Numerical modelling study of the effects of suspended aquaculture farms on tidal stream energy generation

Abstract

Recent endeavours have focused on the possibility of developing multi-use marine areas that integrate open-ocean aquaculture in conjunction with marine renewable energy device deployment. Advantages of performing mariculture activities within offshore tidal stream farms are manifold, including increased spatial efficiency, shared infrastructures and reduced labour costs due to linkage of individual activities of both industries. This work investigates the combined impacts of a suspended installation hosting aquaculture developments and potential energy-production capacity of tidal stream devices installed beneath the aquaculture farm. Numerical modelling studies of the impacts of the suspended aquaculture farms on energy production are conducted. The study adopts an amended version of an existing three-dimensional hydro-environmental model to describe the effects of aquaculture structures. The effects of suspended mariculture canopies are simulated using a laboratory validated, vertically varying drag coefficient profile within the canopy, along with a two-equation turbulence closure scheme, which includes additional turbulent production and dissipation terms. The quantifiable energy production capacity of the tidal stream devices with and without the suspended canopy is considered. In particular, the research investigates the optimum density and distribution of suspended shellfish cultivation that ensures viable growth and economic production of the shellfish while increasing production capacity of the tidal energy farms. Results demonstrate that there is potential to optimize energy generation by combining turbine arrays with suspended aquaculture farms.