Wind energy
The need of generating renewable energy to face the climate
change threat had opened a new horizon in the generation ambit. A
successful example is wind energy, which had been more than doubled
its worldwide installations since 2005. The turnover of the wind
sector worldwide reached 40 billion in the year 2008. The market
for new wind turbines showed a 42 percent increase and reached an
overall size of 27.261MW. Ten years ago, the market for new wind
turbines had a size of 2.187MW, less than one tenth of the size in
2008.
Pacific Hydro had take advantage of this effervescent
market and with more than A$20 billion to be invested in new carbon
free electricity generation over the next decade, became the
Australian leader wind energy expert.
World Wind Energy Report 2008
- Worldwide capacity reaches 121'188MW, out of which 27'261MW
were added in 2008.
- Wind energy continued its growth in 2008 at an increased rate
of 29 percent.
- All wind turbines installed by the end of 2008 worldwide are
generating 260TWh per annum, equalling more than 1,5 percent
of the global electricity consumption.
- The wind sector became a global job generator and has created
440.000 jobs worldwide.
For the first time in more than a decade, the USA took over the
number one
position from Germany in terms of total installations.
China continues its role as the most dynamic wind market in the
year 2008, more than doubling the installations for the third time
in a row, with today more than 12GW of wind turbines
installed.
Source: http://www.wwindea.org
To Download the World Wind Report published Feb 09
click here
Did you know that Pacific Hydro's installed wind farms save as
much as 380,000 tonnes of global warming pollution from being
emitted each year?
That benefits the environment as much as keeping almost 90,000
cars off the road.
Electricity-producing windmills were first used in Europe, and
today are found right across the world. In Australia, wind is still
a relatively new source of clean energy - our country's first wind
farm wasn't built until 1987.
Windmills
Windmill
blades are modeled after airplane wings. They're designed so that
they rotate because of a difference in pressure, caused by air
moving over the surface of the blade. The blades cause a rotor to
turn, which then drives an electrical generator.
The windmills installed at Pacific Hydro's wind farms are 'smart
machines' - able to operate without human intervention. Each
windmill uses its own internal computer system to monitor the
direction and speed of the wind, with electricity production
commencing automatically at wind speeds above 14km/h.
The amount of electricity produced continues to increase with
the wind speed until the wind generators reach their maximum or
'rated' capacity at winds of around 55km/h.
With blades rotating slowly at 17 revolutions per minute, the
wind generators continue to operate at their maximum output until
the wind speed reaches 90km/h, at which point the windmills
automatically shut down and turn out of the wind to avoid being
damaged.
However, winds of that speed are not very common. In fact, only
one windmill needed to shut down at Challicum Hills in the
development's first eight months of operation.
Glossary of windmill terms
Blades
Most windmills have either two or three blades. Air
passing over the blades creates a difference in pressure and causes
them to lift and rotate. Some windmills are designed to operate
upwind, with their blades facing the wind; others are designed to
run downwind, facing away from the wind.
Gear box
The rotor turns about 22 revolutions per minute (RPM) but
the gearbox has to turn at about 1500RPM. The gearbox connects the
main shaft to the small shaft and converts the 22 revolutions to
1500 revolutions.
Generator
The generator makes electricity when it turns. The current
is then sent down through the tower in large electricity
cables.
Small shaft
The small shaft runs at about 1500RPM - that's very
quickly. It leads the power from the gearbox to the
generator.
Main shaft
The main shaft is turned by the rotor. It has to be very
thick as the rotor uses a large force. The main shaft is connected
to the gearbox.
Nacelle
The rotor attaches to the nacelle, which sits on top of
the tower and includes the gear box, main and small shafts,
generator and brake. A cover protects the components inside the
nacelle. Some nacelles are large enough for a technician to stand
inside while working.
Rotor
The blades and the hub together are called the rotor. The
rotor is bolted on to the big main shaft.
Tower
It's a lot more windy high up in the sky than down on the
ground, so taller towers mean windmills are able to capture more
energy and generate more electricity. Towers are usually made from
tubular steel, which is very strong, or steel lattice, which is
less expensive.
Wind vane
Measures the wind direction and allows the yaw drive to
direct the windmill properly depending on the direction of the
wind.
Yaw drive
On upwind windmills, the yaw drive is used to keep the
rotor facing into the wind as the wind direction changes. Downwind
turbines don't require a yaw drive: the wind blows the rotor
downwind.
Yaw motor
Powers the yaw drive.
Capacity factor
The capacity factor is simply the windmill's actual energy
output for the year divided by the energy output if the machine
operated at its rated power output for the entire year.
Capacity factor (%) = Actual Output (MWh )/ Rated Capacity (MW)
x Time Elapsed (h) x 10
Sources
http://www.nrel.gov/learning/re_wind.html
http://www.windpower.org/en/kids/intro/intronac.htm