Assessment of different end-of-life strategies for wind power plants under uncertainty

The enormous rise in installed wind power capacity worldwide over the last twenty years means most of the wind power plants will soon reach their end-of-life of service. The attention of owners, governments and investors is being drawn to strategies aimed at increasing the useful life of these facilities or the repowering of old wind farms, with the additional benefit of increasing generated power by using more efficient wind turbines. With the aim of evaluating ways to address an actual case of the end of life of a wind power plant in Spain, three strategies are studied to assess the most suitable solutions, allowing the useful life of the current wind turbines to be extended for another ten years, or adopting a repowering strategy, in which the old wind turbines are replaced by new ones with a service life of twenty years. A stochastic techno-economic model is proposed, and the Monte Carlo simulation technique is used, allowing uncertainties and risks associated with the key technical and economic input variables to be considered, also revealing those with the greatest impact on the economic performance of the project. Results provided by the stochastic model are more realistic than the deterministic analysis, revealing an increase in the annual energy production ranging from 9.53% to 56.93%, depending on the strategy adopted, with repowering being the most advisable project. Valuable, practical outcomes for making tactical decisions in optimizing wind energy resources are obtained, considering different levels of improvements to be implemented in wind power plants according to the available resources and the expected return on investments.