Resource Assessment 2011

Tuesday 10 & Wednesday 11 May 2011 SQUARE – BRUSSELS MEETING CENTRE, Brussels, Belgium

Programme & Proceedings

10 May 2011
Session One: Mesoscale Modelling
Session Two: Remote Sensing Panel Discussion
Session Three: Advanced Modelling
11 May 2011
Session Four: Wakes
Session Five: Comparison of Resource and Energy Yield Assessment Procedures

Full list of presenter photos and biographies

Photos of the audience and venue

Session One: Mesoscale Modelling

Mesoscale modelling has become increasingly important in wind resource estimation over the last few years. Where the models previously have been used for the making of wind atlases of mean annual wind speeds, they are now being used to simulate various other related parameters for assessing the wind resource and site conditions. Due to increasingly faster and larger computational resources, the possible resolution in both space and time, and the length of model simulations have increased, and a huge amount of information is now becoming available, for example on time- and spatial-correlations, daily and annual variations and extreme winds (U50).

At the same time, output from various different numerical models are becoming available, such as WRF, ETA, SKIRON, HIRLAM, etc. In these models, different sub- models (for land-vegetation-soil processes, surface and boundary layer parameterizations, etc) are used giving substantially different results with regard to wind resource assessment.

The session covered the following topics:

  • What is a mesoscale model and how can it be used in wind energy applications?
  • What kind of uncertainty can we expect from the mesoscale models and what are the different ways they can be run?
  • Hot topics: what is the effective resolution in space and time and what are their consequences for wind resource assessment, using mesoscale modelling for extreme wind?

Chair: Andrea Hahmann (bio & photos), Senior Scientist, Wind Energy Division, Risø DTU Technical University of Denmark

Mesoscale dynamical and statisticaldownscaling, climatology of low-level jets(pdf – 1.3MB) Daran Rife (bio & photos),Project Scientist II, National Center for Atmospheric Research, Boulder, USA
Regional wind atlas (pdf – 766KB) Sami Niemelä (bio & photos),Head of the Numerical Weather Prediction Group, Finnish Meteorological Institute
General mesoscale modelling,high-frequency wind variability offshore(PDF – 6.7MB) Claire Louise Vincent (bio & photos),Post-Doctoral Student, Wind Energy Division, Risø DTU Technical University of Denmark

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Session Two: Remote Sensing Panel Discussion

Remote sensing technologies, whether ground-based, airborne or satellite, are entering mainstream use in wind energy site assessment and operations. However there is currently a perceived lack of guidance both on how such solutions may be applied to routine engineering operations and on the reliability that can be expected which is itself contingent upon the knowledge and experience of the user.

To address these issues, this session included;

  • an overview of remote sensing technologies and basic operating principles;
  • guidance on the use of RS data and any necessary post-processing steps;
  • recommendations regarding deployment;
  • exploration of the transfer function between RS data and actual wind turbine performance;
  • integration of RS with computer models at both micro and macro-level, including for short-term forecasts.

Chair: Oisin Brady (photos), Director (France), Natural Power

Remote sensing: satellite radar for ocean winds (pdf – 1.5MB) Charlotte Bay Hasager (bio & photos), Senior Scientist, Wind Energy Division, Risø DTU Technical University of Denmark
Laser remote sensing for wind energy (pdf – 3.2MB) Jakob Mann (photos), Research Professor, Risø DTU Technical University of Denmark
Debate with the panellists:

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Session Three: Advanced Modelling

Investors in wind energy are placing ever-increasing demands on accuracy in relation to estimates of long-term energy production and operational costs. In addition, ever-larger turbines in large projects, sited in regions of complex topographic or meteorological conditions, are stretching common working practices beyond their proven envelope of validity.

However, advances in computing power and numerical techniques have opened up new possibilities whereby physical and statistical simplifications can potentially be reduced. This is easier said than done, and how to achieve this was a key focus of this session.

This session therefore covered:

  • micro-scale CFD and how to use it;
  • modelling forestry and complex terrain;
  • accounting for thermal effects;
  • calculating energy yield in the time domain;
  • integration of modelling with measurements.

Chair: Christiane Montavon (bio & photos), Senior Consultancy Engineer, ANSYS Ltd UK

Microscale and forestry modelling over complex terrain: current best practice and
challenges (pdf – 1.5MB)
Peter Stuart (photos), Technical Analyst, Renewable Energy Systems Ltd – RES, UK
Atmospheric Stability in Wind Resource Assessment: Measurements and Modelling
(pdf – 1.1MB)
Javier Sanz Rodrigo (bio & photos),Project Manager – Wind Energy Department, National Renewable Energy Centre of Spain (CENER), Spain
Key findings from a field campaign measuring canopy air flows over complex
terrain (pdf – 1.1MB)
Rosey Grant (bio & photos), PhD student, Institute for Climate and Atmospheric Science, University of Leeds, UK
Meso/Microscale atmospheric model integration: benefits to the wind powercommunity and associated challenges(pdf – 3MB) Line Gulstad (photos), Manager, Global Flow Solutions, Wind & Site Competence Centre, Vestas Technology R&D, Denmark

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Session Four: Wakes

As wind farms get larger and larger our understanding of wind farm wakes (i.e. turbine-to-turbine interaction) becomes more and more important.

This session kicked-off with an introduction to wakes – what are they, what do we know and how do we model them (in simple cases).

It then focussed on a number of important topics that challenge the entire wind energy industry, such as:

  • large wakes;
  • wind farm-to-wind farm wakes;
  • advanced modelling and advanced measurements.

The purpose of the session was to establish the boundaries of the current knowledge within this particular field. It is also aimed to give a clearer view of where to go next.

Chair: Andrew Tindal (bio & photos), Head of Energy, Senior Vice President, GL Garrad Hassan, UK

Wakes – An overview of current issues (pdf – 1.8MB) Andrew Tindal (bio & photos), Head of Energy, Senior Vice President, GL Garrad Hassan, UK
The challenges of wake modelling and the importance of validation data (pdf – 2.2MB) Gerard Schepers (bio & photos), Senior Researcher, Rotor and Farm Aerodynamics, ECN Wind Energy – Energy Research Centre of The Netherlands
Wake effects developments in the Offshore Wind Accelerator (pps -1.5MB) Brian Gribben (bio & photos), Fluids Group Leader, Frazer-Nash Consulting Ltd, R&D Project, Carbon Trust, UK
Large Eddy Simulation study of fully developed thermal wind-turbine array boundary layers (pdf – 1MB) Marc Calaf Bracons (bio & Photos), Laboratory of Environmental Fluid Mechanics and Hydrology, École Polytechnique Fédérale de Lausanne, Switzerland
Debate between participants, presenters and the additional panellist:

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Session Five: Comparison of Resource and Energy Yield Assessment Procedures

The economics of a wind farm project are crucially dependent on the wind resource at a site. A robust estimate of the energy production of a prospective wind farm based on a wind and energy assessment is essential in supporting investment and financing decisions. The process of undertaking a resource assessment is a complex undertaking which involves skill and judgement coupled with a firm understanding of the employed numerical models.

36 organisations participated in this comparison by downloading a high quality pack of information and performing an independent pre-construction assessment of the energy production of a wind farm. The results of their assessment (P50 and P90 estimates) were compared and contrasted with the results from others and presented anonymously.

The results of this assessment are vital in gaining an understanding of the differing approaches and will hopefully lead to a consensus on how loss adjustment factors are arrived at and the levels of uncertainty which are apportioned to the various elements of the process.

Chair: Mike Anderson (bio & photos), Group Technical Director, Renewable Energy Systems Ltd – RES, UK

Financing Wind Farms and the Impact of P50/P90 Yields (pdf – 542KB) Andrew Tindal (bio & photos), Head of Energy, Senior Vice President, GL Garrad Hassan, UK
Presentation of results of the comparison exercise (pdf – 4.2MB) Niels Gylling Mortensen (bio & photos),Senior Scientist, Meteorology Programme, Risø DTU Technical University of Denmark
Panel discussion with:

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