Matching Items (178)
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- All Subjects: Environmental engineering
- Genre: Masters Thesis
- Resource Type: Text
Description
Current policies subsidizing or accelerating deployment of photovoltaics (PV) are typically motivated by claims of environmental benefit, such as the reduction of CO2 emissions generated by the fossil-fuel fired power plants that PV is intended to displace. Existing practice is to assess these environmental benefits on a net life-cycle basis, where CO2 benefits occurring during use of the PV panels is found to exceed emissions generated during the PV manufacturing phase including materials extraction and manufacture of the PV panels prior to installation. However, this approach neglects to recognize that the environmental costs of CO2 release during manufacture are incurred early, while environmental benefits accrue later. Thus, where specific policy targets suggest meeting CO2 reduction targets established by a certain date, rapid PV deployment may have counter-intuitive, albeit temporary, undesired consequences. Thus, on a cumulative radiative forcing (CRF) basis, the environmental improvements attributable to PV might be realized much later than is currently understood. This phenomenon is particularly acute when PV manufacture occurs in areas using CO2 intensive energy sources (e.g., coal), but deployment occurs in areas with less CO2 intensive electricity sources (e.g., hydro). This thesis builds a dynamic Cumulative Radiative Forcing (CRF) model to examine the inter-temporal warming impacts of PV deployments in three locations: California, Wyoming and Arizona. The model includes the following factors that impact CRF: PV deployment rate, choice of PV technology, pace of PV technology improvements, and CO2 intensity in the electricity mix at manufacturing and deployment locations. Wyoming and California show the highest and lowest CRF benefits as they have the most and least CO2 intensive grids, respectively. CRF payback times are longer than CO2 payback times in all cases. Thin film, CdTe PV technologies have the lowest manufacturing CO2 emissions and therefore the shortest CRF payback times. This model can inform policies intended to fulfill time-sensitive CO2 mitigation goals while minimizing short term radiative forcing.
ContributorsTriplican Ravikumar, Dwarakanath (Author) / Seager, Thomas P (Thesis advisor) / Fraser, Matthew P (Thesis advisor) / Chester, Mikhail V (Committee member) / Sinha, Parikhit (Committee member) / Arizona State University (Publisher)
Created2013
Description
In order to adapt to a new culture and new language, children of immigrant families are faced daily with the responsibility of being the intermediaries between the family and the host culture through their language proficiency (Weisskirch & Alva, 2002). This thesis looks into the experiences of English-Spanish bilingual children as they bridge the gap between the family and the non-Spanish speaking community through their interpreting/translating skills. With an emphasis on children of Mexican-origin, the goal is to further understand and illuminate how these children manage this communication in an adult society, their feelings and thoughts about their experiences, and the child's perceptions about the influence that this experience may or may not have on their future. A sample of seventeen children agreed to participate in a semi-structured face-to-face interview to share their experiences. The data from these interviews were analyzed using a thematic analysis approach (Braun & Clarke, 2006). A priori themes of circumstantial bilingual and adaptive parentification were the initial focus of the research while being open to emerging themes. The children's accounts of their experiences indicated primarily that the Mexican-origin values of familism and respeto (respect) were a significant influence on them when they interpreted/translated for their family. With these traditional cultural values and norms as the groundwork, the sub-themes of normalcy and stress emerged as supportive elements of the circumstantial bilingual experience. Furthermore, the theme of adaptive parentification and the sub-themes of choice, expectation/responsibility to assist, and equality to parents offered further insight on how adaptive parentification can result as the roles of these children change. There was an emergent theme, identity negotiation, which increases our understanding of what the circumstantial bilingual child encounters as the attempt is made to negotiate his identity as an individual who has to mediate language between two opposing cultures. Due to the language brokering responsibility that are bestowed upon these children, it is concluded that communicative support by the parents is a necessary component of the parent-child relationship in order to nurture and develop these children as they negotiate and create their identity to become the successful leaders of tomorrow.
ContributorsCayetano, Catalina (Author) / Mean, Lindsey (Thesis advisor) / Waldron, Vincent (Committee member) / Gaffney, Cynthia (Committee member) / Arizona State University (Publisher)
Created2013
Description
There is growing concern over the future availability of water for electricity generation. Because of a rapidly growing population coupled with an arid climate, the Western United States faces a particularly acute water/energy challenge, as installation of new electricity capacity is expected to be required in the areas with the most limited water availability. Electricity trading is anticipated to be an important strategy for avoiding further local water stress, especially during drought and in the areas with the most rapidly growing populations. Transfers of electricity imply transfers of "virtual water" - water required for the production of a product. Yet, as a result of sizable demand growth, there may not be excess capacity in the system to support trade as an adaptive response to long lasting drought. As the grid inevitably expands capacity due to higher demand, or adapts to anticipated climate change, capacity additions should be selected and sited to increase system resilience to drought. This paper explores the tradeoff between virtual water and local water/energy infrastructure development for the purpose of enhancing the Western US power grid's resilience to drought. A simple linear model is developed that estimates the economically optimal configuration of the Western US power grid given water constraints. The model indicates that natural gas combined cycle power plants combined with increased interstate trade in power and virtual water provide the greatest opportunity for cost effective and water efficient grid expansion. Such expansion, as well as drought conditions, may shift and increase virtual water trade patterns, as states with ample water resources and a competitive advantage in developing power sources become net exporters, and states with limited water or higher costs become importers.
ContributorsHerron, Seth (Author) / Ruddell, Benjamin L (Thesis advisor) / Ariaratnam, Samuel (Thesis advisor) / Allenby, Braden (Committee member) / Williams, Eric (Committee member) / Arizona State University (Publisher)
Created2013
Description
The consumption of feedstocks from agriculture and forestry by current biofuel production has raised concerns about food security and land availability. In the meantime, intensive human activities have created a large amount of marginal lands that require management. This study investigated the viability of aligning land management with biofuel production on marginal lands. Biofuel crop production on two types of marginal lands, namely urban vacant lots and abandoned mine lands (AMLs), were assessed. The investigation of biofuel production on urban marginal land was carried out in Pittsburgh between 2008 and 2011, using the sunflower gardens developed by a Pittsburgh non-profit as an example. Results showed that the crops from urban marginal lands were safe for biofuel. The crop yield was 20% of that on agricultural land while the low input agriculture was used in crop cultivation. The energy balance analysis demonstrated that the sunflower gardens could produce a net energy return even at the current low yield. Biofuel production on AML was assessed from experiments conducted in a greenhouse for sunflower, soybean, corn, canola and camelina. The research successfully created an industrial symbiosis by using bauxite as soil amendment to enable plant growth on very acidic mine refuse. Phytoremediation and soil amendments were found to be able to effectively reduce contamination in the AML and its runoff. Results from this research supported that biofuel production on marginal lands could be a unique and feasible option for cultivating biofuel feedstocks.
ContributorsZhao, Xi (Author) / Landis, Amy (Thesis advisor) / Fox, Peter (Committee member) / Chester, Mikhail (Committee member) / Arizona State University (Publisher)
Created2013
Description
To further the efforts producing energy from more renewable sources, microbial electrochemical cells (MXCs) can utilize anode respiring bacteria (ARB) to couple the oxidation of an organic substrate to the delivery of electrons to the anode. Although ARB such as Geobacter and Shewanella have been well-studied in terms of their microbiology and electrochemistry, much is still unknown about the mechanism of electron transfer to the anode. To this end, this thesis seeks to elucidate the complexities of electron transfer existing in Geobacter sulfurreducens biofilms by employing Electrochemical Impedance Spectroscopy (EIS) as the tool of choice. Experiments measuring EIS resistances as a function of growth were used to uncover the potential gradients that emerge in biofilms as they grow and become thicker. While a better understanding of this model ARB is sought, electrochemical characterization of a halophile, Geoalkalibacter subterraneus (Glk. subterraneus), revealed that this organism can function as an ARB and produce seemingly high current densities while consuming different organic substrates, including acetate, butyrate, and glycerol. The importance of identifying and studying novel ARB for broader MXC applications was stressed in this thesis as a potential avenue for tackling some of human energy problems.
ContributorsAjulo, Oluyomi (Author) / Torres, Cesar (Thesis advisor) / Nielsen, David (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Popat, Sudeep (Committee member) / Arizona State University (Publisher)
Created2013
Description
Law enforcement, schools and universities, health service agencies, as well as social service agencies, each acquire information from individuals that receive their services. That information gets recorded into the respective application system of each organization. The information, however, gets recorded only in the context of each service rendered and within each system used to record it. Information that is recorded by the police department for one individual is entirely different from the information that is recorded by the hospital for that same individual. What if all the organizations used the same system to record information? What if all the organizations followed the same protocols to record information as well as access it? The goal of this research was to analyze a system that allows for all organizations within a community to share information with each other. Technically, this system is feasible. However, public opinion says sharing personal information is unethical, and Federal regulation says it is unlawful. To accomplish an information-sharing system of this type, both regulation and public opinion need to be addressed.
ContributorsPullin, Britton Scott (Author) / Schildgen, Thomas (Thesis advisor) / Prewitt, Deborah (Committee member) / Ralston, Laurel (Committee member) / Arizona State University (Publisher)
Created2012
Description
Biofuel from microbial biomass is a viable alternative to current energy production practices that could mitigate greenhouse gas levels and reduce dependency on fossil fuels. Sustainable production of microbial biomass requires efficient utilization of nutrients like phosphorus (P). P is a limited resource which is vital for global food security. This paper seeks to understand the fate of P through biofuel production and proposes a proof-of-concept process to recover P from microbial biomass. The photosynthetic cyanobacterium Synechocystis sp. PCC 6803 is found to contain 1.4% P by dry weight. After the crude lipids are extracted for biofuel processing, 92% of the intercellular P is found within the residual biomass. Most intercellular P is associated with nucleic acids which remain within the cell after lipids are extracted. Phospholipids comprise a small percentage of cellular P. A wet chemical advanced oxidation process of adding 30% hydrogen peroxide followed by 10 min of microwave heating converts 92% of the total cellular P from organic-P and polyphosphate into orthophosphate. P was then isolated and concentrated from the complex digested matrix by use of resins. An anion exchange resin impregnated with iron nanoparticles demonstrates high affinity for P by sorbing 98% of the influent P through 20 bed volumes, but only was able to release 23% of it when regenerated. A strong base anion exchange resin sorbed 87% of the influent P through 20 bed volumes then released 50% of it upon regeneration. The overall P recovery process was able to recover 48% of the starting intercellular P into a pure and concentrated nutrient solution available for reuse. Further optimization of elution could improve P recovery, but this provides a proof-of-concept for converting residual biomass after lipid extraction to a beneficial P source.
ContributorsGifford, James McKay (Author) / Westerhoff, Paul (Thesis advisor) / Rittmann, Bruce (Committee member) / Vannela, Ravindhar (Committee member) / Arizona State University (Publisher)
Created2012
Description
The &ldquoMormon; Colonies” in Chihuahua, northern Mexico, boast a sizable population of women originally from the United States who have immigrated to these small Mexican towns. This ethnographic study of the immigrant women in the area focuses on questions of citizenship and belonging, and bolsters the scholarship on U.S. American immigrants in Mexico. Using data from 15 unstructured interviews, the women&rsquos; experiences of migration provide a portrait of U.S. American immigrants in a Mexican religious community. Analysis of this data using grounded theory has revealed that these U.S. American women have created a third social space for themselves, to a large degree retaining their original culture, language, and political loyalty. Their stories contribute to the literature on transnational migration, providing an account of the way migrants of privilege interact with their society of settlement.
ContributorsNielsen, Vanessa (Author) / Mean, Lindsey (Thesis advisor) / Téllez, Michelle (Committee member) / Gruber, Diane (Committee member) / Arizona State University (Publisher)
Created2013
Description
The aim of this study is to test the feasibility of building a storytelling system for older adults to tell and share their life stories based on email. It is measured by the level of participation and people's acceptance of the system. The central goals were to empower people over 60 years old by providing a platform for them to share their wonderful life experience and perspectives on life and lead social services into the digital age by bridging traditional roundtable interaction and modern digital communication. A prototype was built to test the level of participation of the system and follow-up interviews were conducted in order to deeply understand people's acceptance. Content analysis was used to analyze the stories to ascertain what common themes were present. Key design considerations and key factors that affect the feasibility of storytelling system were discussed. This research expands on current research and implementation of Internet-based storytelling system and shed light on the future of combining storytelling with older adults' existing Internet knowledge. Key findings of this research are :(1) Frequency of reminiscence trigger and the number of active participants affect the level of participation collectively. Frequency is considered to be a key determinant. High frequency indicates high level of participation. (2) Categories of topics do not affect the level of participation significantly but serve as key attractions that enhance people's acceptance of the system. (3) Older adults highly accept and get involved in the new email storytelling system. This storytelling program helps them recall their memories and have a profound effect on their own introspection.
ContributorsLi, Yuanyi (Author) / Giard, Jacques R (Thesis advisor) / Margolis, Eric (Committee member) / Larkin, Kyle (Committee member) / Arizona State University (Publisher)
Created2014
Description
The economic crisis in 2008 triggered a global financial shockwave that left many wondering about the origins of the crisis. Similarly, in the early twentieth century, Wall Street faced catastrophic losses that set the stage for the Great Depression, which resulted in a decade of economic depression, leaving millions of people out of work. Using discourse analysis to understand how economic crisis is framed through the mainstream press, this research project analyzed the stock market crash of 1929-1932 and the mortgage-backed financial crisis of 2007-2009 through the lens of two mainstream publications, The New York Times and The Wall Street Journal. Comparative analysis focused on explanations for the causes of the crises, attributions of blame, culprits, and proposed solutions emerging in news coverage of the 1929 panic and the 2007-2009 financial crises. Mainstream media accounts of the 2007-2009 crisis are then compared with `alternative media' accounts of crisis causes, culprits, and solutions. These comparative analyses are contextualized historically within economic paradigms of thought, beginning with the classical economists led by Adam Smith and transitioning to the Chicago School.
ContributorsPrice, Eun (Author) / Nadesan, Majia (Thesis advisor) / Gruber, Diane (Committee member) / Ramsey, Ramsey E (Committee member) / Arizona State University (Publisher)
Created2013