Spar concrete monolithic design for offshore wind turbines

Abstract

Significant research efforts are now being directed at floating offshore wind turbines. The main challenge posed by floating wind turbines is the high construction and installation costs of the substructure, which make it too expensive for commercial exploitation in the current energy market. With the aim of achieving a cost-effective floating platform for offshore wind turbines, a new concept of a monolithic floating spar buoy is hereby presented. The monolithic concrete structure includes both the tower and the floater, built as a continuous single piece. This new concept offers a significant cost reduction during the construction phase and also while in operation, because the platform becomes almost free of maintenance during its lifetime. The main dimensions and the hydrostatic and hydrodynamic properties are presented, including a basic structural assessment of the platform to ensure its structural integrity. The construction and installation processes are presented, taking into account the special requirements of the monolithic design. Finally, a cost comparison between a steel and an equivalent concrete platform design has been performed, showing a material cost reduction larger than 60% in the case of the concrete design.Peer ReviewedPostprint (author's final draft

Sensitivity analysis on the levelized cost of energy for floating offshore wind farms

“…A catamaran ship can be applied for this process instead of heave floating cranes, which reduces installation costs. After erection, the SPAR is connected to the pre-installed mooring system, which consists of three catenary mooring lines[41]. The anchor type that is being used depends mainly on the seabed conditions and can range from drag anchors for sandy sites to suction pile anchors for layered and rocky soils.…”

“…The anchor type that is being used depends mainly on the seabed conditions and can range from drag anchors for sandy sites to suction pile anchors for layered and rocky soils. The decommissioning follows the same principal as the installation process and concrete material may be reused or sold for other purposes[41]. Further information about the specific floating wind turbine concepts can be found on the respective websites of the concept developers, which are listed in the references[31,33, 32].3.2.…”

Baseline Design of the Deep Turbine Installation-Floating, a New Floating Wind Concept

“…Concrete is also cheaper than steel [27], allowing for further reductions in construction costs and therefore the capital expenditure (CAPEX).…”

A symbiotic approach to the design of offshore wind turbines with other energy harvesting systems

“…The steel cost may be offset by reducing the FWT platform 230 mass. Additionally, as discussed in [39] and [40], fabricating the WEC with with concrete instead of steel may reduce the WEC LCOE by up to 50% due to lower capital cost and longer lifetime. Future studies will investigate a concrete WEC design.…”