We thank the numerous University personnel, National Forest, and Bureau of Land Management personnel who helped conduct demonstrations and gather data. The field work for this method was supported by the U.S.D.A. Forest Service Rocky Mountain Research Station, Washington D.C., and Pacific Northwest Region offices. The findings and conclusions in this publication are those of the authors and should not be construed to represent any official U.S.D.A. or U.S. Government determination or policy.

NOTE: Additional details on the operation of the BACB can be found in the operator&#39;s manual that comes with the equipment.
1. Transportation to site
<ol>
	<li>Using a Class 5 commercial duty hitch (ball size 2-5/16 inch or 58.75 cm), hitch the BACB onto a 1-ton or larger pickup truck, adjusting the hitch height to ensure the frame rails are level for transport. Before towing, check the brake controller, break-away system, brakes, wheels, and trailer lighting.</li>
	<li>Make sure BACB&#39;s travel safety pins are properly secured and the firebox is lowered onto the travel pins.</li>
	<li>Once at the desired location, position the unit while still attached to the tow vehicle; it is too heavy to move by hand. Chock the wheels and lower the jack stand. Disconnect it from the tow vehicle. The chassis (green frame) should be level front to back; raise or lower the jackstand to achieve this.
	<ol>
		<li>If the BACB will be sited at a location for more than one day, excavate a shallow trench to accumulate ash. Keep the trench as wide as the conveyor belt. Without this trench, the BACB will have to be moved and repositioned at the same location to continue burning on a subsequent day.</li>
	</ol>
	</li>
	<li>Raise the firebox slightly to remove the travel pins from the front and back of the firebox, clear personnel, and then lower the sides to the ground. Contact with the ground will raise the chassis, but the tires should remain firmly on the ground. If the entire length of the firebox sidewalls is not in contact with the soil, consider moving the unit to a more level location or use shovels or the excavator to level the site.</li>
	<li>Check that the hydraulic motor that runs the shaker panel between the firebox and the enclosed engine is not in contact with the green frame.</li>
	<li>Start the engine and give it sufficient time to warm up before initializing the hydraulics.</li>
</ol>
2. On-site preparation
<ol>
	<li>Place the BACB on a relatively flat surface (slope &#60;3%) fairly close to the pile of wood, ensuring that the firebox is level by using a 4-foot (1.2 m) I-beam level or string level. Ensure the area is free of overhead hazards and has enough room for the mini excavator (Figure 2) to freely load the feedstock over the air manifold.</li>
	<li>Ensure that the air manifold on the BACB is blowing the air curtain in the same direction as the wind. Check any phone weather application daily for local prevailing wind direction or note wind direction on-site before the final BACB siting.</li>
	<li>Do not place the BACB where there are large rocks, vegetation, or debris. Once the equipment is level and the firebox sides are lowered, place soil around the sides to prevent air from moving in and smoke from moving out of the firebox.</li>
	<li>Place the quench pan (Figure 3) on level ground at the back of the BACB. Ensure that it does not touch the conveyor belt. Fill the quench pan with approximately 40 gallons (150 L) of water. Keep approximately 300 gallons (1135 L) of water on-site to refill the quench pan, as needed.</li>
	<li>Select any woody feedstock and use dry material to start the fire in the firebox. Use the mini excavator to keep an adequate supply of feedstock nearby to load the firebox. Cut all feedstock to a length that is shorter than the maximum length of the firebox. 
	NOTE: Large diameter (approximately 10 inch (25 cm) logs should be sawed into smaller lengths (~18-36 inch; 45-91 cm), and very large material (&#62; 20 inch (50 cm) should be cut into sections ~12-18 inch; 30-45 cm) before placing them in the firebox.</li>
</ol>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/66716/66716fig02.jpg" /> 
Figure 2: Example of an excavator moving wood residues. Mini-excavators can be used to load the biochar-producing air curtain burner. This figure has been modified from12. <a href="https://www.jove.com/files/ftp_upload/66716/66716fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/66716/66716fig03.jpg" /> 
Figure 3: Example of the quench basin placement. The quench basin is kept full of water and positioned approximately 2 inches (5 cm) in front of the conveyor belt. This figure has been modified from12. <a href="https://www.jove.com/files/ftp_upload/66716/66716fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
3. Hazard reduction
<ol>
	<li>Before igniting the feedstock, check with the local air quality permitting agency and the local fire department to confirm that the fire danger is not too high for ignition and that air quality monitoring, if required, is in place.</li>
	<li>In addition, before ignition, remove any organic debris from a 6-foot (2 m) area around the BACB to prevent any unintended ignitions. Ensure there is a charged hose connected to an adequate water supply and that the BACB quench pan is filled with water. If possible, keep several 5-gallon (20 L) water buckets ready for dousing unintended ignitions. When burning during elevated fire danger, assess the need to set up sprinklers, a water pump, or a portable water reservoir for extinguishing larger unintended ignitions.</li>
	<li>Ensure that workers can move freely around the sides and back of the machine to access the quench pan, control panel (Figure 4), and the conveyor&#39;s manual control point, which is located at the right rear corner of the BACB.</li>
	<li>Ensure workers do not walk in front of the air curtain across from the manifold and wear durable non-synthetic clothing, high visibility vest, hard hat, leather gloves, and eye and hearing protection.</li>
</ol>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/66716/66716fig04.jpg" /> 
Figure 4: Control panel on the biochar-producing air curtain burner. The control panel is used to turn on the air curtain, conveyor, and system power and to raise and lower the firebox. This figure has been modified from12. <a href="https://www.jove.com/files/ftp_upload/66716/66716fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
4. Pre-operation checks
<ol>
	<li>Check all fuel and fluid levels and filters and lubricate the grease points before igniting the feedstock. Once the BACB is operational and at temperature, it may be impossible to inspect, move, or maintain fluid levels, filters, and grease points.</li>
	<li>Check the weather report for the operating location and ensure wind will not exceed ~20 miles per h (30 km per h) during the burn.</li>
	<li>Before ignition, have a conversation with the mini-excavator operator to agree on hand signals (or use a two-way radio) for loading and orientation of wood to ensure a clean burn. Advise the mini-excavator operator to load over the air manifold and not to load the firebox with the feedstock opposite the air manifold.</li>
</ol>
5. Initial loading and creating a base fire
<ol>
	<li>Initially load the firebox with dry feedstock (if available) using the mini excavator. Load the wood until the firebox is approximately 2/3rd full, alternating the direction of the materials (i.e.,&#160;one load should be perpendicular and the next layer parallel to the sides) to create air space that will help the pile burn. Do not pack material into a tight bundle to ensure the material will ignite easily, and do not use the excavator to compact material in the firebox.</li>
	<li>Make sure feedstock is placed throughout the entire firebox to create an even bed of coals. Pay attention to feedstock gaps at the ends of the firebox to ensure even filling and burning.</li>
	<li>Use an ignition aid, such as diesel, on the wood and then light it with a propane torch or other similar ignition device at several points along the firebox.</li>
</ol>
6. Addition of wood to the firebox
<ol>
	<li>Allow the base fire to burn until the firebox is approximately half full of burning residues and coals.</li>
	<li>Start the engine and adjust the fan speed for fire conditions. Slowly increase engine speed so the air from the manifold does not blow out the fire. Increase engine speed by pressing the RABBIT button on the control panel (Figure 4).</li>
	<li>Once a good base of coals is achieved, signal the mini-excavator driver to add additional feedstock at a rate that does not smother the fire. Smoke is expected for a short period of time as additional feedstock is added and the air curtain is disrupted. Continuously monitor the BACB and the surrounding area for escaped sparks or embers that can cause unintended ignitions.</li>
</ol>
7. Biochar production
<ol>
	<li>When the base fire is established, additional feedstock has been added, and the fan speed has been increased to 2800 rpm, switch the System Power switch to Biochar (Figure 4). Check that the system power is at 1800 psi.</li>
	<li>Switch on the conveyor and shaker. These two functions will cycle automatically every 3 min. Maintain continuous production by toggling the system power switch from Biochar to Firebox (Figure 4). This overrides the intermittent timer mechanism for the shaker and conveyor belt when large amounts of char appear each cycle.</li>
	<li>Collect the biochar in the quench pan and remove biochar from the pan every 5-10 min by using the wide rake to move the biochar to the end of the quench pan and then using the sifting shovel to remove the biochar from the pan and into a pile.</li>
	<li>If the rake gets caught in the conveyor belt, the warning strobe should flash. Toggle the Conveyor switch to OFF at the main control panel, then remove the rake and restart the belt.</li>
	<li>Respond to other warning strobes by checking the pressure gauges on the main control to determine if the shaker panel or the conveyor has stopped. If needed, turn OFF the Shaker to allow the binding wood to burn down or by manually advancing the conveyor belt counterclockwise at the manual control point at the right rear corner of the BACB.</li>
	<li>Refill the quench pans with water, as needed, to allow full dousing of the hot coals. Do not spray water onto the conveyor belt or the ceramic tiles in the firebox.</li>
	<li>Continue adding feedstock into the firebox and creating biochar as long as conditions permit. Make sure larger diameter wood is added earlier in the day so it can be fully converted to char.</li>
</ol>
8. Ceasing operations
<ol>
	<li>Stop loading the firebox approximately 1 to 2 h before the end of the shift.</li>
	<li>Turn OFF the shaker when the remaining material no longer contacts the shaker panel and do not leave hot coals in the firebox or on the conveyor belt at the end of the day.</li>
	<li>Leave the conveyor switch ON until all coals have exited the firebox. At this point, it is appropriate to switch to Biochar mode for intermittent cycling.</li>
	<li>During the day ash accumulates under the conveyor belt (Figure 5). Move the BACB each day&#160;to a new level location&#160;to prevent the ash from impeding conveyor belt movement.</li>
	<li>Once the fire is out and the coals are all quenched, cease the operations for the day. 
	NOTE: In an emergency, the fire in the firebox can be extinguished by loading soil onto the burning coals.</li>
	<li>Leave the sides of the firebox down overnight to insulate the tires from the hot ash under the conveyor belt.</li>
</ol>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/66716/66716fig05.jpg" /> 
Figure 5: Example of ash and biochar under the conveyor belt. During a burn, some ash and biochar will fall through the metal conveyor belt. This figure has been modified from12. <a href="https://www.jove.com/files/ftp_upload/66716/66716fig05large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
9. Re-positioning the BACB
<ol>
	<li>Hitch the BACB to the towing vehicle, raise the sides of the firebox, insert the travel pins, raise the jack stand, and immediately tow the unit straight forward.</li>
	<li>Cool the remaining ash (Figure 6) by mixing it with water and distributing it across the soil. Ensure all coals and ash material are cold to the touch before moving to a new location.</li>
</ol>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/66716/66716fig06.jpg" /> 
Figure 6: Example of ash buildup. By the end of the day, the ash accumulation under the conveyor belt can reach the conveyor belt. Trenching before placing the biochar-producing air curtain burner is one method to extend the burn time in one location. If trenching is not an option, then the equipment should be pulled forward and ash cleaned out each day. This figure has been modified from12. <a href="https://www.jove.com/files/ftp_upload/66716/66716fig06large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Air Curtain Burners and Biochar &#8211; Advancing Forest Health and Carbon Capture

<ol>
	<li>Barrett, S. W., Arno, S. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Indian+fires+as+an+ecological+influence+in+the+northern+Rockies.">Indian fires as an ecological influence in the northern Rockies.</a> J Forestry. 80, 647-651 (1982).</li><li>Savage, M., Swetnam, T. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Early+19th+century+fire+decline+following+sheep+pasturing+in+the+Navajo+ponderosa+pine+forest.">Early 19th century fire decline following sheep pasturing in the Navajo ponderosa pine forest.</a> Ecology. 71, 2374-2378 (1990).</li><li>Sohn, J. A., Hartig, F., Kohler, M., Huss, J., Bauhus, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heavy+and+frequent+thinning+promotes+drought+adaptation+in+Pinus+sylvestris+forests.">Heavy and frequent thinning promotes drought adaptation in Pinus sylvestris forests.</a> Eco Appl. 26, 2190-2205 (2016).</li><li>. Air Burners, Inc Available from: <a target="_blank" href="https://airburners.com/technology/principle">https://airburners.com/technology/principle</a> (2024)</li><li>U.S. Department of Energy. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2016+Billion-ton+report:+Advancing+domestic+resources+for+a+thriving+bioeconomy.">2016 Billion-ton report: Advancing domestic resources for a thriving bioeconomy.</a> U.S. Department of Energy. , (2016).</li><li>Jang, W., Page-Dumroese, D. S., Han, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+heat+transfer+and+soil+impacts+of+air+curtain+burner+burning+and+slash+pile+burning.">Comparison of heat transfer and soil impacts of air curtain burner burning and slash pile burning.</a> Forests. 8, 297 (2017).</li><li>Rhoades, C. C., Fegel, T. S., Zaman, T., Fornwalt, P. J., Miller, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Are+soil+changes+responsible+for+persistent+slash+pile+burn+scars+in+lodgepole+pine+forests.">Are soil changes responsible for persistent slash pile burn scars in lodgepole pine forests.</a> Forest Eco Management. 490, 119090 (2021).</li><li>Rodriguez Franco, C., Page-Dumroese, D. S., Archuleta, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Forest+management+and+biochar+for+continued+ecosystem+services.">Forest management and biochar for continued ecosystem services.</a> J Soil Water Cons. 77, 60-64 (2020).</li><li>Lee, E., Han, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Air+Curtain+Burners:+A+tool+for+disposal+of+forest+residues.">Air Curtain Burners: A tool for disposal of forest residues.</a> Forests. 8, 296 (2017).</li><li>Fornwalt, P. J., Rhoades, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rehabilitating+slash+pile+burn+scars+in+upper+montane+forests+of+the+Colorado+Front+Range.">Rehabilitating slash pile burn scars in upper montane forests of the Colorado Front Range.</a> Natural Area J. 31 (2), 177-182 (2011).</li><li>Blanco-Canqui, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+biochar+improve+all+soil+ecosystem+services.">Does biochar improve all soil ecosystem services.</a> GCB-Bioenergy. 13, 291-304 (2020).</li><li>. USDA Forest Service Available from: <a target="_blank" href="https://www.fs.usda.gov/">https://www.fs.usda.gov/</a> (2024)</li><li>Razzaghi, F., Obour, P. B., Arthur, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+biochar+improve+soil+water+retention?+A+systematic+review+and+meta-analysis.">Does biochar improve soil water retention? A systematic review and meta-analysis.</a> Geoderma. 361, 1 (2020).</li><li>U.S. Department of Agriculture, Forest Service, Technology and Development Program. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+air+curtain+destructors+for+fuel+reduction.+Fire+Management+Tech+Tips+#0251+1317-SDTDC.">The use of air curtain destructors for fuel reduction. Fire Management Tech Tips #0251 1317-SDTDC.</a> U.S. Department of Agriculture, Forest Service, Technology and Development Program. , 5 (2002).</li><li>Puettmann, M., Sahoo, K., Wilson, K., Oneil, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Life+cycle+assessment+of+biochar+produced+from+forest+residues+using+portable+systems.">Life cycle assessment of biochar produced from forest residues using portable systems.</a> J Cleaner Prod. 250, 119564 (2020).</li><li>Miller, C. A., Lemieux, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emissions+from+the+burning+of+vegetative+debris+in+air+curtain+destructors.">Emissions from the burning of vegetative debris in air curtain destructors.</a> Air Waste Management Assoc. 57, 959-967 (2007).</li><li>Rodriguez Franco, C., Page-Dumroese, D. S., Pierson, D., Nicosia, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biochar+utilization+as+a+forestry+climate-smart+tool.">Biochar utilization as a forestry climate-smart tool.</a> Sustainability. 16, 1714 (2024).</li><li>Busse, M. D., Shestak, C. J., Hubbert, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Soil+heating+during+burning+of+forest+slash+piles+and+wood+piles.">Soil heating during burning of forest slash piles and wood piles.</a> Int J Wildland Fire. 22 (6), 786-796 (2013).</li></ol>

The authors have nothing to disclose.

The first critical step in this method is to ensure the equipment is placed nearly level on both axes so that the firebox side panels block smoke from leaving and air from entering the firebox. Other critical steps are to conduct frequent conversations with the excavator operator to place the feedstock into the firebox where needed and brief all workers on the safety aspects of operating the air burner and excavator. There are a few modifications that can be made with this equipment, but running the conveyor belt and sha...

Across the U.S.A., many forest stands have increased in standing tree volume in the absence of frequent low-intensity fires, historically set by indigenous people and suppressed in modern times1,2. From this fire exclusion, the resulting overstocked stands pose challenges for land managers striving to enhance forest resilience against wildfires, pests, diseases, and drought effects3. Standard management practices for reducing tree volume include prescribed fire, pre-commercial thinning, and mature stand harvesting. These operations generate substantial amounts of low- and no-value woody biomass, often called residues. For example, in the 15 states of the western U.S.A., it is estimated that harvest operations produce nearly 8 million dry tons of residues each year4. Further, the USDA Forest Service has implemented a wildfire crisis plan, which will treat an additional 50 million acres (20 million hectares) over a 10-year period. This will result in the need to dispose of additional unmerchantable material and likely require the use of a variety of place-based options. Although tops, limbs, and unmerchantable trees can be used for bioenergy or biofuels, limited market opportunities often lead to these residues being piled and burned. Building slash piles aims to reduce wildfire and insect risk, create growing space for understory plants, and address other land management objectives.
Open pile burning is a low cost, relatively fast method for reducing wood volume, but it also produces smoke and air pollutants, including greenhouse gases5. Further, it may also cause undesirable impacts on soil physical, chemical, and biological properties, leading to burn scars that can persist for decades6. To mitigate the detrimental side effects of open burning, alternative approaches are needed that reduce negative impacts on climate change, wildfire risk, and soil health7.
Here, we focus on the use of a novel method for continuous biochar production developed through a Cooperative Research and Development Agreement (CRADA) between the U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, and Air Burners, Inc. (Palm City, FL). The resulting technology, henceforth referred to as the biochar-producing air curtain burner (BACB; Figure 1), continuously produces biochar from woody residues while limiting smoke and particulate emissions. Compared with open burning, the functionality of the BACB reduces fire risk and the spread of smoke8, creating avenues for the safe extension of operational burn windows. Unlike traditional methods that leave residue piles on the landscape where they contribute to fuel accumulations9 or alternative combustion methods that primarily produce smoke and ash, the BACB effectively reduces fuel loads while protecting the soil and creating biochar, a consistent, high carbon charcoal, that can be used for soil restorations&#39; on or near the site of processing. Further, the BACB is mobile and can easily be sited, for example, at a log landing, along a roadside, or in a campground. It can also burn wet or dry wood, mixed feedstock types, and sizes, and can be used in inclement weather and at times when weather conditions are too risky for open pile burning.
Biochar produced in the BACB is generally 70%-90% carbon, highly porous, and consistent in particle size distribution, making it suitable for remediating degraded soils, often found at abandoned mines, log landings, skid trails, riparian areas, or agricultural sites. Biochar can also be used as a mix with compost or in livestock feedlots to adsorb nutrients and reduce odor. In general, the best soil uses for woody residue biochar are to reduce erosion and nitrate leaching while enhancing soil aggregate stability and available water in coarse-textured, low organic matter soils10,11.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/66716/66716fig01.jpg" /> 
Figure 1: Mobile biochar-producing air curtain burner. The test site shows the general configuration of the slash and the biochar-producing air curtain burner. This figure has been modified from12. <a href="https://www.jove.com/files/ftp_upload/66716/66716fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Overview of design and operation 
Although there are several types of air curtain burners available, the BACB continuously creates biochar. The unit is approximately 7 m long x 2.5 m wide x 2 m high. It has an air manifold along the top of the firebox that provides a steady curtain of air to contain smoke, particulates, and embers within it and promotes complete oxidation of emissions. For optimal operation, the firebox is loaded to a level just below the manifold, ensuring uninterrupted airflow across the firebox. The BACB can be towed behind any vehicle with a standard hitch package and adequate towing capacity. A level, smooth site is prepared close to the piled biomass (also called feedstock), but with enough room around the site to allow equipment and staff to move freely and safely. Once positioned, the unit is secured by lowering the firebox sides onto the soil using the onboard hydraulic system. A blower motor pressurizes the air curtain manifold, which runs the length of the firebox on one side. Biomass is initially lit and burned to establish a bed of coals in the firebox. Then, additional biomass can be added periodically while keeping incoming material below the air curtain. As the material burns, coal is produced and falls through an opening in the bottom of the firebox, where they are cleared from the machine by the conveyor belt. One panel inside the firebox oscillates to facilitate this process. Ash or fine materials fall through the conveyor belt onto the soil below. Hot coals exit the machine through a slot in the bottom of the firebox and are deposited into a pan filled with water, which stops combustion and cools the biochar to a temperature where it can be handled safely. When ready to cease operation, the firebox is cleared by allowing any remaining material to burn down. Typically, the unit cools overnight and can be moved safely the next day, as needed. Do not attempt to move the BACB while it is burning wood or cooling unless there is an emergency. In case of emergency, sand or soil can be used to extinguish the fire and smother the coals. Water should never be sprayed directly on the ceramic tiles in the firebox.

<table><tbody><tr><td>CharBoss air curtain burner</td><td>Air Burners, Inc.</td><td>T26</td><td>Comes with 36&quot; landscape rake, sifting shovel, 1/2&quot; drive standard ratchet with 1 1/8&quot; socket, grease gun, and quench pan</td></tr><tr><td>Diesel fuel (Ultra-low sulfur)</td><td></td><td></td><td>Purchased locally</td></tr><tr><td>Diesel fuel tanks</td><td>Uline</td><td>H-1849Y</td><td>or similar</td></tr><tr><td>Engine oil (diesel grade)</td><td></td><td></td><td>Any diesel grade oil 15W40 or 10W40.</td></tr><tr><td>Excavator</td><td></td><td></td><td>Local rental company.&amp;nbsp; Smaller sizes require less fuel.</td></tr><tr><td>High temperature anti-seize lubricant (16 oz cartridge)</td><td>McMaster-Carr</td><td>1288K97</td><td>lubricating hydraulic fittings</td></tr><tr><td>Hydraulic Oil</td><td>Amsoil</td><td>HVH05-EA (ISO32) /HVG05-EA (ISO22)</td><td>Any ISO32 synthetic hydraulic oil, ISO22 option for cold weather. Amsoil ISO32 is factory installed.</td></tr><tr><td>Large buckets</td><td>Uline</td><td>5495</td><td>or similar</td></tr><tr><td>Lighting torch (propane)</td><td>Grainger</td><td>9RCF3</td><td>or similar</td></tr><tr><td>1-ton pickup (or larger)</td><td>Rent locally</td><td></td><td>for transporting CharBoss to site</td></tr><tr><td>Viewing step</td><td>Gorilla</td><td>GLP=WP</td><td>Stable step to allow viewing into firebox or other bench-style step&amp;nbsp;</td></tr><tr><td>Water truck</td><td></td><td></td><td>Any available water truck with minimum 300 gallon capacity; gravity feed of water to the quench pan can be used.&amp;nbsp;</td></tr><tr><td>Wheel chocks</td><td></td><td></td><td>Blocks of 4&quot;x 4&quot; lumber or commercially available chocks while hitching/unhitching unit</td></tr><tr><td>&lt;strong&gt;Personal protective equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Ear protection</td><td>Uline</td><td>S-22141</td><td>or similar</td></tr><tr><td>Eye protection</td><td>Amazon</td><td></td><td>or similar</td></tr><tr><td>Fire shirt</td><td>Grainger</td><td>12R487</td><td>or similar</td></tr><tr><td>Fire pants</td><td>Grainger</td><td>39EM96</td><td>or similar</td></tr><tr><td>Hard hat</td><td>Discount Safety Gear</td><td>SFTSCHH1000038126</td><td>or similar</td></tr><tr><td>Leather gloves</td><td>Uline</td><td>S-6777M</td><td>or similar</td></tr><tr><td>Sturdy boots</td><td></td><td></td><td>any thick soled, leather boot.</td></tr><tr><td>&lt;strong&gt;Emergency gear&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Garmin InReach</td><td>Cabelas</td><td>100195666</td><td>or similar</td></tr><tr><td>Pulaski axe</td><td>Forestry suppliers</td><td>85274</td><td>or similar</td></tr><tr><td>Fire rake</td><td>Forestry suppliers</td><td>85210</td><td>or similar</td></tr></tbody></table>

continuous in-woods production of biochar using a trailer-mounted air curtain burner

Fuel treatments and other forest restoration thinning practices aim to reduce wildfire risk while building forest resilience to drought, insects, and diseases and increasing aboveground carbon (C) sequestration. However, fuel treatments generate large amounts of unmerchantable woody biomass residues that are often burned in open piles, releasing significant quantities of greenhouse gases and particulates, and potentially damaging the soil beneath the pile. Air curtain burners offer a solution to mitigate these issues, helping to reduce smoke and particulates from burning operations, more fully burn biomass residues compared to pile burning, and eliminate the direct and intense fire contact that can harm soil beneath the slash pile. In an air curtain burner, burning takes place in a controlled environment. Smoke is contained and recirculated by the air curtain, and therefore burning can be conducted under a variety of climatic conditions (e.g.,&#160;wind, rain, snow), lengthening the burning season for disposal of slash material. The mobile pyrolysis unit that continuously creates biochar was specifically designed to dispose of residual woody biomass at log landings, green wood at landfills, or salvaged logged materials and create biochar in the process. This high-carbon biochar output can be used to enhance soil resilience by improving its chemical, physical, and biological properties and has potential applications in remediating contaminated soils, including those at abandoned mine sites. Here, we describe the general use of this equipment, appropriate siting, loading methods, quenching requirements, and lessons learned about operating this new technology.

From January 2022 through October 2023, the BACB pyrolyzed various feedstocks into biochar (Table 1). Based on field trials, the BACB can burn approximately 1 ton (900 kg)&#160;of feedstock per h, and approximately 11%-25% of dry mass of the feedstock will be retained as biochar, with the balance going to gas (water vapor, CO2, etc.) and ash. Carbon content ranges from 70%-90%. Larger pieces of wood (&#62;30 cm) take a longer time to pyrolyze than wood with a diameter ranging from 2-30 cm. The...

Read this Scientific Article Protocol about Continuous In-woods Production of Biochar Using a Trailer-mounted Air Curtain Burner at JoVE.com

Author Spotlight: Advancing Place-Based Biochar Production for Ecosystem Restoration and Soil Health

We describe the use of a place-based mobile pyrolysis unit equipped with an air curtain to continuously create biochar. The technology reduces the need for open slash pile burning, which results in lower emissions and fewer soil impacts. The protocol includes guidelines for site selection, loading, and quenching.

Continuous In-woods Production of Biochar Using a Trailer-Mounted Air Curtain Burner

Fuel treatments and other forest restoration thinning practices aim to reduce wildfire risk while building forest resilience to drought, insects, and ...

continuous-woods-production-biochar-using-trailer-mounted-air-curtain

Research

JoVE Journal

Environment

784 Views.  USDA Forest Service, Rocky Mountain Research Station. We describe the use of a place-based mobile pyrolysis unit equipped with an air curtain to continuously create biochar. The technology reduces the need for open slash pile burning, which results in lower emissions and fewer soil impacts. The protocol includes guidelines for site selection, loading, and quenching. 

Video: Author Spotlight: Advancing Place-Based Biochar Production for Ecosystem Restoration and Soil Health

Design and Operation of a Continuous 13C and 15N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling

Tracing rare stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes and soil organic matter formation to small-scale stable-isotope biomarker probing. Coupling multiple stable isotopes such as 13C with 15N, 18O or&#160;2H has the potential to reveal even more information about complex stoichiometric relationships during biogeochemical transformations. Isotope labeled plant material has been used in various studies of litter decomposition and soil organic matter formation1-4. From these and other studies, however, it has become apparent that structural components of plant material behave differently than metabolic components (i.e. leachable low molecular weight compounds) in terms of microbial utilization and long-term carbon storage5-7. The ability to study structural and metabolic components separately provides a powerful new tool for advancing the forefront of ecosystem biogeochemical studies. Here we describe a method for producing 13C and 15N labeled plant material that is either uniformly labeled throughout the plant or differentially labeled in structural and metabolic plant components.
Here, we present the construction and operation of a continuous 13C and 15N labeling chamber that can be modified to meet various research needs. Uniformly labeled plant material is produced by continuous labeling from seedling to harvest, while differential labeling is achieved by removing the growing plants from the chamber weeks prior to harvest. Representative results from growing Andropogon gerardii Kaw demonstrate the system&#39;s ability to efficiently label plant material at the targeted levels. Through this method we have produced plant material with a 4.4 atom%13C and 6.7 atom%15N uniform plant label, or material that is differentially labeled by up to 1.29 atom%13C and 0.56 atom%15N in its metabolic and structural components (hot water extractable and hot water residual components, respectively). Challenges lie in maintaining proper temperature, humidity, CO2 concentration,&#160;and light levels in an airtight 13C-CO2 atmosphere for successful plant production. This chamber description represents a useful research tool to effectively produce uniformly or differentially multi-isotope labeled plant material for use in experiments on ecosystem biogeochemical cycling.

Design and Operation of a Continuous 13C and 15N Labeling Chamber for Uniform or Differential, Metabolic and Structural, Plant Isotope Labeling

This method explains how to build and operate a continuous 13C and 15N isotope labeling chamber for uniform or differential plant tissue labeling. Representative results from metabolic and structural labeling of Andropogon gerardii are discussed.

Tracing rare stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes ...

Air-sampled Filter Analysis for Endotoxins and DNA Content

Outdoor aerosol research commonly uses particulate matter sampled on filters. This procedure enables various characterizations of the collected particles to be performed in parallel. The purpose of the method presented here is to obtain a highly accurate and reliable analysis of the endotoxin and DNA content of bio-aerosols extracted from filters. The extraction of high molecular weight organic molecules, such as lipopolysaccharides, from sampled filters involves shaking the sample in a pyrogen-free water-based medium. The subsequent analysis is based on an enzymatic reaction that can be detected using a turbidimetric measurement. As a result of the high organic content on the sampled filters, the extraction of DNA from the samples is performed using a commercial DNA extraction kit that was originally designed for soils and modified to improve the DNA yield. The detection and quantification of specific microbial species using quantitative polymerase chain reaction (q-PCR) analysis are described and compared with other available methods.

Two complementary analyses of atmospheric biological particles from air sampled filters are described herein: the extraction and detection of endotoxin, and of DNA.

Outdoor aerosol research commonly uses particulate matter sampled on filters. This procedure enables various characterizations of the collected particles ...

Extraction and Analysis of Microbial Phospholipid Fatty Acids in Soils

Phospholipid fatty acids (PLFAs) are key components of microbial cell membranes. The analysis of PLFAs extracted from soils can provide information about the overall structure of terrestrial microbial communities. PLFA profiling has been extensively used in a range of ecosystems as a biological index of overall soil quality, and as a quantitative indicator of soil response to land management and other environmental stressors.
The standard method presented here outlines four key steps: 1. lipid extraction from soil samples with a single-phase chloroform mixture, 2. fractionation using solid phase extraction columns to isolate phospholipids from other extracted lipids, 3. methanolysis of phospholipids to produce fatty acid methyl esters (FAMEs), and 4. FAME analysis by capillary gas chromatography using a flame ionization detector (GC-FID). Two standards are used, including 1,2-dinonadecanoyl-sn-glycero-3-phosphocholine (PC(19:0/19:0)) to assess the overall recovery of the extraction method, and methyl decanoate (MeC10:0) as an internal standard (ISTD) for the GC analysis.

Phospholipid fatty acids provide information about the structure of soil microbial communities. We present methods for extraction from soil samples with a single-phase chloroform mixture, fractionation of extracted lipids using solid phase extraction columns, and methanolysis to produce fatty acid methyl esters, which are analyzed by capillary gas chromatography.

Phospholipid fatty acids (PLFAs) are key components of microbial cell membranes. The analysis of PLFAs extracted from soils can provide information about ...

A Gusseted Thermogradient Table to Control Soil Temperatures for Evaluating Plant Growth and Monitoring Soil Processes

Thermogradient tables were first developed in the 1950s primarily to test seed germination over a range of temperatures simultaneously without using a series of incubators. A temperature gradient is passively established across the surface of the table between the heated and cooled ends and is lost quickly at distances above the surface. Since temperature is only controlled on the table surface, experiments are restricted to shallow containers, such as Petri dishes, placed on the table. Welding continuous aluminum vertical strips or gussets perpendicular to the surface of a table enables temperature control in depth via convective heat flow. Soil in the channels between gussets was maintained across a gradient of temperatures allowing a greater diversity of experimentation. The gusseted design was evaluated by germinating oat, lettuce, tomato, and melon seeds. Soil temperatures were monitored using individual, battery-powered dataloggers positioned across the table. LED lights installed in the lids or along the sides of the gradient table create a controlled temperature chamber where seedlings can be grown over a range of temperatures. The gusseted design enabled accurate determination of optimum temperatures for fastest germination rate and the highest percentage germination for each species. Germination information from gradient table experiments can help predict seed germination and seedling growth under the adverse soil conditions often encountered during field crop production. Temperature effects on seed germination, seedling growth, and soil ecology can be tested under controlled conditions in a laboratory using a gusseted thermogradient table.

Traditional thermogradient tables create a range of temperatures across the surface. Welding gussets perpendicular to the surface of a thermogradient table will control temperature in depth increasing possible research applications.

Thermogradient tables were first developed in the 1950s primarily to test seed germination over a range of temperatures simultaneously without using a ...

Production and Measurement of Organic Particulate Matter in a Flow Tube Reactor

Organic particulate matter (PM) is increasingly recognized as important to the Earth's climate system as well as public health in urban regions, and the production of synthetic PM for laboratory studies have become a widespread necessity. Herein, experimental protocols demonstrate approaches to produce aerosolized organic PM by &#945;-pinene ozonolysis in a flow tube reactor. Methods are described for measuring the size distributions and morphology of the aerosol particles. The video demonstrates basic operations of the flow tube reactor and related instrumentation. The first part of the video shows the procedure for preparing gas-phase reactants, ozonolysis, and production of organic PM. The second part of the video shows the procedures for determining the properties of the produced particle population. The particle number-diameter distributions show different stages of particle growth, namely condensation, coagulation, or a combination of both, depending on reaction conditions. The particle morphology is characterized by an aerosol particle mass analyzer (APM) and a scanning electron microscope (SEM). The results confirm the existence of non-spherical particles that have grown from coagulation for specific reaction conditions. The experimental results also indicate that the flow tube reactor can be used to study the physical and chemical properties of organic PM for relatively high concentrations and short time frames.

This paper describes the operation procedure for the flow tube reactor and related data collection. It shows the protocols for setting the experiments, recording data and generating the number-diameter distribution as well as the particle mass information, which gives useful information about chemical and physical properties of the organic aerosols.

Organic particulate matter (PM) is increasingly recognized as important to the Earth's climate system as well as public health in urban regions, and the ...

Continuous Instream Monitoring of Nutrients and Sediment in Agricultural Watersheds

Pollutant concentrations and loads in watersheds vary considerably with time and space. Accurate and timely information on the magnitude of pollutants in water resources is a prerequisite for understanding the drivers of the pollutant loads and for making informed water resource management decisions. The commonly used &#34;grab sampling&#34; method provides the concentrations of pollutants at the time of sampling (i.e., a snapshot concentration) and may under- or overpredict the pollutant concentrations and loads. Continuous monitoring of nutrients and sediment has recently received more attention due to advances in computing, sensing technology, and storage devices. This protocol demonstrates the use of sensors, sondes, and instrumentation to continuously monitor in situ nitrate, ammonium, turbidity, pH, conductivity, temperature, and dissolved oxygen (DO) and to calculate the loads from two streams (ditches) in two agricultural watersheds. With the proper calibration, maintenance, and operation of sensors and sondes, good water quality data can be obtained by overcoming challenging conditions such as fouling and debris buildup. The method can also be used in watersheds of various sizes and characterized by agricultural, forested, and/or urban land.

With the advancement of technology and the rise in end-user expectations, the need and use of higher temporal resolution data for pollutant load estimation has increased. This protocol describes a method for continuous in situ water quality monitoring to obtain higher temporal resolution data for informed water resource management decisions.

Pollutant concentrations and loads in watersheds vary considerably with time and space. Accurate and timely information on the magnitude of pollutants in ...

Continuous Hydrologic and Water Quality Monitoring of Vernal Ponds

Vernal ponds, also referred to as vernal pools, provide critical ecosystem services and habitat for a variety of threatened and endangered species. However, they are vulnerable parts of the landscapes that are often poorly understood and understudied. Land use and management practices, as well as climate change are thought to be a contribution to the global amphibian decline. However, more research is needed to understand the extent of these impacts. Here, we present methodology for characterizing a vernal pond's morphology and detail a monitoring station that can be used to collect water quantity and quality data over the duration of a vernal pond's hydroperiod. We provide methodology for how to conduct field surveys to characterize the morphology and develop stage-storage curves for a vernal pond. Additionally, we provide methodology for monitoring the water level, temperature, pH, oxidation-reduction potential, dissolved oxygen, and electrical conductivity of water in a vernal pond, as well as monitoring rainfall data. This information can be used to better quantify the ecosystem services that vernal ponds provide and the impacts of anthropogenic activities on their ability to provide these services.

Understanding the ecosystem services and processes provided by vernal ponds and the impacts of anthropogenic activities on their ability to provide these services requires intensive hydrologic monitoring. This sampling protocol using in-situ monitoring equipment was developed to understand the impact of anthropogenic activities on water levels and quality.

Vernal ponds, also referred to as vernal pools, provide critical ecosystem services and habitat for a variety of threatened and endangered species. ...

Collection and Extraction of Occupational Air Samples for Analysis of Fungal DNA

Traditional methods of identifying fungal exposures in occupational environments, such as culture and microscopy-based approaches, have several limitations that have resulted in the exclusion of many species. Advances in the field over the last two decades have led occupational health researchers to turn to molecular-based approaches for identifying fungal hazards. These methods have resulted in the detection of many species within indoor and occupational environments that have not been detected using traditional methods. This protocol details an approach for determining fungal diversity within air samples through genomic DNA extraction, amplification, sequencing, and taxonomic identification of fungal internal transcribed spacer (ITS) regions. ITS sequencing results in the detection of many fungal species that are either not detected or difficult to identify to species level using culture or microscopy. While these methods do not provide quantitative measures of fungal burden, they offer a new approach to hazard identification and can be used to determine overall species richness and diversity within an occupational environment.

Determining the fungal diversity within an environment is a method utilized in occupational health studies to identify health hazards. This protocol describes DNA extraction from occupational air samples for amplification and sequencing of fungal ITS regions. This approach detects many fungal species that can be overlooked by traditional assessment methods.

Traditional methods of identifying fungal exposures in occupational environments, such as culture and microscopy-based approaches, have several ...

Operating a Large Biochar Kiln and Implementing Best Practices

Big Box Biochar Kiln Operation and Best Practices

Big Box biochar kilns are an alternative to open pile burning that allows for in-woods biochar production in a simple metal box with no moving parts. This approach is based on technology used by charcoal makers for centuries but with a modern, mechanized approach. A mini-excavator or other piece of machinery is used to load, tend, and empty the kilns. This article will outline Big Box biochar kiln best practices, including the design, transportation, placement, loading, lighting, quenching, and dumping procedures for beginners developing their own Big Box biochar kiln programs. 
Biochar production requires a low oxygen burning environment, and the Big Box kilns use a flame-cap (sometimes referred to as a flame-curtain) method to burn material with limited smoke production. These kilns have been designed to be easily transferred to the site using an adequately rated trailer. A mini-excavator or other piece of machinery is used to load, tend, and empty the kilns. The author is not aware of a more accessible means for people to sequester durable carbon on the farm, ranch, or in the backyard. This article outlines Big Box biochar kiln best practices, including the design, transportation, placement, loading, lighting, quenching, and dumping procedures for beginners developing their own Big Box biochar kiln programs.

Installation of the Big Box Biochar Kiln for Biochar Production

The Utah Biomass Resources Group (UBRG) has scaled-up simple biochar kilns in an innovative approach to hazardous fuel reduction and biochar production using metal boxes, called Big Box kilns, that allow for in-woods biochar production. This article outlines Big Box biochar kiln operation and best practices.

Big Box biochar kilns are an alternative to open pile burning that allows for in-woods biochar production in a simple metal box with no moving parts. This ...

Carbon Sequestration and Soil Enhancement Through Onsite Biochar Production

Producing, Characterizing and Quantifying Biochar in the Woods Using Portable Flame Cap Kilns

One of the biggest challenges in utilizing non-commercial forest biomass is its widely distributed nature. The best solution to the biomass problem, to avoid expensive and carbon-intensive processing (chipping) and transportation costs, is to process it onsite. However, conventional burn piles have destructive impacts on forest soil and provide no benefits other than fuel reduction. Converting forest slash to biochar onsite has many ecological advantages over the current practice of slash disposal by incineration in burn piles, including reduced soil heating and particulate emissions, along with multiple benefits of the biochar to forest soil health and water holding capacity when left in place. Making biochar onsite in the woods is a way to return a pyrogenic carbon component to forest soils that has been missing due to the recent history of fire suppression. Biochar is also a leading method of carbon removal and sequestration for climate change mitigation. In this study, we document a method for making biochar using a portable biochar kiln. This low-cost method utilizes hand crews equipped with water for quenching kilns before the biochar burns to ash. Simple techniques for quantifying and characterizing the biochar produced are incorporated into the method for the purpose of measuring impact and qualifying for carbon removal certificates to help pay for the cost of the work. We describe the CM002 Component Methodology that provides standardized procedures for the quantification of GHG benefits during three stages of the process: waste biomass sourcing, biochar production, and biochar soil application. The CM002 Methodology is based on international best practices, including the most recent VCS methodology VM0044 Standards and EBC C-Sink Artisan Standards. Reliable quantification methods utilizing appropriate safety factors are the first essential step toward eligibility for carbon removal finance.

Author Spotlight: On-Site Biochar Production for Woody Debris Incineration in Forestry 

New methods for disposing of forestry slash piles in place produce pyrogenic carbon for restoring forest soil health and for carbon removal and sequestration. Here, we present a biochar production method integrating a new carbon removal accounting methodology and a digital application.

One of the biggest challenges in utilizing non-commercial forest biomass is its widely distributed nature. The best solution to the biomass problem, to ...