guide

What is wind energy, how it works and what are its advantages and disadvantages

11 January 2021 | Celia Topping

Wind. That invisible force that blows boats over oceans, flies kites, buckles trees, and sends beach umbrellas cartwheeling through other people’s picnics. Sometimes pleasant, sometimes devastating, but almost always present, at least on this blustery British isle of ours – the windiest country in Europe!

Wind has been a vital source of energy for human beings for thousands of years. Since early recorded history, we know that people have harnessed the energy of the wind. Boats were sailing down the Nile as early as 5000 B.C, and by 200 B.C., simple windmills were pumping water in China and grinding grain in Persia and the Middle East.

More recently we’ve been turning the immutable power of wind into electricity. But before we consider that any further, let’s ask a fundamental question:

What is wind?

Wind, simply stated, is the movement of air. And it all begins with the sun. The sun warms the Earth and its atmosphere. But the heat is unevenly distributed because of the irregular nature of the Earth’s surface. Warm air, which weighs less than cold air, rises, causing low pressure near the Earth’s surface. As that warm air rises, cold air rushes in to replace it, causing high pressure – and wind. If it weren't for this rising and sinking motion in our atmosphere, then not only would we have no wind, but we'd have no weather at all; and then how would we fly our kites?

But kites aside, as we enter the 21st year of the 21st century, there’s yet more focus on the devastating impact of burning fossil fuels on the environment. And as a result, we’re increasingly looking to low-carbon, renewable energy to replace it.

Renewable energy, or green energy, provides nearly a third of the power in the UK. And thanks to the great British climate, half of this energy is generated by the wind¹ – a low-cost, low-carbon alternative to fossil fuels.

What is wind energy, and how does it work?

Wind energy harnesses the power of the wind to create electricity.

These days we use wind turbines to turn the wind’s power into electricity. Wind turbines come in all shapes and sizes, but you’ll most likely recognise them in their industrial form – battalions of huge white propellers on giant white stems, ranged over distant fields or stood to attention half a mile out to sea.

To learn about other forms of renewable energy, read our guides to biomass energy and tidal energy.

How do wind turbines work?

A wind turbine works in the opposite way to an electric fan. Fans use electricity to make wind. Wind turbines use wind to make electricity. If you’ve ever flown a kite, you’ll know the higher you go, the windier it is. That’s why wind turbines are so tall – to capture more energy and generate more electricity.

The wind in the air turns propeller-like blades around a rotor, which spins a shaft, which connects to a generator to create electricity. The electricity is then fed into the National Grid. The bigger the sweep of those long slender blades, the more energy is generated. The easiest way to increase the energy potential of a wind turbine is to lengthen the blades. But there are limits, of course!

Because wind doesn’t always blow in the same direction, the ‘nacelle’ (the boxy bit that’s attached to the propellers at the top) can rotate on the tower to whichever direction best captures the wind.

Wind turbines need a wind speed of around 9 mph (a gentle breeze) to start turning. And in very high winds of over 55 mph, they shut down, to avoid damage.

Read more about wind turbines and how they work, in our comprehensive and educational guide

How much wind energy is generated in the UK?

Boxing Day 2020 set a new green energy record, with wind turbines generating more than half the UK’s electricity for a whole day, for the first time². The 100mph winds caused by Storm Bella helped push wind energy generation to 50.67%. An unprecedented figure which bodes well for the future of wind energy.

There are almost 11,000 turbines on and offshore in the UK, generating nearly 66 million MWh of electricity a year. That’s the equivalent of powering over 18 million homes³!

The UK is in fact the sixth largest global producer of wind energy, after China, US, Germany, India and Spain. We now generate twice as much energy from wind as from coal. That’s great news for the environment!

Of course, wind energy is only one type of renewable energy. Official data from the government states that all renewable energies – wind, hydro, tidal, solar and biomass – made up 47% of the UK’s electricity generation in the first quarter of 2020⁴. And in July, August and September of 2019, the UK’s renewable energy sources generated more electricity than all the coal, oil and gas power stations put together. Pretty impressive stuff.

And it’s good news for the rest of Europe, too. In the first half of 2020, 40% of Europe’s electricity was generated by renewables – leaving fossil fuels trailing at 34%. And wind and solar alone generated a huge 21% of Europe’s total electricity production⁵.

Would you like to know more about the impact of fossil fuels, and how we will become coal-free? Read our guide on the no-coal goal, and the future of renewables.

FInd out more renewable energy facts in our new blog, and get inspired!

What are the different types of wind energy?

Offshore wind

Offshore wind energy is harnessed out at sea. And it seems the tidal breezes around the UK are pretty darn gusty. In fact, the UK proudly holds the number 1 spot as world leader in offshore wind generation.

Offshore wind farms are generally much bigger than onshore turbines because of the space available. If you happen to be in Liverpool, it’s easy to spot the UK’s tallest turbines of Burbo Bank wind farm. At 195 metres, they’re taller than Blackpool Tower. Just one rotation of their 80-metre-long propeller blades can power a home for 29 hours!

Onshore wind

Wind farms on land are generally built on flat, open areas. We currently have 1,500 operational wind farms in the UK.

Advantages of wind energy

Wind energy gets a thumbs up from governments, businesses and the general public alike. So why is wind energy seen as such a good thing?

The main attraction of wind energy in our climate-conscious times is that it’s a clean fuel source. It doesn’t release any nasty carbon emissions, like traditional power plants burning fossil fuels – it’s very eco-friendly.
Wind is in endless, abundant supply – so by nature, it’s sustainable. We may not always be enamoured with our wet n’ windy climate, but in terms of generating offshore wind energy, we’re second to none.
Wind energy helps countries meet their emissions reduction targets, in line with the Paris Agreement.
Industrial-scale wind power is one of the lowest-priced energy sources available today.
Building and maintaining the infrastructure for wind energy creates thousands of jobs.
Having our own reliable energy source reduces the need for imported energy.
Located out to sea, wind farms are a good use of available space.
The Government recently gave its support for both on and offshore development of wind farms.

Disadvantages of wind energy

There are always going to be nay-sayers, and opposition to wind energy is no exception. Despite its many advantages, some points can be raised in protest:

To some, they’re a blot on the landscape. Those who aren’t fans consider our tall white giants an eyesore on the UK’s green and pleasant land.
The slowly rotating blades have been known to kill birds and bats (but not as many as cars, power lines, fracking and high-rise buildings). As with most things, these issues must be weighed rationally against the benefits.
Wind is an inconsistent and unreliable source of energy. The wind doesn’t always blow – but with carefully-placed turbines, this isn’t an issue here in the UK. Plus, the development of storage for wind energy means we should increasingly be able to use excess power in times of need.
There’s a high initial investment needed to develop the farms.
Noise pollution. Wind turbines do make some noise as the blades turn – but more modern models are far quieter. Plus, they have to be built a minimum distance away from residential properties, so disturbance should be minimal.

How efficient is wind energy?

A well-positioned wind turbine can produce electricity around 70-85% of the time. Output varies depending on wind speed and consistency – but in the space of a year, a wind turbine can typically generate 30% of its theoretical maximum output. This is known as the ‘load factor’. It doesn't sound like much, does it? But considering a conventional power station’s load factor is 50%, it’s not actually bad. Add to the fact that the wind blows for free, the appeal of wind energy is clear.

What is the carbon payback time on a wind turbine?

Sure, the power of the wind is free, and creates no-carbon. But the carbon emissions released during the manufacture, construction and maintenance of wind turbines is another matter. The good news is, according to various studies⁶, the pay-back time is a surprisingly short 7 to 9 months. Considering the lifecycle of a wind turbine is around 25 years, that’s a huge tick in the low-carbon cost box.

Can wind energy be stored for later use?

While wind is an inconsistent source of power (sometimes it blows, sometimes it doesn’t), we can, thankfully, store the electricity it generates for later use. Batteries play a key role in helping us do this – and as we invest more money into research and development, their efficiency is improving all the time.

Read more about the latest technology in energy storage, and how to power your home in a greener way.

Can I power my home with wind energy?

Theoretically, yes. With a bit of time and effort, you could install a pole or building-mounted wind turbine at your home. People living in very windy areas are adopting this technology to help save money on their energy bills. A typical system in an exposed site could easily generate more power than a home can use.

But, practically speaking, at the moment, it’s not viable for many homes to do this. A large plot of unobstructed land is required to install an effective wind turbine. Plus the installation and maintenance costs are currently pretty high in the domestic market. Financially speaking, installing rooftop solar panels is a far better renewable energy option for most of us. Find out more about the benefits of installing solar panels in our useful blog post.

If you do go ahead with installing a wind turbine of your very own, it could actually make you money – as any excess energy generated can be sold to the Grid. Check out how to do this with our guide on the Smart Export Guarantee.

What’s the difference between a windmill and a wind turbine?

A good question! They both harness the wind’s power. The real difference actually lies in how they do it, and how that wind power’s used:

A windmill turns the wind’s power into mechanical energy via a camshaft. All the power goes directly into the work at hand, be it milling grain, or pumping water.
A wind turbine, on the other hand, turns wind energy into electricity via a generator. This is then fed into the National Grid on an industrial level. It can also be used locally to power electrical equipment, or get stored in batteries.

What is a wind farm?

A wind farm – also known as a wind power station or plant – is a group of wind turbines that generates electricity on a national level. They range from just a few turbines, to hundreds spread over a vast area. Wind farms are connected to the National Grid and provide electricity to millions of homes and businesses.

Where are UK wind farms?

There are 1,500 wind farms spread across all 4 corners of the United Kingdom, including:

Whitelee Wind Farm in Glasgow – the largest onshore wind farm, with 215 wind turbines generating 539 megawatts of electricity at peak capacity. That's enough electricity to power around 300,000 homes.
The Pen y Cymoedd Wind Farm – opened in 2017, it has 76 turbines and a capacity of 228 megawatts. That’s enough power for 188,000 homes. It also means a whopping reduction of 300,000 tonnes of carbon emissions. Now that’s what we call environmentally-friendly!
Slieve Rushen Wind Farm in Northern Ireland – 18 turbines may not sound many, but they still have a 54 megawatt capacity to power 30,000 homes.

What is the biggest wind farm in the UK?

Photo credit: Orsted

Until just last year, the Walney Extension, off the West coast of the UK, was Britain’s (and the world’s) largest offshore wind farm. It provided clean electricity for almost 600,000 homes. But in 2020, it was dwarfed by the colossal Hornsea One – the first phase of an ambitious 3 phase project. Located 75 miles off the Yorkshire coast, Hornsea One covers a vast 253 square mile area. Its 174 turbines, each standing 190 metres tall, can generate 1.2 gigawatts of energy. That’s enough electricity for well over a million homes. Hornsea Two and Three will be even bigger and more powerful. It’s estimated that at completion, over 4 million homes could be supplied by the Hornsea Project.

What does the future for wind energy look like?

If you’ve read this far, then you’ll know the wind energy industry’s future is bright (and breezy!). Thanks to global efforts to combat climate change, such as the Paris Agreement, renewable energy is seeing exponential growth – with wind energy at the forefront.

Happily, the UK Government is supporting wind energy all the way – with a promised £60 million investment. When Boris Johnson revealed his 10 Point Green Plan for a Green Revolution in October 2020, he pledged to reach 40GW of offshore wind by 2030. This could provide enough electricity for every home in the UK!

Many other governments around the world are also offering tax incentives to spur on wind-energy development – making it a key player in the future of energy.

Also, according to analysis from Ember, in the first half of 2020, renewable energy generated more electricity than fossil fuels in Europe. Pretty impressive stuff, considering only 5 years ago Europe generated double the amount of electricity from coal than it did wind.

Industry experts predict that if this pace of growth continues, by 2050 one third of the world's electricity needs will be met by wind power⁷.