Accurate wave measurements are required for wave energy applications, including resource assessments and performance assessments. In response, wave data are measured from deployment sites, commonly using wave buoys or other point wave sensors. Spatial variability in the wave field will introduce inaccuracies to the analysis of data captured from a single point to represent a separate location or area. This thesis describes research undertaken to quantify the effect of spatial variability on the accuracy of direct wave measurements taken at a wave energy site. An array of four timesynchronised wave buoys were deployed, separated by 500m, in a location close to the Wave Hub wave energy test site in Cornwall, UK. These data were subject to close scrutiny in terms of data processing and quality control, which raised specific issues regarding data processing and the validation of wave data for a new measurement facility. Specific recommendations are made for data captured from this facility, and bespoke quality control routines were developed. This process minimises the possible contribution of errors to the processed data, which is observed to be of the highest importance when analysing simultaneous data sets, and provides a data set that is particularly suited to the examination of the spatial characteristics of ocean waves. The differences between simultaneous data demonstrated local physical processes to be causing a deterministic difference between the waves at the measurement sites, which contributed to a significant difference between the power statistics at different locations within the site. Instantaneous differences between measurements were observed to agree well with theoretical estimations of random error, based on sampling theory. The culmination of the research is a unique analysis of the spatial properties of ocean wave fields on the scale of a wave energy test site, of direct relevance to the development and monitoring of wave energy test sites.

Edremit geothermal field with 42-62 &deg / C discharge temperatures is utilized for space heating. Alternation of permeable and impermeable units created two superimposed aquifers in the area: upper unconfined and lower confined. Water samples from 21 (hot, warm, cold) wells were taken in this study. 8 of these wells penetrate the deeper confined, while 13 penetrate the shallower unconfined aquifer. Geochemical analysis revealed Na+K&ndash / SO4 nature for the hot (&gt / 40&deg / C), Ca&ndash / HCO3 nature for the cold (&lt / 30&deg / C) and Ca&ndash / SO4 nature for the warm (30-40&deg / C) waters. &delta / 18O-&delta / D compositions point to a meteoric origin for all waters, while 14C analyses suggest longer subsurface residence times for the hot, compared to the cold/warm waters. Chemical and isotopic compositions indicate that &ldquo / mixing&rdquo / and &ldquo / water-rock interaction&rdquo / are the possible subsurface processes. When silica and cation geothermometers are evaluated together with fluid mineral equilibria calculations, a 110&deg / C reservoir temperature is expected in the field. Saturation indices indicate potential silica scaling for waters at temperatures lower than discharge temperatures. Hydrogeology of the study area is highly affected by faults. The groundwater is percolated (down to 3 km depth) via deep seated step faults, heated at depth and ascends to surface at the low lands, especially through intersection of buried, mid-graben faults. During its ascent towards surface, geothermal water invades the two superimposed aquifers and mixing between hot and cold waters takes place in the aquifers. Resource assessment studies suggest a 3.45x1013 kJ accessible resource base and 9.1 MWt recoverable heat energy for Edremit geothermal field with 90% probability.

The U.S. Minerals Management Service has completed a preliminary assessment of in-place gas hydrate resources in the Gulf of Mexico. A probabilistic model built on a mass balance approach to assessment provides a high degree of spatial resolution and supports detailed mapping. The model produces a Monte Carlo distribution of in-place resources that ranges from 314 trillion to 974 trillion cubic meters (TCM) with a mean value of 607 TCM. Additional work on development of a technically recoverable model component is under way.

The kinetic energy present in tidal currents and other water courses has long been appreciated as a vast resource of renewable energy. The work presented in this doctoral thesis is devoted to both the characteristics of the hydro-kinetic resource and the technology for energy conversion. An assessment of the tidal energy resource in Norwegian waters has been carried out based on available data in pilot books. More than 100 sites have been identified as interesting with a total estimated theoretical resource—i.e. the kinetic energy in the undisturbed flow—in the range of 17 TWh. A second study was performed to analyse the velocity distributions presented by tidal currents, regulated rivers and unregulated rivers. The focus is on the possible degree of utilization (or capacity factor), the fraction of converted energy and the ratio of maximum to rated velocity, all of which are believed to be important characteristics of the resource affecting the economic viability of a hydro-kinetic energy converter. The concept for hydro-kinetic energy conversion studied in this thesis comprises a vertical axis turbine coupled to a directly driven permanent magnet generator. One such cable wound laboratory generator has been constructed and an experimental setup for deployment in the river Dalälven has been finalized as part of this thesis work. It has been shown, through simulations and experiments, that the generator design at hand can meet the system requirements in the expected range of operation. Experience from winding the prototype generators suggests that improvements of the stator slot geometry can be implemented and, according to simulations, decrease the stator weight by 11% and decrease the load angle by 17%. The decrease in load angle opens the possibility to reduce the amount of permanent magnetic material in the design.

The West Coast of Vancouver Island (WCVI), with an average gross wave energy flux of 40-50 kW/m at the continental shelf, possesses one of the most energetic wave climates in the world and has the potential to meet the electric demands of the utility grid on Vancouver Island and numerous coastal remote communities. However, the development of wave energy sites has the potential to interrupt other existing marine activities and wave energy operations could damage the sensitive marine ecosystems. The objective of this thesis is to identify strategically important sites for wave energy – sites that have great economic potential in an energy generation context yet have minimal impacts on existing economic uses and minimal ecological impacts. Wave energy technology agnostic frequency and directional filters were developed based on a unionized representation of Wave Energy Converter (WEC) performance generated by combining four types of WEC performance characteristics. These two filters improved the quantification of extractable wave resources by accounting for the technological limits of wave frequencies and directions. Subsequently, a detailed economic evaluation was developed to estimate the influence of the distance to the coastline and transmission network, electricity market sizes, and a technology agnostic description of WEC farm physical layout on the selection of wave energy sites. The technology-agnostic description of WEC farm physical layouts was designed based on the cable properties, cable termination/distribution, and cable protection used in real-world projects. The WEC farm capacities are constrained by the transmission cable to minimize the cost for developing wave energy sites. Lastly, a multi-criteria analysis, which includes four stakeholder perspective scenarios, was developed to identify the strategically important sites for future wave energy development along the WCVI. A total of 16 regions, covering an area of 392 km2 and having an average of 35.68 kW/m wave energy flux, were identified as strategically important sites for wave farms. These regions show the potential to meet the electric demand of Vancouver Island, and they are worth further investigated when selecting a location for future wave energy development. / Graduate

The tidal current energy resource is challenging to assess with accuracy and precision. An accepted standard methodology is lacking, which in turn perpetuates uncertainty and hinders the industry’s development. Technical Committee 114 of the International Electro-technical Commission (IEC-TC-114) is working to develop a standard for emerging tidal energy conversion systems. The draft standard prescribes methods for determining, objectively and reliably, the scale and character of tidal current energy resources at a site. The IEC-TC-114 draft standard for tidal energy resource assessment and characterisation has not yet been tested in a real world case study. Hence, it is not yet known whether the proposed methods will yield the desired outcome. This research has adopted the Fundy Ocean Research Center for Energy (FORCE) project in Minas Passage, Nova Scotia, for pilot application of the draft standard on tidal current resource assessment. The Bay of Fundy, located on the Atlantic coast of North America between the Canadian provinces of New Brunswick and Nova Scotia, is known for having the highest tidal range in the world and has long been recognised as an ideal stage for tidal energy development. The thesis is presented in three main parts. Firstly, the latest peer-reviewed scientific literature is summarised and the standard is reviewed in view of lessons learned. The aim of this exercise is to establish a scientific basis for and to develop suggestions towards improving and extending future revisions of the standard. Secondly, a comprehensive assessment of the tidal current energy resource at the FORCE project site is conducted in a manner that is consistent with IEC-TC-114 protocol based on available measurements from static current profiler surveys and a two-dimensional hydrodynamic model of the upper Bay of Fundy developed for this study. Thirdly, a sensitivity analysis is performed to determine the main sources of error and uncertainty affecting resource assessment, a topic which has yet to be addressed in the literature.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18969号 / 工博第4011号 / 新制||工||1618(附属図書館) / 31920 / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 小池 克明, 教授 松岡 俊文, 教授 田村 正行 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

Utilising tidal currents as a renewable energy resource is presently under consideration to meet the requirements of increasing worldwide energy demand and the need to reduce carbon emissions. In this respect, in-stream tidal devices are proposed to convert the kinetic energy of currents into useful extractable power. In order to extract a useful amount of energy from tidal currents, the proposed devices need to be deployed in an array or farm-like format. Due to the thrust exerted by the devices within an array, the natural flow regime will inevitably be changed. In light of this, this study aims to estimate the maximum power that can be extracted by tidal turbine arrays and assess the far-field effects of energy extraction in the designated areas around the UK for various array configurations. In this thesis, the ocean tides are modelled using the long wave equations, commonly referred as the shallow water equations (SWEs). A numerical solver based on a Runge-Kutta discontinuous Galerkin finite element method is employed to solve the SWEs. One main advantage of the discontinuous Galerkin method is that it approximates the solution individually at each element, which allows for discontinuities within the solution system while ensuring mass conservation locally and globally. The selected numerical solver has been verified against several benchmark tests. It is then modified to include a line discontinuity to represent the effect of tidal turbine array(s) in a coastal basin. The algorithm implemented in the numerical solver involves a sub-grid model, which is based on Linear Momentum Actuator Disk Theory (LMADT) to approximate the local flow-field in the presence of the turbines. This near-field approach allows the flow velocity at the turbine to be estimated with a greater accuracy. As the power available to the turbines is related to the velocity at the turbine blades, the characterisation of the designated tidal site as a resource using LMADT may be more accurate than previously proposed methods. An additional advantage of using LMADT is that it provides a distinction between the power extracted by the turbines and the total amount of power that is removed from the tidal stream, including the wake mixing losses. The methodology employed in this thesis has been applied to two tidal basins around the UK; the Anglesey Skerries (a headland) and the Bristol Channel (an oscillating bay). A comprehensive unstructured triangular finite element model has been constructed to simulate the naturally occurring tides at these regions. The constructed model has then been validated against field measurement. The validated model is used to conduct parametric studies, which evaluate the importance of tidal array locations, configurations and operating conditions on the available power at the Anglesey Skerries and the Bristol Channel sites. The parametric study aims to evaluate a realistic upper limit of available power at each site considered. This study also provides a unique analysis to examine the potential tidal farm interactions by deploying several tidal arrays at both Anglesey Skerries and the Bristol Channel.

Reasons like increases in the price and demand of energy in the last years, growing interest and support in the renewable energy resources, development of social environmental consciousness, interest in using domestic resources, having legal regulations has promoted the interest in the electricity production from geothermal energy. For the effective and productive use of existing resources, important data of geothermal regions are obtained with well tests. Well tests are the studies which starts while the well is drilling, continues after the well completion during the process of operation planning with optimum performance suitable to geothermal source and presents continuation also in the operation stage as required for the dynamic structure of geothermal systems. In Aydin Kuyucak Pamuk&ouml / ren region three wells are drilled, achieved results are positive. At AP1 well only CO2 emission is present, no test is done for this well. With the tests for AP2 and AP3 wells temperature, pressure and production values are determined. By the results of these tests, it is determined that this region will be one of the important fields in the West Anatolian Region with current temperature and production rate. In this study, the geothermal energy recoverable from this region is calculated with volume method of geothermal resource assessment. Monte Carlo simulation technique is used with an add-in software program @RISK to Microsoft EXCEL. Electrical power capacity of Aydin-Pamuk&ouml / ren geothermal field is determined as 45.2 MW with 90 % probability. The most likely electrical power value was found to be 78.75 MW with a probability of 69 %. The number of wells required are 10 for a production capacity of 200 t/hr and 7 for a production capacity of 300 t/hr at each well head.