New methodologies and scenarios for evaluating tidal current energy potential

Abstract

Transition towards a low carbon economy raises concerns of loss of security of supply with high penetrations of renewable generation displacing traditional fossil fuel based generation. While wind and wave resources are increasingly forecastable, they are stochastic in nature. The tidal current resource, although variable has the advantage of being deterministic and truly predictable. With the first Crown Estate leasing round complete for wave and tidal current energy, plans are in place to install 1000 MW of tidal capacity in the Pentland Firth and Orkney waters. The aim of the work presented in this thesis is to examine the role tidal current energy can realistically play in the future electricity mix. To achieve this objective it was first necessary to develop new methodologies to capture the temporal and spatial variability of tidal current dynamics over long timescales and identify metrics relevant in a tidal energy context. These methodologies were developed for project scale resource characterisation, and provided a basis for development of a national scale dataset. The creation of project and national scale tidal datasets capture spatial and temporal variability at a level beyond previous insight, as demonstrated in case studies of three important early stage tidal current energy development sites. The provision of a robust national scale dataset enabled the development of realistic scenarios for the growth of the tidal current energy sector in UK waters. Assessing the various scenarios proposed indicates that first-generation technology solutions have the potential to generate up to 31 TWh/yr (over 8% of 2009 UK electricity demand). However, only 14 TWh/yr can be sensibly generated after incorporating realistic economic and environmental limitations proposed in this study. The preceding development of methodologies, datasets and scenarios enabled statistical analysis of the matching characteristics of future tidal energy generation potential with the present UK electricity demand and trends of electricity usage. This analysis demonstrated that the UK tidal current energy resource is much more in phase than has previously been understood, highlighting the flaws in previous studies suggesting that a combined portfolio of sites around the UK can deliver firm power. As there is negligible firm production, base-load contribution is insignificant. However, the time-series generated from this analysis identifies the role tidal current energy can play in meeting future energy demand and offer significant benefit for the operation of the electricity system as part of an integrated portfolio.