Wind: 102

HAWT  /  VAWT

The amount of power transferred to a wind turbine is
directly proportional to the area swept out by the
rotor, to the density of the air, and the cube of the
wind speed.
Thus the usable power P potentially available in the
wind is given by:
,
where P = power in watts, α = an efficiency factor
determined by the design of the turbine, ρ = mass
density of air in kilograms per cubic meter, r = radius of
the wind turbine in meters, and v = velocity of the air in
meters per second.
WIND POWER
WIND ON THE FREEWAY?
This is a computer generation of what is one of many
possibilities for using wind energy.  This is only a theory but
it is the ideas like this one that change outcomes.
This freeway was a Cadcam by  a  student.
Wind power on top
of large buildings,
VAWT can produce
at that hights 50 kw
or more to supply
electrical power
Wind power can be used to produce  electrical
power in off grid remote locations. for
HAWT
HAWT advantages
·        Variable blade pitch, which gives the
turbine blades the optimum angle of attack.
Allowing the angle of attack to be remotely
adjusted gives greater control, so the turbine
collects the maximum amount of wind energy
for the time of day and season.
·        Tall tower allows access to stronger
wind in sites with wind shear. In some wind
shear sites, every ten meters up, the wind
speed can increase by 20% and the power
output by 34%.
HAWT disadvantages
·        HAWTs have difficulty operating in near
ground, turbulent winds.
·        The tall towers and long blades up to 90
meters long are difficult to transport on the
sea and on land. Transportation can now
cost 20% of equipment costs.
·        Tall HAWTs are difficult to install,
needing very tall and expensive cranes and
skilled operators.
·        Need massive tower construction to
support the heavy blades, gearbox, and
generator.
·        The FAA has raised concerns about tall
HAWTs effects on radar near Air Force bases.
·        Their height can create local opposition
based on impacts to viewsheds.
·        Downwind variants suffer from fatigue
and structural failure caused by turbulence.
·        Need additional yaw control
mechanism to turn the blades toward the
wind.
VAWT
VAWT advantages
·        Lower construction cost as compared to
HAWTs because there is no need to build a
massive tower structure to support the heavy
HAWT blades and turbine assembly.
·        As the rotor blades are vertical, a yaw
drive|yaw device is not needed, reducing cost.
·        Can be easier to maintain if the moving
parts are located near the ground.
·        VAWTs have a higher airfoil pitch angle,
giving improved aerodynamics while
decreasing drag at low and high pressures.
·        VAWT systems generate 50% more
energy than its HAWT counterpart. Newer
systems are made with rare-earth-alloy
magnets which are 25 times stronger than
ferrite magnets also eliminates any need for
grease or oil since no parts actually touch
each other.
·        Straight bladed VAWT designs with a
square or rectangular crossection have a
larger swept area for a given diameter than
the circular swept area of HAWTs.
·        Lower wind startup speeds than
HAWT's. Typically, they start creating
electricity at 6 m.p.h.
·        Usually have a lower Tip speed
ratio/Tip-Speed ratio so less likely to break in
high winds.
·        Low height useful at location where
laws do not permit structures to be placed
high.
·        Mesas, hilltops, ridgelines and passes
can have faster winds near the ground
because the wind is forced up a slope or
funnelled into a pass and into the path of
VAWTs situated close to the ground.
·        Does not need to turn to face the wind if
the wind direction changes making them
ideal in turbulent wind conditions.
·        VAWT blades are easily seen by birds.
Jay Leno
Jay has added a
renewable energy
generating system to
both  his Big Dog
Garages.  Here on the
display room Solar n
Wind ties in a 10 kw
VAWT vertical axis wind
turbine and 2 kw  Solar
system, while a 54 kw
solar alone system is
installed on the  
machine and
fabrication shop.  The
solar system alone
provides Jay sufficient
electrical power during
daily operations to
offset the electrical
power draw of this
commercial building
dropping its
environmental footprint
to almost Zero.
VAWT vs HAWT
VAWT disadvantages
·        Do not take advantage of the stronger wind at higher elevation as the HAWTs do.
·        Most VAWTs have low starting torque, and may require energy to start the turning.

Advantages of Solar PV and Wind VAWT's
Hybrid using both solar and wind with VAWTs can greatly improve the power per acre for new solar
or wind farms of this design.  Currently the largest hybrid with over 30 Megawatts of PV solar
combined with 120 Megawatts of wind to have a maximum output of 150 Megawatts.  This is the
largest in north america. This new combination of these two energy producers can only be
acheived by use of low speed VAWT's.