Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
6 results
Search Results
Item Socioeconomic Impacts of Policy Interventions in the Food-Energy-water Nexus(2022) Kumar, Ipsita; Sun, Laixiang; Feng, Kuishuang; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The food-energy-water (FEW) nexus is considered essential for human survival and critical for the achievement of the Sustainable Development Goals. However, pressures on each component of the nexus are growing as a result of population and economic growth. The FEW nexus can also be affected by competition for limited land, climate change, and demand and supply changes. Although government policies targeting one of the components of the nexus will directly affect the others, they are still not accounting for the interconnectedness of all three. The dissertation, through three essays seeks to understand how government policies would affect the FEW nexus, focusing on Thailand or Brazil. The first essay assesses challenges with crop residue burning in Thailand. Additionally, the essay highlights policies implemented that target residue burning or its use and the potential solutions through crop residue use. The second essay examines specific policies on crop residue burning and renewable energy (RE) production to understand their impacts on sustainability. An extended input-output model is run to using policy scenarios for the future to gauge its impacts on total output, gross value added, employment, labor income, key input use, land use, water use and CO2 emissions on Thailand and Northeast Thailand. The final essay explores food and energy security given water supply limitations as water availability greatly impacts availability of food and energy. It uses a region in Sao Paulo, Brazil, where RE policies and other interventions have helped make ethanol production and use cost effective. A model is developed to maximize profits while optimally allocating water to food, energy and municipal water. The study looks at a normal rainfall year, and also runs a future demand change scenario. The dissertation concludes by detailing the challenges that exist, future potential for the FEW nexus policies, limitations and uncertainties. The dissertation establishes that given the interlinked nature of the FEW nexus, policies need to be implemented to account for all three components. The first essay shows that over time, an increasing number of policies in Thailand target crop residue burning through controlling burning or its use in RE production. Although these policies have been implemented, there are still shortcomings in the policy targets for biomass use, and in the large water use by the sector, as highlighted in essay 1 and 2. Essay 2 also demonstrates social, economic and environmental benefits of using crop residue for RE through employment generated, labor income increases, and CO2 emission reduction in Thailand and Northeast Thailand. We also see increasing competition for land for energy, with sugarcane potentially overtaking rice in Northeast Thailand. In essay 3, we see that while Brazil has implemented sound policies on RE, there are water security challenges, and competition between food, energy and municipal water supply. We see that the current infrastructure cannot satisfy future demand, leading to competing demands and equity challenges. Finally, in the conclusion, the research highlights uncertainties about future demand, water supply, technology, price, etc. along with potential policies.Item Nighttime Photovoltaic Cells: Electrical power generation by optically couping with deep space(2019) Deppe, Tristan; Munday, Jeremy N; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Photovoltaics possess significant potential due to the abundance of solar power incident on earth; however, they can only generate electricity during daylight hours. In order to produce electrical power after the sun has set, we consider an alternative photovoltaic concept that uses the earth as a heat source and the night sky as a heat sink, resulting in a “nighttime photovoltaic cell” that employs thermoradiative photovoltaics and radiative cooling to output as much as 10 W/m^2 from ambient radiation. This thesis will discuss the principles of thermoradiative photovoltaics, the theoretical limits of coupling a device with deep space, the potential of advanced radiative cooling techniques to enhance their performance, and a discussion of the practical limits, scalability, and integrability of this nighttime photovoltaic concept.Item Evaluation of treatment and resource recovery potential of bioelectrochemical systems to DC Water process streams by bench and pilot system(2018) Leininger, Aaron Matthew; Kjellerup, Birthe V; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Microbial fuel cell and microbial electrolysis cell systems were developed and tested with different wastewater process streams from DC Water Blue Plains Advanced Wastewater Treatment Plant. These biofilm-based systems provide an alternative to the conventional activated sludge system by oxidizing wastewater organics without the need for mechanical aeration. In bench-scale systems, the application of high-strength solids-dewatering wastewater as a feedstock was shown to increase both treatment energy savings and energy recovery. Current densities in meso-scale microbial electrolysis cells were 3.3 and 3.6 times higher when fed dewatering-filtrate or a blend of filtrate and primary effluent as compared to reactors operating with primary effluent. An integrated 800L pilot biocathode microbial fuel cell system was designed and constructed, and initial results are reported. Over the first 43 days of operation, the system averaged 15% removal of chemical oxygen demand and a load removal of 110 g_tCOD/(m^3*day).Item National Renewable Energy Policy in a Global World(2017) Jeong, Minji; Hultman, Nathan E.; Public Policy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Increasing trade of renewable energy products has significantly contributed to reducing the costs of renewable energy sources, but at the same time, it has generated protectionist policies, which may negatively affect the trend of the cost reduction. Although a few recent studies examined the rise of renewable energy protectionism and trade disputes, they are limited in addressing the conflict between the original goal of traditional renewable energy policies and the new protectionist policies under the globalized renewable energy industry. To fill this gap, this dissertation explores how the globalized renewable energy industry has changed national renewable energy policies. Through three analyses, three aspects of the globalized renewable energy industry are examined: the rise of multinational corporations, international interactions among actors, and the changes of the global and domestic market conditions. First analysis investigates how multinational renewable energy corporations have affected national policies. A content analysis of the annual reports of 15 solar photovoltaic multinational corporation shows that solar multinationals have been influenced by national policies and have adapted to the changes rather than having attempted to change national policies. Second analysis examines how diverse actors have framed renewable energy trade issues through a network analysis of the Chinese solar panel issue in the United States. The result shows that the Chinese solar panel issue was framed differently from the traditional environmental frame of renewable energy, being dominated by multinational corporations headquartered in other countries. Third analysis explores what has caused the increasing diversity in national renewable energy policies through the case studies of the U.S. and South Korea. The result reveals that the globalization of solar industry has affected the diversification of solar policies in two countries by generating both challenges, which needed to be addressed by new and additional policies, and opportunities, which strengthened the political power of domestic solar industries. The three analyses show that the globalized renewable energy industry has led to the diversification of national renewable energy policies by increasing international interactions between actors and by introducing both challenges and opportunities to domestic renewable energy industries. This research contributes to the literature on trade and the environment by analyzing a new pattern of the conflicts between traditional environmental policies and “green” protectionist policies. It also contributes to the literature on protectionism by adding an empirical case of green protectionism, one of the forms of “murky” protectionism that has risen after the global financial crisis.Item Offtake Strategy Design for Wind Energy Projects under Uncertainty(2014) Zhu, Xinyuan; Cui, Qingbin; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Energy use from wind, solar, and other renewable sources is a public policy at the federal and state levels to address environment, energy, and sustainability concerns. As the cost of renewable energy is still relatively high compared to fossil fuels, it remains a critical challenge to make renewable energy cost competitive, without relying on public subsidies. During recent years, much advance has been made in our understanding of technology innovations and cost structure optimization of renewable energy. A knowledge gap exists on the other side of the equation - revenue generation. Considering the complexity and stochastic nature of renewable energy projects, there is great potential to optimize the revenue generation mechanisms in a systematic fashion for improved profitability and growth. This dissertation examines two primary revenue generation mechanisms, or offtake strategies, used in wind energy development projects in the U.S. While a short-term offtake strategy allows project developers to benefit from price volatility in the wholesale spot market for profit maximization, a long-term offtake strategy minimizes the market risk exposure through a long-term Power Purchase Agreement (PPA). With Conditional Value-at-Risk (CVaR) introduced as a risk measure, this dissertation first develops two stochastic programming models for optimizing offtake designs under short and long-term strategies respectively. Furthermore, this study also proposes a hybrid offtake strategy that combines both short and long-term strategies. The two-level stochastic model demonstrates the merit of the hybrid strategy, i.e. obtaining the maximized profit while maintaining the flexibility of balancing and hedging against market and resource risks efficiently. The Cape Wind project in Massachusetts has been used as an example to demonstrate the model validity and potential applications in optimizing its revenue streams. The analysis shows valuable implications on the optimal design of renewable energy project development in regard to offtake arrangements.Item ENVIRONMENTAL SUSTAINABILITY AND WASTE TREATMENT CAPABILITIES OF SMALL-SCALE ANAEROBIC DIGESTION SYSTEMS(2012) Moss, Andrew Robert; Lansing, Stephanie A.; Environmental Science and Technology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Anaerobic digestion is a common form of waste treatment and energy production throughout the world, and in the United States the number of agricultural digesters is increasing at a rate of approximately 10% annually. As the number of digesters grows, efforts to assess the environmental cost of their installation and the potential utility of their by-products are required. This research investigates the relative environmental sustainability of small-scale digesters treating dairy manure in the U.S. and human waste in Haiti, and explores the biogas potential and nutrient transformations resulting from the anaerobic digestion of dairy manure. Specifically, the objectives of the research are: 1) to conduct an eMergy analysis on the two digestion systems to assess the effect of waste source, climate, and infrastructure on system sustainability; and 2) to provide an overview of waste treatment and energy production options for agricultural digesters treating dairy manure in the United States.