A numerical modelling study is presented in which tidal stream turbine performance and wake development in offshore conditions are assessed. The model implements the Blade Element Momentum method for characterising turbine rotor source terms which are used within a Computational Fluid Dynamics model for predicting the interaction between the turbines and the surrounding flow. The model is applied to a rectangular domain and a range of slopes are implemented for the water surface to instigate flow acceleration across the domain. Within an accelerating flow, wake recovery occurred more rapidly although rotor performance was not affected.
There are considerable efforts to reduce Carbon emissions at a European scale to comply with ambitious emission reduction targets. In the UK for instance, the Climate Change Act was passed into law recently whereby an 80 % reduction in greenhouse gasses compared to 1990 levels is legally required by 2050 (Climate Change Act, 2008). One of the strategies for achieving this is a move from the burning of fossil fuels towards renewable energy alternatives for power generation. In Wales, one attractive option is the exploitation of tidal stream energy. Some of the most suitable tidal streams for power generation in Europe, let alone the UK, in terms of both energy levels and accessibility, lie along the Welsh coastline, particularly around Anglesey to the North and Ramsey to the West. Many such suitable sites tend to lie in very environmentally sensitive and protected locations (Willis et al., 2010). Environmental impact assessments are therefore required prior to deployment of tidal stream turbines to assess their likely influence on existing hydrodynamics and their effects on the environment. Considering the large financial investment into the development and production of these devices, their performance in such complex environments must also be assessed and detailed feasibility studies would be required prior to deployment.