Wind Power Physics 310 J. Newman

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Wind PowerPhysics 310 J. Newman

• At the end of 2006, worldwide capacity of
  wind-powered generators was 73.9 gigawatts
• Although wind currently produces just over 1 of
  world-wide electricity use, it accounts for
  approximately 19 of electricity production in
  Denmark, 9 in Spain and Portugal, and 6 in
  Germany and the Republic of Ireland (2007 data).
  Globally, wind power generation more than
  quadrupled between 2000 and 2006.
• There is an estimated 72 TW of wind energy on the
  Earth that can potentially be converted to
  electricity and that is commercially viable, or
  over five times the world's current energy use in
  all forms .

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Wind turbines near Aalborg, Denmark. A standard
doorway can be seen at the base of the pylon, for
scale.
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GE Wind Energy's 3.6 megawatt wind turbine is one
of the largest prototypes ever erected. Larger
wind turbines are more efficient and cost
effective.
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The world's largest wind plant is the Raheenleagh
Wind Farm located off the coast of Ireland. At
full capacity (it's currently operating at
partial capacity), it will have 200 turbines, a
total power rating of 520 MW and cost nearly 600
million to build.
Machine sizes have increased for two reasons.
Larger machines are cheaper and they deliver more
energy. The energy yield is improved partly
because the rotor is located higher from the
ground and so intercepts higher-velocity winds,
and partly because they are slightly more
efficient.
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Magnetically levitates vertical blades using
neodymium permanent magnets wind speed as low
as 1.5 m/s ( 3 mph) can be used to generate
power In principle, these wind turbines could
each generate 1 GW of power, some 200 x more than
a typical standard wind turbine, with much less
of a footprint Last November construction of
the first one began in China -
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Power Calculation

• Power KE/sec ½ (m/sec)v2
• But, mass/sec r(V/sec) and
• V/sec Av, so
• Power ½ rAv3
• We need to throw in an efficiency factor, a,
• so Power ½ arAv3
• Numerics with v 20 mph (10 m/s) and an
  effective rotor diameter of 45 m and a 1
• Power 1 x 106 W 1 MW

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Efficiency

• Betz calculated that because of air
  slowing/breakup at the rotors, the efficiency a
  59
• Also, there is the capacity factor of power
  generated out of the maximum possible with wind
  all the time typical values are 35
• Also wind is intermittent need good energy
  storage in order to rely on this as only source

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Areas designated class 4 or greater are suitable
with advanced wind turbine technology under
development today. Power class 3 areas may be
suitable for future technology.
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Some References

• http//www.windpower.org/en/core.htm
• http//windeis.anl.gov/index.cfm
• http//www.worldenergy.org/