The following study explores the worldwide spatial and temporal distributions of electrical power that can be extracted from the ocean's stored solar energy via the process of closed-cycle ocean thermal energy conversion (OTEC). Special emphasis is placed on resources surrounding the state of Florida. The study combines oceanographic input from a state-of-the-art ocean circulation model, the Hybrid Coordinate Ocean Model, with a state-of-the-industry OTEC plant model to predict achievable power values across the world. These power predictions are then constrained by local replenishment rates of cold deep sea water to provide an upper limit to the sustainable OTEC resource. Next, the geographic feasibility of OTEC-coupled and OTEC-independent sea water cooling (air conditioning and refrigeration) are explored. Finally, the model data is validated against in situ oceanic measurements to ensure the quality of the predictions. / by Lynn Rauchenstein. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

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An Enhanced Geothermal System (EGS) allows for the generation of electricity using the Earth's heat by improving ('enhancing') the fracture permeability of rock and flowing fluid through the optimized medium. The complex behavior of EGS fracture systems and heat flow processes are being studied at various scales to determine the practical capabilities of EGS technology. The EGS collaborative (Collab) project is focused on experimentation of intermediate-scale (i.e., 10's of meters) EGS reservoir generation processes and model validation at crystalline rock sites. A key phase of the project involves seismic characterization of a rock mass intended to be representative of EGS reservoir rock. A suite of boreholes was drilled from inside a mine drift on the 4850-foot (~1.5 km) level of the Sanford Underground Research Facility (SURF) in Lead, South Dakota. The boreholes, comprised of one stimulation (injection) well, one production (extraction) well, and six monitoring wells, were each nominally drilled approximately 200 feet (~60 meters) deep into the surrounding crystalline rock formation near the location of a previous experiment at this site (kISMET). Active source seismic data were collected using an electrical sparker source and an electro-mechanical impulse source to generate compressional (P-) wave and shear (S-) wave energy, respectively, at varying depths in the stimulation well. Seismic receivers were deployed in the sub-parallel production well, in addition to receivers installed in the monitoring wells, to detect P- and S-wave arrivals. Over the summer, I picked all the P-wave arrivals and helped generate initial tomographic models. The 3D P- and S-wave velocity models associated with these are presented here with a discussion of the elastic parameters they imply. The rock is found to be more complicated and heterogeneous than expected. Velocity and calculated elastic moduli values are reasonable for crystalline rock. These elastic parameters are used for modeling and monitoring seismic hypocenters that are associated with fracture propagation during EGS stimulation activities.

The demand for energy is increasing worldwide. All applications contributed to increase the demand of all energy industry, and therefore the effect on the environment and the rise in pollution increased significantly. This is considered a large problem, and researchers focused their research on renewable energy for reducing the cost of energy in the future. Geothermal energy has significant impact as a source of electricity generation since it will not harm the environment. There are more than twenty countries that benefit from geothermal plants, which generate more than 6000 megawatts .Three alternatives of geothermal energy technology (GHP, Direct use of Geothermal Heat, and Geothermal Electricity) can be used for supporting electrical systems in Oregon. At the same time, the success of using the geothermal energy alternatives in Oregon relies on different goals for achieving the best geothermal development. Oregon has been ranked third in the potential use of geothermal energy after Nevada and California. The objective from the research study was to develop an assessment model framework that can be used for supporting cost effective renewable energy in Oregon by the development of geothermal energy sources. This research of study was done by using the Hierarchical Decision Model (HDM) and consisted of four levels: Mission, objectives, goals, and alternative. Criteria used in this research study are based on five objectives to know what are the most important factors in the decision-making process. These objectives are: social, environmental, economical, technical, and political. The decision model connected objectives, goals, and alternative for obtaining the accurate decision. HDM used for this purpose to analyze the result of data collected from experts. Seven experts who had experience in the geothermal field participated in this research study, and they gave their judgment in the questionnaire survey link by using pair-wise comparison method. The outcome analysis of the results showed that in terms of objectives that Minimizing Environmental Impact was rated at the highest value at 0.26 with respect to the mission. Within the category of Minimizing Environmental Impact, Seismic Activity and GHG Emissions had higher values. The results show that "Geothermal Electricity," with a rating of 43%, was ranked as the most important alternative with respect to mission, objectives, and goals. "Direct Use of Geothermal Heat" was ranked as the second most important alternative with 31%. The results of this research study were discussed with the experts to get their feedback, and learn from them what requirements are necessary for improvement in the geotechnical energy sector for future research. The experts agreed that this methodology is a good approach to help reach the right decision since this methodology (HDM) divides the problem into small sets, which will make the decision process easier.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1981. / Supervised by Richard P. Von Herzen and John G. Sclater. Vita. Includes bibliographical references.

Thesis (M.Eng.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 88-91.

Ziel dieser Arbeit war es, die Auswirkungen der geothermischen Energieerzeugung aus umwelt- und naturschutzfachlicher Sicht zu untersuchen und zu bewerten. Auf der Grundlage einer umfassenden Literaturstudie, von Expertenbefragungen sowie der Besichtigung des Hydrothermalen Erdwärmekraftwerkes in Neustadt-Glewe und der Erdwärmesondenanlage auf dem Max-Planck-Campus in Golm wurden die für eine behördliche Genehmigung der Erschließung und Nutzung von Erdwärmevorkommen notwendigen gesetzlichen Regelungen systematisch aufgearbeitet und die mit den Techniken zur Erschließung bzw. den Anlagen zur Nutzung von Erdwärme verbundenen umweltrelevanten Wirkfaktoren ausgewiesen und systematisch dargestellt.<br /> Darauf aufbauend wurden die potenziellen Wirkungen auf die Schutzgüter des UVPG qualitativ erfasst und, soweit es in Anbetracht des derzeitigen Standes der Forschung möglich war, quantifiziert. Die Wirkungen wurden schließlich hinsichtlich ihrer Bedeutung und Erheblichkeit im Rahmen von behördlichen Genehmigungsentscheidungen bewertet und miteinander verglichen. Die Anforderungen an den Inhalt von Antragsunterlagen wurden dargestellt.<br><br> Gutachter / Betreuer: Dr. Holger Rößling ; Dipl.-Biol. Karl Scheurlen

This study presents an investigation of the concept of harvesting geothermal energy that remains in heavy oil reservoirs after abandonment when steamflooding is no longer economics. Substantial heat that has accumulated within reservoir rock and its vicinity can be extracted by circulating water relatively colder than reservoir temperature. We use compositional reservoir simulation coupled with a semianalytical equation of the wellbore heat loss approximation to estimate surface heat recovery. Additionally, sensitivity analyses provide understanding of the effect of various parameters on heat recovery in the artificial geothermal resources. Using the current state-of-art technology, the cumulative electrical power generated from heat recovered is about 246 MWhr accounting for 90percent downtime. Characteristics of heat storage within the reservoir rock were identified. The factors with the largest impact on the energy recovery during the water injection phase are the duration of the steamflood (which dictates the amount of heat accumulated in the reservoir) and the original reservoir energy in place. Outlet reservoir-fluid temperatures are used to approximate heat loss along the wellbore and estimate surface fluid temperature using the semianalytical approaches. For the injection well with insulation, results indicate that differences in fluid temperature between surface and bottomhole are negligible. However, for the conventional production well, heat loss is estimated around 13 percent resulting in the average surface temperature of 72 degrees C. Producing heat can be used in two applications: direct uses and electricity generation. For the electricity generation application that is used in the economic consideration, the net electrical power generated by this arrival fluid temperature is approximately 3 kW per one producing pattern using Ener-G-Rotors.

Sixteen percent of New Zealand’s power comes from geothermal sources which are primarily located within the Taupo Volcanic Zone (TVZ). The TVZ hosts twenty three geothermal fields, seven of which are currently utilised for power generation. Ngatamariki Geothermal Field is the latest geothermal power generation site in New Zealand, located approximately 15 km north of Taupo. This was the location of interest in this project, with testing performed on a range of materials to ascertain the physical properties and microstructure of reservoir rocks. The effect of burial diagenesis on the physical properties was also investigated. Samples of reservoir rocks were taken from the Tahorakuri Formation and Ngatamariki Intrusive Complex from a range of wells and depths (1354-3284 mbgl). The samples were divided into four broad lithologies: volcaniclastic lithic tuff, primary tuff, welded ignimbrite and tonalite. From the supplied samples twenty one small cylinders (~40-50mm x 20-25mm) were prepared and subjected to the following analyses: dual weight porosity, triple weight porosity, dry density, ultrasonic velocity (saturated and dry) and permeability (over a range of confining pressures). Thin sections impregnated with an epoxy fluorescent dye were created from offcuts of each cylinder and were analysed using polarised light microscopy and quantitative fluorescent light microstructural microscopy. The variety of physical testing allowed characterisation of the physical properties of reservoir rocks within the Ngatamariki Geothermal Field. Special attention was given to the petrological and mineralogical fabrics and their relation to porosity and matrix permeability. It was found that the pore structures (microfractures or vesicles) had a large influence on the physical properties. Microfractured samples were associated with low porosity and permeability, while the vesicular samples were associated with high porosity and permeability. The microfractured samples showed progressively lower permeability with increased confining pressure whereas samples with a vesicular microstructure showed little response to increased confining pressure. An overall trend of decreasing porosity and permeability with increasing density and sonic velocity was observed with depth, however large fluctuations with depth indicate this trend may be uncertain. The large variations correlate with changes in lithology suggest that the lithology is the primary control of the physical properties with burial diagenesis being a subsidiary factor. This project has established a relationship between the microstructure and permeability, with vesicular samples showing high permeability and little response increased confining pressure. The effects of burial diagenesis on the physical properties are subsidiary to the observed variations in lithology. The implications of these results suggest deep drilling in the Tahorakuri Formation may reveal unexploited porosity and permeability at depth.

In this study, the co-optimization of carbon dioxide sequestration and enhanced oil recovery and the co-optimization of carbon dioxide sequestration and methane recovery studies were discussed. Carbon dioxide emissions in the atmosphere are one of the reasons of global warming and can be decreased by capturing and storing carbon dioxide. Our aim in this study is to maximize the amount of carbon dioxide sequestered to decrease carbon dioxide emissions in the atmosphere and maximize the oil or methane recovery to increase profit or to make a project profitable. Experimental design and response surface methodology are used to co-optimize the carbon dioxide sequestration and enhanced oil recovery and carbon dioxide sequestration and methane recovery. At the end of this study, under which circumstances these projects are profitable and under which circumstances carbon dioxide sequestration can be maximized, are given. / text