Techno-economic analysis of wind farm repowering strategies in France

Sammanfattning: French wind farms are aging. By 2025, the French Environment & Energy Management Agency estimates that 1 GW per year of operating wind turbines will reach their expected lifetime. The handling of wind turbines end of life is relatively new to wind farm owners, both technically and economically. New aspects to handle appear, such as dismantling, strategies of maintenance for the last years of living or again the repowered wind farm construction timing. This work aims at giving an overview of the volume France is going to have to handle in the coming years and how to handle it. The report gives insights for the main questions’ developers should ask themselves when they start thinking about the repowering of their assets. Those insights are based upon what is permitted by the current regulation, which will certainly evolve with the growing experience authorities will soon acquire. From those insights, different strategies will emerge, some more attractive from a technical point a view, but more difficult to set up in agreement with the regulation, common sense, and acceptance of local population. The goal will be to find the best balance between technical feasibility and aimed improvement. Those strategies can then be studied from an economical point of view to try to find the optimum rate of return. This profitability is not unique for a chosen technical scenario but can be optimized. An economic analysis tool will be set up. This tool can perform sensitivity analysis on a scenario, accepting as inputs the parameters that have the most influence on the results. Finally, a concrete application is given on an old and still operating wind farm. This shows one methodology that can be followed when thinking of repowering. There is, of course, multiple available solutions. The goal of this work is to provide developers with all the tools to perform a quick, efficient and accurate analysis of their repowering.