WIND FARM DECOMMISSIONING: A DETAILED APPROACH TO ESTIMATE FUTURE COSTS IN SWEDEN

Abstract: Although targets for renewable energy exist in Sweden, developing wind energy has proven to be challenging for developers. This is due in part to the demands made by authorities for monetary amounts to be set aside to take care of wind turbine dismantling and site restoration costs at the end of their lifecycle. There has been a large degree of uncertainty surrounding the amounts being demanded and the level to which sites must be restored, partially due to a lack of guidelines. Coupled with ambiguity, there has been a tendency by authorities and developers to use figures from previous high court decisions and previous permit applications to project decommissioning costs for current applications.This thesis evaluates seven different wind farm decommissioning scenarios using a model developed to estimate future costs, with the turbine model and the quantity of turbines being the parameters that vary. The model uses data from numerous sources, including real case decommissioning projects and figures from an existing model that had already been used to forecast costs in Sweden. One of the assumptions of the model developed is that scrap metals in wind turbines will have a residual value when decommissioning occurs; this was not allowed for in a recent decision made by a county administrative board following an environmental high court decision. An argument is made to justify that a minimum scrap value for wind turbines should be considered, based on the findings of the model. A further case is made to allow for the security bonds to be paid over an extended period of time, considering the initial value of wind farms.The results of the model show that the turbine model has an impact on the decommissioning costs and the potential residual value that can be obtained. In addition, the quantity of the wind turbines has a considerable effect on the decommissioning costs. These results suggest that each wind development project should be treated on a case-by-case basis using a calculation-based approach when determining the cost for a security bond. Recommendations for future research include considering wind farm location in the model.