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

Summary

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.

Abstract

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., 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.

Introduction

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 times^1,2. 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....

Protocol

NOTE: Additional details on the operation of the BACB can be found in the operator's manual that comes with the equipment.

1. Transportation to site

1. 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.
2. M.......

Discussion

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.......

Materials

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