All language subtitles for Impossible Engineering s02e04 Worlds Most Powerful Dam.eng

Today on
"Impossible engineering,"

the Three gorges dam,

the largest hydroelectric
power station in the world.

Generating 11 times more power
than the Hoover dam.

Just listen to that.

That is the sound
of huge quantities of water.

It took
revolutionary engineering...

Each one of these turbines
can, in a day,

produce enough power
to power over 16,000 TV sets.

...To make
the impossible...

Possible.

Captions by vitac
www.Vitac.Com

captions paid for by
Discovery communications

China, the world's
most populous country.

At 1.3 billion people
and rising,

the country's infrastructure
is under immense pressure.

Living in downtown
Shanghai, it's so easy to see

how much energy is consumed
on a daily basis.

In this city alone, population
has grown to 24 million people.

China relies heavily
on coal for energy.

The country consumes
almost as much coal

as the rest of the world
combined.

China needs
a more sustainable way

to keep the lights on.

??

Their solution --
the Three gorges dam,

the largest
hydroelectric power station

in the world.

It's over 7,500 feet long,

that's 21 football fields,

and holds back
a 400-square-mile reservoir.

The area is prone
to catastrophic floods.

To lessen the possibility
of flood damage

and to create
a source of clean power,

engineers have dreamed
of building a dam like this

for the last hundred years.

After decades of work,
the dam is almost finished.

For deputy director
of construction technology,

Mr. Qihua Ding,

it's the project of a lifetime.

Construction began on
the Three gorges dam in 1994.

Getting the build right
is a matter of life and death

for the millions of people

who live along
the Yangtze river.

With millions of tons of water
pushing against the wall,

the residents downstream

are really depending
on this wall to stay up.

Any imperfections

and the consequences
could be catastrophic.

A concrete structure
of this magnitude

would be impossible
without one of America's

greatest
engineering achievements.

In the early 20th century,
the parched American southwest

was desperate
for water and power.

An epic engineering
solution was needed.

And professor
of civil engineering

Andrew Smith is getting
a bird's-eye view of it.

Wow.

This is the Hoover dam.

At the time of its construction,

this was the world's
largest concrete structure

that had ever been built.

Even today,
roughly 80 years later,

it takes your breath away.

The Hoover dam is like
nothing built before it.

Weighing in at
6.6 million tons of concrete,

this was an unparalleled
engineering marvel.

The dam harnesses the power

locked within
the mighty Colorado river.

The dam stands 700 feet tall

and has a base thickness
of 660 feet.

The biggest problem

and the biggest challenge
was one of sheer scale.

The extreme heat
in the southwest

makes building a structure
as big as the Hoover dam

extremely difficult.

So, what i have here
is cement as well as water.

And these are really
the two main active ingredients

in the curing process.

Now before it really
starts to cure,

let's quickly
check the temperature.

Before i dipped it
into the concrete,

the thermometer was already
reaDing 44 degrees celsius,

gives you an idea
of how hot it is here.

It takes just half an hour
for the temperature of the mix

to reach its peak
at 155 degrees Fahrenheit.

So, that's an increase
from our original temperature

of 24 degrees celsius.

And you could really,
really feel the heat.

If they poured all
of the Hoover dam's concrete

in one go,
it would take 125 years

for it to cool and cure,
meaning uneven setting

and potentially
catastrophic cracking.

Hoover dam project supervisor,

Frank Crowe, came up
with an ingenious solution,

one that can still be seen
deep within

the old inspection tunnels
running through the dam.

So Frank Crowe, nickname here
on the site, "Hurry up" Crowe,

came up with an ingenious method

for cooling the concrete
to help it cure faster.

The solution was to pass
extremely cold water

through one-inch pipes.

The amazing thing is we can
actually still see evidence

of those pipes here.

In 1931, thousands of workers
began building the Hoover dam

using gigantic blocks,
cooling the concrete

with ice water produced
by a refrigeration plant.

It worked perfectly.

The whole job was finished
two years ahead of schedule.

This record-breaking dam

created a record-breaking
body of water behind it.

This is lake mead.

When the dam was erected,

it became the world's
largest man-made lake.

At full capacity, they say
the volume of water

could cover
the state of Connecticut

with 10 feet of water.

As an engineer, this is
an incredible sight to see.

Over 80 years later,
the Hoover dam

still provides electricity
to three states.

The Three gorges dam
is five times bigger

and generates an incredible
11 times more power

than the Hoover dam.

building it requires

almost a billion cubic feet
of concrete.

In 1998, pouring begins.

To accelerate the curing process

and reduce
the risks of cracking,

engineers take techniques
pioneered at the Hoover dam

to a whole new level.

The ingredients are air cooled
before they're mixed.

High-speed conveyors take
the concrete from mixing zone

to site in just 15 minutes.

Workers pour an average
of 700,000 cubic feet every day.

Water cooling is supplemented

with a mist sprayed over
the working area

to reduce the effects
of the hot summer weather.

It takes eight years
to pour all the concrete.

The concrete is in place,

but the massive
Three gorges dam now blocks

one of China's
most vital shipping routes.

The river is the lifeblood

for the thousands of people
who live along it.

To get ships
past the dam,

engineers use a solution that
dates back to medieval times.

??

At nearly
a mile and a half long,

China's Three gorges dam
is one of the most

ambitious engineering projects
ever attempted.

This massive structure harnesses

the clean
hydroelectricity potential

of China's largest river,
the Yangtze.

The Yangtze river
is the third largest

and longest in the world.

And the river
is now the lifeblood

for the thousands of people
who live along it.

Blocking this busy
waterway with a giant dam

is simply not an option.

To get the ships through,

the three gorges team
are employing a technique

that dates back
to medieval times.

The lock is almost a mile long.

It raises and lowers
river traffic 370 feet

through five giant steps.

But there's a catch.

Taking four hours
to pass through the locks

is simply too slow for most
ships traveling down the river.

So Mr. Ding
and his fellow engineers

need to come up
with a solution fast.

In 1870, designer Edwin Clark
was asked to solve

a particularly tricky problem

facing the small village
of Anderton

in the north of England,

one that's familiar
to the engineers

at the Three gorges dam
in China.

He was asked to link
the busy Trent and Mersey canal

with the adjacent Weaver river

to speed up journey times

for barges carrying valuable
commercial cargos of salt.

This was a pretty stiff
challenge for Clark

in the late 1800s because
the height between the canal

and the river was about 50 feet.

Transferring the salt
from the canal to the river

was time consuming, laborious,
and it was really slow.

So Clark had to come up
with an ingenious solution.

??

Almost
a century and a half later,

Dr. Rhys Morgan
is visiting that solution.

Known as the iron spider,

the Anderton is the oldest
operating boat lift

in the world.

It's extraordinary.

It's a three-story-high marvel
of victorian engineering.

It's just fabulous.

Clark's creation
scoops up barges

and the water
they're floating in,

transferring them
in one smooth action.

He used what was, at the time,
a cutting edge technology,

technology that would inspire
future builders

all over the world,

including the engineers

at the gargantuan
Three gorges dam.

??

The Three gorges dam

is the largest
hydroelectric power station

on the planet.

It's also a major obstacle
for boat traffic

trying to navigate up and down
one of China's busiest rivers.

The three gorges engineering
team needs to figure out a way

to speed up travel time
for ships passing through.

Dr. Rhys Morgan is in
the small village of Anderton

in the north of England,
where 150 years ago,

designer Edwin Clark came up
with an ingenious solution

for a problem very similar
to that facing the three gorges.

It's a three-story-high marvel
of victorian engineering.

It's just fabulous.

Clark's creation
scoops up barges and the water

they are floating in,

transferring them
in one smooth action.

It does this using
what was, at the time,

revolutionary technology.

The basic principles
of all hydraulic systems

are defined by a law
which was created

by a French mathematician
called Blaise Pascal.

And it goes something like this.

If you apply a pressure
on a liquid in a closed system,

then that pressure
is distributed

throughout the whole liquid
in the system.

And Edwin Clark
used this to great effect

with his boat lift at Anderton.

He started off by making
two watertight caissons.

These are the tanks
which held the boats

and the water
in which they floated.

And he supported those caissons
on top of two hydraulic rams,

and there was a liquid
in those rams

and a pipe
joining them both together.

So as i exert
some additional force

to this hydraulic ram,

i can start to see

that the pressure
is being pushed through

the adjoining pipe and lifting
up my other hydraulic ram.

It's brilliant.

Edwin Clark's design
is genius in it's simplicity.

The two caissons
are perfectly balanced,

so all that's required
to push the upper caisson down,

which in turn
lifts the lower caisson,

is an extra two inches of water.

The result,
an effortless rise and drop

for up to four boats
simultaneously.

And most importantly,
the journey time

took less than half an hour.

And that saved
huge amounts of time

and enabled the trade
to be much quicker.

It's just a fabulous piece
of engineering.

It's wonderful to be here.

Edwin Clark proved
that raising and lowering boats

could be done quickly
and efficiently,

inspiring engineers
around the world.

At the Three gorges dam,
designers are building

a ship lift similar to
Edwin Clark's,

but on an epic scale.

Engineer Yewande Akinola is
getting a chance to ride on it

while it's still
under construction.

It's the weirdest
sensation. It's really insane.

It feels like I'm in a big,
massive swimming pool,

and I'm being pulled up

or in a lift
with a massive pool in it,

being lifted up.

It's an engineering feat,
a beauty in so many ways.

And super impressive.

The Three gorges ship lift

can carry
a 3,000-ton passenger liner.

Reinforced concrete towers

support the lift's
433-foot steel pool.

Instead of hydraulics,

the lift uses massive
counterweights and pulleys

to raise the pool and vessels
floating in it

a vertical distance of 370 feet.

This world record-breaking lift
allows ships

to pass through the dam
quickly and easily.

To keep passengers
happy, when this is complete,

it will take
only 30 to 40 minutes

of travel time
from top to bottom.

Now this is
a brilliant solution.

Behind the Three gorges dam

is almost 400 square miles
of water.

Over the last 200 years,

there have been
over 200 catastrophic floods,

which have cost
over 300,000 people their lives.

To tame the mighty Yangtze,

engineers will need even more
impossible engineering.

??

The massive
Three gorges dam in China.

Stretching nearly
a mile and a half

across the Yangtze river,

it holds back an almost
400-square-mile reservoir.

Every 10 years or so,

the Yangtze river
floods quite seriously.

In fact, over the last
200 years,

there have been
over 200 catastrophic floods,

which, unfortunately, have cost
over 300,000 people their lives.

Dams control the effects
of excessive rainfall,

but extreme floodwaters
can cause a dam to collapse

with catastrophic consequences.

An engineers greatest fear
is toe scour,

when water spills
over the top of the dam

and wears it's foundations away.

Now, if we imagine
a flood situation

where we have lots and lots
and lots of water

flowing over this dam,

we've got all that water
hitting the bottom of the dam.

As we can see here,
the integrity of the dam

becomes very questionable
and it starts to collapse.

Oh, there it goes.

The consequences of
a dam failing on

the Yangtze river
are almost unimaginable,

something that the builders
of the three gorges

will not leave to chance.

??

This is an amazing
but quite terrifying experience.

Dr. Rhys Morgan is
getting up close and personal

with the mighty Mar�ges dam,
a 1930s engineering marvel

that laid the groundwork

for the Three gorges
engineering team.

I'm here
with this huge dam behind me,

and I'm stood next door
to this overflow channel.

And luckily for me today,
the gates aren't open.

Because if the reservoir
was too high,

the water was overflowing,
then the gates would be opened

and some 700 cubic meters
per second of water

would be gushing out,
flowing down this spillway.

And I'd probably be blown away
just by stanDing here.

The Mar�ges dam
is almost 300 feet tall.

Its builders feared
that if there was a flood,

water would overtake the dam
and thunder down to its base,

eventually leading
to a collapse.

Engineer Andr� Coyne
had an ingenious idea.

His solution lies
halfway down the gorge.

This is a ski jump spillway,

so called because it has
a lip at the bottom,

just like a ski jump.

And the ski jump prevents
that water carrying

all the way down
to the base of the dam,

where it can seriously erode
the foundations.

Instead of carrying on all
the way to the base of the dam,

it gets flicked into the air,

and all that water
turns into droplets

as it's mixed with the air,
and the energy is dissipated.

??

The Mar�ges dam holds back

over a billion cubic feet
of water.

Its director of engineering
knows just how important

Coyne's ski jump is.

The ski jump spillway
is necessary

for the water to be transferred
from upstream to downstream.

Otherwise, the water would
over top and overflow

the crest of the dam

and then impact
the toe of the dam,

which would undermine
the foundation

and generate
the total collapse of the dam.

Andre Coyne's innovation
was a major milestone

in dam engineering,
and his ingenuity and foresight

opened up a whole new world
of possibility

for dam engineers.

Coyne changed the way
dams were designed forever.

??

The colossal Three gorges dam

uses 46 ski jump spillways.

When reservoir levels rise
and water needs to be released,

the spillways launch
the floodwaters 300 feet,

far from the dam's foundations.

For deputy director
of construction technology,

Mr. Qihua Ding, the design
is more than practical.

When the spillways
are in full flow,

it's easy to see
how the Three gorges dam

has the potential to be
a hydroelectricity superpower.

So, how do engineers harness
the power of the Yangtze river

to make the Three gorges dam

the most productive
hydroelectric power station

on Earth?

??

The Three gorges dam
on China's Yangtze river

is the largest in the world.

It holds back a nearly
400-square-mile reservoir

and has spillways capable
of discharging

3.8 million cubic feet of water
every second.

But how do engineers harness
all that moving water

into much needed
hydroelectric power?

Ancient miners first built dams
to collect water,

then release the wave
to scour the land.

In the middle ages,
islamic engineer al-jazari

designed a number of ingenious
water powered devices,

from irrigation systems
to clocks.

But it was
the industrial revolution

that really took hydropower
to the next level.

It was 1834 when British
born engineer James b. Francis

eeringin the busy textile town
of Lowell, Massachusetts.

At the time James Francis
arrived here in lowell,

massive mills like this one
were sprouting up

all along the vast canal system.

The mill complex
ultimately would produce

up to 160 miles of cloth
every day.

But the power began to run out.

As the textile industry's
thirst for energy grew,

the water in the canals
became more valuable.

James Francis was asked

to squeeze as much power
as possible out of every drop.

The problem was that the mills
here in lowell

were being driven
by simple water wheel systems.

These are relatively
inefficient.

They're driven by water
falling into the buckets

to make them turn,

only using a portion
of the energy available

here in the canal system.

What Francis designed
changed the world forever.

His original invention
can still be found

deep within
lowell's canal complex.

Wow.

So this is it.

This is the site of the very
first James Francis turbine.

It's amazing to think
that this turbine, right here,

started
the hydropower revolution.

James Francis
took the idea of a waterwheel

and turned it on it's side.

He enclosed the turbine,

so water was in constant contact
with the wheel.

He added a series of vanes

to direct the water
at the optimum angle.

So, here we have
a deconstructed Francis turbine.

This was actually
one of the last turbines

installed here in lowell,
and we can see how it works.

So you can imagine the water
would be guided in

with directed vanes, then would
hit these runner blades,

and then if you watch here
what happens,

so as the water
strikes the runner blades,

it drops down and comes
all the way out down below here.

The sum total
of all those enhancements

lead to nearly 90% efficiencies
of the turbine.

It was so successful
that, even today,

the Francis turbine is still
the world's most used design.

Francis was a brilliant engineer

who made a massive contribution
to the industrial revolution.

??

The Three gorges dam

is the biggest hydroelectric
project of all time.

So it's fitting

that it should use the world's
largest Francis turbines.

This is one of
the two turbine buildings.

And just listen to that.

That is the sound
of huge quantities of water

traveling at up to
80 miles per hour,

turning the 32 largest-ever
Francis turbines built.

Installing the giant turbines

was an engineering feat
in its own right.

Each turbine weights 450 tons.

The crane needed
to install them is so large

it had to be factored in
to the design of the dam.

These 450-ton turbines

can generate
the equivalent electricity

of 25 million tons of crude oil

and, wait for it,

50 million tons of coal.

Water enters
through a series of huge inlets

and falls 260 feet
towards the Francis turbines.

With a flow rate of up to
33,000 cubic feet a second,

each turbine rotates
at 75 revolutions a minute,

driving the generator above.

Each one of these turbines
can, in a day,

produce enough power
to power over 16,000 TV sets.

I think that is just amazing,
really cool.

But generating hydroelectricity

is only one part
of the challenge.

Sending vast amounts of energy
huge distances

with minimal losses

is a seemingly
impossible challenge.

??

In 1994, work began
on one of the most

ambitious engineering projects
of all time,

China's colossal
Three gorges dam.

It's designed
to combat catastrophic floods

and produce vast amounts
of much needed clean energy.

The potential for China is huge,

but the dam's location,
600 miles away from Shanghai,

presents a seemingly
impossible challenge.

Engineers needed a system
that would deliver that energy

huge distances
with minimum losses.

And they wouldn't
be able to do it

without one of history's
most extraordinary inventors.

??

In the 19th century,
distributing electricity

was a huge challenge.

But that changed after engineers
tapped into one of the world's

most awe-inspiring
natural phenomena.

Here at Niagara Falls,

150,000 gallons per second
pours over the top.

Four of the five Great Lakes
of north America

empty into the niagara river

and pour over the top
of these falls

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