Wind power is one of the more mature renewable energy segments and India needs large volumes of wind power installations to meet its clean energy targets. While the role of a wind turbine’s blades and generator cannot be ignored, towers and foundations are the backbones of these machines. The foundation, firmly anchored in the ground, provides the necessary stability for the towering structure and withstand tremendous forces that wind turbines encounter. Meanwhile, the tower, rising to impressive heights, not only elevates the turbine’s rotor to capture maximum wind energy but also bears the weight of the nacelle and blades. This article explores different technologies for wind towers and foundations and presents their outlook.
The stability of a wind turbine is very important and is ensured by providing an appropriate foundation. The main task of the foundation of a wind turbine is to transfer and spread the loads in the soil at depth. The height of a wind turbine tower usually varies from 40 metres to 130 metres.
Onshore foundation: Onshore wind turbine foundations are the structural bases that provide stability and support to wind turbines installed on land. Tailored to specific soil conditions, project requirements and environmental factors, these foundations form the bedrock of safe and efficient wind energy endeavours. Within this domain, distinct types of onshore wind turbine foundations emerge, each meticulously designed to harmonise with specific considerations.
These include slab foundation, which resembles a sturdy plate and effectively distributes the wind turbine’s loads to the underlying soil. Its broad area facilitates load dispersion. The foundation’s design often adopts cylindrical or square prism shapes. Meanwhile, the pile foundations utilise the concepts of deep foundation and emerge as sleek columns or elongated cylinders constructed from materials such as steel or concrete. Pile foundations find their suitability in situations involving more pliable topsoil conditions.
Offshore wind turbine foundations are specialised structures crafted to support turbines stationed in seas or oceans. Their purpose is to safeguard the stability, security and efficiency of offshore wind farms. The foundations’ design evolves to align with water depths, with variations introduced based on the construction location of wind farms in offshore regions.
Within this space, monopile foundation is perfectly suited for water depths less than 30 metres and seabeds of sand and gravel and helps in improving cost-effectiveness. It secures turbines to the seabed, providing a stable anchor for the structure. Meanwhile, gravity base foundation is anchored in shallow waters and derives its stability from self-weight. A substantial circular pile is topped by a concrete plate structure resting on the seabed, ensuring stability in the nearshore regions.
The tower of a wind turbine raises the critical wind turbine components to maximise the capture of wind energy. It is vital for absorbing and disseminating static and dynamic forces and guarantees stability, safety and efficiency. A variety of wind turbine tower designs cater to a range of requirements.
Lattice tower: Forged from welded steel profiles, lattice towers provide a cost-effective solution by using around half the amount of steel material required for tubular steel towers, while maintaining comparable rigidity. However, they find limited use in contemporary, larger wind turbines owing to aesthetic considerations.
Tubular tower: Dominating modern wind turbines, tubular steel towers are assembled on-site using 20-30 metre sections bolted together to achieve height. Their conical shape bolsters strength while optimising material use.
Guyed tower: Suited for smaller turbines, guyed towers employ narrow pole structures supported by guy wires. While cost-efficient, they present access limitations and are more prone to intentional damage.
Hybrid tower: Striking a balance between techniques, hybrid towers merge attributes to tailor solutions, considering structural integrity, cost-effectiveness and aesthetics.
Challenges and outlook
The role played by each element within a wind power plant is pivotal in enhancing generation efficiency. Given that towers and foundations offer essential structural support, they are critical for ensuring the overall safety and functionality of wind power installations. With significant decline in tariffs, profitability margins for developers and manufacturers have substantially diminished. This trend might lead to cost-cutting during construction, potentially resulting in suboptimal designs. Instead, manufacturers must prioritise efficiency of manufacturing procedures to bolster their profit margins.
By Anusshka Duggal