Wind turbines turn wind energy into electricity using aerodynamic force from rotor blades. When wind flows across the blades, air pressure creates lift and drag, causing a rotor to spin. The rotor is connected to a generator, either directly, or through a shaft and gearbox, which then converts the energy into electricity.
People have been using wind turbines as a source of energy for thousands of years – for pumping water, and grinding grain. Early turbines were also used in homes to pump water into plumbing systems.
The first known wind turbine was built by Professor James Blyth in Scotland in 1887. At 10 metres high, it was installed in his garden and was used to provide lighting inside his cottage. His house was the first in the world to have its electricity supplied by wind energy. Nowadays, the average wind turbine has a capacity of 3 megawatts and stands around 80 metres tall.
There are two types of wind turbines – horizontal-axis wind turbines (HAWTs) and vertical-axis wind turbines (VAWTs). Horizontal turbines are the most common type and they typically have three blades that are shaped like an aeroplane propellor.
The materials used to build wind turbines
According to the National Renewable Energy Laboratory’s Cost of Wind Energy Review 2015, wind turbines are typically made from steel, fiberglass, resin or plastic, iron, copper, and aluminium. Steel is predominantly used to support the structure and is typically coated with a zinc alloy for protection against extreme weather conditions.
Fibreglass or aluminium is typically used for the nacelle of the turbine, which is a hollow shell that contains the drive shaft and the gear box, as well as other essential components. Copper is typically found in the generator, alongside steel, and plastic or resin is used for the blades.
The components of a wind turbine
The main components of a wind turbine are:
The tower – Made from steel, the tower has to be solid to withstand extreme weather conditions. Inside, it has an inner ladder that leads to the nacelle.
The nacelle – This part sits at the top of the turbine behind the rotor and blades and contains all the machinery. It’s connected to the tower using bearings to allow it to rotate in the direction of the wind.
Rotor and rotor blades – The rotor and the rotor blades are located at the front of the turbine, at its highest point. When the wind passes over the blades, the rotary mechanical movement powers the generator inside the nacelle. Most turbines have horizontal axis blades made from carbon-fibre plastics or fibreglass.
Electronics – Inside the nacelle is the turbine’s electricity grid infeed system, as well as various sensors for measuring wind speed, direction and temperature.
Other components – The wind turbine also has components for heating, cooling, and fire extinguishing equipment. A utility box is located at the base of the tower and various cables connect the box the nacelle.
The construction process of a wind turbine
The first step in building a wind turbine is sourcing a suitable location. The site needs to have reliable winds with speeds of more than 25 kilometres per hour, and the air temperature needs to be considered as colder locations mean more power consumption.
Typically, wind farms are best located in rural, open areas, surrounded by hills or mountains to concentrate the airflow. Mountains help create natural wind tunnels with more powerful winds.
Once the location has been identified, the first component that’s built is the tower. The steel structure is usually constructed on-site, but sometimes, it may be built off-site in a factory. The steel sections are bolted together and placed in position using a crane.
In the factory, the gearbox, drive shaft, and other essential electronic parts are assembled and mounted inside the fibreglass nacelle. Two blades are typically added to the nacelle, with the third being added before the component is elevated into position at the top of the tower.
In cases where an entire wind farm is being built, roads need to be made to provide access to the site. At the foot of each turbine, the surrounding land needs to be levelled and graded. A concrete foundation is then laid, followed by underground cables that connect each turbine in series.
Each turbine is then connected to a remote control centre, where the wind farm’s performance can be monitored and electricity is distributed to the power company.
Once a wind farm is operational, the turbines require regular maintenance. Routine check-ups are carried out frequently to avoid failures and thorough inspections are scheduled every few months.
The future of wind turbines
Advances in green technology are creating more efficient wind turbines with lower component costs. Scientists are also working on designs that can withstand extremely high winds, so they can continue to operate during storms. Likewise, turbines that can run at very low wind speeds are also in development, so they can be used in a greater variety of locations.
Over the next decade, as the number of wind farms increase exponentially and innovation takes hold in the energy sector, we’ll continue to see a transformation in the design and manufacture of wind turbines.
For example, new research from Oxford Brookes University has found that vertical axis wind turbines are more efficient in large scale offshore wind farms than traditional horizontal axis turbines. When set in pairs, the vertical turbines can increase each other’s performance by up to 15%, according to the study.
Energy research centre ORE Catapult reports that rotor blades are set to increase in size to improve aerodynamic performance and durability, with robotic blade crawlers and drones being used for inspection and repair.
In recent years, companies like General Electric (GE), Vestas and Siemens Gamesa have announced plans to develop huge commercial wind turbines. For example, GE is currently building Vineyard Wind 1, which will be the first utility-scale offshore wind energy project in the US that spans over 15 miles, off the coast of Massachusetts.
The facility will use 13 MW versions of the company’s Haliade-X turbines, each with a height of up to 260 meters, a rotor diameter of 220 meters and 107-metre blades.
Taller wind turbines are able to capture more energy as winds generally increase alongside altitudes, and bigger rotor diameters allow turbines to sweep more area. Longer blades also capture more wind, which means turbines can generate more electricity.
Wind Engineer jobs in the energy industry
Earlier this year, we published our Energy Outlook Report 2021-22 and revealed that the renewables sector is rapidly increasing in popularity among energy industry professionals. Specifically, in the oil and gas sector, 56% of workers are willing shift towards renewables.
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