Scenario-based LCA for assessing the future environmental impacts of wind offshore energy: An exemplary analysis for a 9.5-MW wind turbine in Germany.

Background: Offshore wind energy (OWE) will play a significant role in achieving climate neutrality. For example, several scenarios for Germany (e.g., Kopernikus base, Kopernikus 1.5 degree, Prognos CN65, and CN60) depict substantial OWE annual installed capacity additions, especially after 2030. This tendency promotes OWE technology development as deployment expands, allowing manufacturers to gain expertise and optimize wind turbine construction. The global trend towards ever-larger components (e.g., hub height and rotor diameter) is critical to achieving higher-rated capacities. These aspects and others, such as wind quality, influence not only OWE annual electricity production but also its environmental performance. In addition, future supply chains might reduce their environmental impacts and enhance OWE climate change mitigation. In this paper, a prospective life cycle assessment (pLCA) is developed and applied exemplarily for a 9.5-MW offshore wind turbine (OWT) on the North Sea coast of Germany for the years 2030 and 2050. Considering that the current OWTs under construction in Europe have an average capacity of 10 MW, Germany plans to instal OWTs of 9.5-MW. This exemplary OWT describes the potential advances for offshore wind turbines in 2030 and 2050, considering component scale-up and learning effects. Yet, the methodology is adaptable to various installed capacities and regions. This approach allows us to analyse not only the potential future characteristics of wind turbines, but also future developments in OWE supply chains. Therefore, relevant parameters related to OWT construction and operation (e.g., rotor diameter, hub height, distance to the shore, lifetime, etc.) as well as prospective life cycle inventory data for background systems that reflect potential future developments in the broader economy are considered. In this way, scenarios (e.g., optimistic, moderate, and pessimistic) for OWE elucidate the expected environmental impacts, such as climate change, marine eutrophication, and abiotic depletion potential, in 2030 and 2050. Results: The findings describe the variability of the environmental impacts of a 9.5-MW offshore wind turbine representing the technologies expected to be available in Germany in 2030 and 2050 and show that climate change impacts could vary between 7 and 18 g CO₂-eq per kWh produced in 2030 and between 5 and 17 g CO₂-eq per kWh in 2050. However, marine eutrophication could experience a significant increase (100% increase), depending on the consideration of hydrogen as a fuel in the electricity mix, as demonstrated in the climate-neutral scenarios adopted for Germany. Overall, construction efficiency improvements in 2050 might reduce the required materials, leading to a 6% decrease in abiotic depletion potential compared to 2030 values. Conclusions: This paper highlights the need to consider temporal improvements in LCA studies, particularly when assessing the environmental impacts of offshore wind turbines. The complex nature and rapid growth of offshore wind technology require a comprehensive life cycle approach to deepen our understanding of its potential environmental impacts. [ABSTRACT FROM AUTHOR]