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Grex Science Item 83: electricity from the air!
Entered by tsty on Sun Oct 27 10:17:04 UTC 2002:

Forbes Magazine Wind Rush 
Monday September 30, 4:19 pm ET 
By Victoria Murphy

A new generation of wind power is online--and profitable. FPL En-
ergy  leads  this  tiny  industry with the biggest project in the
country. So far.

Though wind, like other renewable energy sources  such  as  solar
and  geothermal, benefits greatly from government tax credits and
subsidies (like accelerated depreciation), it is closer to becom-
ing  a  lucrative  business  even  without  the perks.  Thanks to
bigger, more efficient turbines, the cost of producing wind ener-
gy is down 80% from ten years ago.

In the race for efficiency, size matters. The turbines at  State-
line,  designed by Danish maker Vestas, can produce 660 kilowatts
each from a triplet of blades 75 feet long. With the hub 164 feet
off  the  ground, that means the tip of an upright blade is about
240 feet up in the air. The turbine's power is six times that  of
its  decade-old  predecessors.  Vestas  now  sells an even bigger
machine, a 1.8-megawatt turbine that stretches to a height of 328
feet (see above). These monsters are in Germany and Canada.

Higher is better. It is windier at higher elevations and,  thanks
to the laws of physics, the power in wind per square yard of area
captured by the windmill blades is proportional to  the  cube  of
the  wind's velocity. (The kinetic energy in a moving object of a
given weight is proportional to the square of its  velocity;  and
the  weight  of  air  passing a given spot is proportional to the
air's speed. Multiply those factors and you get a cube.) Also, of
course, longer blades cover more square yards than short ones.

At some projects built in the  late  1980s  crews  had  to  drive
around  several  times  a  day to check whether the turbines were
spinning. Today's turbines take care of themselves. Vestas'  tur-
bines  self-adjust  to sudden gusts by changing the blades' pitch
and increasing rotor speed up to 10%.  If  gusts  blow  above  55
miles  an hour, the turbine shuts itself down and waits until the
wind slows for at least ten minutes  before  starting  up  again.
This  prevents  damage  to the gearbox. Motorized controls rotate
the turbines so the hub faces into the wind.

Better technology  means  less  manpower  to  run  Stateline:  20
maintenance  guys for all 400 turbines, an 80% reduction in labor
from FPL's older farms. At Stateline, 140  miles  of  fiber-optic
cable  connect turbines to a computer in a trailer. Operators re-
motely monitor some 60 parameters, such as voltage spikes,  gear-
box temperature and oil viscosity in the generator.

Wind still has one big limitation: Sometimes it just won't  blow.
With  an  intermittent  source  like  wind, transmission lines go
unused about two-thirds of the time, compared  with  conventional
energy  generators,  which fill power lines 80% of the time. Gaps
in transmission make wind energy twice as costly to transport for
PacifiCorp Power Marketing, the wholesaler.

Stateline may one day be overtaken by  Rolling  Thunder  or  some
other   large-scale   wind   project   in   the   U.S.  The  next
breakthrough--one that subsidy-happy developers might be  shy  to
announce--will  come when the cost of wind power falls far enough
to wean it off our tax dollars.

5 responses total.

#1 of 5 by cmcgee on Sun Oct 27 17:05:22 2002:

When visual pollution gets metrics like air and water pollution have,
windmills will become noxious objects.  I was at a "wind farm" on the
edge of the North Atlantic this summer, and the landscape was as
destroyed by the windmills as it would have been by an open pit mine.

#2 of 5 by rcurl on Sun Oct 27 18:42:16 2002:

Windmills also increase bird deaths, so siting is important. (There is
more controversy than data on this issue:
http://www.tompaine.com/feature.cfm/ID/4270)

#3 of 5 by keesan on Mon Dec 9 20:10:50 2002:

Windmills do not affect the defense budget like petroleum does.  I don't know
of any cases of war over wind rights.

#4 of 5 by gull on Mon Dec 9 21:44:59 2002:

I could imagine it happening, though not in North America.  There are
wars over access to water.  If wind became an important source of power,
it wouldn't be surprising to see countries fighting over who had access
to the most productive hilltops.

#5 of 5 by russ on Tue Dec 10 02:53:00 2002:

Bidding wars, maybe, but fights?  Get real.  All one side would have
to do is "lose", wait while the other guy installs all the foundations
and puts up the turbines, then take the territory back with all the
capital improvements.  Power lines re-route too easily.

Ground-based wind may not even be the best way to capture it; look
up Bryan Roberts on the web.

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