Exploring How Wind Energy is Generated, its Types and Drawbacks
One of the most promising and quickly expanding renewable energy sources, wind energy is essential to the world's shift to cleaner, more sustainable electricity generation. Wind and solar energy have become essential solutions as the world looks to lessen its dependency on fossil fuels and combat climate change.
Wind energy is generated by the movement of air masses in Earth's atmosphere. The fundamental driving force behind wind is the uneven heating of the Earth's surface by the Sun. Areas that are heated more (such as the equator) create higher pressure, while cooler areas (such as the poles) have lower pressure. Air moves from areas of high pressure to low pressure, creating wind. The flow of wind is harnessed to generate wind energy using wind turbines.
How Do Wind Turbines Work?
A wind turbine turns wind energy into electricity using the aerodynamic force from the rotor blades, which work like an airplane wing or helicopter rotor blade. When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag.
The force of the lift is stronger than the drag and this causes the rotor to spin. The rotor connects to the generator, either directly (if it’s a direct drive turbine) or through a shaft and a series of gears (a gearbox) to generate electricity.
Components of a Wind Turbine
1. Foundation: The foundation is a large, heavy structural block of concrete in the ground that supports the entire turbine and the forces acting on it. In offshore turbines, the foundation is underwater.
2. The tower: The tower is usually made of steel. The tower usually has three sections and is assembled on-site. Its height varies, but it is generally the same as the diameter of the circle that the blades create when they spin. The tower also contains the power cables that connect the nacelle to the transformer on the ground.
3. The nacelle: The nacelle is located on top of the tower and can turn 360° on its own axis, depending on the direction of the wind. It is named after the part of the wing of an airplane that contains the jet engines. It houses the key mechanical elements: the gear box and generator.
4. The rotor and hub: Rotor consists of three blades and a central part connecting the blades, the hub. The hub is the nose that points forward at the centre, the blades are attached to it, and it is in turn connected to the mechanical parts in the nacelle, which is located behind it.
5. The blades: These are located on top of the turbine. The average length is 170 feet (52 meters). Wind causes the air pressure on one side of the blade to decrease and the difference from the other side creates both lift and drag: when the lift is stronger than the drag, the rotor will spin.
6. Drive train: The drive train consists of low –speed shaft, gear box and a high-speed shaft. It also has support bearings, couplings, brake and rotating parts of generator.
7. Yaw drive: The function of this is to keep the turbine aligned to the wind. It turns the nacelle with rotor as per the wind direction using a rotary actuator engaging on a gear ring beneath the nacelle. The yaw drive is powered by the yaw motor.
8. Wind vane: This measures the wind direction. It provides information to the controller for orienting the turbine properly (yawing) with respect to the wind direction.
Types of Wind Turbines
1. Horizontal-Axis Turbines (HAWT): Horizontal-axis wind turbines are what many people picture when thinking of wind turbines. They typically have three blades and operate upwind, which means that the blades face into the wind. HAWTs generally have a yaw mechanism that allows the turbine to rotate and face into the wind. This orientation is crucial for capturing the optimal wind energy, as wind direction can change.
2. Vertical axis wind turbines (VAWT): They have a vertical axis of rotation, meaning the rotor spins perpendicular to the ground. The blades are attached to a vertical shaft that allows the turbine to capture wind from any direction without needing to be oriented. VAWTs are typically smaller and more compact than HAWTs, and they are often used in residential applications or in urban environments where space is limited.
Types of Wind Energy Generation:
1. Onshore Wind Generation: Onshore wind farms as the name suggests are situated on land, usually in regions like wide fields, ridgelines, and coastal plains where average wind speeds are strong. Due to lower infrastructure expenses, onshore wind is typically less expensive to build than offshore wind. Tall towers are used to install turbines, and power cables are used to send the electricity produced to the grid.
2. Offshore Wind Energy Generation: Offshore wind farms are located in bodies of water, typically in shallow areas of the ocean. Offshore wind farms have the potential to generate more energy than onshore wind farms due to the stronger and more consistent winds found at sea. Offshore wind turbines are typically larger and placed farther apart to avoid turbulence, allowing for more efficient energy generation.
Challenges of Wind Power
1. Wind power must compete with other lower cost energy sources. When comparing the cost of energy associated with new power plants, wind and solar projects are now more economically competitive than gas, geothermal, coal, or nuclear facilities. However, wind projects may not be cost-competitive in some locations that are not windy enough.
2. Ideal wind sites are often in remote locations. Installation challenges must be overcome to bring electricity from wind farms to urban areas, where it is needed to meet demand. Upgrading the nation’s transmission network to connect areas with abundant wind resources to population centres could significantly reduce the costs of expanding land-based wind energy.
3. Turbines produce noise and alter visual aesthetics. Wind farms have different impacts on the environment compared to conventional power plants, but similar concerns exist over both the noise produced by the turbine blades and the visual impacts on the landscape.
4. Wind plants can impact local wildlife. Although wind projects rank lower than other energy developments in terms of wildlife impacts, research is still needed to minimize wind-wildlife interactions.
Wind Energy in India
India's total electricity generation capacity has reached 452.69 GW, with renewable energy contributing a significant portion of the overall power mix. As of October 2024, renewable energy-based electricity generation capacity stands at 203.18 GW, accounting for more than 46.3 percent of the country's total installed capacity. Wind contributed with 47.72 GW, driven by the vast potential of the coastal and inland wind corridors across the country.
Source: PIB
Several states in India have emerged as leaders in renewable energy capacity, contributing significantly to the nation's progress. Rajasthan tops the list with an impressive 29.98 GW of installed renewable energy capacity, benefiting from its vast land and abundant sunlight. Following closely is Gujarat, which boasts a capacity of 29.52 GW, driven by its strong focus on solar and wind energy projects.
Tamil Nadu ranks third with 23.70 GW, leveraging its favourable wind patterns to generate substantial energy. Karnataka rounds out the top four with a capacity of 22.37 GW, supported by a mix of solar and wind initiatives.