Wind turbines convert wind power into electricity. As the wind rotates the turbine’s blades, a generator attached to the blades generates electricity. The turbine’s blades and tower – the pole carrying the blades – determine the amount of electricity generated.
Tall wind turbines with large blades generate more electricity than short turbines
with small blades. An 853 feet-tall tower with a blade span of 722 feet powers 12,000 homes, and a 100 feet tall turbine with a 23 feet span covers an average home’s electricity bill.
This discussion will consider the following key areas:
- Wind Turbines Come In A Variety Of Heights
- How Is The Height Of The Wind Turbine Linked To Electricity Generation?
- The Different Sizes Of Wind Turbine Blades
- Must Wind Turbine Blades Be Long?
- How Useful Are The Different Sizes Of Wind Turbines?
The height of turbine towers and the length of their blades increased over the past 20 years. Let’s see how the correct size of a wind turbine affects its effectiveness.
How Tall Are Wind Turbines?
The turbine’s tower supports the blades. Wind towers’ height average is 196 to 390 feet, but the tallest wind turbine in the U.S., in Canyon, Texas, is 410 feet tall in total. The Vineyard Wind 1 turbines, due in 2022, are 813 feet tall each.
The most commonly used G.E. 1.5-megawatt wind turbine is 328 feet tall -when adding the 116 feet long blades to its 212 feet tower. The 1.8 MW Vestas turbine from Denmark, is 399 feet altogether. Many new models exceed 600 feet in total height.
A limit exists as to how high turbines can go due to limitations to the strength of the materials towers are made of, mainly steel and concrete. The tower carries the blades’ load, the power of the wind, and the force of the blades’ rotation.
Other height limiting factors are the size of the bigger, taller turbines, the manufacturing limitations to such components, and transport capabilities. In some areas, aviation regulations and environmental restrictions limit the turbine’s height.
Why Do Wind Turbines Need To Be Tall?
Wind turbines need to be as tall as possible because the wind is much stronger at higher altitudes. The wind slows down close to the earth due to friction, trees, houses, hills, and mountains.
The length of a turbine’s blade is crucial to its power generation capacity, and taller towers can push the blades into height wind streams while keeping the blades and the generation mechanism of the turbines solidly anchored into the ground.
A crucial factor is that turbines with higher towers encounter stronger winds that are not hampered or disrupted by various obstacles. Therefore, the wind’s velocity (the
horizontal speed and direction of its motion) will be much higher, generating more power.
According to the Department of Energy, taller turbines benefit from a sizeable increase in wind capacity, meaning that the turbine can generate power more effectively from winds at a higher altitude.
Tall turbines make commercial sense. The National Renewable Energy Laboratory (NREL) Report considered four turbine heights (260 feet, 360 feet, 460 feet, and 520 feet) and found that in 70% to 90% of the cases, the 520 feet height was economically better.
How Big Are Wind Turbine Blades?
As wind turbine towers grow taller, their blades get longer. The length of the blade contributes to the turbine’s power generation capacity. Most in-use blades in the U.S. are 116 feet long on average. The Vineyard Wind 1 blades are between 538 and 728 feet long.
Wind turbines are fitted with blades of different lengths, according to the specific conditions where each turbine will be installed. Some offshore wind turbines have massive blades that stretch to 60% of the tower’s height.
G.E.’s Haliade-X offshore wind turbine blades are 351 feet long, covering more than 80% of the tower’s height. It is about 30% longer than a Boeing 777 and shorter than a football field.
Why Do Wind Turbine Blades Need To Be So Long?
Just like the height of the tower, the size of the turbine’s blades affects the amount of power that the turbine generates. A few big turbines will generate the same power provided by numerous smaller turbines.
The effect of using big turbine blades on power generation is substantial. The Haliade-X needs a single rotation of its 351 feet long blades to power an average home for two whole days, while 74 GWh are generated annually by a single turbine.
It is important to note that while turbine blades are long – they are also thin, which helps them be more effective aerodynamically.
The wind is, in fact, not pushing the blade, but flowing over it, generating a lift – just like an airplane’s wing would do.
How Are Turbines Of Different Sizes Used?
Wind turbines installations are grouped according to the location in which they will generate wind power. The groups are land-based wind power, offshore wind power, and distributed wind power. Each installation’s location dictates the size of the turbine used.
Land-Based Wind Power
Land-based wind power is generated by stand-alone turbines, used locally and linked to a nearby grid. Connected turbines grouped in large numbers in so-called wind farms are used to generate large amounts of electricity. Land-based turbines are cheap and clean.
Stand-alone turbines are best suited to small groups of users, such as small towns, farming communities, and homeowners, while wind farms are used to supply electricity to large consumers, such as whole states.
It follows that stand-alone turbines will be smaller – and cheaper – to accommodate small types of users.
In contrast, wind farms will opt for taller wind turbines with larger blades to generate electricity.
Offshore-Based Wind Power
In terms of their operation and uses, offshore-based turbines are more likely to be grouped into wind farms based on floating wind turbines. With minimal interferences to its flow, the wind will be much more robust, necessitating larger, more powerful towers and blades.
One of the largest offshore installations, the Vineyard Wind 1 Project, is situated 13 nautical miles south of Martha’s Vineyard and Nantucket.
When completed, the farm’s 62 wind turbines will generate 800 megawatts of electricity annually, powering over 400,000 homes.
Distributed Wind Power
Unlike the centralized form of electricity generation, where power is generated at a central plant and distributed over the grid to consumers, distributed generation uses smaller turbines that generate electricity at the consumer’s location to be used on-site.
These are smaller, cheaper, and simpler units that consumers use to generate electricity and feed all excess power back into the grid. Using distributed power is less of a risk of energy waste, as the source is close to the consumer.
The size of the wind turbines is determined by the various elements we discussed here. Firstly, the amount of energy required and its end-destination – factory or school, farmer’s home or hotel, small town or State.
Extensive energy needs may require that taller turbines with larger blades are installed. The location of the turbine may define its size. Land-based turbines installed in wind farms may be small but numerous, while a sizeable turbine may cover the needs of a nearby town.
Lastly – small turbines are increasingly built to suit single users in a distributed wind power scenario.
The user may combine a wind turbine with solar panels to facilitate the effective generation of electricity for their use and distribution.
Are Big Wind Turbines Better?
The EERE – the government office dealing with the efficiency and renewability of energy, stands at the forefront of a campaign to support the design, building, and installation of large wind turbines, under the slogan “Wind Turbines: the Bigger, the Better.”
Taller towers with longer blades catch higher, faster, more stable, and consistent winds, resulting in more electricity.
This energy is clean, renewable, and affordable. Wind power emits small quantities of carbon and releases almost no pollutants.
References
- https://www.energy.gov/eere/wind/how-do-wind-turbines-work
- https://www.thegreenage.co.uk/advantages-of-onshore-wind-turbines/
- https://www.eia.gov/energyexplained/wind/where-wind-power-is-harnessed.php
- https://electricalacademia.com/renewable-energy/wind-turbine-parts-functions/
- https://www.energy.gov/eere/wind/distributed-wind
- https://windexchange.energy.gov/markets/offshore
