The Application of Caisson-Type Solutions to the Current Offshore Wind Energy Market

Abstract

The current offshore wind energy market is not only focused on the design of WTG foundations, but also on the design of offshore infrastructures that lead to an improvement in the current grid connection system, such as artificial islands. For all these type of projects, caisson-type solutions can be applied with numerous advantages. The present article present three different projects in which caisson-type solutions were used: the foundation of a WTG (Gravi3® patent) in the Portuguese Coast, the foundation of a meteorological mast installed in Scotland and the design of an artificial island in the North Sea. The main advantage of this solution is the well-developed construction principle to build the caissons, which is based in the employ of a floating dock in a shelter area. As the caissons are cellular elements, the interior is empty; they float, so they are transported to the place in question to be deployed by means of filling with water the cells that comprised the caisson. This technology is rather used in Spain, being most of the kilometres of breakwater built using caissons thank to their high production rates. The three examples that will be presented in the article are proof of the versatility of this solution. Whereas the case of Gravi3® consists in a gravity based solution for WTG, which is comprised of 3 circular caissons connected by means of a steel tripod; the meteorological mast is formed by a rectangular caisson and a steel shaft. Finally, the artificial island is a mixed solution that uses caissons in the perimeter and hydraulic filling in the inner part. Furthermore, these solutions could be also applied in ports, integrating the WTG on the current or future dikes.