KEY STAGE 5 & 5/CfE Level 4 and Senior
FACT SHEET – WIND POWER
Wind is caused by the sun heating the atmosphere unevenly. This causes convection
currents, where warm patches of air rise and cooler air blows in to replace them. Wind
turbines are, therefore, indirectly collecting solar energy.
The UK is the windiest country in Europe, and
potentially has the largest offshore wind resource in
the world. In 2007, wind energy overtook hydro
power to become the largest renewable electricity
source in the UK, providing around 5.5% of the UK’s
electricity supply.
History
Since earliest times, humans have harnessed the
power of the wind. The Babylonians and Chinese
were using wind power to pump water for irrigating
crops 4,000 years ago, and people were using wind
power to drive boats at least 5,000 years ago on the
River Nile in Egypt.
In the early 19th century, over 10,000 windmills
were in use in Britain, mainly to grind corn (which is
where the term “windmill” comes from). Windmills
began to be used for generating electricity at the
end of the 19th century. However, during the
industrial revolution, when the cost of burning coal
became cheap, wind power became much less used
in Europe.
In the 1970s there was renewed interest in
renewable energy. Wind turbine technology has
developed hugely since then. Today, there are
currently 5000 wind turbines in the UK, with an
installed capacity of 1025MW (as of August 2013).
That is enough green electricity to power over five
and a half million UK homes.
Most wind turbines spin at a constant speed.
The tips of the blades of a typical wind turbine
move at approximately 140mph (64m/s).
Modern wind turbines are far more efficient than
old style windmills. Windmills were up to 23
metres high, had blades of up to 22 metres in
diameter and produced up to 30kW. By
comparison, the world’s largest wind turbines
have a rotor diameter of 126 metres and a tower
135 metres high. These turbines are rated at
7MW, and are predicted to produce enough
electricity to power about 5,000 households.
However, a more typical modern 2.3MW wind
turbine will generate enough electricity to meet
the annual needs of over 1,250 households
(based on annual electricity consumption per
home of 4,700 kWh).
The first UK wind farm was built at Delabole in
Cornwall in 1991. Farr Wind Farm, near Inverness,
is RWE npower renewables’ most powerful
renewable energy project. It consists of 40
turbines, with a total installed capacity of 92MW.
The wind farm generates enough electricity to
meet the average annual needs of 54,000 homes
(more than half of all the homes across the
Scottish Highlands).
The Quiet Revolution is
a small-scale wind
turbine that has been
designed to work well in
urban environments,
where wind speeds are
lower and wind
directions change
frequently.
Most wind turbines spin
at a constant speed.
The tips of the blades of
a typical wind turbine
move at approximately
140mph (64m/s).
WIND POWER CONT…
Rhyl Flats is located approximately 8 kilometres
off the coast of North Wales, and is currently the
largest operating renewable energy scheme in
Wales and one of the most powerful offshore
wind farms in the UK (pictured). It comprises 25
wind turbines and provides enough clean, green
electricity to satisfy the needs of approximately
61,000 homes every year.
Rhyl Flats offshore wind farm
A small difference in the wind speed makes a big
difference to the power output of a wind turbine.
(The power in the wind is proportional to wind speed
cubed.) The wind speed increases the higher up you
go, which is why wind turbines are so tall. The power
output of the turbine is also related to the swept
area of the turbine blades. The greater the area, the
larger the amount of power the turbine can convert
from the wind. Modern wind turbines produce
electricity 70-85% of the time, but generate different
outputs depending on wind speed. Over the course
of a year, they will generate about 30% of the
theoretical maximum output. This is known as its
capacity factor.
How wind turbines work
The energy in the wind can be turned into
electricity by using a turbine to drive an
electrical generator. The wind turns the turbine
blades, which turn a shaft inside the nacelle (the
box at the top of the turbine). In the majority of
wind turbines, the shaft goes into a gearbox,
which increases the rotation speed enough for
the generator, which then uses magnetic fields
to convert the rotational energy into electricity.
The electricity then goes into a transformer,
which converts it into a higher voltage for
distribution.
Advantages
Disadvantages
Wind power does not cause climate
change or pollution.
The speed of the wind is affected by many
different factors such as weather, time of day
and landscape. This makes it an intermittent
source of energy, which cannot be used to
generate electricity on demand.
Wind is a renewable resource – as long
as the sun shines and the wind blows it
will never run out.
Wind energy is a cheap way to produce
renewable energy.
The land underneath wind turbines can
still be used for farming.
Wind turbines can be seen from long
distances, and some people do not like the
way they look.