A novel foundation design for the hybrid offshore renewable energy harvest system

Abstract

Establishing a hybrid offshore renewable energy harvest system (HOREHS) on a shared platform can reduce energy costs and increase productions. This paper aims to propose a HOREHS supported by a foundation consisting of a monopile and a plate to integrate various offshore renewable energy devices. Taking the Sheringham shoal wind farm as a case study, the benchmarking monopile dimensions were determined using design guidance and an equivalent monopile-plate combination was determined from FEM simulations. Parametric studies of system mechanical responses were conducted using FEM simulation. It is found that, to maintain the same mechanical response, the embedded depth of the monopile supporting the HOREHS should be increased by about 17% comparing with that supporting an offshore wind turbine. Adding a 14 m diameter steel plate can avoid the extra 17% embedded depth. Adding a plate has no effect on the size of influence zone of lateral soil stress. However, due to the shorter embedded depth, the magnitude of lateral stress for the hybrid foundation is larger than that for monopile, with the maximum increase being about 18%. The system response at the mudline level shows the highest sensitivity to the changes in embedded depth and plate diameter.