Thesis
Life cycle assessment of biofuel from poplar trees and switchgrass in the Inland Pacific Northwest United States
Washington State University
Master of Science (MS), Washington State University
12/2019
DOI:
https://doi.org/10.7273/000003988
Handle:
https://hdl.handle.net/2376/124295
Abstract
Climate change and increased energy demand have led to the search for alternative sources of energy with low or no global warming potential (GWP). Energy crops are a promising alternative to fossil fuels for a renewable energy future. Both poplar trees and switchgrass are attractive options for perennial energy crops for biofuel production. In this study, a life cycle assessment (LCA) methodology was used to evaluate three agricultural systems. These systems are monoculture poplar trees (PM), monoculture switchgrass (SM), and switchgrass intercropping with poplar trees (IC), grown for ethanol production in an irrigated farm in northeastern Oregon. The objective of this study was using LCA "from cradle to gate": (i) to determine the carbon footprint (CF) of poplar and switchgrass production in monoculture and intercropping systems, and (ii) to assess the energy efficiency of these crops in the systems. The results indicate the CF per unit energy produced and net energy productivity were improved in the intercrop system compared to monoculture of either poplar trees or switchgrass. Although the CF for IC was 160% more than PM and 15% more than SM in CO2 eq ha-1, CF was 5% less than PM and 42% less than SM in CO2 eq MJ-1. In fact, when biomass C was accounted in the CF, all systems have a negative CF. The IC system also contributed to increased energy efficiency compared to monoculture systems, as the energy efficiency ratio was 1.8, 2.0, and 2.9 for PM, SM, and IC respectively. Irrigation, equipment, and fertilizers were the most dominant factors in the systems' environmental impacts. Assessment indicated the potential of increasing the net energy ratio and reducing CF of bioenergy crops by choosing the most energy efficient and water efficient irrigation system, replacing fossil fuels used in field operations with renewable fuels, and using efficient methods for soil fertilization and enrichment. However even without further improvement, all three biofuel crop systems were net energy producers
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Details
- Title
- Life cycle assessment of biofuel from poplar trees and switchgrass in the Inland Pacific Northwest United States
- Creators
- Fatimah Ali Al Jaafar
- Contributors
- Lynne Alane Carpenter-Boggs (Advisor) - Washington State University, Department of Crop and Soil Sciences
- Awarding Institution
- Washington State University
- Academic Unit
- School of the Environment (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900890798501842
- Language
- English
- Resource Type
- Thesis