Life cycle assessment of floating offshore wind farms: an evaluation of operation and maintenance

One of the key objectives for renewable energy technologies is to reduce the environmental impact of energy generation. Floating offshore wind technologies have been developed in recent years, to exploit the wind energy resource available at deep waters where bottom-fixed technologies are not economical. However, few studies exist that analyse the environmental impact of such technologies. These studies can be used to identify hotspots where potential exists to further improve designs and processes to decrease environmental impacts. Particularly, offshore activities such as those required for Operation and Maintenance (O&M) are not represented in detail in previous studies. The present study addresses these gaps by performing a Life Cycle Assessment using an advanced O&M model to quantify the environmental impact of a floating offshore wind farm. Different O&M philosophies - assuming towing to shore for major operations vs. performing all operations on site - and their impact are evaluated and discussed for two case studies inspired by real pilot park deployments. To this end, publicly available data is exploited. The results show that the contribution of O&M on the overall environmental impact highly depends on the chosen strategy with contributions on Global Warming Potential (GWP) ranging from 26 to 49%. Assuming O&M strategies to be the same for fixed and floating offshore wind could result in a 20.0% underestimate of GWP, whereas the vessel choice resulted in up to 29.6% variation in the estimated GWP. An environmental impact perspective provides key insights on the choice of different designs, operation strategies and asset management, and thus should be used in the decision-making process.