The mountains outside of Seattle accumulate
a lot of snow.
This snowpack, all this frozen water,
has been used by the city of Seattle for over
a century as a source of stored energy.
As the snow
melts, gravity takes over and the water makes
its way to the streams and rivers that feed
the
Puget Sound.
Starting early in the 20th century, Seattle
City Light began building dams that
would harness the energy of this water speeding
toward the Sound.
Inside the dams are turbines
that are spun by this rushing water.
People have been using water to power things
for centuries.
Now this is an example of a 19th
century water wheel that they used to use
to generate electricity a long time ago.
In the 21st
century we're still using water to power things.
But instead of a wooden wheel, we're using
metal turbines because they last longer and
they create far more energy.
Here's how they work.
Water is stored behind a dam.
To generate power, the water is directed
through tunnels called penstocks.
The penstock brings the water to the powerhouse
turbines.
At
the turbine, veins called wicket gates control
the water's energy and direct the water into
the
turbine runner's blades causing the turbine
to spin a shaft connected to a series of large
magnets
in the generator.
These magnets are spun inside large coils
of copper wire, generating electricity.
This electricity is transferred using the
generator to transformers which dramatically
increase the
voltage and allow the electricity to be sent
hundreds of miles to Seattle over transmission
lines.
Gorge Powerhouse on the Skagit River was one
of the very first built by Seattle City Light
and
has been generating electricity since the
1920s.
Every few decades though, the turbines have
to
be replaced because they get worn down and
don't generate electricity as efficiently.
It's what
they've been doing recently at the Gorge Powerhouse.
They're replacing what they call
Generator 24.
Ross McCormick: "This particular one happens
to be a complete turbine overhaul where the
generator had been built in the early 1950s,
hasn't been touched hardly at all until 2006
and
needs a complete overhaul."
While it takes an immense amount of work to
do this, the efficiency of the turbine will
increase
greatly.
McCormick: "We're upgrading the machine from
an 80 watt machine probably all the up to
a
100 watt machine which is a huge improvement
in 50 years.
Technology in the building of the
turbine wheels has increased so much."
Seattle City Light has been upgrading all
of its turbines at a cost of 64 million dollars.
But the
utility will make back 112 million dollars
in increased power production over the life
of the new
turbines, so it's a good investment.
Doing the work is both technical and time-consuming.
Some
workers even have to wear these moon suits
with an independent air supply to do the modern
upgrades.
And there's another tool used here that also
looks like something you'd see in
astronaut training.
Seattle City Light workers created it.
Rob Fuchs: "It's actually called a boaring
bar and what that operation is for is to machine
the
existing surfaces in the turbine area for,
to accommodate some of the new parts we're
going to be
putting into unit 24."
What's interesting is that the utility put
the turbine overhaul out for bid and Seattle
City Light
workers won the contract.
Ross McCormick: "We came out about a half
million dollars lower than the next lowest
competitor.
That was competing throughout the world.
As far as China had bid on it.
So all of the
equipment that we have at the shop we've collected
through the years has allowed us to compete
with the outside world."
City Light workers have been caring for these
turbines and these hydro systems for a long
time.
So they've accumulated very specialized machining
tools for nearly a century.
Ross McCormick: "A lot of parts were made
back in the early '20s and no longer available
so we
will reverse engineer what's broken and upgrade
it and make it today's standards in our shop.
We have all the equipment and the tooling
to do that and the manpower to do it."
So the city's long experience with hydro generation
is now saving ratepayers quite a bit of
money.
These turbines are keeping the lights on using
only snowmelt and gravity to do it.
In
addition, these hydro projects were built
above traditional salmon spawning grounds
so they're
also environmentally friendly.
Seattle citizens completed their first hydro
project on the Cedar River in eastern King
County all
the way back in 1905 and that powerhouse is
still in operation.
