Today, an old wind blows anew. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
It's time for a progress
report on windmills: We heard a lot about windmills
10 or 15 years ago. Fields of windmills with
propeller blades sprouted up -- mostly in
California. Now Robert Thresher and Susan Hock give
us an update, and it is promising.
By now those fields of windmills have quietly come
to represent an installed capacity of some 1600
megawatts of energy. That's only 1/2000 of
America's total energy production. Still, it is
enough to supply a typical major city.
When those windmills first went in, in the early
'80s, the capital and operating costs came to a
pricey 25 cents per kilowatt-hour. They could exist
only with government subsidies. By now good
engineering has brought the cost down to around 8
cents per kilowatt-hour.
That's still too high to compete on the open
market, but the open market is deceptive. Fossil
fuel costs are low because we subsidize them
invisibly: in health care for lung disease,
struggles with Middle East oil-producing countries,
and likely costs of coping with global warming.
We're borrowing from the future.
Meanwhile wind-power costs keep dropping. We now
look for a price of only 4 cents per kilowatt-hour
by the year 2000. The modern power-generating
windmill began taking form during the 1750s, when
engineers added automatic control elements. They
invented the fan-tail device for constantly
orienting the blades into the wind and
blade-reefing devices to change the pitch of
But coal-powered steam engines distracted us. We
forgot about windmills except for remote locations
-- farms and early railroad stops. So what we've
done with windmills in recent years is a direct
continuation of what began in the 18th century and
continued in airplane propeller design after WW-I.
Today, a typical power generation windmill has a
3-bladed propeller, maybe 80 feet in diameter. It
might generate 250 kilowatts. As aerodynamic blade
design improves, and as computer control systems
become more sophisticated, efficiency also rises.
These modern windmills once captured 20 percent of
the wind energy passing through them. Now they
capture 70 percent. The new generation of windmills
will sit on 200-foot towers and produce 500
kilowatts -- 40 times as much as the best
But I sound a warning: All power sources bring
mischief when we commit ourselves to them fully.
Water wheels exacted such a cost in wood by 1300
that European forests vanished. Our commitment to
oil creates worldwide economic havoc. Completely
harnessing the wind would tie up huge tracts of
land and affect the winds themselves. The wind is
filled with promise today. But it'll only fulfill
that promise in a diversified energy economy.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds