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00:00I'm in the Austrian Alps, driving one of the country's greatest exports.
00:10The Porsche 356 has its origins just down the road from here.
00:14It's one of my all-time favourite cars, and this is the first time I've ever driven one.
00:21But this series is all about the world of being.
00:24And this episode isn't about what I'm driving in.
00:27It's what I'm driving on.
00:30This is the Columbrine Dam, one of the biggest dams in the world.
00:44And it can use this huge reservoir of water to generate enough electricity to power an entire city for a week.
00:53How do you make a wall big enough and strong enough to hold back 200 million tonnes of water?
01:03And how do you use that water to power hundreds of thousands of homes in an instant?
01:10Here I go.
01:12I'm Richard Hammond.
01:13Hello.
01:14Hello.
01:15And I'm on a mission to explore the really, really big.
01:19Awesome!
01:20Top ten list of insane things I've ever been involved in doing.
01:23This is number one.
01:25And yes, I know, everything seems big to me.
01:28Am I climbing into an engine?
01:29I feel like I've been shrunk.
01:31I'll uncover the incredible ways engineers have supersized our world.
01:36Well, I'm sure it's supposed to be this close.
01:38Oh!
01:39I looked over my shoulder.
01:40I shouldn't have done that.
01:42Reveal that sometimes it's the tiny things that make the Titanic possible.
01:47Stealing their power!
01:50I could not do this for a job.
01:53And meet the heroes who design, build and live big.
01:59If I do it wrong, are we all blown to pieces?
02:02Maybe.
02:13I'm standing on top of one of the biggest walls on the planet.
02:17It's 200 metres high.
02:19That's the same as 63 London buses on top of one another.
02:23Two big bends.
02:24Two statues of liberty.
02:26125 horses.
02:282,099 Big Macs.
02:31111 clubs.
02:33You get what I mean.
02:34It's really big.
02:35And I'm stalling for time.
02:37Because I'm pretending not to be scared.
02:39I've done it again!
02:41Big sometimes also means high, Hammond.
02:45And this is really high.
02:49And I'm not good at high.
02:53And down here.
02:54Oh!
02:55Yeah, that is really high up.
02:58But all the time behind me, just here, that's the wall.
03:02200 million tonnes of water there.
03:05A huge battery cell of potential energy.
03:11This isn't just a story about a big wall.
03:14This is a story about how humankind has re-engineered nature on an epic scale.
03:20Using it to power the modern world by turning water into electricity.
03:25I mean, this is really, really big.
03:29In fact, the dam is so big, the only way for me to get a sense of the size of this modern wonder, and how it fits into the landscape, is from above.
03:43Hello!
03:47That is a powerful lift.
03:53The director left his stomach up there.
03:54My pilot is Peter Hohenberger.
03:56He's been flying rescue missions in these mountains for the last 16 years, and knows this part of the Alps like the back of his casually heroic hand.
04:06Oh, that is absolutely glorious.
04:09What a way to see it.
04:11You do get a sense of scale up here.
04:13You can also see why they chose this exact location in the Alps to build the dam.
04:20Engineers had to pick a spot where there was plenty of rain and snowfall to add to the water in a reservoir.
04:28But then they needed a big, deep valley to make a big, deep reservoir.
04:32They had to hold enough water to make it worthwhile.
04:35Not only that, it had to have ideally a narrow opening, a single gap that they could span with a single dam to contain that water.
04:44He's not looking where he's going at all.
04:45It's just not paying attention.
04:46I mean, something could have come the other way, a bird or something, or another mountain.
04:51Okay, now we go lower.
05:01You really get a sense of all that weight, that potential energy just being held back, waiting here to get on with his job and make power.
05:16It looks so thin, and it is.
05:19For its height, this is the thinnest in the world.
05:21That's about as thin as you could possibly make a dam that big.
05:25You're welcome.
05:27The spectacle, the scale and the forces involved are no doubt appreciated by the dam's chief engineer, who I'm on my way to meet.
05:31I've just got to work out how to get my new toy off his wall.
05:38Right.
05:39I don't think I'll turn this round here.
05:40I didn't think this through.
05:41I'm going to have to...
05:42I'll reverse.
05:43Reversing.
05:44Sorry.
05:45Coming through.
05:46I think it's up here.
05:47I think it's up here.
05:48Luckily for me, it's up here.
05:49Luckily for me, the office is right here.
05:50It's up here.
05:51It's up here.
05:52Luckily for me, the office is right here.
05:53It's up here.
05:54It's up here.
05:55It's up here.
05:56It's up here.
05:57Yeah.
05:58It's up here.
05:59It's up here.
06:00I don't think I'll turn this round here.
06:01I don't think I'll turn this round here.
06:02I didn't think this through.
06:03I'm going to have to...
06:04I'll reverse.
06:05I'll reverse.
06:06Reversing.
06:07Sorry.
06:08Coming through.
06:09I think it's up here.
06:12I think it's up here.
06:13Luckily for me, the office is right next to the dam.
06:17It was originally built as a base for the engineers in the 1970s, to whittles the
06:25stand the extreme alpine blizzards.
06:35But inside, it's not quite what I was expecting.
06:38Today, the dam attracts so many visitors, they've turned the office into a hotel.
06:49Wasn't me.
06:53Wasn't me.
06:54Chief Engineer Roman Kerler has spent a lifetime building some of the biggest dams in the world.
07:00Hi, you're Roman.
07:01Hello.
07:02Welcome to our world.
07:03Right.
07:04It's there.
07:05I want to know what's so special about this one.
07:08Roman, so, because you've built dams all over the world.
07:12A few countries, in Turkey, in Bulgaria, in Iran.
07:15You know this dam probably more intimately than anybody else.
07:18It looks so delicate.
07:19It looks...
07:20It doesn't look like everything.
07:22It's relying on its shape.
07:24This shape of it then, this curve.
07:26It's like an arch.
07:27If you turn it by 90 degree, it looks like that.
07:30The dam's arch shape means the force of the water on the wall is transferred into the mountains on either side.
07:40So it actually uses the power of the water behind it to secure itself into the valley.
07:46It does this so well, they were able to make it very thin, using far less concrete in the process.
07:52So the load on it, and from here, you can see that amount of water is pushing against that.
07:58Exactly, yeah.
07:59It's straining to hold its back.
08:01It's pushing into the mountain.
08:03But the Columbine dam is not just curved in one direction, it's curved in two, horizontally and vertically,
08:10transferring the force of the water not only to the mountains at the sides, but also into the ground.
08:17The forces exerted on the wall are so immense, Roman and his team must monitor them constantly, 24-7.
08:25And today, I'm going to join them.
08:28Hello, Richard, come in. This is our office.
08:30Very nice.
08:31We have a lot of measuring devices here.
08:33The dam is moving when the water rises, the dam is moving when it gets hotter or colder.
08:38So we're going to measure how much it's moving?
08:40Yes, we will measure how much it's moving, how much water is coming into the dam.
08:44Yeah.
08:45We will carry all the devices for us, so you get a special jacket.
08:49Right.
08:51Am I being set up here at all? So I wear this.
08:54Oh, wait a minute, it's an enormous dam.
08:57And that's somehow relevant?
08:59Yeah, but that's very accurate.
09:01Put that where it goes on my special magical jacket.
09:03I mean, I like kit as much as the next chap, but...
09:06This one in this pocket.
09:08Wait, why am I the pack horse?
09:10Because you have no experience. We work with our head and you work with...
09:14The masters.
09:15Yeah.
09:16So let's go.
09:17Okay, after you.
09:18Yeah.
09:19Lead the way, I don't work with your head, I'll just carry stuff.
09:21We're going in the dam.
09:22Well, inside the wall.
09:28Oh, we're going to the underground.
09:29What, in this lift?
09:31In this lift, yes.
09:32So it's just the hotel lift, but it goes, oh, secret floors.
09:36Secret floors, yeah.
09:37Yeah.
09:38So we're going to the lower reception and just keep going down?
09:39Yeah.
09:40Cool.
09:43Hello, ladies.
09:44Hi.
09:45Morning, ladies.
09:46Hi.
09:47Come in.
09:48I think one has to step from the other side.
09:50No, it'll be all right.
09:51We'll step around.
09:52This is awkward.
09:53No.
09:54What are you doing here?
09:56Just engineering stuff.
09:58We're going for the secret floors.
10:01Different day.
10:02This is awkward.
10:04Bye, have a nice day.
10:05Bye.
10:06Have a nice day.
10:07Have a nice day, ladies.
10:13How deep is this?
10:1530, 40 meters.
10:16Oh, wow.
10:18Next, I get to witness the unimaginable power of the water behind the dam.
10:24Oh, look.
10:25It's denting it.
10:26And I'm forced to face my fear of heights.
10:29Again.
10:30Oh, we're not in the hotel now, are we?
10:31That is different.
10:32I'm with engineer Roman Kerler.
10:33Actually inside the giant columbrine dam.
10:35One of the biggest in the world.
10:37Not only is it hollow, turns out it's also an enormous maze with two miles of tunnels.
10:42Roman's asked me to help out with some vital inspections.
10:43I think he actually trusts me.
10:44And what are we doing now?
10:45We're measuring the opening of this block of China.
10:47So this is the gap between two of these massive concrete blocks that make up the dam.
10:52The dam weighs 4 million tons and is made up of 30 columns called blocks, each one 20 meters
11:17wide and up to 200 meters high.
11:20And they move as the water level, and therefore the pressure on the wall, changes.
11:26Measuring these gaps between the blocks, known as block joints, is just one of 300 different measurements
11:32that must be taken every day and compared with previous readings.
11:37So that's 155.32.
11:41158.91.
11:43The dam's collapsing.
11:44Get out.
11:45Save yourselves.
11:46No.
11:47But it means the dam's moved.
11:49Yes.
11:50A little bit.
11:51But you don't seem alarmed.
11:52No.
11:53This is the measurement we've done in May, so four months ago.
11:55Oh, yeah.
11:56Where there was a very low water level and the block joint was opened.
11:59And now it's closed.
12:00If the dam moves to the upstream, these gaps are opening.
12:04And if the water increases, the dam is moving to the downstream and the gap is closing.
12:08So you're not worried that they do move a bit?
12:11No.
12:12The dam is breathing.
12:13Not collapsing?
12:14No.
12:15Doing what you expect?
12:16Yes.
12:17Breathing?
12:18Yeah.
12:19So the force behind the dam is enormous enough to move the concrete blocks that make it up.
12:26And to show what else this massive weight of water can do, I'm heading to a meeting with some ninjas in the middle of the reservoir.
12:34Right, the power of water.
12:39I've set up a frankly brilliant, if perhaps overly elaborate, demonstration of something we probably all know, but it's unlikely we've ever actually seen in action.
12:49I'm going to use this magnificent rig and the help of my terrifying systems over there.
12:56So, barrel, lowerable platform, cameras so we can see what happens to it.
13:00If we're all ready, members of the Austrian special forces that we seem to have recruited, can we please lower the barrel into the water?
13:08Well, of course.
13:09As the barrel goes deeper, there's more water above it, and a greater weight pushing down on it, so the pressure on that barrel increases as it descends.
13:23Oh, 1.3 metres, 1.6 metres, 1.9, 2.1 metres.
13:29Oh, whoa!
13:30Whoa, we've already gone!
13:31It's already...
13:32It's denting it!
13:33This is just...
13:35Just water pressure doing this.
13:37We're only at a few metres, and it's already squashing it.
13:40That's a 60-litre metal oil drum being squashed and deformed at just a few metres of water.
13:47As we pass 5.5 metres, it's bending wildly out of shape.
13:52Any messages from the Royal Society for the Protection of Barrels, you can email at don'tberidiculous.com.
14:02And this is at a fraction of the depth at the very bottom of this reservoir.
14:08All that force acting outward on that thin dam wall.
14:14The water in this reservoir is 190 metres deep.
14:22That means a total pressure on the wall equivalent to one million jumbo jets at full throttle, all pushing on the dam at the same time.
14:33And Roman has agreed to show me the one place in this dam that's under more pressure than anywhere else.
14:39So now we'll take you deeper into the dam.
14:42Deeper into the dam?
14:43Yes.
14:44How far down do we get?
14:45To the very bottom of the dam.
14:46Really?
14:47Yes.
14:48Alright, I'm interested.
14:49The dam is so big, getting to the bottom means climbing down 800 steps.
14:54Very steep steps.
14:56This would be a long fall.
14:58Oh, I can see water coming out of the wall down there.
15:09I don't want to be rude about your dam, mate, but it's leaking really badly.
15:14Is this not bad news?
15:16It's working perfectly.
15:17It's all about uplift pressure.
15:20Uplift pressure happens at the base of the dam, where water pressure is the highest.
15:25Water from the reservoir is forced down into the bedrock and then pushes up on the dam from below.
15:32Why is upwards pressure such a problem?
15:36Because it would heave the dam.
15:37With enough pressure, it could lift the dam itself.
15:40Yeah, but we have to relieve it.
15:41Yeah.
15:42We release the water and you see that you relieve the pressure very fast.
15:48So if we open it totally, you see...
15:51So it's only a dribble of water creating that pressure.
15:53It's not a lot.
15:54Yeah, the small amount of water causes the uplift pressure.
15:57Is that now open to what was...
15:59So that water is...
16:00Has that bit of water there come from there?
16:03Yes, it comes from there.
16:04And this small amount of water is coming under the dam.
16:07Yes, under the dam.
16:08So if it lifts it, could it...
16:11If it's too high, the uplift pressure, but it isn't.
16:15The reason it doesn't topple over is down to, well, taps.
16:19600 of them positioned throughout the base of the dam.
16:22Right.
16:24So I should be glad that it's leaking.
16:26Yes.
16:27I can demonstrate this uplift.
16:29Thankfully, I've remembered to bring a bit of wood, some marbles and a Tupperware box with a hole in it.
16:34Uplift pressure.
16:36The ability of water to lift millions of tonnes of dam off the ground and destabilise it.
16:41I have a demonstration here.
16:43This is my dam.
16:44This behind it is the reservoir and these marbles are the water.
16:48Some of which...
16:50Some of which has gone where I wanted it.
16:51Right, let's stack that in there.
16:53So that is the dam holding back the water.
16:56That's how it works.
16:57Now, immense pressure because of the height of that water.
17:00If some of that water, just a little tiny bit of it, as the dam heaves forwards under that pressure,
17:05gets underneath the dam and pops up, it destabilises it.
17:12It's as simple as that.
17:14To keep the dam stable, not only do Roman and his team of engineers need to relieve uplift pressure,
17:20they also have to check that the structure's connection to the mountain is rock solid.
17:27And that's what I'm going to look at next.
17:29I've got to go and meet a man called Thomas, who is, well, as well as working at the dam, he's a very keen mountain climber.
17:36So he skips about this place like a mountain goat.
17:39I've got to meet him down there in some sort of cave.
17:42And he's arranged for me as a special treat, the opportunity to abseil down there.
17:51It's the kind of thing he loves doing.
17:53So he's set up ropes, people to help me, everything I need.
17:56But, I mean, I think he's misunderstood the meaning of the word, treat.
18:03Really?
18:05That's not a treat.
18:08I mean, this is...
18:09Your helmet's on.
18:10Definitely.
18:11Helmet.
18:12What difference is that going to make?
18:19There we go.
18:20Too tight.
18:21Oh, I'm faint.
18:22Oh, I'm going.
18:24Okay.
18:25That's you ready to go.
18:27Oh, God.
18:30This is going against everything in my head.
18:35Yep.
18:36Yep.
18:37I'm not looking down.
18:38I'm not looking.
18:41Oh, good God.
18:51Oh, I can't keep this up.
18:52That's not actually me.
18:54I, well, I bottled it.
18:56I really, really don't like heights.
18:58It actually went something like this.
19:05Amazing mate, well done.
19:06Oh, that's how comfortable.
19:20Okay.
19:21Okay, let's dive it out.
19:25That was a...
19:26Hello!
19:28Hello!
19:30Hello!
19:31Hello?
19:32Come to me, climb up!
19:34What, are you Thomas?
19:36Do what?
19:38Climb up!
19:40Up there!
19:41Yes!
19:42Hello!
19:43Fear of heights or not, it appeared there was no way of ducking out of this one.
19:48Come to me!
19:50Okay.
19:52Okay.
19:53Oh, this is just stupid.
20:00Hello, Thomas.
20:02Hello.
20:03Hello.
20:05I'm very unhappy, Thomas.
20:09Right.
20:10In you go.
20:12Didn't work.
20:14Totally didn't work.
20:16It's not a day out you're giving to Thomas.
20:19Um.
20:20In the 1950s engineers first dug out a cave here to test the strength of the rock and check
20:29it was strong enough to hold the dam.
20:32So as caves go, this is an important one.
20:35They had to make sure that the rock was the right strength to hold the dam up.
20:39That's how a large dam works.
20:40It relies on the strength of the mountain.
20:42So, they drilled this hole, they lined it with concrete, they put it inside a massive machine
20:46that I've trollingly braced against the side.
20:49And they decided, yeah, the rock is strong enough.
20:52We can build it.
20:53If it hadn't been, that dam as we see it would not be out of there now.
20:59I think I now live in a cave.
21:01Because the alternative is going back down the steps of terror.
21:05Right.
21:06I've got to be devoted to the use of my eyes eventually.
21:09Don't worry.
21:10If I see you in the next scene, I've got help.
21:15After satisfactorily testing the rock on one side of the valley, it then took 800 workers,
21:21six years and nearly four and a half million tons of concrete to build this enormous structure.
21:27And after all that work and 85 million pounds, they discovered they'd made a colossal mistake.
21:34About 40 years ago, when they finally finished the epic task of building all of this
21:40and started to fill the reservoir behind it, they noticed small leaks appearing.
21:45Not a good moment and probably not a good feeling either.
21:54They investigated it and it turned out that the rocks in the mountain on this side
21:58were slightly stronger, slightly stiffer than the rocks in the mountain on this side,
22:03which meant an imbalance.
22:05And if there's one thing you want in a dam, especially one of this shape
22:09and this record-breakingly thin its symmetry.
22:13They didn't panic and tear it all down.
22:15They thought about it and decided to build a supporting structure.
22:18Think of it as a bit like a second dam right at the base of this one.
22:22And I'm standing on the top of that structure right now.
22:27It might look a bit like your local park, but underneath this grass and these trees,
22:32there's a second dam reinforcing the base of the original wall.
22:36It took a decade to build, cost 140 million pounds,
22:40and you wouldn't even know it was there.
22:45Next.
22:46Please really be careful.
22:48More measuring, obviously.
22:51That's probably bad.
22:53Three, two, one.
22:55And the floodgates open.
22:57Awesome.
22:58I'm in the Austrian Alps at the Colombrine Dam, one of the biggest hydroelectric dams in the world,
23:16to find out how a single wall can hold back hundreds of millions of tons of water.
23:24There are around 60,000 dams worldwide, and when things go wrong, the results can be devastating and even fatal.
23:32Which is why Head of Safety, Eric Wagner, takes his job very seriously.
23:37The responsibility for the safety sits down on your shoulders.
23:41Does it weigh heavy?
23:42The goal we are after is to have such a serious supervision of movement and stresses, strain,
23:51and whatever you find within the concrete, that when things start going bad,
23:57we see it in advance and we have time to make the correct reaction.
24:05To avoid disaster, Eric and his team are constantly monitoring the dam's movements,
24:10taking 300 tiny measurements every day.
24:14One of the most important is to check how much the top of the dam moves,
24:18and it's taken using a very long but surprisingly simple device.
24:24A pendulum.
24:25It's not new, I know. Galileo spotted them in the 1500s, but their application here today is perfect.
24:31I've got this piece of fishing line is attached to the rail on the viewing platform 160 metres above me.
24:37Any movement in that, at the crest of the dam, should be measured down here.
24:42And as I'm using gravity, I've got an absolute.
24:44So you see, I can track its movements with this pen on my piece of graph paper.
24:48I mean, it's a frankly brilliant demonstration of the principle.
24:52I think the problem I'm having here is because of this length of line, the wind is moving at about.
25:00So my pendulum system is pretty basic, and it turns out easily disturbed by wind, and a small television presenter.
25:08But this dam does have a pendulum, which is inside the wall, to protect it from the wind, if not from me.
25:16Because, look, I'm going in there now.
25:18And it is actually one of the most delicate instruments they have.
25:22So, Richard, now we are nearing the famous pendulum chamber.
25:27Yeah.
25:28But this is one of the most sensitive places concerning measurements.
25:32So, please, really be careful.
25:35But go ahead.
25:36Carefully open the door.
25:38It's that sensitive.
25:41Well, that's quite good.
25:42Okay.
25:43If you do it twice, then it's perfect.
25:45Okay, thank you.
25:46Come in.
25:48Walking steadily, not stamping.
25:51I'm guessing don't slam the door.
25:53The pendulum cost 20,000 pounds and can measure even the tiniest movements at the top of the dam without interference from the wind.
26:06It's just a stiff steel wire which goes up 150 meters.
26:11This is one of the main informations if the dam is behaving as we are expecting.
26:16Eric has tasked me with measuring the horizontal movement of the pendulum wire using his high-precision optical instrument, which, he warns me, is also extremely delicate.
26:27One hand here, the other there.
26:29You do know my reputation, Eric.
26:31I'm not entirely reliable.
26:33Okay.
26:34On there like that.
26:36Be very careful.
26:37That's probably bad.
26:40You can take it and fix it on the wire.
26:44Just look through.
26:46Oh, and now inside, there's a graduated scale.
26:49It does.
26:50I move it until the center line is dead center of the wire.
26:53Now, this is measuring down to one one-hundredth of a millimeter.
26:57It's about 95 times thinner than a single strand of human hair.
27:0258.94.
27:05Today, the reservoir is very full.
27:08We have here the reading when the reservoir level was more or less very low.
27:13129.
27:15So it's moving due to the water load.
27:18It's moving downwards.
27:20Oh, because this one will have been taken when the dam was, when the reservoir was empty.
27:25Exactly.
27:26As the reservoir fills and empties over different seasons, the top of the dam moves as much as 14 centimeters.
27:35But if there's too much water and the wall moves too far, the pendulum triggers an alarm, and Eric must take drastic measures.
27:43He'll need to release the pressure of the water on the wall, which is why at the base of the dam is a huge valve, a massive emergency tap.
27:56And today, Eric is putting it to the test.
27:59It only happens twice a year, and apparently it's quite the spectacle, which explains why news crews have gathered to see it.
28:06Oh, wow.
28:07Big stuff.
28:09This looks significant.
28:10This is a big tap.
28:12Wow.
28:13It's more or less the same you find in your kitchen.
28:17Yeah, pretty much.
28:19Little bit larger.
28:20Yeah.
28:21The outlet pipe is the last line of defense to divert disaster.
28:26An enormous relief valve for the dam.
28:33At the end of this long pipe, there's the valve right down there.
28:36That's the one the water ultimately comes out.
28:38At the moment, this is dry.
28:39Water's up to there.
28:40Okay, right.
28:41We better begin the process.
28:46So now we start the filling process.
28:48If water from the dam simply rushed into the main pipe, it would explode under the pressure.
28:53So the first step is to use a smaller pipe to gradually fill the huge chamber.
28:58So that is now filling this huge pipe with water.
29:02And that water, don't forget, is being pushed into here by that huge reservoir out there.
29:09No need to pump it.
29:10I can now hear a different sound starting.
29:13And that's the last of the air in the top of the pipe being shoved out by the water.
29:19There's an escape valve up there.
29:22And you can hear it hissing.
29:25Honestly, it sounds a bit like the plumbing in my house.
29:28If you run a bath, it makes this much noise.
29:31So it's familiar.
29:32And so now this valve is fully open, the last little dribble at the end.
29:47The dam's of an age.
29:49It happens to us all.
29:52190 metres of water pressure right the way through.
29:55So that is now effectively connected to the bottom of the reservoir.
30:00And that down there has just become the final tap.
30:04So now we get to see the effect of that pressure.
30:08We get to see it in action.
30:10The real action starts outside.
30:12Okay.
30:13When all of this pressure is turned into velocity.
30:16Velocity.
30:17Now I have been warned that lots of people come to see this and they are here.
30:20That's quite a crowd.
30:21This is quite an event.
30:22Because that's a really big tap.
30:24Eric, are we ready?
30:26Where do we stand when this happens?
30:28You just stay here.
30:29It's not dangerous.
30:30Ten.
30:31Nine.
30:32Eight.
30:33Seven.
30:34Six.
30:35This is fun.
30:36Five.
30:37Four.
30:38Three.
30:39Two.
30:40One.
30:42It doesn't work.
30:43The tap's stuck.
30:47Oh.
30:51That is the effect of 190 meters of water pressure bearing down on the water at the bottom.
31:08Flooring out.
31:1020,000 liters a second.
31:13Traveling up 50 meters per second.
31:16That's the effect of that pressure turned into velocity and it's awesome.
31:26And a reminder, that's because up there, right up there, that's all water.
31:33That's a solid wall of water 190 meters high.
31:38That's an expression of what's happening at the bottom.
31:42That weight of water exerting that pressure turned into velocity.
31:47And you can now see where it just heads off into the valley.
32:00It'll have cleaned all of that off, won't it?
32:03You'll never have to dust down there.
32:06In a matter of moments, it's built itself on a raging river roaring down that stretch of valley.
32:18And that's it.
32:20The end of an expression of power like I've never seen.
32:25Wow.
32:27Honestly feel like I need to lie down after that.
32:29Next, I follow the water on its epic journey to the power station.
32:34Building its speed, tearing down in those pipes.
32:38Where it's finally turned into electricity.
32:42I'm stealing their power!
32:44Aha!
32:55I'm in the Austrian Alps, exploring the Columbine Dam, one of the biggest in the world.
33:00And I'm hitching another lift from Peter the pilot.
33:03Hello. Hello. How's it going?
33:05I've seen how this massive dam lives, breathes and works to hold back millions of tonnes of water.
33:11But this is a hydroelectric dam.
33:14So now I want to know how it goes about its work, turning that water into electricity.
33:20So, ready for takeoff?
33:21Yep!
33:32The Columbine Dam and the turbine hall below,
33:35that it feeds with water to generate electricity,
33:37can send that electricity across Austria,
33:41even into Germany, Italy.
33:43They've got to think big with the product as well as the project.
33:47The water from the dam courses through huge pipes hidden within the valley,
33:52and it has quite a journey to make.
33:5622 kilometres through several mountains,
34:00dropping a thousand metres in height to a power station at the foot of the valley,
34:03where it's turned into electricity.
34:11And as the water makes that thousand metre drop, it gets faster and faster.
34:17The water now beneath us,
34:20hunking towards the station down there.
34:23That's where it'll be turned into power.
34:25But meanwhile, it's building its speed.
34:28Tearing down in those pipes.
34:30If we haven't seen all that we've seen,
34:33I just think, there's just some pipes.
34:35And now I know they're containing all that energy,
34:38direct and raw, from that reservoir and the dam.
34:42There's something so simple, so elemental about it.
34:45It's just water, and it's about to be turned into power,
34:47that can charge your phone and run your TV right now.
34:53OK.
34:55I'd like to congratulate you, you've passed.
35:01This is the Malta Power Plant,
35:04and it produces electricity for hundreds of thousands of homes.
35:07Very nearly journey's end for the water,
35:1122 kilometres from the dam to here.
35:14The drop has increased the pressure six times over
35:16as it makes this last right turn into the turbine hall,
35:20which is where I'm going now.
35:22Right, how do I get into the turbine hall?
35:25This is where the magic happens.
35:28Four giant turbines harness the raw elemental power of the water,
35:33hurtling down from the dam.
35:34One of the turbines has been shut for maintenance,
35:49so I'm being given a very rare treat,
35:52the chance to climb inside and see its inner workings.
35:56So the water roars in through each of these six nozzles.
36:00Deflect it in front, aim it into the right place to hit it.
36:04Once they hit the buckets, set this wheel spinning, 500 RPM,
36:08sets the shaft spinning,
36:10and from there they create electricity.
36:13Responsibility for keeping the turbine in tip-top condition
36:17lies with Walter Staudacker,
36:19and for today only, me.
36:23This is where it all comes together,
36:25and at this point it suddenly becomes about absolute precision.
36:27The precise design and shape of these buckets
36:31enables them to harness as much as 92% of the energy from the water.
36:36Talk to me about the splitter a bit in the middle.
36:38Yes, the splitter in the middle.
36:39There the jet, the water jet, is cutting into two pieces.
36:44You know, like a knife at home, it had to be sharp,
36:48otherwise you need a lot of force.
36:50So I've got to sharpen the splitter?
36:51Yes.
36:52I've never said that before.
36:53Here, there's no running, that's the grinder.
36:55Put on your eyes, and then you'll start grinding up here.
36:58Here, come.
37:00Oh my God, this is right at the heart of the machine.
37:03All the effort we've seen so far
37:06hangs on what happens there.
37:08There is a very good reason why the buckets on this turbine wheel are this shape.
37:20If you had a single scoop, the water would come in here, hit it, turn the wheel.
37:24That's good.
37:25But then some of it would splash back and hit the bucket behind.
37:28That's inefficient.
37:29This is about controlling how the water gets out as well as how it gets in.
37:33With the splitter in place, water comes in, hits it, pushes the wheel,
37:36but then is sort of scooped straight out in two even streams.
37:40It's efficient.
37:41That's how they get to 92% efficiency here.
37:44The reason this has to be sharp, and why I've just been sharpening it,
37:48I can demonstrate with this.
37:50Here's my bucket, my scoop.
37:51Here is the splitter, nice and sharp.
37:53And here comes my flow of water, fresh from the dam.
37:57And as it hits, the splitter is dividing it between the two sides of the bucket.
38:02And that's not bad, I've lost some ping pong balls, but they've ended up pretty much evenly distributed between the two sides.
38:10Maybe we've got 92% efficiency there.
38:12Right, we can reset and demonstrate how it would work with a less sharpened splitter.
38:17Right, so all I'm doing is turning this over.
38:19It's got a blunt edge, it hasn't been sharp.
38:23Same process.
38:24Switch on, water coming all the way from our dam.
38:27Hitting the bucket at the very end.
38:30And it's a disaster!
38:33Every ping pong ball flying away is more water not being used to push the turbine wheel.
38:39You won't stand a chance of hitting 92 odd percent efficiency.
38:43And now we've got to tidy up their turbine hole.
38:47Sorry.
38:49Above the turbine, where the water hits the buckets, is the generator which creates the electricity.
38:56And they're connected by a massive 25 tonne metal shaft.
39:01Wow!
39:15I'm sitting directly above that turbine beneath me.
39:20It's turning as the water pushes it round.
39:23This is the output shaft.
39:25And that means the turbine has done a very clever thing.
39:28It's turned linear motion of the water moving along into rotary, circular motion.
39:34In the old days, that would be a water wheel.
39:37You'd use this to grind corn or even sharpen knives.
39:41Here, they're using it to make electricity.
39:45And how they do that is pretty simple.
39:47This is in miniature what's happening here.
39:50It's a bicycle dynamo line.
39:51And if I persuade it to come apart, you'll see that when your bicycle wheel turns this shaft on the end.
40:01This shaft on the end of it is a magnet.
40:04Magnets are a funny thing.
40:06Move a magnet around a conductive metal like copper.
40:10And it moves tiny particles inside it.
40:13Electrons.
40:15And moving electrons, that is electricity.
40:17So if I reassemble my little dynamo here, I can see if I can use a bit of their power to make my own.
40:33I'm stealing their power.
40:35Ha ha ha!
40:36So that is water from the dam turning that gigantic turbine to turn both the enormous generator above and my tiny bicycle one here and light this light.
40:49I mean, it would be a lot of trouble to go for if that's all it did.
40:53It's on a bigger scale than this.
40:55And so we come to the final part of the process, getting the freshly made electricity to homes all over Europe.
41:07And this is the control room which makes that happen.
41:09Everything we've seen so far, every drop of water and of sweat, if you like, ends up here.
41:19This is the place where big just got bigger.
41:23The Columbine dam we've been looking at is there on this that charts the whole network.
41:28And as you can see, it's just one remote corner in it.
41:31That's how big this network is.
41:34And the water flows along the pipes, as we've seen, to the turbines.
41:39These are the ones here, one of which I've just been in.
41:42And ultimately, the end product is, they call it, from water to wire.
41:47Because it goes from water, as we've seen, gathered behind dams like the Columbine, along the pipes, down to the turbines.
41:54And then it leaves here on the wire.
41:56And there is the wires.
41:58And it's gone.
42:00Turned into power.
42:07The current generated here passes through these transformers into those wires and from there is distributed.
42:13Some of it into the local grid, some of it over the Alps and beyond, Salzburg, Vienna and even further.
42:20And incredibly, whether for some reason to be a national blackout in Austria,
42:23this site here has the capacity to restart the entire national grid.
42:30It did say water was powerful stuff.
42:38The Columbine Dam is the mother of all batteries.
42:42It doesn't just hold back 200 million tonnes of water, it harnesses it, transforming its raw energy into the electricity that powers a nation.
42:51This dam does big things, but it does them with a sort of grace and elegance.
42:58This beautiful shape, people travel just to look at it, as it moves and breathes and works with the water and with the landscape.
43:05And the team of people beneath my feet right now, tending to its every move.
43:10They too are part of the same vast machine that could still be here hundreds of years from now, generating clean power to make people's lives better.
43:23That really is big.
43:25That really is big.
43:26That really is big.
43:30That really is big.
43:31Do you want everyone to see it?
43:32That really is big.
43:34This is very big.
43:35If you thought Lo Is manage based.
43:54The đến 30th of the Titanic.
43:56Theiously Antoinette