Title: A new approach to tidal stream energy resource assessment

Researcher: Luke Blunden

Supervisor: AbuBakr Bahaj



Tidal stream power generation offers the prospect of predictable, low-CO₂ power at a number of locations around the UK and the world.  Previous assessments of tidal energy resources have taken the form of desk studies based on simplified navigational data. Where numerical model data has been used it has been at too low a resolution to capture high velocity tidal flows constrained by coastal topography. Analytical solutions for maximum energy extraction in simple tidal channels have been produced, but they have not been extended to more complex open-boundary cases such as flow around headlands and islands. There is therefore a role for
site-specific numerical modelling, which when validated, offers the twin advantages of a high-resolution picture of the resource and allowing simulation of momentum extraction within the model to take place.
In order to parameterize the sub-grid-scale momentum extraction in such models, a new analytical model of the velocity reduction in a large array of tidal turbines has been derived. The model extends previous models of large wind turbine arrays and uses analogies with flow through submerged vegetation. It provides an equivalent added drag coefficient suitable for use in a 2-D coastal numerical model.