Numerical models for tidal turbine farms

dc.contributor.authorShives, Michael Robert
dc.contributor.supervisorCrawford, Curran of Mechanical Engineeringen_US of Philosophy Ph.D.en_US
dc.description.abstractAnthropogenic climate change is approaching predicted tipping points and there is an urgent need to de-carbonize energy systems on a global scale. Generation technologies that do not emit greenhouse gas need to be rapidly deployed, and energy grids need to be updated to accommodate an intermittent fluctuating supply. Rapidly advancing battery technology, cost reduction of solar and wind power and other emerging generation technologies are making the needed changes technically and economically feasible. Extracting energy from fast-flowing tidal currents using turbines akin to those used in wind farms, offers a reliable and predictable source of GHG free energy. The tidal power industry has established the technical feasibility of tidal turbines, and is presently up-scaling deployments from single isolated units to large tidal farms containing many turbines. However there remains significant economic uncertainty in financing such projects, partially due to uncertainty in predicting the long-term energy yield. Since energy yield is used in calculating the project revenue, it is of critical importance. Predicting yield for a prospective farm has not received sufficient attention in the tidal power literature. this task has been the primary motivation for this thesis work, which focuses on establishing and validating simulation-based procedures to predict flows through large tidal farms with many turbines, including the back effects of the turbines. This is a challenging problem because large tidal farms may alter tidal flows on large scales, and the slow-moving wake downstream of each rotor influences the inflow to other rotors, influencing their performance and loading. Additionally, tidal flow variation on diurnal and monthly timescales requires long-duration analysis to obtain meaningful statistics that can be used for forecasting. This thesis presents a hybrid simulation method that uses 2D coastal flow simulations to predict tidal flows over long durations, including the influence of turbines, combined with higher-resolution 3D simulations to predict how wakes and local bathymetry influence the power of each turbine in a tidal farm. The two simulation types are coupled using a method of bins to reduce the computational cost within reasonable limits. The method can be used to compute detailed 3D flow fields, power and loading on each turbine in the farm, energy yield and the impact of the farm on tidal amplitude and phase. The method is demonstrated to be computationally tractable with modest high-performance computing resources and therefore are of immediate value for informing turbine placement, comparing turbine farm-layout cases and forecasting yield, and may be implemented in future automated layout optimization algorithms.en_US
dc.identifier.bibliographicCitationM. Shives and C. Crawford, "Mesh and load distribution requirements for actuator line CFD simulations," Wind Energy, vol. 16, pp. 1183-1196, 2013.en_US
dc.identifier.bibliographicCitationM. Shives, C. Crawford, C. Hiles, and R. Walters, "Combining numerical methods for basin and turbine scales for improved modelling of in-situ turbine arrays," in Proceedings of the 10th European Wave and Tidal Energy Conference, (Aalborg, Denmark), September 2013.en_US
dc.identifier.bibliographicCitationM. Shives and C. Crawford, "Adapted two-equation turbulence closures for actuator disk RANS simulations of wind & tidal turbine wakes," Renewable Energy, vol. 92, pp. 273-292, 2016.en_US
dc.identifier.bibliographicCitationM. Shives and C. Crawford, "Tuned actuator disk approach for predicting tidal turbine performance with wake interaction," International Journal of Marine Energy, vol. 17, pp. 1-20, April 2017.en_US
dc.identifier.bibliographicCitationM. Shives, C. Crawford, and S. Grovue, "A tuned actuator cylinder approach for predicting cross-flow turbine performance with wake interaction and channel blockage effects," International Journal of Marine Energy, 2017.en_US
dc.identifier.bibliographicCitationM. Shives, "Actuator cylinder model for Instream G3 rotor: Model development, validation, and array studies," tech. rep., Instream Energy Systems Ltd., 2016.en_US
dc.identifier.bibliographicCitationM. Shives and C. Crawford, "Computational methods for tidal turbine farm energy yield, part one: Methods and initial validation," Submitted for review to the International Journal of Marine Energy, 2017.en_US
dc.identifier.bibliographicCitationM. Shives and C. Crawford, "Computational methods for tidal farm energy yield part two: Rotor models and large farms," Submitted for review to the International Journal of Marine Energy, 2017.en_US
dc.rightsAvailable to the World Wide Weben_US
dc.subjectTidal Turbinesen_US
dc.subjectNumerical Modelsen_US
dc.subjectComputational Fluid Dynamicsen_US
dc.subjectActuator Disken_US
dc.subjectActuator Lineen_US
dc.subjectEnergy Yielden_US
dc.subjectTurbulence Modelsen_US
dc.subjectBay of Fundyen_US
dc.subjectTurbine Wakesen_US
dc.subjectField Dataen_US
dc.subjectWake Interactionen_US
dc.subjectTurbine Farmen_US
dc.subjectBlockage Effecten_US
dc.subjectBlockage Ratioen_US
dc.subjectResource Characterizationen_US
dc.subjectImpact Assessmenten_US
dc.subjectEconomic Feasibilityen_US
dc.subjectLayout Optimizationen_US
dc.subjectLayout Studiesen_US
dc.subjectHorizontal axis turbineen_US
dc.subjectvertical axis turbineen_US
dc.titleNumerical models for tidal turbine farmsen_US


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