0:00:05 > 0:00:08This is one of the strangest places on Earth.
0:00:09 > 0:00:11CLAP ECHOES
0:00:12 > 0:00:16It's the inside of a vast, sophisticated machine,
0:00:17 > 0:00:21which is driven by an ancient technology.
0:00:21 > 0:00:26It's a tanker with a cargo that can power London for about a week.
0:00:28 > 0:00:34A cargo equivalent to the energy of 55 nuclear bombs.
0:00:36 > 0:00:40This huge ship is carrying liquefied natural gas,
0:00:40 > 0:00:43millions of litres of the stuff.
0:00:43 > 0:00:46At room temperature, it turns into a highly flammable gas.
0:00:46 > 0:00:47That's why people want it.
0:00:49 > 0:00:53The liquid inside these tankers becomes gas for cooking,
0:00:53 > 0:00:54and heating your home.
0:00:54 > 0:00:59Creating the technology to transport it is very complex.
0:00:59 > 0:01:04Yet these ships owe their existence to some surprising connections...
0:01:05 > 0:01:08..kitchen cutlery,
0:01:08 > 0:01:11the father of evolution...
0:01:11 > 0:01:12And there it goes.
0:01:12 > 0:01:15..the world's first steam engine,
0:01:17 > 0:01:20World War II fire engines,
0:01:23 > 0:01:26and air-to-air refuelling.
0:01:46 > 0:01:51Transporting natural gas around the planet is a big business.
0:01:56 > 0:01:59This supertanker is larger than the Titanic
0:01:59 > 0:02:03and is designed to carry natural gas all over the globe.
0:02:07 > 0:02:09She's a big ship, yeah,
0:02:09 > 0:02:12so you know everything about her is going to be super-scale
0:02:12 > 0:02:15but it's only when you get close up do you realise how big.
0:02:19 > 0:02:22Admittedly, I'm not the tallest chap you'll meet,
0:02:22 > 0:02:26but it would make even him feel small.
0:02:26 > 0:02:30The propeller alone is more than five times my height
0:02:30 > 0:02:34and weighs 48 tons.
0:02:34 > 0:02:37The whole ship is nearly 300 metres long.
0:02:37 > 0:02:41about two-and-a-half football pitches.
0:02:41 > 0:02:44And it takes a lot of looking after.
0:02:45 > 0:02:49Every time she comes in to dry dock like this she's repainted.
0:02:49 > 0:02:53She is quite big, so it is quite a lot of paint -
0:02:53 > 0:02:5812 tons of it gets applied.
0:02:58 > 0:03:02I didn't come here simply to feel small, I can do that anywhere.
0:03:02 > 0:03:04I came here because I want to see how these ships
0:03:04 > 0:03:09shift huge quantities of gas all around the globe.
0:03:11 > 0:03:16They have vast tanks but getting inside them is very tricky.
0:03:18 > 0:03:21The ships have to be in dry dock and the tanks
0:03:21 > 0:03:26have to be completely purged of any trace of their hazardous cargo.
0:03:31 > 0:03:37This is the inside of one of the tanks and as far as we know,
0:03:37 > 0:03:42nobody's ever actually filmed inside one of these before.
0:03:42 > 0:03:46That seems a shame because...look at it.
0:03:46 > 0:03:51All you need is one light, one camera
0:03:51 > 0:03:53and you can make a sci-fi movie.
0:03:53 > 0:03:54And listen to it.
0:03:54 > 0:03:59FINGER-CLICK ECHOES
0:03:59 > 0:04:03That echo is real - analogue, not a digital effect.
0:04:03 > 0:04:06Real sounds bouncing around this cavernous tank.
0:04:06 > 0:04:09CLAP ECHOES
0:04:09 > 0:04:14There's room for 34 million litres of liquid gas in here -
0:04:14 > 0:04:18the equivalent volume of water would allow the average British home
0:04:18 > 0:04:22to flush the toilet for 1,200 years.
0:04:25 > 0:04:33And there are four of these, each at minus 160 degrees inside.
0:04:33 > 0:04:36Just another world.
0:04:36 > 0:04:38It's just crazy.
0:04:43 > 0:04:47Just like oil, natural gas is a fossil fuel
0:04:47 > 0:04:50found where ancient organisms decomposed.
0:04:50 > 0:04:55It can be shifted in pipelines but they are expensive.
0:04:55 > 0:04:58and impractical for crossing oceans.
0:04:58 > 0:05:04Instead, engineers had to work out how to transport it by ship.
0:05:04 > 0:05:06That's a challenge when you remember
0:05:06 > 0:05:10that natural gas ignites at any air temperature found on Earth.
0:05:14 > 0:05:18To learn how you transport gas safely
0:05:18 > 0:05:22I went to a high security research facility in northern England.
0:05:26 > 0:05:32This is a blast-proof chamber, a sort of industrial-scale oven.
0:05:36 > 0:05:40Right, well, this device here is a supply of gas
0:05:40 > 0:05:42up through this tube here.
0:05:42 > 0:05:45This is an igniter. It'll create a spark, light the gas,
0:05:45 > 0:05:46and it'll burn.
0:05:46 > 0:05:49It's quite a lot of gas - a lot more than you're used to at home
0:05:49 > 0:05:53but don't worry, this place we're in can take it.
0:05:53 > 0:05:57This is a specialised blast testing facility.
0:05:57 > 0:05:59They use it to test industrial safety equipment
0:05:59 > 0:06:02on a massive scale, so it will be OK.
0:06:02 > 0:06:06Nevertheless, I think I'll get out while we light it.
0:06:10 > 0:06:13Since someone had left the oven door off,
0:06:13 > 0:06:17we had to retreat to a safe distance.
0:06:17 > 0:06:19Cue the spark.
0:06:23 > 0:06:28Five, four, three, two, one, release gas.
0:06:33 > 0:06:35That's just a few litres of gas.
0:06:35 > 0:06:39Imagine a cargo of many millions of litres
0:06:39 > 0:06:42that could be ignited by the tiniest of sparks.
0:06:46 > 0:06:52That cargo has the energy equivalent of 55 atomic bombs.
0:06:52 > 0:06:56Spilling it could be a massive disaster.
0:06:58 > 0:07:00But there has never been any major accident
0:07:00 > 0:07:04and the operators plan to keep it that way.
0:07:04 > 0:07:06Fortunately, there's a simple solution -
0:07:06 > 0:07:09turn the gas into a liquid.
0:07:09 > 0:07:12As a liquid, it can't catch fire and what's more,
0:07:12 > 0:07:15it takes up much less space.
0:07:15 > 0:07:17If the cargo were in gas form,
0:07:17 > 0:07:20the tanker would need to be impossibly big.
0:07:20 > 0:07:24It would have to be six hundred times more voluminous,
0:07:24 > 0:07:28which would make it ten times longer than this ship.
0:07:28 > 0:07:32Two and a half thousand metres. A mile and a half.
0:07:33 > 0:07:39To make the gas liquid, you chill it to minus 162 degrees Celsius,
0:07:39 > 0:07:42that's nearly twice as cold as it ever gets in Antarctica.
0:07:44 > 0:07:48But it only has to warm a little bit
0:07:48 > 0:07:52to turn back into highly flammable gas,
0:07:52 > 0:07:57so the crew are ultra-cautious with their volatile cargo,
0:07:57 > 0:08:02as I found out when I went on board a fully-laden tanker.
0:08:02 > 0:08:05As a liquid, it won't explode, nor will it burn.
0:08:05 > 0:08:11But the operators of LNG carriers can't take any chances with safety.
0:08:11 > 0:08:16So to avoid even the remotest risk of igniting any gas vapour
0:08:16 > 0:08:20electronic devices are not allowed anywhere near those tanks.
0:08:20 > 0:08:24If I want to go forward from here, the bridge at the stern,
0:08:24 > 0:08:29I can't even wear a microphone. So, er...it's got to go.
0:08:32 > 0:08:33There you go.
0:08:38 > 0:08:41Neither can I take my telephone,
0:08:41 > 0:08:45my camera and certainly not a TV crew beyond the bridge.
0:08:47 > 0:08:50They take no chances with this precious cargo.
0:08:54 > 0:08:57If you could hear me I'd be saying that under my feet is a tank
0:08:57 > 0:09:01exactly the same as the one I climbed inside earlier.
0:09:03 > 0:09:07It's one of four full of ultra-cold liquid.
0:09:09 > 0:09:13That's an awful lot of natural gas on these ships.
0:09:13 > 0:09:18Keeping it as super-cold liquid is the first and best line of defence.
0:09:20 > 0:09:26But what if any of the cargo warmed up and turned back into gas?
0:09:26 > 0:09:29The consequences would be dire.
0:09:29 > 0:09:33So, there is a second line of defence.
0:09:35 > 0:09:40Normally the cargo is the other side of these walls,
0:09:40 > 0:09:45tens of millions of litres of it. And remember that's in liquid form.
0:09:45 > 0:09:50Expand it into gas ready to use and it's billions of litres.
0:09:50 > 0:09:55And if any of the liquid made its way and leaked out
0:09:55 > 0:09:58and turned back into vapour, well that could be a big problem.
0:09:58 > 0:10:02But it doesn't, thanks to a prewar mail plane.
0:10:04 > 0:10:08In the 1930s, Empire flying boats delivered mail
0:10:08 > 0:10:12and passengers from Britain to Australia in 700-mile hops.
0:10:14 > 0:10:16They couldn't cross the Atlantic
0:10:16 > 0:10:20until they were able to take on fuel during flight.
0:10:23 > 0:10:26Nowadays, we take mid-air refuelling for granted.
0:10:26 > 0:10:31But, aviation fuel, just like natural gas, is highly flammable.
0:10:31 > 0:10:35A single spark when the refuelling pipe makes contact and, well,
0:10:35 > 0:10:36it's kaboom.
0:10:36 > 0:10:39PILOT: Bingo!
0:10:41 > 0:10:45What aviators needed was something to stop an explosion
0:10:45 > 0:10:47if there was a spark.
0:10:47 > 0:10:49What they needed, in fact, was noxious air -
0:10:49 > 0:10:52that's the name Daniel Rutherford gave nitrogen
0:10:52 > 0:10:55when he first isolated it in 1772.
0:10:55 > 0:10:58There might be lots of nitrogen around in the atmosphere
0:10:58 > 0:11:02and there is a lot but in its pure state, we can't breathe it.
0:11:02 > 0:11:06Sadly it took a dead mouse in a container of the stuff
0:11:06 > 0:11:09to make that particular scientific advance.
0:11:09 > 0:11:12But the point here is nitrogen is an inert gas,
0:11:12 > 0:11:15it doesn't react readily with anything at all.
0:11:15 > 0:11:19And more importantly, it stops fuel combining with oxygen
0:11:19 > 0:11:20if there's a spark.
0:11:20 > 0:11:25Ignition is impossible if there's enough nitrogen around.
0:11:25 > 0:11:29Fires can't breathe nitrogen either.
0:11:29 > 0:11:34And that's a claim that just needs to be put to the test.
0:11:34 > 0:11:39So, time to fire up the industrial oven once again,
0:11:39 > 0:11:42this time with nitrogen inside it.
0:11:44 > 0:11:48First, it's sealed to contain the toxic gas safely.
0:12:00 > 0:12:02Nitrogen on.
0:12:06 > 0:12:10I get to watch from inside a special canopy to the side.
0:12:16 > 0:12:19A meter shows how the oxygen level drops,
0:12:19 > 0:12:23as nitrogen replaces the normal air around the igniter.
0:12:28 > 0:12:31Remember, the theory is that gas won't burn
0:12:31 > 0:12:34unless there's enough oxygen present.
0:12:37 > 0:12:40That 10 means there's hardly any oxygen in the chamber.
0:12:40 > 0:12:44it's now mostly nitrogen.
0:12:44 > 0:12:47I know the science, I know the physics,
0:12:47 > 0:12:50I know this should work but suddenly I'm strangely nervous.
0:12:50 > 0:12:52Maybe it's just the drama of the surroundings.
0:12:52 > 0:12:56Right, if we're ready to do this, let's kill the nitrogen supply.
0:12:59 > 0:13:03OK, let's have the spark on then please.
0:13:03 > 0:13:06This is the igniter. No gas in there yet, remember.
0:13:06 > 0:13:10So very soon we'll see the sparks at the top of the funnel.
0:13:10 > 0:13:13Let's have a look. There they go - that's the spark.
0:13:13 > 0:13:17Smoke on then, please. Now, the smoke is purely an indicator here,
0:13:17 > 0:13:20because otherwise we won't be able to see when the gas starts flowing.
0:13:20 > 0:13:22Right now, no gas going in, you can see the smoke.
0:13:22 > 0:13:24As soon as the gas starts,
0:13:24 > 0:13:26it'll pull the smoke up through that funnel.
0:13:26 > 0:13:30The chamber is full of nitrogen.
0:13:30 > 0:13:34The spark is firing.
0:13:34 > 0:13:36We can have the gas on then.
0:13:36 > 0:13:40And at that point, the only thing stopping ignition,
0:13:40 > 0:13:42has to be the nitrogen.
0:13:42 > 0:13:43There goes the gas.
0:13:43 > 0:13:46Look, you can see where the smoke's coming out the top.
0:13:46 > 0:13:48It's being pulled through by the gas.
0:13:48 > 0:13:50That's the same gas we saw burning earlier
0:13:50 > 0:13:53and yet with the nitrogen in there, look at that, nothing.
0:13:53 > 0:13:56I find that strangely comforting.
0:13:56 > 0:13:59Science tells you it should work, but there it is working.
0:13:59 > 0:14:04Look at that, gas charging in there, the nitrogen quashing it.
0:14:04 > 0:14:06It can't ignite. It can't burn.
0:14:10 > 0:14:15Nitrogen also protects gas tankers, and mid-air refuelling.
0:14:18 > 0:14:21A quick squirt of nitrogen down refuelling pipes
0:14:21 > 0:14:23removes any risk of explosion.
0:14:27 > 0:14:28Thanks to nitrogen,
0:14:28 > 0:14:34an Empire flying boat made its first transatlantic flight back in 1938.
0:14:37 > 0:14:41On gas tankers, the potentially poisonous nitrogen
0:14:41 > 0:14:44is safely sealed inside the gas tank insulation.
0:14:46 > 0:14:51This thin layer of aluminium - almost foil - is the outermost skin.
0:14:51 > 0:14:54But obviously, if I were to poke my finger through it,
0:14:54 > 0:14:56it wouldn't go straight into a tank
0:14:56 > 0:15:00full of tens of millions of litres of liquefied natural gas.
0:15:00 > 0:15:03On the other side of the aluminium there's a layer of insulation
0:15:03 > 0:15:06that's, critically, to keep the temperature low.
0:15:06 > 0:15:08Then there's the aluminium tank itself.
0:15:08 > 0:15:11But that layer of insulation isn't just about temperature.
0:15:11 > 0:15:14It's porous and it's been steeped in nitrogen.
0:15:14 > 0:15:16So if there is a problem in the tank
0:15:16 > 0:15:19nothing can burn - there's no oxygen.
0:15:19 > 0:15:21It's inert.
0:15:23 > 0:15:25In case of a leak,
0:15:25 > 0:15:29nitrogen stops the volatile cargo reacting with oxygen,
0:15:29 > 0:15:32and the insulation keeps it in liquid form.
0:15:36 > 0:15:38The gas is chilled on shore
0:15:38 > 0:15:42and the liquid is then piped onto the tanker.
0:15:42 > 0:15:48But these super-cold temperatures pose big engineering challenges.
0:15:48 > 0:15:51You can't just use standard steel pipes to do the job.
0:15:52 > 0:15:56Moving the ultra-cold liquid around the place -
0:15:56 > 0:15:59off the ship and around the ship on pipes like these -
0:15:59 > 0:16:01presented a whole new set of problems
0:16:01 > 0:16:06that could only be resolved by recourse to the engineering might
0:16:06 > 0:16:08of this.
0:16:08 > 0:16:11And...of this.
0:16:11 > 0:16:14And even...of this.
0:16:14 > 0:16:19No, no, not actual cutlery, obviously, that would take hours.
0:16:19 > 0:16:21No, what it's made of.
0:16:24 > 0:16:26Stainless steel.
0:16:26 > 0:16:30A hundred years ago, cutlery was made of other metals -
0:16:30 > 0:16:34silver, say, or plain steel for everyday tableware.
0:16:34 > 0:16:39But steel rusts, off-putting at dinner and, like many materials,
0:16:39 > 0:16:45it changes completely when you put it in the deep, deep freeze.
0:16:45 > 0:16:48Sub-Antarctic temperatures are a game changer.
0:16:48 > 0:16:51Suddenly strong things that you thought you could rely on
0:16:51 > 0:16:54like metal, behave differently
0:16:54 > 0:16:56when you put them in the deep, deep freeze.
0:16:56 > 0:17:00It's all about ductile to brittle transition temperatures
0:17:00 > 0:17:03which is how the properties of things change with temperature.
0:17:03 > 0:17:04An example, bread.
0:17:04 > 0:17:08At room temperature, a slice of bread is bendy, flexible -
0:17:08 > 0:17:10ductile in the jargon.
0:17:10 > 0:17:17Take the same piece, freeze it, it's harder but brittle.
0:17:17 > 0:17:24Wouldn't it be terrible if steel behaved the same way?
0:17:24 > 0:17:25It does.
0:17:26 > 0:17:30Jackie Butterfield, a materials specialist
0:17:30 > 0:17:34and steel consultant, introduced me to a medieval torture device.
0:17:34 > 0:17:37This is the sort of equipment that we'd use
0:17:37 > 0:17:39to test the toughness of a metal.
0:17:39 > 0:17:42- Right, can I help?- Absolutely. - Oh, good, what do I do?
0:17:42 > 0:17:44First thing you can do is lift this weight up
0:17:44 > 0:17:46and we'll lock it in position.
0:17:46 > 0:17:48I always get the nice jobs.
0:17:48 > 0:17:50Right, so just swing this back.
0:17:50 > 0:17:53It's got a lot of weight!
0:17:53 > 0:17:56'Just for the record, I'm not being a complete weakling.
0:17:56 > 0:17:59'It is actually quite heavy. Well, 10kg.'
0:17:59 > 0:18:02- So it's a fitness programme. - It is, absolutely.- Right.
0:18:02 > 0:18:05So that's...the weight is primed.
0:18:05 > 0:18:09Yep, so what this is going to do, this weight has potential energy.
0:18:09 > 0:18:12So that's a measured dose of energy that we can apply to the sample down there.
0:18:12 > 0:18:15It's the same each time because the weight is the same.
0:18:15 > 0:18:19Step forward victim number one - a length of standard steel tube,
0:18:19 > 0:18:21just like a scaffolding pole.
0:18:21 > 0:18:22Triggering test.
0:18:22 > 0:18:26So this is going to return a specific amount of potential energy
0:18:26 > 0:18:29transferred into kinetic energy that will be absorbed, or not,
0:18:29 > 0:18:30by the sample.
0:18:30 > 0:18:31OK, here we go.
0:18:31 > 0:18:33Three, two, one.
0:18:36 > 0:18:38Woohoo! It's, er...
0:18:40 > 0:18:42..not even dented it.
0:18:42 > 0:18:46Despite the full force of the weight slamming into it,
0:18:46 > 0:18:51at air temperature, the bog-standard carbon steel remained undamaged
0:18:51 > 0:18:55whilst the energy ricocheted through the frame around it.
0:18:55 > 0:18:59- So this sample has survived then? - Absolutely.- What do we do now?
0:18:59 > 0:19:01We test some of the carbon steel
0:19:01 > 0:19:04at the cryogenic temperatures with the liquid nitrogen.
0:19:04 > 0:19:09- So this is where we introduce our tricky sub-Antarctic temperatures? - Absolutely.
0:19:11 > 0:19:13Cue liquid nitrogen.
0:19:13 > 0:19:17Minus 195 degrees Celsius.
0:19:17 > 0:19:21This will give the steel the same kind of thermal shock
0:19:21 > 0:19:25as the chilled liquid natural gas going into the tanker.
0:19:25 > 0:19:28Thank you, mysterious man with a large...
0:19:28 > 0:19:30large vat of liquid nitrogen.
0:19:30 > 0:19:31He just follows me around.
0:19:31 > 0:19:34I've got to be really careful here.
0:19:34 > 0:19:35Goggles.
0:19:38 > 0:19:40- Erm, I just put it in?- Yep.
0:19:40 > 0:19:45So...the liquid nitrogen is going to be removing the heat from the steel.
0:19:45 > 0:19:48For how long do we have to leave that?
0:19:48 > 0:19:50Just for about ten seconds.
0:19:50 > 0:19:52It should get down to the right temperature.
0:19:52 > 0:19:54In ten seconds that liquid nitrogen
0:19:54 > 0:19:57will have removed that much heat energy from the steel?
0:19:57 > 0:19:58- Yes.- That quickly?
0:19:58 > 0:20:01No wonder you have to be careful not to spill it on yourself.
0:20:02 > 0:20:04Right, coming through.
0:20:04 > 0:20:07So, the liquid nitrogen has dramatically lowered
0:20:07 > 0:20:09the temperature of the steel,
0:20:09 > 0:20:14just as the gas cargo would do as it's piped on board the ship.
0:20:14 > 0:20:19Right, if we're ready. Three, two, one.
0:20:29 > 0:20:32It's broken...badly.
0:20:32 > 0:20:33Look at that!
0:20:33 > 0:20:36It's just shattered.
0:20:36 > 0:20:40So it's exactly the same sample, same metal.
0:20:40 > 0:20:43This one barely a scratch, this one...
0:20:43 > 0:20:47well, ruined. Just shattered. It behaved completely differently.
0:20:47 > 0:20:51- In a brittle manner. - Brittle, ductile, brittle, ductile.
0:20:51 > 0:20:53Cold.
0:20:53 > 0:20:58Clearly then, you wouldn't want to rely on that anywhere really cold.
0:20:58 > 0:21:01in a liquid gas tanker for instance.
0:21:02 > 0:21:05Instead, the tanker engineers needed a material
0:21:05 > 0:21:08that can withstand super-cold temperatures,
0:21:08 > 0:21:12which brings us back to cutlery, of the stainless steel variety.
0:21:14 > 0:21:17In 1913, British chemist Harry Brearley
0:21:17 > 0:21:20was looking for a tough metal for gun barrels.
0:21:21 > 0:21:24He mixed chromium and steel...
0:21:24 > 0:21:25but it was too soft.
0:21:30 > 0:21:34However, the reject alloy revealed two unexpected benefits.
0:21:34 > 0:21:37It didn't rust, which was good for cutlery.
0:21:37 > 0:21:41And even better for liquid gas tankers,
0:21:41 > 0:21:44putting this new stainless steel in the deep freeze
0:21:44 > 0:21:46doesn't make it brittle.
0:21:48 > 0:21:50So, loading it in.
0:21:50 > 0:21:51Ooh!
0:21:51 > 0:21:55Oh, that's slightly sort of frightening when you do that.
0:21:59 > 0:22:04Right, here is the frozen sample.
0:22:04 > 0:22:06Three, two, one.
0:22:09 > 0:22:12It's completely... it's just shrugged it off.
0:22:12 > 0:22:15So what's actually happening in it that's so different?
0:22:15 > 0:22:19Why is this fine and that ruined?
0:22:19 > 0:22:23Because of the alloying elements in the stainless steel,
0:22:23 > 0:22:25it's changed the crystal structure -
0:22:25 > 0:22:28the way the atoms are arranged in the metal.
0:22:28 > 0:22:31So the difference between these two samples
0:22:31 > 0:22:34- is right down at the atomic level. - It is, yes.
0:22:34 > 0:22:36And that's where its ability to absorb the energy
0:22:36 > 0:22:41or be ruined by it stems from, right down at that level.
0:22:42 > 0:22:46Simply adding some chromium can make ordinary brittle steel
0:22:46 > 0:22:50stand up to cryogenic temperatures.
0:22:50 > 0:22:54The engineers who built the LNG carriers
0:22:54 > 0:22:57ensured that not only were the hulls fit for the seven seas
0:22:57 > 0:23:00but that the thousands of metres of intricate pipe-work
0:23:00 > 0:23:04with all their vulnerable bends, joints, and tapes
0:23:04 > 0:23:08were made of a material that could take it when the going gets cold -
0:23:08 > 0:23:10stainless steel.
0:23:10 > 0:23:16But transporting liquid by ship brings another challenge -
0:23:16 > 0:23:19stopping it from sloshing.
0:23:20 > 0:23:25And engineers have two liquids to worry about on these tankers.
0:23:25 > 0:23:27On the way out, they have a cargo of liquid gas,
0:23:27 > 0:23:30and on the return journey when it's empty,
0:23:30 > 0:23:34they carry water as ballast to stabilise the ship.
0:23:34 > 0:23:37The same problem in two different forms.
0:23:39 > 0:23:43If a liquid cargo starts to wash around on a ship,
0:23:43 > 0:23:45it can be a real problem.
0:23:45 > 0:23:47Basically when wind or waves rock the ship itself
0:23:47 > 0:23:51that can send the liquid sloshing from side to side in the tanks.
0:23:51 > 0:23:55That motion can build, emphasising the rocking of the ship itself
0:23:55 > 0:23:57and well, it can be disastrous.
0:23:59 > 0:24:02It's called the free surface effect.
0:24:02 > 0:24:06I set out to discover just how bad it can be.
0:24:08 > 0:24:12And, yeah, given my driving record I am, well,
0:24:12 > 0:24:14perhaps more than a little nervous.
0:24:14 > 0:24:16But only a bit.
0:24:19 > 0:24:23Right, what I have here is a van, perfectly ordinary
0:24:23 > 0:24:27apart from the massive tank fitted into the back containing water,
0:24:27 > 0:24:31a lot of it. Water that's free to slosh about.
0:24:31 > 0:24:34So what I'm looking to experience is for myself, first hand,
0:24:34 > 0:24:36the free surface effect.
0:24:37 > 0:24:41The free surface is literally the area available
0:24:41 > 0:24:44for a liquid to slosh around freely.
0:24:44 > 0:24:47And just in case it does affect the van
0:24:47 > 0:24:49I'm securely harnessed inside a roll cage.
0:24:51 > 0:24:56First, I took it slowly to ensure just a little bit of sloshing.
0:24:58 > 0:24:59As I turn into the corner,
0:24:59 > 0:25:02obviously, the water wants to stay where it is
0:25:02 > 0:25:04and sloshes off to the right.
0:25:04 > 0:25:08Ooh, it does, yes. It is sort of affecting the way it feels.
0:25:08 > 0:25:12If I go this way and then this way to get the feel.
0:25:14 > 0:25:16Yeah, it's sloshing.
0:25:16 > 0:25:19I can feel it suddenly jerk the vehicle
0:25:19 > 0:25:21in a direction other than the one in which I want it to go.
0:25:23 > 0:25:26I don't know whether it's me driving or the tank of water.
0:25:27 > 0:25:29That's a strange feeling.
0:25:30 > 0:25:33Time to step on it and imagine our ship
0:25:33 > 0:25:37and its liquid cargo rolling through stormy seas.
0:25:37 > 0:25:41Well, step on it as much as I can in a van.
0:25:43 > 0:25:46Yeah, a lot of water going everywhere. It's very unpleasant.
0:26:04 > 0:26:07Yeah, that didn't go as well as it might have done.
0:26:08 > 0:26:14As I corner, the momentum of the slosh capsizes my little van.
0:26:18 > 0:26:21Yeah, that is the free surface effect.
0:26:21 > 0:26:23As it turns out, it's deeply uncomfortable.
0:26:25 > 0:26:30Scale my tumble up to a whole ship and disaster ensues.
0:26:30 > 0:26:33In 1987, the free surface effect
0:26:33 > 0:26:36capsized the Herald Of Free Enterprise ferry
0:26:36 > 0:26:40when water gushed in through doors that had accidentally remained open.
0:26:40 > 0:26:43And almost 200 people died.
0:26:45 > 0:26:50Liquid natural gas tankers have a surprising solution to this problem.
0:26:50 > 0:26:55To reduce the free surface area the gas tanks are spherical,
0:26:55 > 0:26:58like great big balls. There's less room for sloshing
0:26:58 > 0:27:02as long as the tank is full or nearly empty.
0:27:03 > 0:27:07These tankers fill up with cargo -
0:27:07 > 0:27:0898% full.
0:27:08 > 0:27:14Set off, make a long journey, get there and discharge it
0:27:14 > 0:27:15or nearly all of it,
0:27:15 > 0:27:20keeping back just enough to use as fuel for the journey home.
0:27:20 > 0:27:27So the tank in normal circumstances is either almost entirely full,
0:27:27 > 0:27:30or almost entirely empty.
0:27:30 > 0:27:31No sloshing.
0:27:35 > 0:27:39Empty of cargo, the tanker would ride high in the sea.
0:27:39 > 0:27:42To lower it, water is pumped into ballast compartments
0:27:42 > 0:27:46in the hull beneath the gas tanks.
0:27:46 > 0:27:50Space doesn't allow these compartments to be spherical,
0:27:50 > 0:27:55so preventing sloshing here calls for a different solution.
0:27:58 > 0:28:01Rewind to World War II.
0:28:01 > 0:28:03Bombing raids kept British fire fighters busy.
0:28:06 > 0:28:11They used a tanker lorry, carrying almost 4,000 litres of water.
0:28:11 > 0:28:15The free surface effect made it dangerous to drive.
0:28:20 > 0:28:25By contrast, modern fire engines hurtle around without overturning.
0:28:25 > 0:28:28And that is thanks to baffles.
0:28:28 > 0:28:31Not as in confusion but load dividers.
0:28:31 > 0:28:33These are physical barriers,
0:28:33 > 0:28:38first introduced in the 1880s to stop oil tankers capsizing.
0:28:38 > 0:28:42Obviously, what led to my slight incident there
0:28:42 > 0:28:46was the free surface affect allowing the water to slosh from side to side
0:28:46 > 0:28:48and it brought the whole van over.
0:28:48 > 0:28:51So the key ones here in my baffles are these longitudinal ones
0:28:51 > 0:28:54that stop the water going from side to side.
0:28:54 > 0:28:58Apparently this works. Let's find out.
0:29:09 > 0:29:11Yeah, so far, all seems OK.
0:29:13 > 0:29:16And just as they keep the van stable,
0:29:16 > 0:29:19baffles also protect tankers from capsizing.
0:29:22 > 0:29:25Dividers in those ballast compartments under the gas tanks
0:29:25 > 0:29:28stop the water from sloshing around.
0:29:29 > 0:29:31No free surface effect.
0:29:31 > 0:29:35Surprisingly, they don't use baffles in the gas tanks,
0:29:35 > 0:29:39one reason is because friction could heat up the cargo,
0:29:39 > 0:29:40turning it back into gas.
0:29:40 > 0:29:43And you wouldn't want that.
0:29:44 > 0:29:47Empty or full, these ships are stable.
0:29:52 > 0:29:57But propelling a full tanker is more than a little challenging.
0:29:57 > 0:30:02Fully laden this tanker weighs 113,000 tons.
0:30:04 > 0:30:11Once underway, it takes an hour to bring it to a complete standstill.
0:30:11 > 0:30:16But how do you get it going in the first place?
0:30:16 > 0:30:18You might expect a modern vessel
0:30:18 > 0:30:20to be driven by a complicated computer system
0:30:20 > 0:30:23with some very fancy mechanisms.
0:30:23 > 0:30:27Well, you'd be right about the computers,
0:30:27 > 0:30:30but the mechanisms are a different matter.
0:30:30 > 0:30:33At the heart of this vast tanker
0:30:33 > 0:30:37there is, not surprisingly, a vast engine.
0:30:37 > 0:30:43It's immensely powerful, making 30,000 horsepower, in fact,
0:30:43 > 0:30:47to drive the ships across the seas around the world.
0:30:47 > 0:30:50It's very clever, it's very high tech
0:30:50 > 0:30:53but inside it's based on a principle
0:30:53 > 0:30:57that was first used hundreds of years ago.
0:30:57 > 0:30:59Tens of hundreds in fact.
0:30:59 > 0:31:02Meet the 2,000-year-old aeolipile
0:31:02 > 0:31:04or, as it's more commonly known, Hero's engine,
0:31:04 > 0:31:07after the Greek scientist who invented it.
0:31:07 > 0:31:11Here's how it works. In the base here is a reservoir of water.
0:31:11 > 0:31:14What I'm going to do is heat that water up, thus.
0:31:14 > 0:31:17When you heat the water it turns to steam.
0:31:17 > 0:31:21This bit goes on top, so the steam rises up here
0:31:21 > 0:31:23and now the only way out for the steam
0:31:23 > 0:31:28is through tiny, tiny holes in the ends of these nozzles here.
0:31:28 > 0:31:29Then it all gets a bit Newtonian,
0:31:29 > 0:31:31because when the steam comes out that way
0:31:31 > 0:31:33it exerts an equal and opposite reaction
0:31:33 > 0:31:37and push that way and sets the top spinning.
0:31:37 > 0:31:42All we've got to do now is wait for it to build up pressure.
0:31:42 > 0:31:45There wasn't much to be doing in those days, obviously,
0:31:45 > 0:31:47so waiting for things was great.
0:31:47 > 0:31:51Do some philosophy while we wait, perhaps.
0:31:59 > 0:32:03You might think this spinning pot is simply a toy.
0:32:03 > 0:32:07But no, this same principle was used by the Ancient Greeks
0:32:07 > 0:32:09in a machine to open temple doors.
0:32:13 > 0:32:16Fast forward a couple of thousand years
0:32:16 > 0:32:22and steam transforms the world, powering industry and transport.
0:32:22 > 0:32:25And then steam engines went the way of top hats
0:32:25 > 0:32:29and now we think of them as yesterday's machines.
0:32:29 > 0:32:32But, in a safely remote muddy field, I set out to learn
0:32:32 > 0:32:36what the engineers of liquid gas tankers know very well.
0:32:36 > 0:32:40Steam is powerful. You just need to put it under pressure.
0:32:42 > 0:32:43The more the better.
0:32:45 > 0:32:49I've brought steam engine specialist Richard Gibbon -
0:32:49 > 0:32:53Gibbo - along to demonstrate steam's true potential...
0:32:53 > 0:32:54with a bomb.
0:32:56 > 0:32:59We're going to put water in this super strong container
0:32:59 > 0:33:01buried in the mud.
0:33:01 > 0:33:05Steam from the traction engine will heat the water.
0:33:05 > 0:33:10Normally it would boil, turn into gas and escape,
0:33:10 > 0:33:12just as it does from your kettle.
0:33:12 > 0:33:17But that shiny lid prevents the water from turning to steam
0:33:17 > 0:33:21because it can't expand. There isn't room.
0:33:21 > 0:33:26Instead the pressure inside will simply get higher and higher
0:33:26 > 0:33:28until it explodes.
0:33:28 > 0:33:31So this whole set up, Richard, is all about the power of steam.
0:33:31 > 0:33:35Now, I'll be honest, I think steam - aw, look at that sweet old thing,
0:33:35 > 0:33:39it's from the past and you've got this little pot in the ground
0:33:39 > 0:33:41here and a pipe. Is stream that powerful?
0:33:41 > 0:33:43Yes, it is and there's a massive amount of energy
0:33:43 > 0:33:46locked up in water that is changing to steam
0:33:46 > 0:33:49and that's what this experiment will demonstrate.
0:33:49 > 0:33:51Er, Richard, what's the shed for?
0:33:51 > 0:33:54The shed's just to demonstrate
0:33:54 > 0:33:56that steam has a lot of force, power, energy.
0:33:56 > 0:33:59- So you're going to break this shed, I'm guessing.- Hope so.
0:34:01 > 0:34:06Even well above its normal boiling point, the water won't turn to steam
0:34:06 > 0:34:10until the pressure is released when the lid bursts off.
0:34:10 > 0:34:16Then it will expand instantaneously creating an explosion.
0:34:16 > 0:34:19First though, the sacrificial shed.
0:34:19 > 0:34:23Nobody walk on the big disc.
0:34:23 > 0:34:27How many crack engineers does it take to move a garden shed?
0:34:27 > 0:34:31Well, quite a lot it seems, and even then they managed to break it.
0:34:31 > 0:34:34- Oh, no, has anyone seen the steam bomb?- Oh!
0:34:34 > 0:34:36Well, we'd never done this before. It's new!
0:34:36 > 0:34:39It's going well this.
0:34:41 > 0:34:45With the soon to be ex-shed in place, we fired up the boilers
0:34:45 > 0:34:50and Richard opened the valve to pump steam into our underground kettle.
0:34:52 > 0:34:54I'm slightly nervous.
0:34:57 > 0:35:02Our steam bomb is ticking and now all we can do is wait.
0:35:03 > 0:35:05As the metal kettle gets hotter
0:35:05 > 0:35:09you can see the puddles around it boil and turn into steam.
0:35:09 > 0:35:13But the water inside, although it's well above boiling point,
0:35:13 > 0:35:17can't turn into steam until the lid blows off.
0:35:21 > 0:35:23- It's moving.- Yes, it's moving.
0:35:23 > 0:35:26The pressure gauge needle slowly ticked up.
0:35:26 > 0:35:29Gibbo expected it to blow at around 5.5 bar,
0:35:29 > 0:35:33which is five-and-a-half times atmospheric pressure.
0:35:41 > 0:35:46The boiling muddy puddles make the shed steam like a Finnish sauna.
0:35:46 > 0:35:51The kettle lid starts to buckle under the mounting pressure.
0:35:54 > 0:35:56I think we should be at the bridge.
0:35:56 > 0:35:59We retreated.
0:35:59 > 0:36:00Six-and-a-half.
0:36:02 > 0:36:07And now we really are into unknown territory.
0:36:09 > 0:36:11Coming up to seven.
0:36:11 > 0:36:15Properly dangerous now.
0:36:15 > 0:36:20Any more and we'll be close to running out of steam.
0:36:20 > 0:36:25The traction engine can only handle ten bar and if that lets go...
0:36:40 > 0:36:43That went! Brilliant.
0:36:43 > 0:36:46- What did that reach? - Seven-and-a-half bar.
0:36:47 > 0:36:49And the shed is no more.
0:36:54 > 0:36:56The simple power of boiling water
0:36:56 > 0:37:00had given our shed an extreme steam-clean
0:37:00 > 0:37:02and completely obliterated it.
0:37:02 > 0:37:07The vessel itself was fine, while the lid had been blown off.
0:37:07 > 0:37:09- There are the discs.- Yeah.
0:37:09 > 0:37:15And you can't really see but the vessel is empty and dry.
0:37:15 > 0:37:18Every single bit of water turned instantly to steam,
0:37:18 > 0:37:23and therefore expanded massively. So it's just force.
0:37:23 > 0:37:25- Sorry about your shed. - You've ruined it.
0:37:25 > 0:37:29Yep, steam is perhaps more powerful than I thought.
0:37:30 > 0:37:33And it's that same steam power
0:37:33 > 0:37:37that drives giant liquid gas carriers through the world's oceans.
0:37:37 > 0:37:41As you might expect, everything about these tankers
0:37:41 > 0:37:45puts our mini steam-bomb to shame.
0:37:45 > 0:37:47This is also a pressure vessel.
0:37:47 > 0:37:51Like the one I used to clean the shed, only it is a bit bigger.
0:37:51 > 0:37:52And there are two of them.
0:37:52 > 0:37:57And these are generating high pressure steam all day, every day.
0:37:57 > 0:38:00So although in some ways this whole engine room looks a bit inert,
0:38:00 > 0:38:04a bit inactive, it's actually generating
0:38:04 > 0:38:10and containing incredible quantities of energy and power, all the time.
0:38:13 > 0:38:17Compared to 140 degrees in our pressure kettle in the shed,
0:38:17 > 0:38:21the steam here is at 510 degrees.
0:38:21 > 0:38:24And the pressure is eight times higher.
0:38:26 > 0:38:31Mark Hodgson manages a liquid gas tanker fleet.
0:38:31 > 0:38:33'He puts the power produced
0:38:33 > 0:38:36'by those two massive containers into perspective.'
0:38:36 > 0:38:38They're just boilers making steam
0:38:38 > 0:38:44and together they produce 110 tons an hour.
0:38:44 > 0:38:48That is equivalent to about an Olympic-sized swimming pool
0:38:48 > 0:38:52processed by these units every day.
0:38:52 > 0:38:53And that steam pressure
0:38:53 > 0:38:57and temperature is delivered downstairs to the turbine.
0:38:57 > 0:38:59So steam made here in big boilers.
0:38:59 > 0:39:03Steam goes downstairs to the turbine and this is where Hero's Engine comes in.
0:39:05 > 0:39:09So, the same principle that turned Hero's engine
0:39:09 > 0:39:11powers these monster tankers.
0:39:12 > 0:39:15It turns the propeller.
0:39:15 > 0:39:18It also provides all of the electricity
0:39:18 > 0:39:21for every single appliance on board,
0:39:21 > 0:39:23right down to the crew's TV.
0:39:23 > 0:39:27On these ships, the secret of harnessing power from steam
0:39:27 > 0:39:28lies in their turbines.
0:39:28 > 0:39:32Mark shows me the amazingly simple machine
0:39:32 > 0:39:34that generates the ship's electricity.
0:39:34 > 0:39:38Its lid was off and you could see the hundreds of turbine blades
0:39:38 > 0:39:40that the steam physically turns.
0:39:40 > 0:39:43OK, so steam comes in that end?
0:39:43 > 0:39:45- Yes.- And then what?
0:39:45 > 0:39:49As the steam is injected at each stage this is where you get
0:39:49 > 0:39:53the rotational forces applied to the rotor itself.
0:39:53 > 0:39:56So this is where it starts to turn the whole thing.
0:39:56 > 0:39:58So there's an immense amount of force
0:39:58 > 0:40:00which explains the enormous stud bolts here,
0:40:00 > 0:40:02because the pressure contained within this
0:40:02 > 0:40:04when it's up and running is huge.
0:40:04 > 0:40:07It's a large casing, it has to contain 60 bar steam.
0:40:07 > 0:40:10There is such a thing as a beautiful simplicity and this,
0:40:10 > 0:40:16this incredibly clever device has one moving part.
0:40:16 > 0:40:20The engine that drives this entire ship has one moving part -
0:40:20 > 0:40:23this, turned by steam.
0:40:23 > 0:40:28- You wouldn't want to catch your tie in it would you?- Not really.
0:40:28 > 0:40:32This turbine is powerful but the one that drives the ship
0:40:32 > 0:40:36delivers seven-and-a-half times more power.
0:40:36 > 0:40:40The steam made in the boilers drives the turbine over there behind me.
0:40:40 > 0:40:42That comes through to the gear box
0:40:42 > 0:40:46and from the gear box is transferred to the propeller shaft there
0:40:46 > 0:40:48and then out there at the stern of the ship
0:40:48 > 0:40:50the propeller shaft turns the propeller itself.
0:40:50 > 0:40:52At that point it bites into the water
0:40:52 > 0:40:55and shoves forward with incredible force.
0:40:57 > 0:41:01These tankers are designed to be super-efficient.
0:41:01 > 0:41:04They cannibalise their own cargo to produce steam.
0:41:04 > 0:41:08And for the 25 tons of water they consume every day
0:41:08 > 0:41:11they turn to the surrounding ocean.
0:41:13 > 0:41:16But salt water is horribly corrosive
0:41:16 > 0:41:19and the crew just refuse to drink it.
0:41:19 > 0:41:21Softies.
0:41:21 > 0:41:25So all the sea water is boiled and evaporated to remove the salt.
0:41:29 > 0:41:33And once again it's steam that does the work.
0:41:34 > 0:41:36But to make it even more efficient
0:41:36 > 0:41:40calls for a principle noted by the father of evolution,
0:41:40 > 0:41:43naturalist Charles Darwin.
0:41:44 > 0:41:47Investigating wildlife in the Andes mountains,
0:41:47 > 0:41:49Darwin noticed something
0:41:49 > 0:41:52that plagues all mountaineers who try to boil potatoes -
0:41:52 > 0:41:54they take ages to cook.
0:41:55 > 0:41:59Darwin put it down to altitude. And he was right.
0:42:02 > 0:42:05We learn that water boils at 100 degrees C.
0:42:05 > 0:42:08But as Darwin noticed the boiling point varies
0:42:08 > 0:42:11if you're up a mountain.
0:42:11 > 0:42:14The potatoes were taking longer to cook because at altitude
0:42:14 > 0:42:19air pressure is lower, so water boils at a lower temperature.
0:42:19 > 0:42:21The boiling water just wasn't hot,
0:42:21 > 0:42:24and you can't cook potatoes in cold water.
0:42:27 > 0:42:30You can even boil water without heating it at all
0:42:30 > 0:42:34if you reduce atmospheric pressure enough.
0:42:34 > 0:42:37Right, switch the pump on.
0:42:37 > 0:42:40That is sucking the air out of there, that's lowering the pressure.
0:42:40 > 0:42:43This is to prove that water will boil
0:42:43 > 0:42:46at a lower temperature at lower pressure.
0:42:46 > 0:42:51So my marshmallow man is to prove - see - that's a vacuum in there.
0:42:51 > 0:42:56As you can see, marshmallows expand in low pressure. Useful to know.
0:42:58 > 0:43:00Yeah...it's grisly, sorry
0:43:00 > 0:43:04But the point here is not to prove what happens to marshmallow men
0:43:04 > 0:43:07in low pressure - albeit quite funny -
0:43:07 > 0:43:09it's what happens to water.
0:43:09 > 0:43:12Actually this is just like taking it up to high altitude
0:43:12 > 0:43:14where the pressure's lower. But this is easier.
0:43:14 > 0:43:16In fact, the pressure in the jar
0:43:16 > 0:43:19is the equivalent of being at 85,000 feet -
0:43:19 > 0:43:21almost three times the height of Mount Everest.
0:43:21 > 0:43:24I think I can see some bubbles at the bottom.
0:43:24 > 0:43:26Remember, I'm introducing no heat here,
0:43:26 > 0:43:29it's just at room temperature and this room is...
0:43:29 > 0:43:31at a very low temperature.
0:43:32 > 0:43:34Oh, dear.
0:43:38 > 0:43:40And there it goes.
0:43:41 > 0:43:44That's not just splashing about for the fun of it.
0:43:44 > 0:43:45That water is boiling
0:43:45 > 0:43:48and that's not because I've introduced any more heat to it,
0:43:48 > 0:43:51that's because I've lowered the pressure.
0:43:51 > 0:43:57Right, I shall now prove that it really is just at room temperature.
0:44:01 > 0:44:03Air flooding back in. Pressure coming back up,
0:44:06 > 0:44:09Sorry marshmallow man - bad day.
0:44:09 > 0:44:14The point being - room temperature, in fact really very cold.
0:44:14 > 0:44:17But boiling away happily. You wouldn't want to make a cup of tea with it
0:44:17 > 0:44:20but point, I think, is proved.
0:44:20 > 0:44:25So, boiling doesn't mean water reaches 100 degrees.
0:44:25 > 0:44:28It simply means it turns from liquid to gas,
0:44:28 > 0:44:32which it does at different temperatures, according to pressure.
0:44:32 > 0:44:36And on this ship, just as I did in my vacuum flask,
0:44:36 > 0:44:40they boil water at a low temperature by reducing the pressure.
0:44:41 > 0:44:44Once again, they harness steam.
0:44:44 > 0:44:49But they reverse the high-pressure process,
0:44:49 > 0:44:52when you make water expand quickly into steam.
0:44:55 > 0:44:59You make low pressure by going back the other way.
0:44:59 > 0:45:03Condensing steam rapidly into water.
0:45:03 > 0:45:06You need something called a flash condenser.
0:45:06 > 0:45:08I'm going to build my own. One barrel to start off with.
0:45:08 > 0:45:12On board they use leftover steam from the engines,
0:45:12 > 0:45:15but I need to rustle up my own.
0:45:15 > 0:45:18So, first, add a little water.
0:45:18 > 0:45:21Apply heat.
0:45:26 > 0:45:27Wait. And wait.
0:45:29 > 0:45:30And wait.
0:45:31 > 0:45:34And hey presto.
0:45:34 > 0:45:37Right, finally we've got steam.
0:45:37 > 0:45:40So, very quickly, I'm going to remove the heat
0:45:40 > 0:45:42and seal it, as quickly as I can.
0:45:42 > 0:45:46So, the heat comes out.
0:45:46 > 0:45:48Lid goes on.
0:45:51 > 0:45:55I'm going to really seal it cos it's important no air can get in.
0:45:57 > 0:46:01That's sealed. Right, it's full of steam, what I'm going to do now
0:46:01 > 0:46:04is condense that steam back into water, quickly.
0:46:04 > 0:46:05Here's the way.
0:46:06 > 0:46:07Right.
0:46:09 > 0:46:14Cold water will flash condense the steam, reducing the pressure.
0:46:17 > 0:46:18You can hear it creaking and groaning
0:46:18 > 0:46:23as that steam condenses back into water, shrinks,
0:46:23 > 0:46:25lowers the pressure in there...
0:46:25 > 0:46:28and the outside of the barrel still has to stand up, remember,
0:46:28 > 0:46:31to atmospheric pressure pushing in.
0:46:31 > 0:46:32Ooh!
0:46:38 > 0:46:42Yep. That's what happens when you lower the pressure inside.
0:46:42 > 0:46:45There was no way for air to get in to build the pressure up again.
0:46:45 > 0:46:49Atmospheric pressure was too much and, bang, it collapsed.
0:46:50 > 0:46:54Liquid gas carriers instantly turn steam back to water
0:46:54 > 0:46:56using flash condensation.
0:46:57 > 0:47:01And that creates a low pressure area like my vacuum jar,
0:47:01 > 0:47:05in which they boil sea water at just 50 degrees C.
0:47:05 > 0:47:08They don't bother with the marshmallows.
0:47:08 > 0:47:09That was just my idea.
0:47:09 > 0:47:13Thanks to a principle noted by the father of evolution...
0:47:16 > 0:47:19..gas tankers save a huge amount of energy.
0:47:19 > 0:47:23And energy is the precious cargo these ships deliver.
0:47:25 > 0:47:30This is not some fuel-wasting monster carrying a ticking bomb.
0:47:31 > 0:47:36This giant ship is a smart and self-sufficient recycling plant.
0:47:38 > 0:47:42It takes all the water it needs from the ocean.
0:47:42 > 0:47:45It generates its own electricity.
0:47:45 > 0:47:50And its own cargo powers it day and night around the globe.
0:47:51 > 0:47:57You could say these ships are like huge self-propelled gas bottles.
0:47:57 > 0:47:59Well, you could.
0:47:59 > 0:48:01But the fact is they are remarkable vessels,
0:48:01 > 0:48:04using extraordinary technology
0:48:04 > 0:48:09to keep a potentially hazardous cargo safe...and very cold.
0:48:10 > 0:48:13And it was all made possible by...
0:48:13 > 0:48:15stainless steel cutlery,
0:48:16 > 0:48:19a problem with a fire truck,
0:48:21 > 0:48:23an ancient method for opening tomb doors,
0:48:27 > 0:48:30Charles Darwin's potatoes
0:48:30 > 0:48:32and a pre-war mail plane.
0:48:37 > 0:48:41Subtitles by Red Bee Media Ltd
0:48:41 > 0:48:45E-mail subtitling@bbc.co.uk