how do wind turbines work?

A brief guide to how electricity is generated from one of the UK’s most abundant renewable sources: wind.

One of the most popular questions people ask us is how is our renewable electricity generated. The simple answer is through wind, sun and rain – but this doesn’t really paint the whole picture.

How do we turn energy from the sun, wind and water into clean electricity to power our homes? Here’s (almost) everything that you need to know about generating electricity from the wind.

How wind turbines generate electricity, diagram.

How do wind turbines work?

Wind turbine blades rotate when hit by the wind. And this doesn’t have to be a strong wind, either: the blades of most turbines will start turning at a wind speed of 3-5 meters per second, which is a gentle breeze.  

It’s this spinning motion that turns a shaft in the nacelle – which is the box-like structure at the top of a wind turbine. A generator built into the nacelle then converts the kinetic energy of the turning shaft into electrical energy. This then passes through a transformer, which steps up the voltage so it can be transported on the National Grid or used by a local site.

From micro-turbines for an individual house right up to enormous, off-shore windfarms, all wind turbines use the same mechanics to generate electricity.

How much electricity can a wind turbine create?

Most onshore wind turbines have a capacity of 2-3 megawatts (MW), which can produce over 6 million kilowatt hours (kwh) of electricity every year. That’s enough to meet the electricity demand of around 1,500 average households.

 Up to a certain level, the faster the wind blows, the more electricity is generated. In fact, when the wind speed doubles, up to eight times more electricity is generated. But if the wind is too strong, turbines will shut themselves down to prevent being damaged.

All this means that the ability of a wind turbine to generate the maximum amount of power it can depends on the wind. Wind farms are carefully planned to make sure they’re in locations with a reliable amount of wind all year round. This tends to be on the summit of a hilltop with lots of open space around, and in coastal locations. It’s why there are quite a lot of wind farms in places such as Cornwall and Scotland.

How efficient is wind power?

A wind turbine is typically 30-45% efficient – rising to 50% efficient at times of peak wind. If that sounds low to you, remember that if turbines were 100% efficient, the wind would completely drop after going through the turbine.

Wind turbines in the UK are producing electricity 70-80% of the time, making them a reliable source of power throughout the year. 

Why is the UK particularly well-suited to wind power?

The UK’s exposed position on the north-western edge of Europe makes it particularly windy, with Scotland being the windiest place in the whole of the continent.

The wind blows all year round – making wind power a reliable renewable power source. It also tends to be windiest in winter, meaning wind turbines can produce are producing more power at the time of the year when we’re also using the most electricity.

Both of these points make the UK well positioned to make the most of both offshore and onshore wind power and reduce its reliance on fossil fuels.

Another added bonus is the low carbon footprint that is created in building wind farms – it’s one of the smallest among new renewable generators.

How much of the UK’s electricity comes from wind power?

In 2019, just under 20% of the UK’s electricity was generated from wind power [1]. Just six years before, this percentage was just over 7% [2]. This demonstrates just how fast wind power capacity in the UK is growing.

How many wind turbines are there in the UK?

There are roughly 8,600 onshore wind turbines and 2,300 offshore turbines in the UK. Go to RenewableUK for the latest statistics. Altogether, they produce enough power to meet the annual electricity demand of around 12 million homes [1].

At Good Energy, we have two windfarms that together produce enough electricity to power almost 12,000 average UK homes. We also buy power from independent renewable generators, many of whom generate electricity using wind power.

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