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From YouTube: Boulder's Hydroelectric Program
Description
This video explores the City of Boulder's use of hydroelectric power.
A
On
the
eastern
edge
of
the
rocky
mountains
is
boulder
colorado,
a
city
of
100
000
people
known
for
the
beauty
of
its
surroundings,
the
healthy
lifestyle
of
its
residents
and
its
commitment
to
environmental
conservation
and
because
of
its
natural
geography.
The
city
has
become
a
leader
in
the
field
of
renewable
energy.
A
Snow
falls
on
the
high
peaks
of
the
continental
divide
and
melts
in
the
spring
filling
reservoirs
within
the
40
square.
Miles
of
the
boulder
creek
watershed
nearly
18
000
total
acre
feet
of
water
stored
in
the
reservoirs
or
directly
diverted
from
stream
flows
is
delivered
by
gravity
through
miles
of
various
sized
pipelines
to
the
city's
potasso
water
treatment
plant,
then
into
boulder
as
water
travels
down
the
pipelines
to
elevations
that
are
thousands
of
feet.
A
Lower
excess
water
pressure
develops
and
for
nearly
80
years,
boulder
used
pressure,
reducing
valves
to
dissipate
the
excess
energy
of
the
water
that
all
changed
in
the
early
1980s
after
boulder's
city
council
approved
the
development
of
a
hydroelectric
program.
The
idea
of
using
boulder's
water
pipelines
to
generate
electricity
was
first
proposed
in
1906
and
finally
became
a
reality.
When
the
first
hydro
came
online
in
1985.
A
today,
eight
hydro
plants
in
seven
locations
are
owned
and
operated
by
the
city
of
boulder
and
are
located
throughout
the
city's
municipal
water
system.
The
hydro's
reduced
much
of
the
excess
water
pressure
in
the
pipelines
and
the
electricity
from
the
plants
is
fed
into
the
excel
energy
power
grid.
Providing
enough
electricity
for
over
8
000
homes,
hydro
hydropower
is
a
natural
fit
for
boulder.
Most
of
the
pipelines
used
to
transport
water
to
the
city
were
already
in
place.
A
It's
also
a
renewable
resource
that
is
replenished
each
year
by
mountain
snowfall
through
the
natural
hydrologic
cycle.
Boulder's
hydro
plants
also
generate
revenue
through
the
sale
of
electricity
to
excel
energy.
This
revenue
is
enough
to
pay
for
the
hydro
equipment
and
its
operating
and
maintenance
costs.
The
revenue
also
means
reduced
water
rates
for
the
city's
water
customers.
A
Hydroelectric
turbines
convert
the
energy
of
flowing
water
into
rotating
mechanical
energy,
which
then
turns
a
generator.
The
generators
use
rotors
and
stators
to
create
an
electrical
field
when
turned
by
the
turbine
boulder's.
Eight
hydro
plants
use
two
types
of
turbines,
depending
on
both
the
inflow
and
discharge.
Conditions
of
the
water.
Pelton
turbines
are
used
on
the
city's
untreated
pipelines
above
the
water
treatment
plant,
where
the
incoming
water
has
a
high
pressure
head
and
drops
more
than
800
feet.
A
Pelton
turbines
remove
all
the
pressure
from
the
water,
so
they
are
also
used
where
no
residual
pressure
is
needed
in
the
outflowing
water
at
locations
within
the
city's
treated
water
system.
Francis
turbines
are
used
at
these
plants.
The
incoming
water
has
a
medium
pressure
head
between
100
and
800
feet.
The
outflowing
water
must
have
enough
pressure
after
the
turbine
has
been
turned
to
ensure
water
delivery
to
customers,
four
of
boulder's
hydros
use,
pelton
turbines
and
four
other
plants
use
the
francis
design.
A
Pelting
turbines
are
very
compact
in
size
for
the
power
output.
The
water
flow
is
controlled
by
needle
valves
which
direct
water
into
buckets
on
a
runner.
The
water
hits
the
center
of
each
bucket
on
a
flow
splitter,
so
there
is
equal
force
on
both
sides
of
the
buckets
after
the
water
has
turned
the
runner
and
has
no
remaining
pressure.
Gravity
carries
it
out
of
the
buckets
and
into
an
open
area
called
a
tail
race.
A
A
draft
tube
in
the
center
of
the
francis
turbine
collects
water
that
is
at
a
lower
pressure
than
the
water
entering
the
runner
and
transports
it
into
a
downstream
pressurized
pipe,
which
then
delivers
water
to
boulder
users.
The
francis
turbine
is
somewhat
similar
to
a
centrifugal
pump.
In
fact,
at
two
of
boulder's
hydros
that
have
francis
turbines,
water
flow
can
be
reversed
in
direction
to
use
the
facilities
as
pumping
stations
when
pipe
pressure
drops
upstream.
A
Boulder's
hydro
plants
use
relatively
simple
mechanical,
but
complicated
electrical
and
control
equipment.
Each
hydro
station
has
local
and
remote
control
that
can
start
and
stop
the
units
on
command
or
when
abnormal
conditions
arise.
Boulder
has
installed
an
extensive
fiber
optic
and
radio
communication
network
which
connects
all
of
the
facilities.