‘Offshore’ is still very much ‘near shore’, and deep waters are still not deeper than the length of a blade. This is shown by an analysis of the world’s producing wind farms.
By Mads Kromann-Larsen and Karsten Prinds
There is still a long way to go for offshore wind – a huge potential, you could argue. If all the offhore wind turbines in the world produce to their maximum, they could cover the power consumption of Ireland.
This can be seen in the Global Offshore Renewables Map – a gathering of data from all the producing offshore power plants. The research has been undertaken by the Knowledge Center at Lindoe Offshore Renewables Center (LORC). At the dawn of this year, a total of 3658.47 megawatts could be produced from all the worlds offshore wind turbines. This roughly corresponds to the consumption of 3.2 million homes.
A closer look at the sites shows that there is still a lot of ocean to be conquered. The existing offshore wind turbines stand in very shallow waters. Three quarters of offshore sites have turbines at depths less than 16 meters.
Not only are most sites in shallow water, they are also close to land. Three quaters of the sites are less than 10 kilometers off shore, as the data from LORC Knowledge shows. Here we see one of the implications of offshore wind being a young industry. Many of the existing sites are meant for test or demonstration where a location close to shore is an advantage. A quarter of all sites is less than 1.2 kilometers from shore.
Installing gravity-based support structure at Roedsand II, Denmark. Gravity-based structures are the world’s second most popular. Photo: Bilfinger Berger Group
Looking at the types of support structures, there are monopiles and gravity structures – and then all the others.
29 of the world’s 51 sites now have turbines installed on monopiles and 14 sites use gravity-based support structures. Many look towards jackets for future installations, but so far only three sites use this structure type – one of these being an oil rig with a wind turbine mounted.
There is a slight tendency towards putting gravity-based structures in lower waters, then monopiles, multipiles and jackets the further distance there is to the seabed. The gravity-based sites in the world are placed in depths from 2 to 27.5 meters. Monopiles make it 10 meters deeper, and then come the multipiles, i.e. tripiles or quadpiles. They are just beaten by jackets in the competition for deep waters. But when it comes to popularity, you cannot argue with the monopile. At least not yet.
Further data can be found in the interactive map at LORC Knowledge. Go to www.lorc.dk/offshore-wind-farms-map for a closer look.