We've used the wind as an energy source
for a long time.
The Babylonians and Chinese were using wind power
to pump water for irrigating crops 4,000 years ago, and sailing
boats were around long before that.
Wind power was used in the Middle Ages, in Europe,
to grind corn, which is where the term "windmill" comes
How it works:
The Sun heats our atmosphere unevenly, so some patches
become warmer than others.
These warm patches of air rise, other air blows in
to replace them - and we feel a wind blowing.
We can use the energy in the wind by building
a tall tower, with a large propellor on the top.
The wind blows the propellor round, which turns a
generator to produce electricity.
We tend to build many
of these towers together, to make a "wind farm"
and produce more electricity.
The more towers, the more wind, and the larger the
propellors, the more electricity we can make.
It's only worth building wind farms in places that
have strong, steady winds, although boats and caravans increasingly
have small wind generators to help keep their batteries charged.
Video clip: Building a wind turbine
Avonmouth docks, near Bristol
The best places for wind farms are in coastal
areas, at the tops of rounded hills, open plains and gaps in mountains
- places where the wind is strong and reliable. Some are offshore.
To be worthwhile, you need an average wind
speed of around 25 km/h. Most wind farms in the UK are in Cornwall
Isolated places such as farms may have their
own wind generators. In California, several "wind farms" supply
electricity to homes around Los Angeles.
The propellors are large, to extract energy
from the largest possible volume of air. The blades can be angled to "fine"
or "coarse" pitch, to cope with varying wind speeds, and the
generator and propellor can turn to face the wind wherever it comes from.
Some designs use vertical turbines, which don't need to be turned to face
The towers are tall, to get the propellors
as high as possible, up to where the wind is stronger. This means that
the land beneath can still be used for farming.
- Wind is free, wind farms need no fuel.
- Produces no waste or greenhouse gases.
- The land beneath can usually still be used for
- Wind farms can be tourist attractions.
- A good method of supplying energy to remote areas.
- The wind is not always predictable - some
days have no wind.
- Suitable areas for wind farms are often near the
coast, where land is expensive.
- Some people feel that covering the landscape with
these towers is unsightly.
- Can kill birds - migrating flocks tend to like
However, this is rare, and we tend not to build wind farms on
migratory routes anyway.
- Can affect television reception if you live nearby.
- Can be noisy. Wind generators have a reputation
for making a constant, low, "swooshing" noise day and
night, which can drive you nuts.
Having said that, as aerodynamic designs have improved modern
wind farms are much quieter. A lot quieter than, say,
a fossil fuel power station; and wind farms tend not to be close
to residential areas anyway. The small modern wind generators
used on boats and caravans make hardly any sound at all.
See the graphic on the right, from December 201. In this example,
at the distance the turbine is from houses, it makes less noise
than your fridge.-->
Click to enlarge
Is it renewable?
Winds will keep on blowing, it makes sense to use them.