Abstract
Assessing the tidal stream energy resource, its intermittency and likely environmental feedbacks due to energy extraction, relies on the ability to accurately represent kinetic losses in ocean models. Energy conversion has often been implemented in ocean models with enhanced turbine stress terms formulated using an array-averaging approach, rather than implementing extraction at device-scale. In depth-averaged models, an additional drag term in the momentum equations is usually applied. However, such array-averaging simulations neglect intra-array device wake interactions, providing unrealistic energy extraction dynamics. Any induced simulation error will increase with array size. For this study, an idealized channel is discretized at sub 10 m resolution, resolving individual device wake profiles of tidal turbines in the domain. Sensitivity analysis is conducted on the applied turbulence closure scheme, validating results against published data from empirical scaled turbine studies. We test the fine scale model performance of several mesh densities, which produce a centerline velocity wake deficit accuracy (R2) of 0.58–0.69 (RMSE = 7.16–8.28%) using a k-Ɛ turbulence closure scheme. Various array configurations at device scale are simulated and compared with an equivalent array-averaging approach by analyzing channel flux differential. Parametrization of array-averaging energy extraction techniques can misrepresent simulated energy transfer and removal. The potential peak error in channel flux exceeds 0.5% when the number of turbines nTECs ≈ 25 devices. This error exceeds 2% when simulating commercial-scale turbine array farms (i.e., >100 devices).
Highlights
Coordinated efforts to set renewable energy targets have enhanced interest in the marine renewable energy (MRE) sector [1,2]
Tidal energy converter (TEC) technologies that transfer kinetic energy of tidal stream currents into electrical power are moving from the testing and feasibility stage [2] to commercial scale array deployments
We investigate whether coastal models discretized at individual device-scale, sufficiently capture more hydrodynamic feedbacks compared with array-averaged models
Summary
Coordinated efforts to set renewable energy targets have enhanced interest in the marine renewable energy (MRE) sector [1,2]. Tidal energy converter (TEC) technologies that transfer kinetic energy of tidal stream currents into electrical power are moving from the testing and feasibility stage [2] to commercial scale array deployments. NOVA Innovation have three 100 kW devices deployed in Shetland, and Meygen have four 1.5 MW devices in the Pentland Firth, UK. Prior to large-scale development, it is crucial that we understand the physical feedbacks of energy extraction with the resource itself and the surrounding environment (e.g., [3,4]). Ocean models can aid this process, uncertainties in the way that energy extraction is represented in models should be robustly quantified and minimized.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
