Portable Dry Kiln Demonstration and Outreach
Why Kiln Dry?
Many pests, diseases, and pathogens have resulted in Federal regulations that restrict movement of wood products. Movement of infested wood products is seen as one of the most likely pathways for spreading new pest outbreaks. Key threats in the United States include the Asian longhorned beetle, hemlock wooly adelgid, sirex wood wasp, emerald ash borer, pine shoot beetle, European larch canker, sudden oak death, and thousand cankers disease. The impact of these outbreaks can be staggering and threaten a forest products industry that contributes over $230 billion to the U.S. economy each year. Managing the emerald ash borer outbreak alone has cost over $10.7 billion. These issues are not going away. The National Insect and Disease Risk Map project uses 188 models to predict how different tree species will react to various threats. The 2006 map shows 58 million acres at risk in the United States. Other studies paint a similarly dismal picture, with models suggesting a 32% chance of another major U.S. wood borer crisis within the next 10 years. This same research estimates that wood borers cost local governments $1.7 billion per year and annually lower private property values by $830 million.
Fortunately, there are proven methods for utilizing wood without contributing to the spread of forest pests. While specific treatment options depend on the particular insect or pathogen targeted, the emerald ash borer infestation provides a good example for describing treatment protocols. The EAB's infestation only penetrates about one inch deep into an affected log. This means that wood products are generally accepted as safe (and thereby not posing risk as a vector for pest movement) if they are kiln-dried, heat treated, fumigated, or bark-free. Kiln-drying and heat treatment are largely seen as the most viable and practical options for sanitization of forest products. These options create a real opportunity to obtain value from infested trees in a way that does not threaten forest health. As with all issues relevant to state and federal safety quarantines, processors should check with regulatory agencies prior to determining a treatment plan for infested wood.
Kiln drying also holds significant potential for improving the economic value and marketability of forest products. Having appropriate moisture content in wood is critical for maintaining quality in most applications. Air drying wood does reduce the moisture content of lumber, but not beyond the point where it is in equilibrium with ambient air conditions (typically to ~15-20% MC). For wood to be suitable for indoor applications, particularly where rooms are climate controlled, a much lower moisture content is required (~6-8%) in order to prevent the wood from warping, checking, shrinking, or otherwise degrading. Overall, kiln drying improves the market options and adds value to most wood products. While estimates vary greatly, reports show a net increase of $125-$1000 in value per 1,000 board feet when lumber is kiln dried. Finally, purely from a transportation viewpoint, kiln dried wood weight significantly less than green or air-dried wood and is more affordable when shipping is required.
Portable Dry Kiln Technology
Unlike the popularity of portable sawmill operations, which are extremely common (even in major metropolitan areas), kiln services are not as widespread in most regions. Especially for users such as small woodlot owners or community forestry operations with infrequent wood drying needs, hauling lumber to a kiln can add major investment to an already complicated process. In an effort to promote greater utilization and value-added processing of removed urban trees, California Department of Forestry and Fire Prevention began leasing both portable Wood-Mizer sawmills and portable dehumidification kilns to local governments and nonprofit organizations beginning in 2001. The project promoted the creation of dimensional lumber, wood turning blanks, finished furniture, and custom products, all from salvaged trees. Their rationale for the portable kilns was to provide an accessible, mobile, easily powered (electric), and easy-to-use option to add value to wood without a significant capital investment. This leasing program is still in operation in 2013.
Following this model, Advanced Technologies and Land Services (ATLS) of Niles, Michigan, applied for a Natural Resources Conservation Service Conservation Innovation Grant to duplicate this portable technology and to bring it to Michigan in 2013. The ATLS team converted an insulated box trailer into a portable drying unit with the installation of a Nyle dehumidification kiln. The Sustainable Resources Alliance (formerly the Southeast Michigan RC&D Council) was selected by ATLS to conduct a training workshop around this concept. The workshop, held on September 6, 2013 at Michigan State University's Department of Forestry, included information on basic forest management, forest health threats, principles of wood utilization, and the primary concepts of kiln drying. The workshop was intended to target forest landowners, urban and community forestry managers, and NRCS cost-share participants (primarily agricultural owners of small woodlots). In order to make this information accessible to all interested parties, the SRA is providing recorded footage of the event through the links below.
Forest Management: Mike Smalligan - Smalligan Forestry, LLC
Higher-Value Wood Utilization: Jessica Simons - Southeast Michigan RC&D Council
Building a Portable Dry Kiln: Mike Studer - Advanced Technologies and Land Services
Wood Drying 101: Dr. Pascal Nzokou - Michigan State University Department of Forestry
This project was funded through a contract from Advanced Technologies and Land Services with Conservation Innovation Grant funding from the USDA Natural Resources Conservation Service. Michigan State University's Department of Forestry provided essential technical assistance and support to this project. Partners in this project are equal opportunity providers and employers.