Thorsten Hoeser, Claudia Kuenzer

With the promotion of renewable energy production and a planned phaseout of fossil fuels until 2040, the offshore wind energy sector has started to expand and will continue to increase its capacity in the upcoming decades. This study presents how the installed capacity can be derived from radar imagery provided by the Sentinel-1 mission for all offshore wind turbines on the entire Earth. By further combining freely available Earth observation and GIS data, commonly reported attributes of the offshore wind energy sector are compiled. All attributes are investigated to provide an in-depth overview of the developments of the offshore wind energy sector over the last five years. Between 2016 and 2021, the installed capacity worldwide grew from 13.5 GW to 40.6 GW. This corresponds to an increase of 27.1 GW or 200\%. In total 8,885 offshore wind turbines (OWTs) were installed until June 2021 with an additional 852 under construction. The European Union (15.2 GW), China (14.1 GW) and the United Kingdom (10.7 GW) are the three major contributors to the offshore wind energy sector. China has seen the largest growth in the last five years of 13 GW, followed by the EU with 8 GW and the UK with 5.8 GW. The provided in-depth analysis at the end of this study describes the offshore wind energy sector to be in a transition phase between decades of maturity and massive growth at a time when carbon-neutral energy production is massively supported. Overall the proposed methods for independent offshore wind turbine capacity estimation and spatiotemporal investigation of the offshore wind energy sector can be used by all stakeholders involved in the upcoming challenge of integrated planning and implementation of offshore wind energy projects.