With wind turbines evolving towards larger and longer blades, advanced materials, engineering solutions and manufacturing processes are becoming increasingly important to improve performance reliability, and cost competitiveness. India, with its growing wind power market and rising status as a global manufacturing and export hub, has significant potential to adopt these technologies. However, challenges related to design capabilities, automation, material qualification, supply chains and policy frameworks must be addressed to fully unlock this potential. In an interview with Renewable Watch, Jesper Sloth, Vice President, Sales, Wind Materials, Gurit, discusses the key global trends in blade technology, the specific requirements of Indian wind conditions, and measures needed to strengthen India’s wind turbine blade and component manufacturing ecosystem. Edited excerpts…
What are the key technology and engineering advancements currently shaping the global wind turbine blade industry?
The primary advancement shaping the global blade industry is the continued increase in blade length. However, as blade lengths increase, several interrelated factors must be considered.
One, how to achieve sufficient stiffness in the blade without overly increasing the weight. This is typically accomplished by replacing the infused glass spar cap with a carbon pultruded spar cap.
Two, as carbon fibre conducts electricity and glass fibre does not, replacing the spar cap material introduces a significant lightning risk, requiring the lightning protection system to be redesigned. Lightning usually strikes the outermost part of the blade, so you will typically notice a solid aluminium metal tip and several metal receptors along the blade’s surface, acting as targeted strike points. Blades also use internal or external conductors built into the structure during the moulding process. These direct the current into the ground and feature equipotential bonds to handle the inevitable current flow into the carbon spar caps.
Three, as blade length increases, the mass increases non-linearly, resulting in an increased static moment that requires a more advanced blade root-to-nacelle interface. In larger blades, traditional T-bolt solutions are typically replaced with advanced root solutions such as butterfly wedges, which allow for a greater number of bushings within a similar-sized bolt circle diameter. The primary consideration here is ensuring the strongest possible bond strength between the wedge and the laminate, as well as between the wedge and the bushing, to prevent bushing shear-out.
Four, transportability is another critical concern when increasing blade length. Engineers often look at weight and/or height reductions, which can be achieved, for example, through a smaller root diameter or optimised material usage.
Five, an increase in length often increases the blade tip speed (a similar RPM with a longer blade means higher speed). When tip speed increases, the erosion on the outer part of the blade can be significant. In a country like India, where monsoon rains and dust are perpetually present, this issue is especially critical. Therefore, using proper leading-edge protection (LEP) becomes a necessity, particularly when exceeding the 85m/s tip speed boundary. The most durable solutions are polyurethane shells, which are often used on the outer 8-10 metres of the blade, transitioning into a lower-grade solution as the speed decreases further inwards.
Six, new manufacturing standards rely to a greater extent on subcomponents – such as root wedges, web-feet and the main laminate – which are made offline and allow for a higher degree of automation and quality control. This trend to modularise and standardise is needed to bring down costs and improve quality.
Which advanced blade technologies and engineering solutions are widely deployed in global wind markets but have seen limited adoption in India?
Indian wind farms have witnessed a slower uptake of larger turbine designs compared to other regions. Consequently, many blades still incorporate infused glass spar caps, simple lightning protection systems, hand-cut core kits, and traditional T-bolt root connections, with less focus on LEP.
One of the challenges when transitioning to longer blades with more advanced material systems is ensuring process consistency. While this shift requires more advanced processing equipment and automation, it ultimately results in higher quality and improved reliability when executed correctly.
What specific blade technologies and design features are needed to ensure optimum performance and reliability in Indian conditions?
As the wind conditions are primarily suited for low-wind-speed turbines, long, light and slender blades are highly preferred. A steep power curve is more important than a high MW rating. This calls for slender and light carbon blades with a small root diameter. Furthermore, given the challenges of the monsoon season (lightning and rain), and the prevalence of dust, a well-designed lightning protection system and a high-performance LEP are beneficial.
What are the key engineering challenges related to blades that will need attention?
If we just talk about India, then I believe the most important aspect is to improve design capabilities. Today, most new designs are acquired from China, which means they are often a few generations behind, and full design information may not always be available. If the design is not thoroughly understood, it becomes far more challenging to make localised improvements and ensure the blade meets qualification criteria.
Additionally, in a Chinese design, most of the pre-qualified materials are also of Chinese origin. Transitioning to Indian-sourced materials then becomes a major challenge due to complex qualification requirements. For example, specifications may call for a particular resin type in a precast product, rather than defining requirements based on interface performance and required mechanical properties.
Given that India has a strong foundation of engineering talent, it is surprising that we are not yet seeing more in-house design by domestic manufacturers.
How do you assess the current state of India’s wind turbine blade and component manufacturing ecosystem, and where do you see the biggest opportunities for advanced materials and technologies?
Progress has been good in India. However, I regard the prevalence of manual processes as one of the biggest opportunities to address quality inconsistencies. In many factories, manual labour – such as simple in-house core kitting, gluing processes by hand, and the manual coiling of pultrusions – is preferred over automation. While this approach may at first seem more flexible and cost-effective, it is not an optimal solution for ensuring the quality, consistency, and reliability required in longer and more advanced blades. Ultimately, quality problems are likely to emerge.
What are the key challenges faced by international blade technology and material players in accessing and operating in the Indian wind market, including issues related to pricing, scale, technology qualification and supply chains?
I believe many international players are interested in the Indian wind market due to the growing domestic market and the position of India as an export hub for materials. The primary challenge for India is remaining competitive with manufacturing in China – something that is evident even within the domestic Indian market. To address this, India requires a more competitive vertical supply chain alongside policies that foster local manufacturing to help it scale up to competitive levels.
The current geopolitical situation is creating momentum for India’s expansion as a supply hub for exports to the European Union and the US. This momentum should also be used to ensure growth within India itself, with volumes being established through an “India for India” mentality.
What policy and industry measures would you recommend to strengthen India’s wind turbine component manufacturing ecosystem and facilitate the adoption of advanced blade technologies?
India should review its existing policies around import duties, which appear to be very complex. Streamlining these policies to strengthen the ecosystem and its foundations will be critical to supporting long-term growth. Two examples:
An anti-dumping duty of 20 per cent on virgin polyethylene terephthalate granules was recently introduced in India; however, no extra duty has been introduced for the import of core kits containing polyethylene terephthalate (except a concessional 5.5 per cent duty by the Ministry of New and Renewable Energy). The net effect is that it has become less cost efficient to manufacture these materials in India.
A duty of 11 per cent exists when importing balsa as an independent core kitter; however, when importing balsa as a blade manufacturer, the duty is only 5.5 per cent. The net effect is limited investment in advanced balsa kitting.
Many Western players are interested in increasing their investment in India, and these duties were probably introduced to encourage that while improving the overall competitiveness of the Indian market. However, the onerous and inconsistent nature of these policies has, unfortunately, had the opposite effect.
Overall, I believe India is well positioned for significant growth in the wind market, both domestically and as an export hub for materials, blades and turbines. By continuing to strengthen local demand, manufacturing capabilities and the wider ecosystem, India can build a highly competitive foundation for high quality and reliable wind products.
That ecosystem should extend beyond blades and turbines to include systems, advanced materials, and Tier 2 raw materials. With the right policy support and industry collaboration, there is real potential for India to become an even stronger force in the global wind industry, and it is exciting to see how this market could develop in the years ahead.
