Hazardous Fuels Reduction Using Flame Cap Biochar Kilns
Hazardous fuels are a problem across the West. From 2000-2017 bark beetles affected 85,000 square miles of forests in the western U.S. (an area the size of Utah). The accumulation of this beetle-killed timber occupies many forested slopes posing a fire risk to citizens, landscapes, and nearby infrastructure. Additionally, invasive species such as Russian olive (Elaeagnus angustifolia L.) and tamarisk (Tamarix spp.) choke streams and rivers and prevent native species from growing and supporting the ecosystem. The accumulation of hazardous fuels such as beetle-killed timber and invasive species is dangerous, additionally as dead and dying trees decompose through cellular respiration, greenhouse gases (CO2 and CH4 methane) are released into the atmosphere. To deal with this excess fuel, trees are removed from forests generating large quantities of "waste wood". This waste wood is commonly called slash; it is often piled and burned (known as pile burning), releasing stored carbon and greenhouse gasses into the atmosphere (figure 2). While effective for dealing with large quantities of slash, piling and burning results in extreme heat pulses into the ground, which has negative consequences on the physical, chemical, and mineralogical properties of the soil under the slash piles (Arocena & Opio, 2003; Jiménez Esquilín, Stromberger, Massman, Frank, & Shepperd, 2007).
An innovative alternative to this approach utilizes fire to dispose of slash, but contains the fire in simple metal kilns (figure 3). When compared to the pile and burn method, this approach produces considerably less smoke, does less damage to the soil, is safer, extends the season possible for fuel reduction efforts, sequesters carbon, and yields biochar, a charcoal like product made from organic material.