Current trend in offshore wind energy sector and material requirements for fatigue resistance improvement in large wind turbine support structures – A review

Abstract

At present, the UK government is driving the survival of the wind energy industry by using interventions that encourage investment in the sector. The use of a Contract for Difference (CfD)/Strike price model by the UK government supports the wind industry and guarantees that wind energy generators have a stable premium over a period of 15 to 20 years; however, this may not last forever. The growth and stability of the wind industry will depend essentially on continued reductions in wind energy cost, even below that of fossil-fuel based energy sources. Huge cost reduction beyond the present strike price of £57.50/MWh for some projects to be delivered in 2022/2023 may be achieved quickly through efficient and optimized turbine support structure. Consequently, the offshore wind industry is currently making enormous efforts to upscale wind turbines (WTs) from 8MW to 9.5MW,10MW and then 12MW HAWT (Horizontal Axis Wind Turbine). This level of upscaling no doubt creates tough challenges because the mass of the turbine increases linearly with the cube of the rotor radius. Monopiles having diameters larger than 7m have been proposed, with a wall thickness section in the range of 70 to 110mm. It is generally thought that Thermo-Mechanical Controlled Process (TMCP) steels are well suited for extra-large (XL-WTs). This paper reviews the present status of WTs and critically assesses the material factors in the structural integrity concerns that may confront the use of XL steel plates in the design of XL-WT support structures.

The influence of microstructure on the fatigue crack growth rate in marine steels in the Paris Region

“…The TMCP steel grades have been manufactured specifically for offshore pipelines, platforms, pressure vessels and modern wind turbine installations. [28][29][30] Currently, they are replacing the more traditional ones in Table 1. The BS4360 Grade 50D is equivalent to S355J2 + N hot rolled normalized steel.…”

Local Scour around a Monopile Foundation for Offshore Wind Turbines and Scour Effects on Structural Responses

“…The global installed capacity reached more than 14,300 MW at the end of 2016 [1], and an increased potential for growth in future was estimated [2,3]. To achieve high energy harvesting efficiency, the industry is currently advancing into deeper waters accompanied by upscaling the offshore wind turbines (OWTs) from 5 to 8 MW, 10 MW and then 12 MW [4] (see Figure 1). The steady upward trends in both water depth and size of OWTs have led to consequential growth in the loading, further aggravating the deformation of the foundations and potentially jeopardizing the operation of the OWTs.…”

“…Subsequently, we examine existing research on the effects of local scour on the responses of the monopile foundation. Growth in size and power of horizontal axis wind turbine [4].…”

Raindrop Erosion of Composite Materials: Some Views on the Effect of Bending Stress on Erosion Mechanisms

“…Rotor diameters of commercial scale, multi-megawatt, wind turbines have grown in size dramatically [1]. This increase in blade length has progressed due to; advances in blade technology, optimising aerodynamic profiles and improvements with the materials.…”