Hazardous Fuels Reduction Using Flame Cap Biochar Kilns

Hazardous Fuels This fact sheet describes a do-it-yourself technique for Reduction Using making backyard biochar. The Utah Biomass Flame Cap Biochar Resources Group has demonstrated this method Kilns for reducing hazardous By: Darren McAvoy, Megan Dettenmaier forest fuels while creating a valuable product (biochar) Introduction using simple, Warning: Fire use requires extreme caution. low-cost materials. Hazardous fuels are a problem across the West. From 2000- 2017 bark beetles affected 85,000 square miles of forests in the western U.S. (an area the size of Utah). The accumulation of this beetle-killed timber occupies many forested slopes posing a fire risk to citizens, landscapes, and nearby infrastructure. Additionally, invasive species such as Russian olive (Elaeagnus Figure 1. Metal biochar kiln processing feedstock in Utah. angustifolia L.) and tamarisk (Tamarix spp.) the season possible for fuel reduction efforts, choke streams and rivers and prevent native sequesters carbon, and yields biochar, a species from growing and supporting the charcoal like product made from organic ecosystem. The accumulation of hazardous material. fuels such as beetle-killed timber and invasive species is dangerous, additionally as dead and What is biochar? dying trees decompose through cellular Biochar is the result of the thermochemical respiration, greenhouse gases (CO2 and CH4 separation that occurs when biomass is fired to methane) are released into the atmosphere. To temperatures ranging from 400 to 600 degrees deal with this excess fuel, trees are removed C. Because of biochar’s high porosity and from forests generating large quantities of surface area, when added to soil, it increases “waste wood”. This waste wood is commonly water holding capacity, making it available to called slash; it is often piled and burned plants over an extended period of time (Karhu, (known as pile burning), releasing stored Mattila, Bergström, & Regina, 2011; Tryon, carbon and greenhouse gasses into the 1948). Biochar as a soil amendment dates atmosphere (figure 2). While effective for back 7,000 years where it was used to improve dealing with large quantities of slash, piling and nutrient deficient Amazonian soil known as burning results in extreme heat pulses into the “Terra Preta de Indios” (Lal, 2009). Tapping ground, which has negative consequences on into biochar as a means for soil carbon storage the physical, chemical, and mineralogical may be a useful way to mitigate climate properties of the soil under the slash piles change (Batista et al., 2018). (Arocena & Opio, 2003; Jiménez Esquilín, Stromberger, Massman, Frank, & Shepperd, We have demonstrated a practical method for 2007). producing biochar using simple metal kilns that: An innovative alternative to this approach utilizes fire to dispose of slash, but contains the 1) give people an easy way to mitigate fire fire in simple metal kilns (figure 3). When danger both affordably and locally, compared to the pile and burn method, this 2) help citizens take fuel reduction projects into approach produces considerably less smoke, their own hands in wildland and rural settings, does less damage to the soil, is safer, extends and Figure 2. Typical hand ignited slash piles. Figure 3. Metal biochar kiln processing feedstock. 2 METAL KILNS PILE AND BURN Pile and burn technique simply Flame cap technique contains the SMOKE burns entire feedstock piles in combustion, which burns feedstock IMPACTS unregulated way, this creates more efficiently, creating less smoke. significantly more smoke. Piling and burning occurs directly Containing the fire in a metal kiln on the soil surface. The SOIL creates a barrier between the heat consequences to the forest floor IMPACTS and soil, buffering and protecting the can be extremely detrimental to soil soils from extreme heat pulses structure and microorganisms VALUE- Using kilns creates biochar, a Piling and burning does not result ADDED valuable product for soil carbon in any value-added product. PRODUCT sequestration, and amending soils 3) create a valuable product with many benefits: biochar. By carefully following fire escape precautions, these techniques are appropriate in the wildland-urban interface zone, where many people reside. The danger of introducing fire in this environment requires an abundance of caution, preparation and planning; however, under favorable weather and fuel moisture conditions and by following a few simple guidelines, anyone can make biochar. We outline the biological, environmental, and economical benefits to using simple kilns when compared with traditional pile and burn methods. The table above describes consequences for smoke accumulation, soil health, and byproducts when piling and burning vs. using Figure 4. Demonstration that biochar can be biochar kilns to remove hazardous fuels. made in a parking lot, or in the forest. 3 Metal Kilns There are infinite varieties of kiln shapes and sizes for making biochar. We have adopted the “Oregon Kiln”, or flame cap kiln made from 14- gauge steel. The kilns described in this process are 5’ by 5’ by 2’ deep, they weigh approximately 200 lbs. and can easily be carried by four people. Kilns are tapered at the bottom, which makes them easy to stack and transport. The flame cap kilns work well for Figure 5. Making biochar using a simple metal stock tank. forestry operations because they are portable and maneuverable in the woods. Crews have used these simple kilns for more than 100 firings, and they maintain their durability. The capacity of the kilns described here People make biochar using various kiln styles obviously cannot tackle the size and complexity using whatever materials available (figure 5). of the hazardous fuels problem in the West With open source plans, welding shops in Utah today. However, this technique can make an manufacture flame-cap kilns for approximately impact on the edges of areas where fuel $800 (figure 6). reduction efforts are needed. Figure 6. Open source plans for building biochar kiln. 4 Location and Timing Only personnel from appropriate public agencies are legally permitted to operate kilns on public lands. These kilns and techniques are appropriate to use on private land, however extreme caution should be taken to avoid an accidental wildfire. Even on private land, fire restrictions and burning permits are required. Consult with fire agency personnel; consider weather and surrounding fuel conditions and fire preparedness long before attempting to make biochar. Although this approach somewhat contains the flames within a box, there is ample opportunity for escaped embers to start an unwanted fire. Do not operate kilns in windy conditions, or near extremely dry fuel sources, including yards and homes. Each Figure 7. Biochar kilns stacked and ready for situation is different and should be evaluated transport. on a case by case basis. 5) Have an active water source readily at hand SAFETY e.g. fully charged hose. This will allow you to One of the benefits of the flame cap kilns is knock down embers and spot fires that result their mobility (figure 7). Kilns are easily moved from embers. Be prepared to deal with rapidly and can be used in the forest where the moving firebrands and sparks carried by biomass is located, eliminating the costly unexpected winds. expense of feedstock transportation (figure 6). 6) Have a shovel, Pulaski and a chain saw on Making biochar in the forest requires the hand to extinguish unwanted fire starts. creation of a diligent fire safety plan. To avoid the risk of accidental ignition: 7) Wear proper personal protective gear, preferably fire retardant clothing. At minimum, 1) Place kilns where the flames will not impinge participants should wear leather gloves, boots, on nearby vegetation, flammables, overhead and eye protection. Choose cotton clothing and obstructions or other hazards. avoid wearing polyester. 2) Avoid operating kilns in windy conditions to 8) Communicate with your local fire authorities avoid embers starting unwanted fires. and inform them of operations, including 3) Prepare the site with hand tools or contingency plans. machinery to ensure kilns will rest on level 10) Use care and proper form when moving the ground. kilns, as they are heavy and moving them can 4) Dig a trail or firebreak around the kilns to cause injury, especially when full of coals and contain any burning material that may fall out of water (do not move a kiln that is full of water, the kiln. drain or dump first). 5 Figure 8. Examples of feedstock size separation. Feedstock preparation In Utah, we used the flame cap kilns for making biochar from juniper, pinyon, aspen, Douglas- Figure 9 (top), 10 (bottom). Demonstration of fir, tamarisk, and Russian olive. Feedstock how to load a kiln. preparation is more important than species. For the most efficient burn use the driest feedstock ensure there is no flammable material within possible. Cut feedstock into lengths slightly 100 feet of the kiln. smaller than the kiln length to maximize space and kiln capacity. Sort and stack feedstock into Fill the kiln with dry branches and logs up to 6 rough diameter classes; small diameter sticks inches diameter; pile layers in a crisscross in one pile, medium in another and logs up to 8 pattern (figure 9). Then pile small, dry sticks inches in diameter in third pile; this organization (kindling) on top of the logs and light the kiln will help when loading the kiln (figure 8). from the top (figure 10). This technique will soon form a ‘cap’ of flames across the top of Initial Kiln Loading the kiln; maintaining the flame cap is an important part of the process; as combustibles Place the kiln on a flat surface that can rise through the flame cap they are consumed withstand heat (not directly on pavement) and by the flames, resulting in a very clean burn. 6 Kiln Operation Keep loading the kiln with pre-cut feedstock over the next 2 to 4 hours (figures 11, 12, 13).

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