Posters

Abstract

ReWind is cloud-based software as a service product and spin out company from DNV that provides wind farm owners with decision-making tools for end of life management of wind farms. Owners of aging wind assets have a need to maximise the life-cycle value of their wind farms from an economic and environmental impact perspective including the dismantling and decommissioning phase.  Two of the major characteristics of environmental impact of this phase are the contribution to the circular economy and the net carbon emissions impact of decommissioning. Until now ReWind has focused on enabling users to make significant contributions to the transition to a circular economy in the wind industry.   To provide a holistic view of the environmental impact of decommissioning ReWind partnered with the wind farm owner and developer Statkraft to complete a proof-of-concept study on the emissions associated with decommissioning wind farms before repowering. Statkraft wished to understand the emissions associated with the dismantling, transport and material processing (recycling) of wind turbines from a decommissioning project as well as the associated cost in order to select the optimal decommissioning plan and service providers. The goal of the project was to calculate the emissions associated with each stage of decommissioning, compare the cost to benefit ratio of different solutions and recommend an optimal decommissioning plan.  A sample repowering project in mid Norway nearing the end of its usable life was selected to investigate the carbon footprint of the decommissioning of an onshore wind farm. To focus the study the scope was restricted to the dismantling, transport and recycling of wind turbine blades.  Nine different decommissioning scenarios were considered including five different blade recycling technologies including mechanical grinding, pyrolysis, solvolysis, microwave pyrolysis and cement co-processing. Transport of turbines to material processing facilities by land and by sea was considered. The Greenhouse Gas Protocol methodology for the calculation of the life cycle emissions from the wind farm was followed.   A reference case where recycling of metallic components and the nearest available facility and landfilling of all blades was considered.  The cost per tonne of carbon avoided due to the full recycling of wind turbine blades compared to a base case of landfill at the nearest available facility was calculated for each scenario. Data on the cost to recycle wind turbine blades and the emissions associated with each recycling process was gathered through previous studies, public sources and from the recycling facilities themselves. The results that the mechanical recycling of materials and transportation by sea were the most effective solutions. In all cases the carbon footprint due to transport and processing was not offset by the carbon credit generated by the reusable material. Mechanical grinding, cement co processing and microwave pyrolysis all showed net positive carbon impact compared to landfill. Next steps include repeating the methodology for all wind farm components. The results of this study are added to the ReWind software such that users can optimise for cost of avoided emissions due to decommissioning and recycling.