you may have learned in Scouts, light your burn pile from the top, not the bottom." 12-14

  16. -Small-Scale Biochar Production (
      "While none of the techniques listed below approach industrial scale, they are illustrative and engaging ways to make small amounts of charcoal for experimentation. In developing world scenarios, biochar will most likely be made in small amounts using simple techniques like these. Over time, vast areas of soil can be regenerated in places of the world where it is needed the most to ensure food security." 02-15

  17. -Testing Biochar for PAH ( biochar is not heated sufficiently, polycyclic aromatic hydrocarbons (PAHs) may remain. PAH is not good for crops so the manufacturer of the biochar needs to certify, through testing, that its method of making biochar does not leave excess PAH.

  18. -Top Lit Open Burn (TLOB) Biochar Kilns (
      "The TLOB method can be used in cases where biomass will be burned anyway just to dispose of it, for instance, fuel-load reduction in forests or killing pests in orchard and vineyard prunings. Top Lit Open Burning will produce some biochar - perhaps about 10% by volume of the original biomass, depending mostly on feedstock moisture - the drier the better. Perhaps more importantly, the TLOB method drastically reduces the amount of smoke produced, saving our air and our lungs." 02-15

  19. Biochar Characterization (
      Provides a chart relating temperature of the kiln to the feedstock and acidity of the biochar and related information. 02-16

  20. Biochar Kilns: Diagrams (
      "Pyrolysis systems use kilns and retorts and other specialized equipment to contain the baking biomass while excluding oxygen. The reaction vessel is vented, to allow pyrolysis gases to escape. Pyrolysis gases are often called 'syngas'. The process becomes self-sustaining as the syngas produced is combusted, and heat is released."

      "There are two types of pyrolysis systems in use today: fast pyrolysis and slow pyrolysis. Fast pyrolysis tends to produce more oils and liquids while slow pyrolysis produces more syngas." 09-09

  21. Biochar Kilns: How They Work (
      "PYROLYSIS systems produce biochar by baking biomass largely in the absence of oxygen. The process can become self-sustaining as the syngas produced is combusted, releasing heat. There are two types of pyrolysis systems in use today: fast pyrolysis and slow pyrolysis. Fast pyrolysis tends to produce more oils and liquids while slow pyrolysis produces more syngas. Biochar production is optimized in the absence of oxygen." 08-09

  22. Biochar Production (Global-Warming-Arclein)
      "This posting by A. Karve at the terra preta/biochar forum brings fresh practical insight to the task of producing biochar in the field." 05-09

  23. Biochar Production (
      "Biochar production processes utilize cellulosic biomass such as wood chips, corn stover, rice and peanut hulls, tree bark, paper mill sludge, animal manure and most urban, agricultural and forestry biomass residues." 05-09

  24. Biochar-Related Companies (
      Provides a list of companies that have interests in biochar. 08-09

  25. Biomass Drying (
      Provides guidelines for drying biomass. 06-09

  26. Biomass-Fed, Factory-Built Gasifiers (
      Provides 10kw and 20kw units at $1 - $2 per watt. Awesome Library does not endorse this product but provides it as an example. 08-12

  27. Building and Operating a Biochar Pyramid Kiln (
      Provides instructions and photos. 03-16

  28. Comparison of Costs of Fuels (
      Provides a comparison. 12-10

  29. How to Make Biochar Using a 55-Gallon Drum (
      "Charcoal has been used as a fuel for at least 3,500 years. In modern times most people think of charcoal as something bought in a bag and used for barbecues. The best charcoal is the kind that you make yourself, however."

      Editor's Note: If the fuel is chopped or shredded properly, it can be used as biochar to enhance the soil. A forumula of half compost and half biochar is generally recommended so that the biochar has nutrients from the beginning when it is spread into your soil. 08-12

  30. How to Make Biochar in Your Yard (
      "Biochar, a charcoal produced by slow-burning plants, enhances the nutrients within soil, creating a rich growing environment. While you can purchase biochar from gardening supply stores, it is not difficult to make from home."

      Editor's Note: A forumula of half compost and half biochar is generally recommended so that the biochar has nutrients from the beginning when it is spread into your soil. 08-12

  31. How to Make a Charcoal Kiln (
      "These small kilns may not process much wood in one go but are quick and easy to build, transport and use." 05-09

  32. How to Make a Kiln, Iwasaki-Type (
      "In making charcoal, the bamboo or wood that becomes charcoal is steamed. If the flame is made stronger, or a large quantity of air is supplied, the fire from the firewood chamber will spread to the carbonization chamber and the bamboo or wood will burn instead of becoming charcoal. Please keep in mind that with exception of the last phase, the bamboo or wood becomes charcoal by steaming." 06-09

  33. Hybrid TLUD and Rocket Cook Stoves (
      "PlanetStove was designed to use locally purchased firewood, so unlike other available biochar-producing stoves, ours does not require villagers to re-cut their wood."

      "The PlanetStove is a hybrid. It is a fully functional TLUD, but since a TLUD stove sometimes only burns for an hour, we added a door making it similar to a “Rocket Stove”, a more traditional high-efficiency stove being used in development work. The benefit of this hybrid is that once there's no gas left in wood, villagers can add as more wood. This allows a family to cook for hours, even once the initial gasification is complete." 09-12

  34. Inexpensive, Home-Built Biochar Kilns, the Adam-Retort (
      Produces about one metric ton of biochar a week and burns/recycles the syngas produced. 06-09

  35. Kilns (
      "Kilns are thermally insulated chambers, or ovens, in which controlled temperature regimes are produced. They are used to harden, burn or dry materials." 06-09

  36. Kilns for Charcoal (
      "The metal kiln could easily be fabricated locally at a low cost as it can be made from empty oil barrels which can be purchased in Kassala market. A manufacturing instruction list and technical drawings have been made to help with its dissemination. The charcoal makers were very happy with the metal kiln, particularly regarding ease of operation and the time it saved. The quality of charcoal was also reported superior to that produced from earth-mound kilns."

  37. Kilns for Charcoal (
      Provides 8 foot diameter round kilns for around $1,740. Made in England.

      Awesome Library does not endorse these products but provides them as an example. 06-09

  38. Kilns for Charcoal (
      "Built by Moses Byrne in 1869 to supply charcoal for the iron smelting industry in Utah, these conical limestone kilns measure 30 feet across and 30 feet high. Only three of the original 40 kilns remain. It was estimated that during 1873, the kilns could produce 100,000 bushels of charcoal."

  39. Lucia Cook Stove (IBI.ogr)
      "Biochar advocates at the conference were very intrigued with the Lucia stove invented by entrepreneur Nat Mulcahy of WorldStove. Mulcahy is an industrial designer who has thrown himself into the project of bringing a sophisticated, high performance biomass stove to mass markets worldwide. Contrary to the approach of many stove designers who search for designs that can be easily manufactured in poor countries, Mulcahy wondered what could be accomplished using advanced manufacturing technology. He found that metal injection molding allowed him to make a burner with a swirl pattern resulting in highly efficient combustion and heat transfer. When used with a fan, the stove can be operated in a pyrolysis mode that produces charcoal. You can see his pyrolysis demonstration at the WorldStove YouTube channel." 12-13

  40. Makers of Biochar (
      Provides a list of manufacturers, including a description of each. 06-09

  41. Portable Charcoal Kilns (
      Provides kilns. Located in Singapore. 05-11

  42. Quenching Biochar Kilns (UbetBiochar)
      "Don Morrison reports: 'The 55 gal reservoir is just the right volume for quenching the coals from the 5' kiln by raking and spraying. I also liked the ease of tipping the kiln and dumping by one person with cable attached to handle and 4-wheeler. Next I tried the dry snuff method using the lid sealed with dirt. I use a little bit of water to knock the flames down and then put the lid on. Came back the next day and there were still a few hot spots that need some water to put out. But the char was basically pretty dry. Dry char is lighter and easier to unload than wet, sticky char.' " 02-15

  43. Requirements for Biochar Production (
      "When the possibility of USDA/Rural Development funding for fabrication of a farm-scale retort (an Adam-Retort fabricated by New England Biochar, LLC) presented itself, NESFI requested that MassDEP provide formal guidance on pyrolysis system requirements. The result was the “MassDEP Interim Requirements for the Installation and Operation of Biochar/Charcoal Production Units,” a document approved and signed by Assistant Commissioner James Coleman on 11/30/2010. Essentially an expanded articulation of the May 2010 communication, the document specifies thresholds for energy input (expressed in MMBtu/hour) and air contaminant emissions – sufficient to enable design and fabrication of a farm-scale retort (Adam-Retort) that can meet MassDEP regulatory concerns."

      "Throughout the process, it has become apparent that communication between MassDEP and the NESFI/PVBI has proven pivotal in achieving an interim regulatory framework. The value of this achievement is that all parties now posses a clear understanding of what is allowed, what is not allowed, and which regulations apply to a variety of scales of biochar production equipment. Notably, the November 2010 document issued by MassDEP contains specific references for determining the thresholds for compliance on the air emission limitations without resorting to cost-prohibitive stack testing of individual devices."

      "Based on the experiences of the group in New England, it is recommended that if you are operating a pyrolysis unit anywhere in the United States and have questions regarding your area's environmental requirements in regard to biochar production/utilization, you should contact the local Department of Environmental Protection for more information. It may be that your local DEP will also be starting this process from a zero baseline, as in Massachusetts, but by working with your DEP you can help to foster a positive dialogue and lay the groundwork for additional adoption and uptake of relevant guidance in other states." 04-11

  1. Argentine Brick Kiln (
      "Before discharging the charcoal, when the kiln is sufficiently cool, sufficient water must be available to avoid re-ignition when opening the door of the kiln. One drum of about 200 litres is sufficient for one kiln. The kiln is discharged by two or three men. The charcoal is conveniently removed from the kiln with a special fork known as a stone fork. It has 12-14 teeth and a tooth spacing of 0.02 m. This allows the bulk of the fines (less than 20 mm) to fall through and remain in the kiln. The charcoal is placed on a 1.2 m square piece of canvas and carried by two men out of the kiln." 07-09

  2. Building a Dome-Shaped Kiln (
      "The free-standing dome approach has a number of advantages. It is a relatively easy and very time-efficient method, which we think is within the skill set of someone who is ready to build a brick oven. Additionally, because the brickwork is accessible from the inside the entire time the dome is being built, it is possible to continually check the dome for the accuracy of the brick laying at all times. You can continually clean the inside of the dome brickwork, which will result in a better-looking end product." 07-09

  3. Earth Mound Kiln (
      "The charcoal iron industry of Sweden (2, 23) brought the design and operation of large mound type furnaces to a high stage of perfection. The main improvements were the use of an external chimney connected to a flue constructed beneath the pile and adoption of a circular ground plan for the pile which reduced heat loss during carbonization and improved gas circulation." 07-09

  4. Making Charcoal and Biochar Using a Pit (
      "To produce approximately 10 000 tons per year will need 28 teams each of 5 builders and 2 burners."

      "Total = 196 men and 1,680 pits must be made and burned each year."

      The cost would be $70 per ton to make charcoal. 07-09

  5. Making Charcoal in a Brick Kiln Compared to a Metal Drum (
      Provides clear directions and pictures. "Retort" means that a pipe moves the gases from the top of the barrel to the bottom so that the syngas created is used by the kiln to power it--while burning off the gas. 07-09

  6. Making Charcoal in an Adam-Retort Brick Kiln (
      "It makes sense to introduce the “adam-retort” at forest projects or other areas which cultivate wood energy plantations. The farmers are more motivated to plant energy trees because the wood gets a higher economic value because of an about doubled recovery rate for the charcoal! Its also recommended to use the “adam-retort” as well in areas where sustainable trees exist. This is the case in many areas of East- and South Africa where the Lelechwa wood grows." 08-09

  7. Making Heat-Resistent Kiln Bricks (
      "It is important to note that it is easily possible to improve the capability of a kiln to reach higher temperatures, simply by enclosing it, sealing it against a lot of heat loss. Next we need to consider that the biggest cost of kilns is the high tech bricks so widely believed to be necessary. But the reality is that in brick production the simple addition of common 'creek sand' to a common, red firing earthenware clay, plus sawdust, can be easily undertaken by those who are in the business of producing building brick. This will give a heat resistant brick for kiln construction, at little additional cost to that of ordinary building brick."

      "In practice, in making the brick it may be a good idea to use 75% clay to 25% creek sand, then whatever amount of sawdust, whether hard brick or insulating."

      "And sawdust, at about 60 mesh, can be burned out, leaving voids in the brick. Sawdust can contribute greatly to an insulating brick, cutting fuel costs and as an aid to environmental responsibility." 07-09

Purchase Resources
  1. Biochar Pyramid Kiln (
      Provides a kiln. Awesome Library does not endorse the kiln but provides it as an example. 03-16


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