Global Wind Day: How do wind turbines work?

Tuesday, 15 June 20215 minute read
Energy Industry

15 June 2021 marks Global Wind Day. To celebrate, wind turbine super fan and Pure Planet team member Laura explains exactly how they work.

Photo by Waldemar Brandt on Unsplash

You’ve probably seen a wind turbine before, maybe as part of a wind farm, on its own or even out at sea. But how are they able to power the equivalent of 18.4 million UK homes every year?

It helps that the UK is one of the windiest countries in Europe. We’ve got lots of wind turbines, and we’ve also got the world’s biggest offshore wind farm.

Here at Pure Planet, our wind-generated electricity comes from Gwynt y Mor off the North Wales coast and Muirate in Aberdeenshire. In fact, between April 2019 and March 2020 89% of our electricity came from wind.

In this blog, we’ll explain how wind turbines work and how much electricity they’re able to generate.

A history of the wind turbine

From Babylonian irrigation projects to Dutch windmills, humans have been harnessing the power of wind for over 3,500 years. But it was only in 1887 that we began using wind power to generate electricity.

Like any new invention, there were lots of different ideas for how they should work and what they should look like. Over the years, we’ve experimented with the number of blades, the vertical orientation and different materials, before settling on the three blade composite horizontal design we know today.

Why three blades? It’s the best compromise between air resistance and stability. If you’d like to dive into the detail of why that is, there’s a good summary here.

The first wind turbine to generate electricity was built by Charles F. Brush in Scotland, in 1887. The ‘sail’ was made of cloth. Credit

An example of a turbine with two blades in 1981 in Washington. Credit

How wind turbines work

Wind turbines have come a long way since 1887. Modern ones can turn to face the wind, using an anemometer (say that three times fast!) to sense the direction and turn.

Here’s how a wind turbine generates electricity:

  • When wind speeds reach between 8 and 16 miles per hour, a controller starts the turbine. If there’s a storm or really high winds, the turbine stops to protect itself from damage
  • When operating, the wind turns the turbine’s blades slowly on a rotor. This turns a gearbox, which increases the speed to turn the high speed shaft
  • This drives a generator, which converts the kinetic energy into electricity
  • Once the electricity is generated, a transformer ‘steps up’ the voltage — a higher voltage reduces the amount of energy that’s lost when it’s transported by cable. If the turbine is part of a wind farm, this will go to a substation that connects up several turbines. The voltage is ‘stepped up’ again and transported to the National Grid
  • Finally, the voltage is stepped down to a safer voltage before it gets to your home.

Diagram of a wind turbine, Office of Energy Efficiency and Renewable Energy. Credit

How big is a wind turbine?

All of this tech sits within the body of the turbine (known as a nacelle). Some nacelles are big enough for a helicopter to land on, which comes in handy when maintaining off-shore turbines.

The larger a wind turbine is, the more efficient it is at generating electricity. It’s more cost effective too, when you factor in installing and maintaining it. As technology has improved and manufacturing methods have progressed, turbines have just been getting bigger and bigger.

Wind turbine sizes over time. Credit

Theoretically, there’s no limit on how big a wind turbine can be. However, transporting them around by land gets a little tricky, especially when you have to turn a corner.

A 88.4m wind turbine blade on the move. Credit

How much electricity does a wind turbine produce?

Some of the largest wind turbines have an 8 MegaWatt (MW) capacity. But what does that actually mean? Over a year, one 8 MW wind turbine can power the equivalent of 6,099 average UK homes.

To think of it another way, the city of London would need 1,569 8MW offshore wind turbines to be completely powered by wind over a year. The wind farm would take up 1,615.4 km2, which is 103% of the size of the city, according to RS. Compare this with other major cities around the world here.

16.4% of the energy used in the EU and the UK last year came from wind. And with the UK set to install more wind turbines than any other European country over the next five years, you can expect to hear (and see) a lot more about wind power soon.

Want to power your home with electricity generated by wind, the sun and water? Switch to one of Pure Planet’s 100% Green tariffs today. Get a quote in 30 seconds.

Household equivalent calculation: Calculated using the most recent statistics from the Department of Business, Energy and Industrial Strategy (BEIS) showing that annual GB average domestic household consumption is 3,578kWh (as of December 2020, updated annually).

Number of households powered as: number of megawatts installed, multiplied by BEIS's "all wind" (onshore + offshore) load factor expressed as a fraction of 1, multiplied by number of hours in a year, divided by average annual domestic electricity consumption expressed in MWh.

8MW capacity x 0.3114 (BEIS “all wind” load factor) x 8,760 hours (in a year) / 3.578MWh annual consumption = 6099.19 homes powered equivalent per year.

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