Tidal stream power resource assessment of the Churchill Barriers in the Orkney Islands, Scotland

Abstract

In order to tackle climate change challenges, various renewable energy sources are required to provide sufficient energy to phase out fossil fuel and decarbonise electricity generation. This research project aimed to present a detailed methodology to conduct a tidal stream power resource assessment using the TELEMAC-2D hydrodynamic numerical model and investigate the prospect of harnessing the tidal resources. The site identified for this study was the Churchill Barriers No.1 and No.2 in the Orkney Islands, Scotland. The Churchill Barriers have served a number of important roles over the years: from initially providing wartime defences for the Royal Naval anchorage in Scapa Flow during the Second World War, to currently providing vital road links between the Mainland and the islands; and now with the prospect of harnessing tidal resources, to providing electrical energy.

The TELEMAC-2D model set-up, calibration and validation, evaluation of performance indices, and harmonic analysis were discussed. Field measurements, bathymetric and coastline data were required to calibrate and validate the numerical model.

The main findings of the research project include: 1) a detailed parametric analysis of key input parameters of the TELEMAC-2D model, 2) a long-term study of the tidal cycle of the study area to observe the annual and seasonal variations of the mean power density, 3) an investigation and evaluation of the potential for extracting tidal power at the site when opening up several proportions of the barriers and incorporating tidal stream turbines, 4) an assessment of the impact of lateral spacing and blockage effect of turbines on power extraction, and 5) a conclusion of the optimum number of turbines and lateral spacing for the selected tidal channels.