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This work introduces novel methodology for the simultaneous modelling and forecasting of three-dimensional wind field. This is achieved based on a quaternion wind model, which by virtue of its division algebra accounts naturally for the coupling between the three wind dimensions. To fully exploit the available second order statistics, we employ the newly developed augmented quaternion statistics and perform prediction based on the widely linear model. The proposed quaternion domain processing also facilitates the fusion of external atmospheric parameters, such as air temperature, yielding improved forecasts. Simulations for wind regimes with different dynamics and over a range of prediction horizons, together with the fusion of air temperature, support the approach.

A coupled blade element momentum – computational fluid dynamics (BEM–CFD) model is used to conduct simulations of groups of tidal stream turbines. Simulations of single, double and triple turbine arrangements are conducted first to evaluate the effects of turbine spacing and arrangement on flow dynamics and rotor performance. Wake recovery to free-stream conditions was independent of flow velocity. Trends identified include significant improvement of performance for the downstream rotor where longitudinal spacing between a longitudinally aligned pair is maximised, whereas maintaining a lateral spacing between two devices of two diameters or greater increases the potential of benefitting from flow acceleration between them. This could significantly improve the performance of a downstream device, particularly where the longitudinal spacing between the two rows is two diameters or less. Due to the computational efficiency of this modelling approach, particularly when compared to transient computational fluid dynamics simulations of rotating blades, the BEM–CFD model can simulate larger numbers of devices. An example of how an understanding of the hydrodynamics around devices is affected by rotor spacing can be used to optimise the performance of a 14 turbine array is presented. Compared to a regular staggered configuration, the total power output of the array was increased by over 10%.

Abstract In this paper we develop an efficient mathematical solution method for an articulated raft wave energy converter. Representative of Pelamis and the Cockerell raft design, it is comprised of a series of floating pontoons connected via hinges. Power is generated through the relative motions of adjacent elements which are excited by the incident wave as it passes along the length of the device. Using an efficient semi-analytic solution we are able to generate results more quickly than would be possible using a panel-based numerical code such as WAMIT. This allows us to explore the parameter space quickly and thus to develop an understanding as to what elements of raft-type wave energy converter design allow it to generate power so successfully. We find that the capture factor increases proportionately to the number of pontoons, a focusing effect that allows the device to absorb far more power than that which is directly incident upon its frontage. Hinge position and device proportions are also significant with results favouring long, narrow rafts made up of pontoons of increasing length from fore to aft.

AbstractMaking electricity grids smarter is a challenging, long-term, and ambitious process. It consists of many possible transitions and involves many actors relevant to existing and potential functions of the grid. We applied a two round Policy Delphi process with a range of sectoral experts who discussed important drivers, barriers, benefits, risks and expected functions of smarter grids, to inform the development of smarter grids. Our analysis of these expert views indicates broad consensus of the necessity for smarter grids, particularly for economic and environmental reasons; yet stakeholders also associated a range of risks and barriers such as lack of investment, disengaged consumers, complexity and data privacy with measures to make the grid smarter. Different methods for implementing smarter grid functions were considered, all thought to be more likely in urban settings. Implications for policy and future research are considered.