Factors propelling the growth of composite wind turbine components

The wind energy sector is picking up speed, with an anticipated CAGR of 9.4 per cent and is projected to reach over £9.4 billion by 2023. There are a number of factors propelling the growth of wind turbine components made from composite materials, including expanding wind power generation capacity, stringent environmental regulations pertaining to emissions from burning conventional fuel, more demand for larger blades and increased government support for wind power projects.

Wind turbine components that could benefit from the properties afforded by composite materials include crush washers, shear pins, high-tensile bolts and generator internals. Made up of fibre and matrix, the composite material manufactured from reinforced fibre and matrix is far superior to that of conventional metals such as steel and aluminium. Thanks to the high strength and stiffness of composite materials combined with their low density, they can be used to produce structures with sufficient stiffness to withstand extreme stresses. For instance, crush washers have to withstand a high load without failing and have proved in applications to be 80% better in crush than their steel versions.

In recent times, carbon fibre-based composites have been the material of choice in modern wind turbines, but the high relative cost of carbon fibre materials, originally developed for the aerospace industry, has prohibited broad adoption of their use within the cost-driven wind industry.

In addition, carbon fibre is quickly falling out of favour with manufacturers and engineers. Sustainability is now at the top of every industry’s agenda and is redefining itself since the pandemic, placing carbon fibre under more scrutiny.

Once cited as the ‘wonder material’, carbon fibre often cannot be recycled and usually ends up in landfill, a major obstacle being it cannot simply be melted down. So what would provide a feasible alternative in today’s changed world, one which carries the same if not more superior properties while ticking the box in terms of energy efficiency and sustainability?

Aluminium Matrix Composites (AMCs) are a family of lightweight high-performance metals, already been used in multiple applications across the aerospace, automotive and industrial sectors. They are beneficial to wind applications for a number of reasons, one being due to the low weight requirement.

Alvant, a UK-based specialist in the testing, design and manufacture of AMCs, believes the material has superior strength compared to steel at less than half the weight, meaning highly loaded components made from traditional metals, such as steel, titanium and aluminium can be replaced by lightweight, low inertia parts.

AMCs also offer multiple advantages over polymer fibre reinforced materials, such as carbon composites, including higher transverse strength and stiffness, a higher thermal operating range, superior damage tolerance and more opportunity to recycle. And if AMC components do get damaged while in use, they are more impact-tolerant than carbon fibre, meaning that they retain more performance after damage.

Alvant is also taking AMCs one step further by working on a customisable metal matrix composite (MMC) multi-phase material called CorXal, that offers a viable alternative to titanium and carbon sandwich composite offerings. This multi-phase material method ensures the product is more resistant to shrinkage, damage and high temperatures, making it eminently suitable for harsher environments and therefore particularly ideal for wind turbine applications.

The focus on sustainability has also changed a notch, as it now also encompasses the entire product life cycle and the ability to reuse, nowadays very much a factor in design development. Alvant’s AMCs are more sustainable thanks to the ability to separate the fibres from the aluminium at the end-of-life stage. Designers must take further into account the ‘whole life cost’ aspect of the design process and it is an area where AMCs score well. And while the full impact of AMCs will not be understood just yet, one thing is clear, which is the growing awareness of specific disadvantages with materials such as carbon composites and polymer composites.