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WES Windfacts
On
this page you will find general information about wind energy. Click on
the questions below to read the answers.
Q1)
How does a wind turbine make electricity?
Q2)
What influences the output of the wind turbine?
Q3)
How much of the time do wind turbines produce electricity?
Q4) Two-bladed
versus Three-bladed Wind turbines, waht is the difference?
Q5) How safe is wind
energy?
Q6) Local law and
subsidies
Q7) What advantages
do I get if I place the wind turbine?
Q8)
Do I need permission for placing a wind turbine?
Q9)
How much wind is needed to produce electricity?
Q10)
How do I read the characteristics?
Q11)
How much service cost is there?
Q12)
If I supply the over production to the grid, will I get paid for?
Q13) How much will
the power company pay per kWh?
Q14)
Can I use a wind turbine without a connection to the power grid
(electricity network)?
Q15) What is the
life expectancy of a wind turbine?
Q)16
Who does the service and maintenance on my wind turbine?
Q)17 Do I need a
grid connection?
Q)18 Can I use a
wind turbine in a diesel-powered grid?
Q)19
My farm/factory uses a lot of electricity. Can I use wind energy?
Q)20 I live in a
hurricane-prone area. What pre-cautions do I take to protect my wind
turbine?
Q)21 Does the wind
turbine switch on and off automatically when the wind speed changes?
Q)22 Does wind
energy have an impact on the environment?
Q)23
Do wind turbines influence birds?
Q)24
Do wind turbines frighten livestock?
Q)25
Are wind turbines noisy?
Q1) How does a wind
turbine make electricity?
The
simplest
way to think about this is to imagine that a wind turbine
works in
exactly the opposite way to a fan. Instead of using
electricity to
make wind, like a fan, turbines use the wind to make
electricity.
Almost all wind turbines producing electricity consist of
rotor
blades which rotate around a horizontal hub. The hub is connected
to a
generator, which are located inside the nacelle. The nacelle is
the
large part at the top of the tower where all the electrical
components
are located. The wind turns the blades round, this
spins
the shaft, which connects to a generator and this is where the
electricity
is made. A generator is a machine that produces electrical
energy
from mechanical energy, as opposed to an electric motor which
does
the opposite!
Q2) What influences
the output of the wind turbine?
- The
average wind speed. More wind
means higher electricity production. It
means both how fast it blows
and how often it happens. More important
is the average speed than
the speed at any given moment.
- The bigger the rotor diameter, the
higher the output.
- The tower height. Wind speeds increase
at higher altitudes. So, the higher the tower, the more wind the turbine
catches.
- Turbine
type; downwind or upwind. Most wind turbines face into the wind, these
are called "upwind
turbines" Turbines that face the other direction
are called "down wind
turbines". A downwind turbine produces less
energy and wears out faster
compared with an upwind turbine. The
reason is that the airflow around
the tower introduces turbulence.
WES
turbines are upwind turbines.
Related entries: Two-bladed versus
Three-bladed Wind turbines.
Q3) How much of the
time do wind turbines produce electricity?
A
modern wind turbine produces
electricity 70-85% of the time, but it
generates different outputs
dependent on wind speed. Over the course of
a year, it will generate
about 30% of the theoretical maximum output.
This is known as its
load factor. The load factor of conventional power
stations is on
average 50%.
Example calculation for a WES18:
One
year
has (24 * 365 hours) = 8760 hours. When full power (= 80kW) can be
generated
all the time, the theoretical yearly output will be 700.800
kWh. In
practice this will be around 30% of this amount = 210.240 kWh.
Example
calculation for a WES30:
One year has (24 * 365 hours) =
8760 hours. When full power (= 250kW)
can
be generated all the
time, the theoretical yearly output will be
2.190.000 kWh. In
practice this will be around 30% of this amount =
657.000 kWh.
Q4)
Two-bladed versus Three-bladed Wind turbines
People do ask about the difference
between two-bladed and three-bladed wind turbines. In general the
following is true:
The
amount
of the blades is not a key factor influencing efficiency of the
wind
turbine (see:What influences the output of the wind turbine?).
- 3- bladed turbines are more expensive.
- 3-
bladed turbines need more wind to start.
- 3- bladed turbines do not have a
passive mechanical pitch system, each blade needs a motor and a
computer.
- Two
cranes are needed to install a 3- blade turbine.
- 3- bladed turbines with active pitch
need more energy.
- 3- bladed turbines can be slightly more
efficient (up to 4 %) in the midsection of the power curve.
Related
entries: What influences the output of the wind turbine?
Q5)
How safe is wind energy?
When
turbine siting and turbine maintenance are done in
the right way wind
energy is one of the safest energy technologies.
No member of the
public has ever been injured by wind energy or wind
turbines anywhere
in the world, despite the fact that there are now
over 100.000
operational wind turbines.
About siting:
Finding the right location for your turbine is important, it is
important to stay away from any obstacle since obstacles disturb the
flow of air and cause extensive turbulence near the obstacle. Wind
turbines can deal with some turbulence from time to time without a
problem. When a wind turbine is exposed to strong turbulence for a
long period of time, problems or even damage to the turbine can occur.
When turbine siting is done it is important to investigate both the current
and future situation.
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The illustration on the
right gives some guide lines on how to deal with
turbulence caused
by obstacles.
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The reality can be more
complex than presented in the schematic drawing above. In the example on
the left hand side two turbines are installed and a third one is being
built on an office park. The development of the office park did not
stop
after the first two turbines had been erected. While more buildings
and offices were built
the flow of air around the park changed, was
disturbed and became more turbulent,
causing problems for the
turbines.
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Q6) Local law and
subsidies
Many
countries
and local authorities support and stimulate renewable energy.
Please
contact your local WES dealer to check what kind of subsidies or
other
support you can get from them when switching to wind energy.
Q7)
What advantages do I get if I place the wind turbine?
Most
imporatnt reason:
- Wind
turbines
pay back for them selves in 3 to 7 years. After this period
wind
turbines generate electricity for many more years without
significant
costs. Contact your local WES dealer to make a calculation
for you.
On
top of this there are various other advantages depending on the
situation you are in:
- A
wind turbine may stabilize an instable grid.
- You decrease your diesel need and
cost.
- You
decrease the diesel generator noise.
- You decrease your electricity cost.
- You
produce green energy for a better environment.
- You educate your community by setting
an example of a better environment
Q8)
Do I need permission for placing a wind turbine?
Yes.
Please contact your local WESdealer for the details.
Q9)
How much wind is needed to produce electricity?
The
WES
wind turbines will start to produce at 3 m/s, however, with an
average
wind speed of 5 m/s it gets economically interesting to produce
your
own electricity with a wind turbine. Stronger wind produces more
electricity.
For example:
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WES18 |
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Wind
speed [ m/sec]
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Annual
production [kWh)
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4,5 |
74.000
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5,5
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130.000
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6,5
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193.000
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7,5
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256.000
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8,5
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313.000
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WES30
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Wind
speed
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Annual production
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4,5
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205.000
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5,5
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370.000
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6,5
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560.000
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7,5
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753.000
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8,5
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930.000
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Q10) How do I read
the characteristics?
- Nominal
Power
is measured in kilowatt (kW) or megaWatt (mW). Nominal power
tells
the maximum amount power that the turbine can produce.
- Production
is
measured in kiloWatt hours (kWh) or megaWatt hours (mWh). Production
tells
you how much electrical energy will generate during a period of
time.
Often the time period is one year.
Q11)
How much does turbine maintenance cost?
Wind
turbines need maintenance.
Service costs for WES turbines are low. The
annual estimated service
cost for a WES18 is Euro 1.500 and for the
WES30 it is Euro 2.000. 3-
bladed turbines are more expensive to
maintain. The down-time for a
WES turbine during a maintenance job is
limited to only a few hours.
Q12)
If I supply the over production to the grid, will I get paid for?
This
depends
on your local regulations. In many countries you get paid for
the
kWh that you supply to the grid, please consult your local
WESdealer
he is aware of all regulations and possible future changes.
Q13)
How much will the power company pay per kWh?
This
all depends on the country
you live in. Many governments have rules and
regulations regarding
the prices per kWh. This should be checked on an
individual basis,
your local WESdealer can help to make calculations.
Q14) Can I use a wind
turbine without a connection to the power grid (electricity network)?
There
are
two types of wind turbines: grid-connected and non-grid-connected.
The
grid connected wind turbines are the larger ones that produce
electricity.
The non-grid-connected are usually the very small wind
turbines that
charge batteries only. The WES turbines are all grid
connected,
except for our Hybrid stand-alone Wind/Diesel system. See:
What is a
hybrid stand-alone wind/diesel system?
Related entries: What is a hybrid
stand-alone wind/diesel system?
Q15) What is the life
expectancy of a wind turbine?
Most medium to large wind turbines
have a life expectancy of 20 years.
Q16) Who does the
service and maintenance on my wind turbine?
When
you purchase a WES wind
turbine from a cetified WES dealer, you can
enter into a service
contract with the WES dealer or a local service
company. The service
contract ensures that your wind turbine gets the
regular bi annual
service it needs on time and you dont have to worry
about keeping
track of the maintenance. For most wind turbine owners
this is the
preferred method.
Q17) Do I need a grid
connection?
Most
wind turbines need a grid connection.
WES manufactures grid connected and
Hybrid Wind/Diesel wind turbines for off grid purposes.
Grid
connected:
When connected
to the grid (the local electricity network) and behind
the meter, the
electricity will be consumed directly by you at your
house, farm or
factory. Excess electricity produced will be fed into
the grid. In
this case a meter keeps track of your supplied kWh to the
grid and
your power company will pay you a certain amount of money per
kWh
(net-metering). This price is usually pre-determined and often
regulated
by the government. In times of insufficient wind, you will
automatically
draw electricity from the grid.
Stand-alone:
In
this case the wind turbine feeds electrical energy into a small
isolated
grid. Often powered by a diesel generator. WES wind turbine
and
diesel genrator use grid frequency to control energy production.
Q18)
Can I use a wind turbine in a diesel-powered grid?
Yes,
WES has installed wind
turbines in small diesel-grids (grids where
diesel generators supply
the electricity). A wind turbine is never a
substitute for the diesel
generator in such a system and it can
generally supply up to 90% of
the total electricity production.
Q19) My farm /
factory uses a lot of electricity. Can I use wind energy?
Yes!
As
a matter of fact, if there is space to install a wind turbine and
there
is sufficient wind, then any farm or factory can use a wind
turbine.
For example: A poultry farmer has a house and a large poultry
shed
and it consumes 120.000 kWh per year. There is sufficient wind
available
and the local regulations allow you to use a wind turbine. In
this
case a WES18 with an 80 kW generator can easily produce 150.000
kWh
per year. Enough for your own electricity needs. At times when
there
is not enough wind, you will automatically draw electricity from
the
power grid. In this case you only pay the power company for the
electricity
you take from them and the rest you get from your wind
turbine. If
you produce more electricity (150.000 to 120.000 kWh =
30.000 kWh)
then you can sell the over production to the power company
and they
will pay you a certain amount per kWh delivered. Many factory
or farm
owners that use WES wind turbines use such a set up.
Q20)
I live in a hurricane-prone area. What pre-cautions do I take to
protect my wind turbine?
The
WES18
wind turbine can be ordered with a special Tilt-Up Tower. This
tower
enables you to install the wind turbine without a special crane,
but
more importantly, you can lower the wind turbine before an
approaching
hurricane.
Q21)
Does the wind turbine switch on and off automatically when the wind
speed changes?
Yes,
the
system is fully automatic. It start automatically when the wind
speed
reaches at least 3 m/s, it follows the wind direction
automatically
and it slows down and stops automatically when the wind
speeds reach
or pass the maximum wind speed.
Q22) Does wind energy
have an impact on the environment?
Yes,
as wind energy is a clean
energy it only has a positive impact! Wind
energy decreases the use
of fossil fuels, nuclear energy and other
polluting energy sources.
It also decreases CO2 emissions.
Q23) Do wind turbines
influence birds?
Many
people
are concerned about the influence wind turbines have on the
safety
of birds. Extensive surveys show that very few birds are killed
by
wind turbines and that they have no influence on the bird migratory
routes
at all.
Q24)
Do wind turbines frighten livestock?
Wind
farming is popular with
farmers, because their land can continue to be
used for growing crops
or grazing livestock. Sheep, cows and horses are
not disturbed by
wind turbines.
Q25) Are wind
turbines noisy?
Wind turbines are not noisy.
The evolution of wind farm technology over
the past decade has
rendered mechanical noise from turbines almost
undetectable with the
main sound being the aerodynamic swoosh of the
blades passing the
tower. There are strict guidelines on wind turbines
and noise
emissions to ensure the protection of residential amenity. It
is
possible to stand underneath a turbine and hold a conversation
without
having to raise your voice. As wind speed rises, the noise of
the
wind masks the noise made by wind turbines. For more information,
read
the facts about noise from wind turbines or why not visit a wind
farm
and
experience it for yourself. The picture on the left gives an
overview
of different sources of noise, including a wind turbine (click
the
picture to enlarge). To find out what the noise level is at a distance use the WES30 noise calculator.
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