Special Session: Extending the LCA Concepts of Sustainable Forest Product Utilization

Typical product life cycle assessment provides an environmental performance on a static condition which can be problematic. This special session will focus on discussing new forest product LCA concepts that are currently being incorporated regarding forest product utilization. Specifically, sustainable utilization of forest products have begun to consider spatial and temporal emissions to fully capture the full environmental and human-health impacts for bioenergy and bio-based products made from wood.

CHAIR: Hongmei Gu
LOCATION: 2311
08:30 Francesca PierobonCody SiffordIndroneil Ganguly and Ivan Eastin

Environmental impact assessment of prescribed fires incorporating air chemistry and pollutants dispersion in the Pacific Northwest

ABSTRACT. In the Pacific Northwest (PNW) a large portion of the harvest residue produced by forest operations is commonly collected, piled and burned in prescribed fires. Fires are responsible for the emission of a large amount of chemicals including particulate matter, organic and inorganic compounds and heavy metals, with potential impact on human health. The impact on human health is not only related to pollutants toxicity, but it also depends on their fate and on human exposure. Air chemistry and physics as well as the background air quality determine pollutants fate and exposure, largely varying based on site characteristics. Despite the importance of site-specific variables to determine the impact on human health, currently in LCA the scientific consensus model used for human health impact assessment – USEtox – is developed with continental and global spatial scales. This study aims to develop a geo-spatially nuanced Life Cycle Impact Assessment tool to assess the environmental and human health impacts associated with prescribed fires in the PNW region by incorporating the outputs from BlueSky and AIRPACT programs. BlueSky is a framework for fire modeling which modularly links numerous fire emissions and dispersion models to site-specific fire information and loading. AIRPACT is a computerized system for predicting air quality in the PNW by calculating the chemistry and physics of air pollutants as determined by pollutants emissions within the context of natural air chemistry and predicted meteorology. Combining the two models it was possible to simulate the behavior of the chemicals emitted in prescribed fires, regarding their fate and human exposure to determine site-specific characterization factors to be used within the LCA framework to evaluate environmental and human health impacts in the PNW region. The proposed approach has proven key to perform a precise and meaningful evaluation of local life cycle impact in order to manage and minimize prescribed fires.

08:45 Cindy ChenRene ZamoraIndroneil GangulyJohn SessionsIvan Eastin and Francesca Pierobon

Extending the LCA Concepts of Sustainable Forest Product Utilization: Modeling the Collection and Transportation Logistics of Forest Residues using Life Cycle Assessment

ABSTRACT. The expansion of wood-based bioenergy has provided new uses for these residues on top of traditional residual treatment such as slash pile burning, but the environmental impacts of residue collection and transportation need to be studied to determine the feasibility of such operation. Geographical location and topographical characteristics can influence the environmental impacts associated with the delivery of woody biomass to bioenergy production facility. Although many studies have investigated the emissions produced from bioenergy production, few have taken road conditions and distance into account. The study focuses on investigating the environmental impacts of three collection and transportation system scenarios under different road conditions (paved highway, gravel road, and dirt road) and distance allocations using life cycle assessment (LCA). The system scenarios are 1) Bin truck with stationary grinder at centralized landing, 2) Bundling in forest with electric grinder at facility, and 3) Mobile chipper with set-out trailer. With the total distance set to 50 miles, the distance of dirt road was set constant at 1 mile, and the distance for paved highway increased from 45% to 85%. The objective of the study is to estimate the emissions produced by each system scenario and the impact of road conditions on the overall emissions. The results suggested that as the distance of paved highway increases, the global warming potential (GWP) decreases in all systems, particularly for system 1 (from 41.36 kg CO2 eq. to 34.17 kg CO2 eq.). This may be due to the higher emissions from bin truck. The mobile chipper system appears to be the most efficient since it is able to reach the slash piles directly, eliminating the need for two transportation stages. The collection and transportation of forest residues play an important role in the biofuel production chain. The economic and environmental burden directly influence the feasibility and demand of biofuel. The results of this study can serve as a reference when developing bioenergy facilities to determine the best location outside the forest site and for estimating the appropriate locations for slash piles.

09:00 Hongmei Gu and Richard Bergman

LCA study for pilot commercial scale production of cellulose nanocrystal (CNC) from wood.

ABSTRACT. Nanotechnology in forest products and production of cellulose nanocrystals (CNC)/cellulose nanofibrils has been growing rapidly with close attention from the pulp and paper industry, governments, universities and research institutes. Nanocellulose has been found in many advanced applications for material enhancement and product improvement. New CNC product technologies have been intensively studied. However, life-cycle analysis (LCA) research that has been conducted on these nano products and their associated production has been primarily on lab-scale operations. Soon with more and more CNC enhanced new products being developed to substitute fossil based products, the basic material CNC’s LCA information will be required for the enhanced products’ environmental impacts. Therefore, such LCA studies on CNC are very important and will be the basis for further research in the field of nanocellulose.

The paper will also lay out a framework on what LCA can do to identify environmental “hotspots” and thus improve nanocellulose production on an environmental basis while enabling nano products’ market penetration. In addition, present LCA research and projects on current nanocellulose technologies will be presented. The primary focus of the paper will be a preliminary LCA conducted on a nanocellulose pilot-scale production line recently developed at the USDA Forest Service Forest Product Laboratory. The pilot-scale operation is only one of the three pilot-scale productions for CNC from wood pulp in North American and produces 25 kg of CNC per batch (or 50~75 kg per week). Once completed, the life-cycle impact assessment results will be used for scaling up to the commercial product line that can produce 1 tonne of CNC per day.

09:15 Blane Grann

A review of carbon loss from wood products in anaerobic landfills

ABSTRACT. Organic materials decompose in anaerobic landfills releasing CO2 and CH4. However, only a fraction of the total organic carbon is released through anaerobic decomposition whereas the rest remains stored in landfills. The fraction which decomposes is referred to by the IPCC (2006) as the fraction of degradable organic carbon that decomposes (DOCf). In this presentation, assumptions and empirical estimates of wood product decomposition in anaerobic landfills are reviewed.

For landfilled wood products, the interquartile range of DOCf in model assumptions in the literature was found to be 9.0-36%. In contrast, the interquartile range of reported empirical estimates for the DOCf of wood products was found to be 0.0-13%.

Empirical methods used to estimate carbon loss have been based on mass balance principles measuring C emissions (as CO2 and CH4), or initial and final carbon content, and have been conducted in both laboratory and landfill conditions. Potential limitations of empirical estimated include: a) adopting a correction factor based on the original and final lignin content, and b) violating mass balance principles by limiting carbon estimates to cellulose, hemicellulose and lignin constituents. Challenges associated with measuring carbon loss from landfill samples have led some authors to use a correction factor (a ratio of the initial and final lignin content of the samples) to estimate the final C content of test samples in terms of the original mass of material. The application of this correction factor was premised on the assumption that lignin does not degrade in anaerobic landfill conditions. However, methods applying this correction factor are potentially invalid given that lignin measurements were based on Klason lignin methods, and Klason lignin has recently been shown to undergo either degradation or re-polymerization in anaerobic conditions (De la Cruz et al. 2014).

These results have important implications for waste management decision support life cycle assessments involving wood products and improving our understanding of the carbon cycle of forest products. To improve accuracy of DOCf estimates, future estimates should be based on mass balance principles that rely on either measurements of CO2 and CH4, or the difference between initial and final C content. As a cross-validation step, both methods should be simultaneously applied.

References

De la Cruz, F. B., Yelle, D. J., Gracz, H. S., & Barlaz, M. A. (2014). Chemical Changes during Anaerobic Decomposition of Hardwood, Softwood, and Old Newsprint under Mesophilic and Thermophilic Conditions. Journal of Agricultural and Food Chemistry, 62(27), 6362–6374. http://doi.org/10.1021/jf501653h