Wind Energy Center requires transmission
Jan 6, 2007 - McClatchy-Tribune Regional News
- Kevin Bonham Grand Forks Herald, N.D.
The $250 million Langdon Wind Energy Center near
here could not begin to deliver wind energy throughout
eastern North Dakota and northwestern Minnesota
without a new $10 million transmission line.
The 115-kilovolt line will replace a 41.6-kilovolt
transmission line owned by Otter Tail.
At Hensel, it connects with other transmission
lines that transfer power throughout the region.
How wind turbines work
Wind turbines capture the wind's energy with two
or three propeller-like blades, which are mounted
on a rotor, to generate electricity. The turbines
sit high atop towers, taking advantage of the stronger
and less turbulent wind at 100 feet (30 meters)
or more above ground.
A blade acts much like an airplane wing:
-- When the wind blows, a pocket of low-pressure
air forms on the downwind side of the blade.
-- The low-pressure air pocket then pulls the
blade toward it, causing the rotor to turn. This
is called lift.
-- The force of the lift actually is much stronger
than the wind's force against the front side of
the blade, which is called drag.
-- The combination of lift and drag causes the
rotor to spin like a propeller, and the turning
shaft spins a generator to make electricity. Overall,
the wind energy centers works like this:
-- A computer automatically controls each turbine.
-- The computer turns the rotor consisting of three
blades and a hub inside a nacelle (enclosure) to
face into the wind.
-- The rotor turns (depending on the type of wind
turbine) at 11 to 22 rotations per minute. As the
wind blows, the pitch of the rotor blade adjusts
to suit the changes in the wind speed. For safely
purposes, the turbine shuts down automatically if
the wind speed exceeds 56 miles per hour.
-- The blades drive the main shaft, which drives
the generator through a gearbox to convert the mechanical
power to electrical power.
-- The electricity is cabled down the turbine tower,
then through a series of transformers and underground
distribution lines before entering the main substation.
-- At the substation, the voltage is stepped up
and delivered to the electric grid. The step-up
enhances the efficiency of energy transmission to
homes and businesses.
Wind: How reliable?
Sophisticated monitoring and wind resource analysis
allow wind developers to estimate with a high degree
of certainty "when" and "how much" wind energy is
available, so customers can plan their wind power
purchases. When the wind blows, it can displace
fossil-fueled generation such as oil and gas. Studies
have shown that when a utility diversifies its power
portfolio with the addition of wind energy, it can
meet demands more reliably.
What if it's not windy?
When the wind is calm, the turbine is at rest.
However, at the hub height of a utility-scale wind
turbine -- usually more than 200 feet above ground
-- on a site selected specifically for its good
wind resources, it is rare for the wind to be totally
Are there wind seasons?
Yes, but they vary by region. In California, the
peak wind season is summer; in the Midwest, it's
fall and winter, and in Texas, spring is peak. Each
wind plant has specific daily and seasonal variations.
Each wind site also has specific wind patterns,
which are determined through wind studies conducted
during early development of a project.
Source: FPL Energy