Original subtitles

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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