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 border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>CharBoss air curtain burner</td>
			<td>Air Burners, Inc.</td>
			<td>T26</td>
			<td>Comes with 36&#34; landscape rake, sifting shovel, 1/2&#34; drive standard ratchet with 1 1/8&#34; 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.&#160; 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&#160;</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.&#160;</td>
		</tr>
		<tr>
			<td>Wheel chocks</td>
			<td></td>
			<td></td>
			<td>Blocks of 4&#34;x 4&#34; lumber or commercially available chocks while hitching/unhitching unit</td>
		</tr>
		<tr>
			<td>Personal protective equipment</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>Emergency gear</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 ...

Our research focuses on implementing place-based biochar production methods as a strategy to reduce hazardous fuels in the forest while simultaneously improving forest and soil health. Currently, most biochar is created in large-scale bioenergy plants, but place-based technologies have a place in many areas where it's too expensive to ship low value woody residues or where infrastructure is lacking. We have learned the appropriate application rates, production methods, and additional uses for in-woods-produced biochar.We're beginning to understand its usefulness for mine site restoration, reduction of invasive weeds, and soil health benefits.

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

Research

JoVE Journal

Environment

625 Views.  USDA Forest Service, Rocky Mountain Research Station. Our research focuses on implementing place-based biochar production methods as a strategy to reduce hazardous fuels in the forest while simultaneously improving forest and soil health. Currently, most biochar is created in large-scale bioenergy plants, but place-based technologies have a place in many areas where it's too expensive to ship low value woody residues or where infrastructure is lacking. We have learned the appropriate application rates, production methods, and additional uses for...

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

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 ...

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. ...

Construction of a Compact Low-Cost Radiation Shield for Air-Temperature Sensors in Ecological Field Studies

Low cost temperature sensors are increasingly used by ecologists to assess climatic variation and change on ecologically relevant scales. Although cost-effective, if not deployed with proper solar radiation shielding, the observations recorded from these sensors will be biased and inaccurate. Manufactured radiation shields are effective at minimizing this bias, but are expensive compared to the cost of these sensors. Here, we provide a detailed methodology for constructing a compact version of a previously described custom fabricated radiation shield, which is more accurate than other published shielding methods that attempt to minimize shield size or construction costs. The method requires very little material: corrugated plastic sheets, aluminum foil duct tape, and cable ties. One 15 cm and two 10 cm squares of corrugated plastic are used for each shield. After cutting, scoring, taping and stapling of the sheets, the 10 cm squares form the bottom two layers of the solar radiation shield, while the 15 cm square forms the top layer. The three sheets are held together with cable ties. This compact solar radiation shield can be suspended, or placed against any flat surface. Care must be taken to ensure that the shield is completely parallel to the ground to prevent direct solar radiation from reaching the sensor, possibly causing increased warm biases in sun-exposed sites in the morning and afternoon relative to the original, larger design. Even so, differences in recorded temperatures between the smaller, compact shield design and the original design were small (mean daytime bias = 0.06 &#176;C). Construction costs are less than half of the original shield design, and the new design results in a less conspicuous instrument that may be advantageous in many field ecology settings.

With the advent of small, low-cost environmental sensors, it is now possible to deploy high-density networks of sensors to measure hyper localized temperature variation. Here, we provide a detailed methodology for constructing a compact version of a previously described custom-fabricated radiation shield for use with inexpensive thermochrons.

Low cost temperature sensors are increasingly used by ecologists to assess climatic variation and change on ecologically relevant scales. Although ...

In Situ Soil Moisture Sensors in Undisturbed Soils

Soil moisture directly affects operational hydrology, food security, ecosystem services, and the climate system. However, the adoption of soil moisture data has been slow due to inconsistent data collection, poor standardization, and typically short record duration. Soil moisture, or quantitatively volumetric soil water content (SWC), is measured using buried, in situ sensors that infer SWC from an electromagnetic response. This signal can vary considerably with local site conditions such as clay content and mineralogy, soil salinity or bulk electrical conductivity, and soil temperature; each of these can have varying impacts depending on the sensor technology.
Furthermore, poor soil contact and sensor degradation can affect the quality of these readings over time. Unlike more traditional environmental sensors, there are no accepted standards, maintenance practices, or quality controls for SWC data. As such, SWC is a challenging measurement for many environmental monitoring networks to implement. Here, we attempt to establish a community-based standard of practice for in situ SWC sensors so that future research and applications have consistent guidance on site selection, sensor installation, data interpretation, and long-term maintenance of monitoring stations.
The videography focuses on a multi-agency consensus of best-practices and recommendations for the installation of in situ SWC sensors. This paper presents an overview of this protocol along with the various steps essential for high-quality and long-term SWC data collection. This protocol will be of use to scientists and engineers hoping to deploy a single station or an entire network.

In Situ Soil Moisture Sensors in Undisturbed Soils

The determination of soil water content is a critical mission requirement for many state and federal agencies. This protocol synthesizes multi-agency efforts to measure soil water content using buried in situ sensors.

Soil moisture directly affects operational hydrology, food security, ecosystem services, and the climate system. However, the adoption of soil moisture ...

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 ...