Arboriculture & Urban Forestry 37(1): January 2011 products. During the interviews, yard owners identified two key reasons for the lack of milling activities. First, land clearing operations typically buck logs into short unusable lengths, and second, the costs and challenges of processing and transporting logs are excessive, particularly for owners of the larger yards. As discerned in the results of the survey questionnaire analysis, yard owners and managers typically criticized the regulation as- sociated with the emerald ash borer eradication program (particu- larly the free wood disposal yards that were established in south- eastern Michigan) as responsible for overall market decline in the region’s wood disposal industry. However, many of the compa- nies that were visited are considering new value-added markets, and three major product types were mentioned: production of pellets, exports of mulch and chips to larger metropolitan areas in the U.S. and Canada, and production of fuel for home stoves. Evaluation of Economic Impact and Potential Alternative Products The supply and production data presented here clearly show wood waste processing facilities have a very important economic impact on the region. These processing facilities provide more than 1,000 permanent jobs, while also processing and marketing significant volumes of material necessary for southeastern Mich- igan landscapes and energy plants. Based on production levels and average selling prices for the various products, the industry contributes $40 million to the local economy. However, for a bet- ter understanding of the full potential of wood residue process- ing facilities, a detailed evaluation of the industry is necessary. The highest-valued utilization of wood residue is typically in the reuse of wood as building materials or interior wood prod- ucts. However, several barriers currently exist that limit the pro- duction of solid wood materials from wood residues. Most wood residues supplied to processing facilities came from land clearing and tree removals. Since land clearing and tree removal activities occur for reasons other than the wood’s ultimate use as a product, trees are not evaluated for their grade or product potential be- fore they are harvested and processed. Furthermore, the compa- nies that perform harvesting and processing operations typically have no direct interest, incentive, or equipment to process and handle large logs in the field. As a result, the logs are usually cut into smaller length for ease of handling, thereby limiting the amount of intact wood available for the higher-valued products. As it currently stands, the volume of timber-quality logs di- rected to these yards is too low (less than 5% of the total wood supply) to justify any serious effort to develop higher-grade solid wood products. It has been demonstrated that wood obtained from land clearing and other tree removals can be milled and used for such items as furniture, trim work, cabinetry, or floor- ing (Bratkovich 2001; Sherrill 2003). However, access to the ap- propriate infrastructure, training, equipment, and markets will be necessary to see any significant movement from the wood dis- posal yard industry in this area. Based on observations made for the present study, it would be possible to increase the relative proportion of log recovery from 5% to 30% of the total wood volume. This could raise the total volume of good quality logs entering disposal yards from 0.08 million tons to 0.48 million tons. Consequently, this also could bring about significant chang- es in the quality and range of products produced at these yards. 17 Another critical difficulty in maximizing the value-added po- tential arises from the uncertainty about the quantities and spe- cies a wood residue processing facility can expect to receive in any given period. These factors pose serious supply challenges to any facility owner desiring to specialize in the production of high-end wood products. Despite the current difficult economy, several processing facilities are assessing new market conditions and desire to take advantage of opportunities by developing other types of higher-value end products, such as wood pellets for the domestic, home-use market and for the export market to Canada. Engineered wood products (e.g., particleboard, oriented strand board, and wood-plastic composites) are another viable product option for this industry (Chow and Zhao 1992). Even when using recovered wood residues, the composite manufacturing process can be achieved if clean and premium materials are used. More research is needed to evaluate the mechanical and physical prop- erties of wood composites manufactured with varying material quality, composition, and species combinations. In addition, a cost- benefit analysis should be conducted to fully assess the economic potential of using yard residues for wood composite products. As both state and federal incentives develop to support a devel- oping bioenergy sector, wood-to-ethanol also emerges as a potential value-added option for wood residues (Petersen et al. 2005). This fermentation process can be done chemically (using acid hydroly- sis) or biochemically (using enzymes), resulting in a product that can be purified and distilled to produce liquid fuel. Biomass feedstocks also can be used to produce other biofuels. Thermal processes can be used to convert the biomass directly to a synthesis gas (syngas) composed of carbon monoxide and hydrogen. However, residues from processing yards would have to be combined with wood from other sources to produce the quantities necessary to supply chemi- cal processing facilities. Therefore, clear standards defining the acceptable properties and conditions of the raw materials would need to be developed to maintain efficient biochemical processes. CONCLUSIONS The goal of this study was to assess the collection and processing of wood residue resources in southeastern Michigan and to evalu- ate potential products for this material. The study found a total 180 facilities and 23 landfills were operating in the study area’s 14 counties, employing an estimated 1,082 people. A total volume of 6,659.6 thousand m3 (5.3 million tons) was supplied to processing facilities leading to a production volume of 2,035.8 thousand m3 (1.6 million tons). This corresponds to a conversion rate of approx- imately 30%, leaving significant opportunity for additional wood recovery and product development efforts. Merchantable logs rep- resented only 5% of the total supply volume, too small to economi- cally justify any extensive effort to develop conversion processes into value added solid wood products. Bottlenecks for improved processing included the handling of trees and logs at the harvesting site, accessibility, and the need to invest in expensive equipment with low potential returns. However, the study suggests that with proper equipment and training, the proportion of quality logs di- rected to wood residue processing facilities could be increased from 5% to 30% of the total supply, thus creating a large enough sup- ply, and economically justifiable for a strategic shift towards val- ue-added solid wood products. In addition, if processing facilities create a sorting mechanism to separate wood by quality, this will help maximize the potential value for each load arriving at yards. ©2011 International Society of Arboriculture
January 2011
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