Ali Alsaleh

ORCID Identifier(s)

0000-0002-7917-0285

Graduation Semester and Year

2016

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil Engineering

First Advisor

Melanie L Sattler

Second Advisor

Mohsen Shahandashti

Abstract

¶One renewable energy source that has witnessed a significant growth in the recent years is wind energy, with the installation of new wind farms around the globe as well as the innovations in wind power technology, which have increased the efficiency of this source. Wind power generates electrical energy from the wind’s kinetic energy without causing emissions or pollution from power production; however, environmental effects are caused by the wind turbine manufacturing, transport, and other phases. Therefore, the overall goal of this study was to analyze the environmental effects associated with wind energy technology by taking into consideration the entire life cycle for wind turbines. ¶ Specific objectives were: 1. To conduct a comprehensive life cycle assessment (LCA) for large wind turbines in Texas, including:  All phases (materials acquisition, manufacturing, transportation, installation, operation and maintenance, and end of life) and  A variety of inventory emissions and resources (greenhouse gases; traditional air pollutants SO2, NOx, VOCs, CO and PM; water depletion; cumulative energy demand). 2. To identify a range of impacts due to uncertainty in LCA model inputs. 3. To compare impacts of wind power to literature values for coal and natural gas, as examples of fossil fuels. ¶ The practical contribution of this study is to provide an LCA for large wind turbines in the US, which includes all life cycle phases. The study’s contribution to the field of LCA is a more comprehensive LCA than has been conducted to-date for wind turbines anywhere, by including several important new elements: 1) maintenance as part of the use phase, 2) traditional air pollutants in addition to greenhouse gas emissions, 3) an energy balance to compare energy produced by the turbines over their lifetime with energy consumed to manufacture and transport them, and 4) a sensitivity analysis that examines more parameters. ¶ The study was conducted 200 Gamesa 2-MW wind turbines G83 (100) and G87 (100) located at the Lone Star Wind Farm near Abilene, Texas. SimaPro8 was used as the modeling platform. Data were collected from different sources, including manufacturers, wind turbine farms, and the database in the software used for modeling (SimaPro8). All the data were modeled according to ISO 14040 standards. Environmental impacts (acid deposition, eutrophication, photochemical smog formation, stratospheric ozone depletion, and climate change), human health impacts (human health potential and respiratory effects), and resource consumption (fossil fuel consumption, water depletion, and cumulative energy demand) were assessed. ¶ Manufacturing was the phase contributing the most impacts: >75% to the impact categories of respiratory effects, human health potential, and eutrophication; >50% to the categories of acidification, global warming, water depletion, and cumulative energy demand; and >25% to fossil fuel depletion, ozone smog formation, and stratospheric ozone depletion. Producing the large parts of the turbine such as the tower and the nacelle consume sizable amounts of energy and materials. Hence, to reduce adverse impacts from wind power, alternative methods of manufacturing should be explored. Impacts of the installation and transportation phases were moderate, but less than manufacturing. To reduce climate change impacts of the installation phase, use of green cement for the turbine foundation should be considered. To reduce impacts of the transportation phase, purchase of locally-manufactured turbines should be considered. Impacts of the remaining phases were very low. Extending the turbine life span lowers impacts per kWh of electricity produced because the impacts, which are due primarily to the manufacturing phase, will be distributed over a longer period of time. For a 20-year lifetime, the turbines produce 39 times more energy than they consume. If the turbine life span is increased to 25 or 30 years, the turbines produce 45 and 50 times more energy than they consume, respectively. ¶ The best-case wind speed recommended by the manufacturer, 8 m/s, overestimated electricity generation by a factor of 43 compared to using the wind rose at the farm site. Site-specific information should therefore be used in evaluating the potential for electricity production. Based on a comparison with values reported in the literature, global warming potential of coal-fired and natural gas power plants with carbon capture and sequestration were still 50 times the impacts of the wind turbines. Other environmental impacts ranged from 4-8 times those of wind turbines, and human health impacts were estimated to be 370 times those of wind turbines.

Keywords

Life cycle assessment, Wind turbines

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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