Objectives and problems to be solved: Europe has large offshore wind energy potential that is poised for exploitation to make a significant contribution to the objective of providing a clean, renewable and secure energy supply. Using experience gained through the demonstration projects currently operating offshore, this project aims to reduce uncertainties in estimating power production introduced due to wake effects in large offshore wind farms particularly those operating in areas affected by the coastal discontinuity where the atmosphere is not at equilibrium with the surface. The major objectives are to evaluate wake models in offshore environments and to develop and enhance existing wake and boundary-layer models accounting for complex stability variations to produce a design tool to assist planners and developers in optimising offshore wind farms. Description of work: The proposed work is divided into five areas. Evaluation of current wake models and production of standardised databases of observations from offshore wind farms to be used in their initialisation. These case studies are used as the basis for evaluation of five different wake models varying in complexity from engineering solutions to complex computational fluid dynamics codes. Development and enhancement of wake and boundary layer models for use in offshore areas and construction of a model interface to link these models. The performance of the models under different atmospheric conditions is utilised to develop consistent model evaluation specifications and define criteria for model improvements. The performance of the coupled models is evaluated based on simulations for existing databases and also results from an offshore wind farm experiment designed to offer direct measurements of the wake influence on downstream profiles of meteorological parameters and power output. During this experiment, SODAR measurements provide additional vertical resolutions. Based on the experience gained, a design tool is under development (and evaluation) for use in offshore wind farm planning. This is based on enhancements to existing commercial software currently used by the wind energy industry. 5. Demonstration of the design tool in different environments offshore. The demonstration projects represent offshore areas of Europe including different wind speed and stability regimes and different water depths. Expected Results and Exploitation Plans: The project focuses on maximizing industry input to enhance existing wind farm design tools. The design tool allows wake impacts on power output from large offshore wind farms to be minimised according to prevailing stability conditions. A module for minimising grid connections will also be incorporated to provide selection criteria for optimal wind farm design. These tools will be rigorously evaluated for both scientific/technological and computing performance prior to their demonstration in the design of three planned offshore wind farms. Significant improvements in the state of art of wake and marine boundary-layer models and a thorough evaluation of wake models and the importance of atmospheric stability in wake propagation are expected. The design tool will ensure that both turbine and wind farm developers have the capability to more accurately design and predict power output from large offshore wind farms.
Funding SchemeCSC - Cost-sharing contracts
BS2 0QD Bristol
AB10 1FR Aberdeen
752 36 Uppsala