Wind energy explained
What is wind energy and how does it work?
Harnessing the power of the wind to create electricity.
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 more often than not – just a bit of a nuisance. At least on this blowy British isle of ours. The windiest country in Europe did you know?
But aside from its poetic properties, wind has been an important source of energy for human beings for millenia. Ancient mariners captured the wind in the sails of their boats. Farmers used it to power windmills to grind their grains and pump water. And more recently we’ve been transforming its power into electricity. But before we consider that any further, let’s ask a fundamental question:
What is wind?
Wind is moving air caused by differences in air pressure within our atmosphere. Air under high pressure moves naturally towards areas of low pressure. And the greater the difference in pressure, the faster the air flows.
But why do we get these differences in pressure?
Well, it's all down to the rising and sinking of air in the atmosphere (which is in-itself down to the sun unevenly heating the surface of the earth). Where air is rising, we see lower pressure near the earth's surface. Where air is sinking we see higher pressure. In fact, 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?
The sun also has a big part to play. It heats the earth to create atmospheric pressure differences. Giving us wind. And plenty of it. And as we charge into the twenty first century with an ever growing concern (in most quarters) for the earth’s finite resources, and the risks of burning fossil fuels, we’re looking increasingly to harness the wind as an energy source – on an evermore grand and global scale.
So...what is wind energy?
The term ‘wind energy’ describes the way we use wind to generate mechanical power or electricity. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity, to power homes, businesses, schools, hospitals...whatever we like.
How was wind energy discovered?
We have no idea exactly how or when the first humans discovered that we could use the wind to do things or go places. Certainly flying insects, winged dinosaurs, and birds caught on pretty early. But 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.
How is wind energy generated today?
These days we use wind turbines to convert 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 – armies of huge white propellers on giant white stems, ranged over distant fields or stood to attention half a mile out to sea.
How do wind turbines work?
Simply put, 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. The wind in the atmosphere turns propeller-like blades around a rotor... which spins a shaft... which connects to a generator to create electricity.
How efficient is wind energy?
A well-positioned wind turbine will produce electricity around 70-85% of the time. The output will vary depending on wind speed. Throughout the year, a wind turbine will typically generate 30% of its theoretical maximum output. This is known as the ‘load factor’. It doesn't sound like much, but it’s not far off the load factor of conventional power stations – which is around 50%. And considering that wind blows for free, the appeal is self-evident.
Can wind energy be stored for later use?
Due to the wind being 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 the efficiency with which they work is improving all the time as we invest more money into research and development.
Can I power my home with wind energy?
Yes, in a nutshell. With a bit of time and inclination you can install a pole-mounted or building-mounted wind turbine at your home. People living in very windy areas are increasingly adopting this technology to help save money on their energy bills, and a typical system in an exposed site can easily generate more power than a home can use.
Can wind energy replace fossil fuels?
The wind energy industry is booming, but when it comes to fossil fuels – that’s a matter of political will. But thanks to global efforts to combat climate change, such as the Paris Agreement, renewable energy is seeing a boom in growth, with wind energy leading the way. From 2000 to 2015, cumulative wind capacity around the world increased from 17,000 megawatts to more than 430,000 megawatts. A pretty impressive leap in volume. And it’s China who are leading the installation efforts. In 2015 alone, they surpassed the whole of the EU when it comes to the number of wind turbines installed.
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 power.
Are there any drawbacks to wind energy?
Some people consider wind farms to be eyesores. Blots on the landscape. (Although others see them as rather beautiful).
Another drawback is that the slowly rotating blades can kill birds and bats (but if you put this in perspective, it’s not nearly as many as cars, power lines, and high-rise buildings). As with everything, these issues need to be weighed fairly and rationally against the benefits of wind energy.
What’s the future of wind energy?
In short: wind is a clean source of renewable energy that has lots going for it.
It produces no air or water pollution. Operational costs are nearly zero once a turbine is erected. And advances in mass production and technology are making both turbines and batteries cheaper and safer. Many governments are even offering tax incentives to spur wind-energy development on, making it a key player in the future of energy.
And the stats back this up too. Over the past decade, wind turbine use has increased by more than 25 percent per year.
Yes, it might only provide a small fraction of the world's energy right now, but wind is set to contribute more and more towards our energy mix as we work towards a cleaner, more sustainable future.