Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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Item Rapid Harvest of Algae for Biofuel Production with the Aggregating Bacterium Bacillus sp. strain RP1137.(2014) Powell, Ryan Joseph; Hill, Russell T; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Algal biofuels represent one of the most promising means of sustainably replacing liquid fuels. However significant challenges remain before algal based fuels become competitive with fossil fuels. One of the largest challenges is the ability to harvest the algae in an economic and low energy manner. In this dissertation I describe the isolation of the bacterium, Bacillus sp. strain RP1137, which can rapidly aggregate several algae that are candidates for biofuel production. This bacterium aggregates algae in a pH dependent and reversible manner and retains its aggregation ability after paraformaldehyde fixation. The optimal ratio of bacteria to algae is described as well as the robustness of aggregation at different salinities and temperatures. Aggregation is dependent on the presence of calcium or magnesium ions and likely occurs via charge neutralization through binding of calcium ions to the cell surface of both algae and bacteria. I show charge neutralization occurs at least in part through binding of calcium to negatively charged teichoic acid residues. A comparison of the aggregation efficiency of RP1137, Bacillus megaterium QM B1551 and Bacillus subtilis SMY showed that RP1137 and B1551 are equally efficient at aggregating algae while SMY does not aggregate algae. The genome of RP1137 was sequenced to understand the molecular underpinning of the mechanism of aggregation. The difference in aggregation phenotypes between the three bacilli was used to inform a genomic comparison which revealed two putative proteins that are predicted to be bound to the cell wall and are found only in RP1137 and B1551 but not SMY. This work characterizes the conditions under which Bacillus sp. RP1137 aggregates algae and the mechanism by which that aggregation occurs.Item The Impact of Cool Roofs in Different Climatic Regions: A Quantitative Empirical Analysis(2014) Petry, Kimberly Johanna; McIntosh, Marla S; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This research investigated regional climate differences and weather impacts on the effectiveness of cool roofs. In most US climate zones, cool roofs can reduce energy consumption because they reflect more sunlight and heat than standard roofs. Since temperatures are expected to increase in many regions, cool roofs may offer greater energy and cost savings than currently estimated. Energy consumption by Department of Energy (DOE) Research Laboratory buildings across the US with cool and standard roofs were assessed using metered energy datasets collected from 2003-2013. Statistical tests were conducted to compare differences in energy consumption of buildings between cool and standard roofs at sites in different climatic regions. In order to better understand the effectiveness of cool roof technologies in a future that is expected to become increasingly warmer, data collected from weather stations near each DOE site were used to interpret the potential influences of weather patterns on cool roof energy savings. This research confirmed that cool roofs do reduce energy consumption, especially at sites with warmer summers and milder winters. Regression analyses of energy consumption and temperature data were conducted to identify associations between air temperatures and heating and cooling degree-days with seasonal energy consumption. While the energy consumption of buildings with cool roofs was generally less than buildings with standard roofs, the differences in energy consumption varied depending on building use and building size.Item Integrated Energy and Environmental Analysis of Utility-Scale Wind Power Production(2008-08-11) Riposo, David Matthew; Kangas, Patrick; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Climate change associated with industrial activity threatens environmental and economic systems worldwide. Wind power was presented as one of several technologies that collectively could mitigate many of the adverse effects of global climate change if deployed at sufficient scale. The objective of this study was to explore the sustainability implications of deploying wind at that scale. The Maple Ridge Wind Energy Facility was identified as the target for analysis. Emergy analysis was performed to explore the total environmental and economic impact of the facility in common units; Energy Return on Energy Investment (EROI) was quantified to explore the net energy yield of the facility. EROI and emergy analyses suggested that Maple Ridge is a sustainable enterprise with moderate environmental impact relative to other electricity generation facilities. Implications of these results on the energy landscape of the future were discussed. Policy options to facilitate wind energy industrial growth were explored.Item An Ecological Perspective of the Energy Basis of Sustainable Bolivian Natural Resources: Forests and Natural Gas(2008-04-29) Izursa, Jose-Luis; Tilley, David R.; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bolivia, traditionally known for being a country rich in natural resources, has suffered from a constant exploitation of its natural resources benefiting only small groups in and outside the country. The devastation of natural resources that occurred for many years was of concern to the latest government, rural communities and indigenous groups. As a result, Bolivia has a more sustainability-oriented forest law that has a strong orientation towards the utilization of natural resources at a national level and encompasses a fast-growing forestry industry than in previous years. In this dissertation, the wealth of Bolivia's national system was evaluated using solar emergy. Emergy (spelled with "m") is the sum of all energy of one form needed to develop a flow of energy of another form, over a period of time. The basic idea is that solar energy is our ultimate energy source and by expressing the value of products in solar emergy units, it becomes possible to compare different kinds of energy, allowing to express the value for the natural resources in Emergy Dollars. It was found out that Bolivia relies heavily in its natural resources and that its emergy exchange ratio with its international trading partners changed from 12.2 to 1 in 2001 to 6.2 to 1 in 2005. This means that Bolivia went from export 12.2 emdollars of goods for each $1 it received in 2001 to export 6.2 emdollars of products for each $1 it received in 2005. The study also showed that under forest certification practices less emergy is removed from forests (1.49E+19 sej/yr) compared to the amount of emergy removed (2.36E+19 sej/yr) under traditional uncertified practices, reflecting that forest ecology does better under certification. The "Ecologically-based Development for the Bolivian Industrial Forestry System" (DEBBIF) simulation model constructed during this study, compared four different scenarios: the Reference Scenario, the Increased Export Scenario, the Increased Domestic Use Scenario and the National Industrialization Scenario. Using two different levels of increment for each scenario, the outcomes of six variables were analyzed: soil, wood, natural gas, assets, money and debt. It was found that if the country doubles its use of natural resources to generate finished products, this will build more assets for Bolivia, and represent more income for the country and a better rate of emergy per person.