Author

Binod Neupane

Date of Award

5-2011

Level of Access

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Forest Resources

Advisor

Anthony Halog

Second Committee Member

Jeremy S. Wilson

Third Committee Member

Jeffrey G. Benjamin

Abstract

A clean and sustainable source of energy is important for the development of a nation. The replacement of fossil fuels with renewable energy is an important strategy promoted by oil consuming countries, notably the U.S. Among the explored sources of alternative energy, ethanol from biomass has garnered much support owing to its renewal and domestic label. Nevertheless, the environmental benefits from bioethanol production depend on the production and processing operations of feedstocks, and fuel and other material inputs during feedstock growth. Similarly, forest biomass harvesting has issues on land use and biodiversity impacts. As a result, environmental and economic viabilities along with potential impacts on land use and biodiversity are important factors for consideration before embarking on a large scale commercial production of bioethanol. One of the tools to assess the environmental sustainability of a product system is life cycle assessment (LCA), which accounts resources consumption and environmental emissions across all life stages of a product. The major life cycle impact categories considered in current LCA practice include climate change potential, acidification potential, eutrophication potential, photochemical oxidants, fossil fuel depletion, fresh water toxicity, etc. Conventional LCA methodology, however, does not account for biodiversity impacts and land use implications in its current methodological framework. This research first applies the conventional LCA approach to analyze the environmental impacts of woodchips production in view of the impending large scale bioethanol production in the U.S. Two types of forests are considered: naturally and artificially regenerated forests. The results show that the dominant environmental contributors in both scenarios for woodchips production are climate change potential and human toxicity potential. Most of the impacts are due to the combustion of fossil fuels (i.e. diesel) used for operating machinery and transportation. The other component of this study is the development of a framework to incorporate biodiversity impact category into the existing LCA method. It applies this framework in the context of woodchips production used in biorefinery for ethanol production. In the revised framework, the Landscape Management System (LMS) tool is used to model forest management activities for a set of harvesting systems under consideration. Forest stands level information, such as habitat type and stand development stages, are used to prepare a habitat-species relationship matrix. This matrix information was incorporated into LCA inventory modeling to prepare a set of characterization factors. Habitat type classifications and corresponding area calculations are spatially presented using Geographical Information Systems (GIS). Different biodiversity impact indicators (e.g. species richness and habitat naturalness, etc.) are used to model the biodiversity impact. The results show that biodiversity impact increases linearly as the ethanol blending proportion to gasoline is increased. The potential biodiversity impact is found to be higher in the first decade of the considered time frame, and it shows a leveling trend towards the next decades. From this analysis the general conclusion is drawn that when a whole rotation length of forest is considered, the potential biodiversity impact is relatively unchanged after the first few decades.

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