With Renewables growing by leaps and bounds, scientists are exploring newer technologies to harness the true potential of renewable energy sources i.e. Solar, Wind, Geothermal etc. Of all Wind Energy is one of the most promising forms of clean renewable energy. Wind energy has also become one of the cheapest forms of renewable energy due to its ever falling installation costs. Wind turbines are getting more bigger and more efficient to harness maximum amount of wind energy.
What is a Wind Farm?
A wind farm consists of a group of wind turbines placed at particular locations where wind flow is steady and strong. A large wind farm consists of several hundreds of wind turbine placed over an extended area. Wind turbines generate electricity through the wind by using the kinetic energy of wind. When the wind flows through the wind turbine, the blades of wind turbine connected to generator rotates in the clockwise direction to produce electricity. The Electricity produced by generators is then collectively fed into substations. These substations are connected to power transmission grids which further transmit power into specific locations. Let us explore how does wind turbine work.
How do wind turbines work?
Wind energy is one of the most technologically advanced forms of renewable energy. With recent advancements in turbine generator technologies, wind turbines are getting more powerful and more efficient. Wind turbine work on the basic principle of energy conversion. Wind turbines utilize the kinetic energy of wind and convert it into electric energy. Basically, wind turbines are of two types i.e. horizontal axis and vertical axis. Horizontal axis wind turbines are more common as they have the higher capacity to produce electricity. Wind turbines consist of four major components Blades, Shaft, Gearbox and Generator.
Components of Wind Turbine
Rotor Blades: Rotor blades are one of the most important components of wind turbines. Rotor blades, when exposed to the wind, rotates in clockwise direction. Blades are aerodynamically designed and are extremely low weight to extract the energy from wind more efficiently. Rotor blades are tough and weather resistant. Rotor blades are generally made of glass fibre composites which give them more strength and durability. The distance between two wind turbines in wind farm is generally calculated by taking in account rotor diameter.
Shaft and Gearbox assembly: The main function of the shaft is to transfer rotational energy to the generator. Gearbox assembly connects low-speed shaft to high-speed shaft. Gearbox assembly increases the rotational speed of the 15-20 rpm low-speed shaft that is connected to rotor blades to 1500-2000 rpm rotating high-speed shaft. The high-speed shaft that rotates at 1500-2000 rpm is connected to electric generators to produce electricity. Shafts are also equipped with the mechanical braking system. Mechanical brakes are used in case of emergency situations when the wind is blowing very fast or when the wind turbine is being serviced.
Electrical Generator: Wind Turbine Electric generator is the key component that converts rotational energy of high-speed shaft into Electrical energy. Most of the Wind farm today use wind turbines made of (PMG) permanent-magnet generators which are made from rare earth metals. Permanent magnet designs utilize high field strengths generated by magnets to produce electricity. As the movement of air across wind turbines is not constant, power output produced by the electric generator varies with time. Hence Pitch control system is used to regulate the output power of wind turbine generator. Also, when the power produced by the wind turbine is directly fed into national power transmission grid, a transformer is attached inside the tower of wind turbines. Transformers convert electricity generated by wind turbine generators into high-voltage low-current power so that it can be effectively transmitted across long distances.
Offshore Wind Turbines: The Next Big Thing
With installation costs of offshore wind turbine reaching a record low, there is no doubt that Offshore wind farms would be the most potent source of clean energy. According to a research, By 2025 energy from offshore wind farms will be cheaper than electricity from new nuclear power plants for the first time. Again innovations in turbine technologies such as Direct-drive wind turbines eliminate the use of gearbox assembly, thereby reducing the overall weight of structure in offshore wind turbines.
One of the challenges associated with offshore wind turbines was that at some particular sites waters were very deep( > 4o metres), conventional pile foundations could not be laid. To overcome these problem researchers have come up with an innovative concept of Floating Wind Turbines. Floating wind turbines are offshore wind turbines mounted on floating foundations in deep waters. Also, Floating wind turbines have added advantage of strong and steady winds as they are located in deep waters in the ocean. Floating wind turbine used in offshore wind farms are proving their worth even in harsh sea conditions.
Offshore wind turbines are getting bigger and better to capture more wind energy so as to minimize costs and increase efficiency. For instance, the first offshore wind turbine installed in Denmark in 1991 was mere 450 kW with the hub height of 35 metres and rotor diameters of 35 metres. Today, world’s most powerful offshore wind turbine has rated capacity of 8 MW with the hub height of 105 metres and rotor diameter 164 metres( larger than London eye).
With more than 50 countries such as Denmark, Hawaii, Maldives etc. pledging to use only renewable energy by 2050, Offshore wind farms would be the most feasible option. By next decade Germany, Denmark, and Belgium are going to install 60 Gigawatts of new offshore wind farms. So it is in no doubt that wind farms and especially Offshore wind farms would be the next big thing in the energy industry.
Featured Image: https://commons.wikimedia.org/wiki/File:Power_County_Wind_Farm_002.jpg
Components of wind turbine: https://energy.gov/eere/wind/how-do-wind-turbines-work
Sheringham Shoal Offshore Wind Park: https://www.flickr.com/photos/[email protected]/8033151828