Utilizing Woody Biomass

printed in the Kittitas County Conservation District April 2009 newsletter

By Thembi Borras

What is Biomass?
In the context of forests, a definition of biomass is woody material that accumulates to an amount that becomes a hazard or a management or disposal problem. Biomass is generated during fire hazard reduction, forest health improvement and from logging, it includes:
· Branches from pruning
· Small diameter trees from thinning
· Slash (tree tops, branches, broken stems) from operations

The Development of Biomass
Biomass is, in part, stored carbon and nutrients, the products of unique processes of plants.

Photosynthesis changes inorganic carbon (carbon dioxide) into organic carbon (carbohydrate). Organic carbon is translocated in vascular tissue from a source, such as a mature needle, to a sink such as roots, the tree bole, and developing cones. Organic carbon is used by the tree to increase biomass and provides the energy to build and maintain that biomass.

Transpiration transports minerals from the soil throughout the plant. In the above ground part of the tree, the needles, leaves, twigs and branches contain a significant portion these nutrients.

The following is excerpted from Keeping Our Forest Soils Healthy and Productive, a publication of WSU Extension. “Removing tree trunks may have little effect on site productivity, but “cleaning up” branch­es and foliage (i.e., slash) appears to have greater potential for nutrient removal than leaving them onsite.”

Biomass Treatment Today
Usually biomass is seen as a nuisance to be disposed of quickly to reduce fire hazard, improve aesthetics and minimize habitat for undesirable insects. The least expensive way to get rid of biomass has been to pile and burn it, but in doing so carbon dioxide is released and the heat and energy created by combustion is not utilized. Also, the nutrients, nitrogen, phosphorus and sulfur, stored in the biomass are volatilized and lost to the atmosphere while other nutrients such as calcium, magnesium and potassium become available in the short term, but are easily leached.

Biomass Utilization
Biomass is a resource and higher and better uses for it include:
· Biomass may be left on-site, which will likely require that it be modified to reduce fire hazard, improve aesthetics and minimize habitat for undesirable insects. Modification methods include lopping and scattering and chipping. Slash may also be crushed into road surfaces no longer in use to augment existing drainage and reduce surface erosion. In this scenario, the release of carbon and nutrients stored in the biomass is metered. Note: Wood chips are one of the best mulch choices for trees and shrubs. They perform well in terms of moisture retention, temperature moderation and weed control. For more information, go to http://www.puyallup.wsu.edu/~Linda%20Chalker-Scott/Horticultural%20Myths_files/Myths/Wood%20chips%202007.pdf
· Biomass, in the form of logs as short as 12’ and with a small end diameter of 2”, may be sold into the chip market. For example, a local landowner may be able to cover operational and hauling expenses if they are within 10 miles of the chipping facility in Cle Elum. Biomass may also be chipped before it is hauled; more biomass can be hauled in chip form than as logs. The advantage of this scenario is that it may help offset the cost of fire hazard reduction or forest health improvement projects. Note: Chips may be used in the pulp industry for paper, rayon or lyocell or the engineered wood products industry. Try to schedule fuel reduction projects to begin after Sept 1 when trees are beginning to go into dormancy when beetles are not as attracted to fresh cuts and slash. Also, in most circumstances, if the project yields less than 5,000 board feet of timber per 12 month period and will be used by the landowner, a Forest Practice Application/ Notification is not needed. Otherwise, a Forest Practice Application/ Notification must be approved by the Washington Department of Natural Resources before operations begin.
· Biomass can be burned in controlled systems to produce heat and/or energy. At the smallest scale, firewood for home heating systems can be gleaned from slash piles that would otherwise be burnt. The following are the approximate number of British Thermal Units (BTUs) produced per air dried cord burned of local species that may be found in a slash pile. Douglas-fir generates 21 million BTUs, white fir 20 million BTUs and ponderosa pine 17 million BTUs. A BTU is the amount of heat necessary to raise one pound of water by 1 degree Fahrenheit (F). A million BTUs equal 293 kilowatt hours. Therefore, one cord of Douglas-fir represents 6,153 kilowatt hours, a number of interest if you heat with electricity. For more information about this opportunity contact the Washington State Department of Natural Resources, the Southeast Headquarters of which can be contacted at 509-925-8510 or the United States Forest Service, which can be contacted at 509-962-9813; usually permits are available by the beginning of June. At a larger scale, biomass may be burned to create heat and/or energy for community facilities such as schools and hospitals. The Enterprise School replaced its oil boilers with an automated wood chip boiler. Due to rising heating oil costs, the school is projected to save over $110,000 annually on energy costs with the new system. To watch a video about this project, go to http://www.sustainablenorthwest.org/quick-links/resources/biomass/the-enterprise-school-project. The following is excerpted from the 2008 publication Where Wood Works Strategies for Heating with Woody Biomass prepared by the Flexible Energy Communities Initiative, “Chip systems are well-suited for large buildings and campuses. Successful projects get their chips locally, usually within 30 miles or so. Chip-handling systems are complex and expensive to build and operate. This is offset by the low cost of the fuel.”
· Biomass may be sold into the compost market.Biomass in the form of small diameter logs may be peeled into round wood products such as poles and posts or sawn into dimensional lumber.

Challenges
Challenges to biomass utilization include hauling distance to markets, processing cost, quality of product and storage. Overcoming these challenges, by in part, developing local markets may be advantageous in job creation, fire hazard reduction, forest health improvement and community self sufficiency.

Thembi Borras is a forester living and working in Kittitas County, WA and can be contacted by email at thembi@mcn.org.