Life cycle assessment of onshore and offshore wind energy-from theory to application

Abstract

This study aims to assess the environmental impacts related to the provision of 1kWh to the grid from wind power in Europe and to suggest how life cycle assessment can inform technology development and system planning. Four representative power plants onshore (with 2.3 and 3.2MW turbines) and offshore (4.0 and 6.0MW turbines) with 2015 state-of-the-art technology data provided by Siemens Wind Power were assessed. The energy payback time was found to be less than 1year for all technologies. The emissions of greenhouse gases amounted to less than 7g CO2-eq/kWh for onshore and 11g CO2-eq/kWh for offshore. Climate change impacts were found to be a good indicator for overall hotspot identification however attention should also be drawn to human toxicity and impacts from respiratory inorganics. The overall higher impact of offshore plants, compared to onshore ones, is mainly due to larger high-impact material requirements for capital infrastructure. In both markets the bigger turbines with more advanced direct drive generator technology is shown to perform better than the smaller geared ones. Capital infrastructure is the most impactful life cycle stage across impacts. It accounts for more than 79% and 70% of climate change impacts onshore and offshore respectively. The end-of-life treatment could lead to significant savings due to recycling, ca. 20–30% for climate change. In the manufacturing stage the impacts due to operations at the case company do not exceed 1% of the total life cycle impacts. This finding highlights the shared responsibility across multiple stakeholders and calls for collaborative efforts for comprehensive environmental management across organizations in the value chain. Real life examples are given in order to showcase how LCA results can inform decisions, e.g. for concept and product development and supply chain management. On a systems level the results can be used by energy planners when comparing with alternative energy sources.