POWER April 2011 - 38

FUTURE POWER
Changing Winds: The Evolving
Wind Turbine
As early as the first century A.D., wind energy was harnessed for practical purposes.
Since then, turbine designs have come a long way from the archetypal
post-mounted four-bladed devices. Today's ubiquitous three-bladed
designs will soon be evolving in many unexpected directions.
By Sonal Patel
T
he first wind turbine used to convert
wind energy into power-unlike windmills,
which are used to pump water or
grind grain-was built by Professor James
Blyth of Anderson's College, Glasgow (now
Strathclyde University) in 1887. Blyth's experiments
with three different turbine designs
resulted in a 10-meter-high (33-foothigh),
cloth-sailed wind turbine, which was
installed in the garden of his holiday cottage
at Marykirk in Kincardineshire. It is said to
have operated for 25 years.
Blyth's invention marked the dawn of wind
turbine development. Close on its heels was
a turbine built by American inventor Charles
Brush in 1888. That 12-kW turbine featured
144 blades made of cedar, each with a rotating
diameter of 17 meters (Figure 1).
Then came the work of Danish scientist
Poul la Cour in the 1890s, which spawned
about 2,500 turbines in Denmark by 1900,
with an estimated combined peak power capacity
of 30 MW. La Cour's wind turbines
produced hydrogen as well as power.
Wind-powered turbines were installed
by the millions around the world thereafter,
particularly in the American Midwest, where
they were used to power irrigation pumps.
By 1931 the first forerunner of the modern
horizontal-axis wind generators was put into
service at Yalta, in Russia. It was a 100-kW
generator on a 30-meter-high tower that featured
a load factor of 32%. And in 1941 the
world's first 1.25-MW turbine was grid-connected
on Grandpa's Knob in Castleton, Vt.
The first modern wind turbine was built
in Denmark around the mid-1950s. According
to the Danish Wind Industry Association
(DWIA), the 200-kW Gedser wind turbine
(Figure 2) was built in 1956 by engineer Johannes
Juul for electricity company SEAS
on the Gedser coast in southern Denmark.
The concept-a three-bladed upwind turbine
with electromechanical yawing and
asynchronous generator-was a " pioneering
design for modern wind turbines, although
its rotor with guy wires looks a bit
38
old fashioned today, " says the organization.
The turbine was stall-controlled; Juul
invented the emergency aerodynamic tip
brakes, which were released by the centrifugal
force in case of overspeed. " Basically,
the same system is used today on modern
stall-controlled turbines, " the organization
says, noting that Juul's turbine ran for 11
years " without maintenance. "
Wind power caught new wind after the
first oil crisis in 1973 as Denmark, Germany,
Sweden, the UK, and the U.S., among other
countries, scrambled to design larger turbines.
In 1979, Danish developers succeeded
in building two 630-kW wind turbines, a
pitch-controlled and a stall-controlled model.
" In many ways they suffered the same fate
as their even larger colleagues abroad, " says
the DWIA. " The turbines became extremely
expensive, and the high energy price subsequently
became a key argument against wind
energy. "
In addition to the design developments
discussed below, which aim to increase efficiency
and lower costs, other developments
in the energy delivery infrastructure will
have an effect on the use of wind power.
The development of a smarter grid will
enable smoother integration and dispatch
of large- and small-scale wind generation
(see p. 46, " The Smart Grid and Distributed
Generation: Better Together " ), and an important
component of any grid in the future
will be more widely available energy storage
(see p. 30, " Energy Storage: Just-inTime
Generation " ).
Horizontal- and Vertical-Axis Turbines
Today, most modern wind turbine designs
continue to be classified according to the
configuration of the rotating axis of their
rotor blades. Two categories dominate: horizontal-axis
wind turbines (HAWTs) and
vertical-axis wind turbines (VAWTs). More
than 90% of wind turbines in use today are
thought to be of HAWT design. According
to Dr. Rigoberto Chincilla, an associwww.powermag.com
POWER
| April 2011
1. The Brush. American inventor Charles
Brush in 1888 built one of the first wind power
turbines. Source: Wikimedia Commons
2. The Gedser. The first modern wind turbine
made its appearance in the mid-1950s and
was built by Danish engineer Johannes Juul.
Courtesy: Danish Wind Industry Association
http://www.powermag.com
POWER April 2011

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