The National Wind-Solar Hybrid Policy was announced in May 2021 with the aim of promoting large-scale grid-connected wind-solar hybrid projects in the country. The MNRE has recently issued a draft guideline for the development of offshore wind energy projects in India, which is expected to accelerate growth of the renewable energy sector in India and contribute towards achieving the country’s target of 450 GW of renewable energy capacity by 2030.
The Indian government has taken several initiatives to promote wind energy, including policy support, tax incentives, and financial incentives for developers and investors. The Indian Wind Turbine Manufacturers Association (IWTMA) has been advocating the establishment of an export promotion council for wind energy equipment. It would help Indian wind turbine manufacturers to expand their businesses globally and increase exports.
The Indian wind sector has also been focusing on improving the efficiency and reliability of wind turbines. The Centre for Wind Energy Technology (C-WET) has been conducting research and development in the field of wind energy to improve the performance of wind turbines.
Basics of Wind Turbines
There are different types of wind turbines, depending on the geography, output, cost etc. Wind turbines use steel, hybrid of concrete & steel, and concrete as raw material.
Application of steel wind turbines:
- Lattice towers
- Tubular towers
- Space frames
- Offshore applications: hybrid (lower part concrete, upper part steel)
- Precast pre-tensioned
- Precast post-tensioned
A wind turbine is a device that converts kinetic energy from the wind into electricity.
A group of wind turbines is called a wind farm. On a wind farm, turbines provide power to the electrical grid. These turbines can be found on land (onshore) or at sea (offshore). Wind turbines are manufactured in different shapes and sizes, but the most common design is the one with 3-blades mounted on a horizontal axis. Their output ranges from as small as 100 kilowatts to as big as 12 megawatts.
They can be placed on many locations like hills, in open landscapes, fixed to the bottom of the sea, and we can even have floating turbines in deep waters.
How does a wind turbine work?
There is a wind vane 1 at the top of each turbine: this indicates the speed and direction the wind is blowing.
The turbine then rotates on the tower to face the wind, and the blades 2 rotate on their axis to create maximum resistance against the wind.
The wind starts turning the blades which are connected to a hub and a low-speed shaft 3.
The low-speed shaft spins at the same speed as the blades (7-12 revolutions per minute), but we need a much faster rotational speed for the generator to produce electricity.
That’s why most wind turbines have a gearbox 4, which multiplies the rotational speed of the low-speed shaft by over 100 times to the high-speed shaft 5, which rotates up to 1,500 revolutions per minute.
This is connected to a generator 6, which converts the kinetic energy into electricity.
Turbines that do not have a gearbox are connected directly from the hub to the generator 6 through their axis (called ‘direct-drive’).
Most widely used design in tubular towers
- Steel plates used in tubular towers support structures for stator and rotor brakes.
- Tubular steel towers use 12mm, 14mm, 16mm, 18mm, 20mm, 22mm up to 63mm in S355 J2+N, J0, JR etc. grade.
- Tubular towers use plates in widths of 1250mm, 1500mm, 2500mm and 3000mm.
- The trend is to use high strength steel plates in combination with wider width plates for reducing the tower weight and joints, respectively. Steel plates for support structures range from 25mm to 50mm in S 355 J2 grade.
The use of heavy steel plates is especially important in larger wind turbines, which require stronger and more durable components to withstand the increased stresses and loads. For example, the latest generation of offshore wind turbines can have a rotor diameter of up to 220 meters and stand over 250 meters tall. These turbines require steel plates that can withstand high wind speeds, waves, and corrosion from harsh marine environments.
Another advantage of heavy steel plates is their flexibility in design. Wind turbine manufacturers can customize the plates to meet specific project requirements, such as thickness, width, and length, depending on the turbine’s design and location. This flexibility also extends to the type of steel used, with manufacturers able to choose from a range of high-strength, low-alloy steels, and carbon steels.
|Typical Steel Grades – Wind tower||Product mix||Supply conditions|
|General Engineering / Structural steel –
Length- up to 16000 mm
Thermo-mechanical controlled rolled
- Supply of TMCP plates against Furnace Normalized/Normalized Rolled plates for improved weldability & handling.
- Supply of steel plates as per exact design and tight dimensional tolerances
- High strength steel (S 420 etc) replacing Standard S 355 grades
- Cost saving model for using high strength steel (welding, handling, cutting etc).
- Reduction in the number of shells in the tower section
- Savings by elimination of additional operations like cutting, handling, welding, assembly etc.
- Reduction of circumferential welding -30% cost saving through reduction of welding
- Taller towers for enhanced power generation
- Greater stability and integrity of structure
- Cost saving due to reduced weight of shells and stiffeners.
Overall, the wind sector in India is witnessing significant growth and development, with the Government taking various initiatives to promote wind energy in the country. The latest developments in the sector indicate that the industry is moving towards greater efficiency, reliability, and sustainability. With the right policies and investments, the wind sector in India has the potential to become a major contributor to the country’s energy mix and play a key role in reducing greenhouse gas emissions.