The influence of waves on morphodynamic impacts of energy extraction at a tidal stream turbine site in the Pentland Firth. (September 2018)

• Record Type: Journal Article
• Authors: Fairley, I.; Karunarathna, H.; Masters, I.
• Is Part Of: Renewable energy. Volume 125(2018)
• Page Start: 630
• Page End: 647
• Publication Date: 2018-09
• Subjects: Tidal stream turbines -- Environmental impact assessment -- Waves -- Morphodynamics -- Numerical modelling -- Pentland firth; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2018.02.035
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: Extraction of energy from tidal streams has the potential to impact on the morphodynamics of areas such as sub-tidal sandbanks via alteration of hydrodynamics. Marine sediment transport is forced by both wave and tidal currents. Past work on tidal stream turbine impacts has largely ignored the contribution of waves. Here, a fully coupled hydrodynamic, spectral wave and sediment transport model is used to assess the importance of including waves in simulations of turbine impact on seabed morphodynamics. Assessment of this is important due to the additional expense of including waves in simulations. Focus is given to a sandbank in the Inner Sound of the Pentland Firth. It is found that inclusion of wave action alters hydrodynamics, although extent of alteration is dependant of wave direction. Magnitude of sediment transport is increased when waves are included in the simulations and this has implications for morphological and volumetric changes. Volumetric changes are substantially increased when wave action is included: the impact of including waves is greater than the impact of including tidal stream turbines. Therefore it is recommended that at tidal turbine array sites exposed to large swell or wind-seas, waves should be considered for inclusion in simulations of physical impact. Highlights: The morphodynamics of a sandbank in the Pentland Firth is modelled using DHI's MIKE3. The influence of waves on morphodynamics and on tidal turbine impact is considered. The impact of including waves in simulations is greater than the impact of turbines. Waves should not be ignored when assessing environmental impact of tidal turbines.