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Delegates are invited to meet and discuss with the poster presenters during the poster presentation sessions between 10:30-11:30 and 16:00-17:00 on Thursday, 19 November 2015.

Lead Session Chair:
Stephan Barth, ForWind - Center for Wind Energy Research, Germany
Marion Jude Eoltech, France
Marion Jude (1) F Habib Leseney (1)
(1) Eoltech, Tournenfeuille, France

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2015 and are published here unedited

Marion Jude has been working in the wind industry for more than 6 years. She has been a wind analyst at Eoltech, the first French independent expert in wind resource assessment, since her graduation (Master Degree in Environment and Process engineering). She has been working on numerous projects -for pre or post construction analysis- located mainly in France but also in the Caribbean, in Norway, in Portugal and in Africa. She has been also involved in the development of in-house tools for the treatment and the analysis of production data.


Poster Download poster (9.23 MB)


Experience feedback on wind resource assessment studies


Eoltech, the first French expert in wind resource assessment, has carried out an experience feedback study based on 97 wind resource assessments of projects located in France. The main objective of this study, co-financed by the ADEME (Environmental French Government Agency), is a comparison between the theoretical production output (estimated) and the effective one (measured) of these wind farms in operation for several years.


The sample includes 97 theoretical studies issued by 15 different independent consultancies and concerns 94 operating wind farms (total power of 1288 MW). Eleven owners or operators have participated in the project: EDF EN, GDF Suez, Kallista Energy, Altech, IWB, Theolia France, Valorem, Eurocape, Quadran, Sorgenia and Aalto Power.
The comparison between the theoretical and the effective output for each park was facilitated by adjusting the production data to comparable levels of park availability and to an equivalent long-term reference period.
The output deviations resulting from this analysis were considered globally, but decompositions linked to the study conditions (roughness, hub height vs measurement height…) were also made in order to try to measure the impact of these criteria. The aim of these decompositions was to consider separately the results linked to specific sites or project conditions, without regard to the author of the wind assessment or the methodology used.

Main body of abstract

Predicted and effective productions were adjusted over the same long term reference period so that the output deviations resulting from this study are not related to long term wind resource variations. As these deviations can be explained both by the uncertainty on theoretical studies and by the uncertainty on the actual performance of the turbines, the concept of “over-” or “under-” estimation cannot be solely attributed to the wind resource but more broadly to the actual production capacity of a wind farm (including wind resource and performance). Changes in the vicinity of the wind parks should be taken into account as uncertainty in our approach (effects not included).
This study highlights mainly the following points:
- One third of the wind farms present reasonable output deviations (between -5 % and +5 %).
- For almost 60 % of the wind farms, theoretical studies tend to overestimate actual production capacities by more than 5 % (and almost a quarter of the wind farms by more than 10 %).
- In terms of portfolio effect (all the wind farms considered together), theoretical studies overestimate the actual production capacities in the order of 6 %.
- For projects located in surroundings with complex vegetation cover (forested or wooded areas), the probability of overestimating the actual capacity seems to increase significantly, especially for turbines with large rotor diameters with regard to the hub height.


In terms of project funding for a large portfolio of projects, considering the P90 value (associated with a global uncertainty of 10%) appears to take into account the risk of overestimating actual output capacities (including the decrease in the wind resource over the past decade). However for a specific project, a slight increase in the usual level of uncertainty on production could be accounted when the vegetation cover is complex, even more so when the case is associated with measures at low height or turbines with large rotor diameter relative to hub height.

Learning objectives
The key finding of this study was to get orders of magnitude of the output deviations between the theoretical production from wind resource assessments and the effective production for a significant number of operating wind farms in France. This experience feedback could allow to adjust the uncertainty level on future theoretical assessment studies.