Date of Award

8-2011

Level of Access

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Forest Resources

Advisor

Anthony Halog

Second Committee Member

Jonathan Rubin

Third Committee Member

Stephen M. Shaler

Abstract

Over the next decade, wood will likely experience substantial growth as an energy feedstock in the US driven largely by the national desire for energy independence and a cleaner fuel source. The two studies contained here within center on the topic of life cycle assessment (LCA) and its application to forest-based energy production. LCA is a tool for estimating resource consumption and environmental impacts associated with a product system. The first study is a technology-based LCA of an emerging forest biorefinery. More specifically, an LCA of wood panels, ethanol and acetic acid co-produced at an oriented strandboard (OSB) biorefinery is performed. This study applies an existing LCA methodology to inform the research and design process by identifying environmental strengths and weaknesses of the OSB biorefinery. Under the baseline assumptions, the OSB biorefinery performs well on toxicity-related measures compared to a conventional gasoline, acetic acid, and OSB system. Global warming potential (GWP), however, increases compared to the conventional system. Several alternative scenarios are formulated to account for uncertainty about the manufacturing process. Based on the most sensitive parameters a target production process is identified that offers substantial reductions in both toxicity and GWP measures. The second study addresses broader policy-level questions regarding the future of forest-based bioenergy consumption in the US: (1) What are the potential market effects and related environmental impacts of widespread adoption of forest-product biorefining and (2) How might various federal biomass restrictions alter these effects? A common economic technique called partial equilibrium (PE) modeling is integrated with LCA to address these questions. More specifically, the output from an existing PE model called the US Forest Products Module (USFPM) is characterized using life cycle inventory (LCI) data. The integrated framework developed is called USFPM-LCA. Potential economic and environmental effects of two competing policy definitions for renewable biomass are analyzed using USFPM-LCA: the Energy Independence and Security Act (EISA) of 2007 and the 2008 Farm Bill. The USFPM projections suggest that even when fuel feedstock demand rises dramatically, similar sources of wood are utilized under both EISA 2007 and Farm Bill 2008 definitions—primarily softwood pulpwood and logging residues from the southern US. Additionally, mill fuel residues will likely be used to some degree. Likewise, the subsequent impacts on domestic and international production of other forest products are similar for both definitions. After characterizing USFPM output using LCI data, three types of indirect greenhouse gas (GHG) impacts were identified. The first results from the substitution of ethanol for gasoline; the second from substituting natural gas for mill fuel residues; and the third due to changes in magnitude and location of production among all forest product sectors. Although substituting wood-based ethanol for gasoline has the potential to reduce GHGs by over 60%, if mill fuel residues are sold by manufacturers as fuel feedstock these environmental benefits could easily be offset. The indirect GHG impacts due to changes in the magnitude of production, or parallel product impacts, appear to relatively small at about 5-8% of gasoline's life cycle impacts.

Share