Steel, Electricity, Sewage Curious Cat

Hello, children, what are you doing?

We're cleaning our paintbrushes.

Good thing you have a sink in your classroom.

Do you know what happens when you send dirty water down the plughole?

Does it go down the drain and underground?

Yes! That's right.

All your dirty water from the sink, bath and toilet all go down pipes

and end up in the same place - underground, into the sewer.

-Would you like to see where the dirty water goes?

-BOTH: Yes, please!

My friend Stewart is waiting to show you round.

Off you go,

down the drain.

-Hello.

-Hello. I'm going to take you down to my sewers.

-Would you like to come with me?

-BOTH: OK.

-We'll open the door first.

-Wow!

Rather deep, isn't it?

Yes. How deep is it?

-It's as deep as two double-decker buses.

-BOTH: Wow!

That's quite deep.

What's down there?

Dirty water, sewage.

-Ugh!

-It comes from your toilet when you flush.

-Can we go down there?

-Of course you can.

-Do you want to go down there with me?

-BOTH: Yes.

-OK, then.

What we need is a helmet and gloves. Put this on your head for me.

I'm going to take you down into the sewers.

Stewart is taking the children into the dark sewer.

We should never go into an underground sewer

without the adults who work there, because it would be very dangerous.

Watch your step!

Right, let's go and look at some sewerage. Come on.

-Are you ready for an adventure?

-Yes!

-Let's go. Keep with me.

-Yes, sir!

You may not realise it, but under our feet,

there are hundreds of miles of tunnels and they are very important.

What is sewage?

If you think of all the houses, everybody lives in a house,

all the water goes down and collects in a big sewer system.

So from every house, all their taps, all the toilets, the baths,

the showers, it all comes down into the sewer system,

and even from the roads. When it rains, it comes down the drains

and then it comes into this great big sewer system.

This is what takes your sewage away from the towns and your houses.

From your toilets, these go into the drains.

A pipe like this.

This is a four-inch pipe, but they can get bigger.

Six, nine inches, 12 inches, 18 inches, 24 inches,

until you get a big eight-foot barrel, like this. A big sewer.

The sewers work on a really important thing called gravity.

Gravity makes water flow downhill.

How does it travel?

To make the sewer system work, all the pipes, they are not flat.

They have a small gradient.

They are slanted like that, to make the water run.

If you have it flat like so, when we put the water in,

nothing comes out the end.

To make the water go, they tilt the pipe.

That's how it flows down the drain, like that.

That's how we take all your waste water away.

-Can we go along the tunnel now?

-Of course.

-Are you ready? Have you got your torches on?

-BOTH: Yes.

OK, then, if you want to follow me. What we do is walk up here.

There's a bit of poo there.

This is a sewage tunnel.

All our dirty water travels from your homes

into these underground tunnels.

This is real sewage.

This is when you go to the toilet, you flush your chain

and it comes down into the sewer system.

-Eugh!

-There's some toilet paper!

That's all toilet paper, yes.

That is so disgusting!

-What do you think of that?

-Er, poo.

-Yuck.

It smells quite yuck.

You have to clean the sewer every day or every week?

No, we clean this sewer every eight weeks.

We have to get a lorry and special pipes

and we go in there and suck up all the grit and dirt

-and take it away.

-That sounds quite yucky.

-It is quite yucky.

OK, children, now that you've seen how a sewer works,

it's time to go back to the surface to see what happens next.

Now it's time to visit the sewage treatment plant,

where Ben will show you round.

-Morning, children.

-BOTH: Morning.

This is a treatment works,

where sewage comes after it's been through the tunnels.

-Do you want to see how we clean and recycle it?

-BOTH: Yes.

Excellent. Follow me.

This is the waste-water treatment works where all the sewage

and waste water, comes to be treated.

It looks like a big water monster!

A big water monster!

-Does it have wee in it?

-It has got wee in it.

-Poo?

-Yes.

Anything from the house is collected through the pipes,

comes to the treatment works to be treated

and this is what it looks like to start with.

What we'll do is take samples as we go round

and show you how it gets cleaner and cleaner.

-Now, we'll go and see the next stage.

-Yeah.

-Yes.

OK? Follow me.

All the dirty water we saw in the sewers

comes to a sewage-treatment plant, like this one,

where they make it all clean again.

The first process is like a sieve,

to get rid of all the big bits of rubbish in the water.

In this machine here,

there is one of these screens for things like cotton buds.

Anything flushed down the toilet that's too big to treat,

this is where we take it out.

Where do the big bits go?

All the bits we take out here we can take to burn, to produce energy,

or we can take to landfill sites.

This way.

Here we have the next stage of the cleaning process.

This is what we call a settlement tank.

Leaving the dirty water to settle in these tanks

let's all the big bits sink to the bottom

so they can be taken away.

So, here, we have taken another sample from these tanks.

Can you see in this one, can you see the sludge settling to the bottom?

BOTH: Mm-hm.

That's sludge we draw out of the bottom of the tank

and this cleaner water we take off the top.

What is sludge?

Sludge is the poo that we've allowed to settle

to the bottom of the tank.

We then suck that out and take it away and use it to help feed plants.

The water looks clean, but there's still tiny germs in it,

so we need to take those out.

I'll show you how we do that. Follow me.

Here, this is the next stage of the treatment,

or the cleaning, process. Although we've taken the solids out,

there are still tiny germs that are in the waste water.

What are germs?

Germs are tiny, tiny bugs you can't see with your eyes.

They are not good for us sometimes, so we need to take those germs out.

We do that in these filter beds.

The water is passed over the stones

and the nice germs that live on these stones

eat the bad germs, so that we get cleaner water off the bottom.

Why do we need to clean sewage?

We need to clean sewage to make sure it's safe.

Because we don't want the nasty bugs

getting into rivers, streams or the sea.

We take out the bad germs, so we don't get ill.

These germs here are called bacteria

and they are really tiny.

But not all germs are bad.

Here, they use good germs,

which attach themselves to these stones,

to eat up the bad germs living in the dirty water.

These special stones have lots of holes,

so the good germs have somewhere to live and grow.

So this is the very last thing we do

and that is to check to make sure it's OK to put back into the stream.

-And this is what it looks like when it goes into the stream.

-Whoa!

-That's really...wow.

-Wow! That is so clear.

See the difference?

It's like you've just put the water in from the tap.

Yes, that's not tap water, it's come from here.

Now you know how sewage is cleaned and treated.

Hello, children, you're back.

What did you find out about where our sewage goes?

All the dirty water goes down the pipes in our homes

and then through big pipes underground, called sewers.

We went down a manhole into a sewer.

It was a big, dark tunnel where the sewage went.

The sewage goes all the way to the sewage-treatment plant,

where it's cleaned.

First, all the bits of rubbish, like toilet paper, get taken out.

The sewage is then sent to a tank,

where the big bits sink to the bottom.

These bits are called sludge.

The sludge can be dried and used to make plants grow.

Next, they have to clean the tiny bits you cannot see

by using special stones.

Then, the water is clean enough to go into the river.

That's brilliant. Well done.

Now we know what happens to our waste once it leaves our homes.

Great work. Bye-bye.

BOTH: Bye-bye, Curious Cat.

Goodbye, children.

Hello, children, what are you doing with those biscuit tins?

-Hello, Curious Cat.

-We're sorting out biscuit tins for our school project.

Looks like you have plenty of tins there.

But do you know how biscuit tins are made?

No.

Let's find out how it all begins.

The tins are made of steel

and steel is made from special rocks underground, called iron ore.

Iron is a metal and it's found in rocks deep underground.

To get to these rocks, we have to use explosives

and big machines, to dig deep and take away the loose earth.

The iron ore rocks are then loaded onto a truck

and transported to the steel factory.

To make steel, you need iron ore, coal and limestone,

which all come from the earth.

Are you curious to find out what happens next?

-BOTH: Yes.

-That would be great.

-Then, off you go.

To find out what happens next,

you'll have to visit the steel plant, which is a huge factory

where all the ingredients are brought together to make steel.

My friend Chris is waiting to show you round.

Hi, my name is Chris

and I'm here to teach you all about our steel-making factory.

All around you can see the raw materials for making steel -

iron ore, coal and limestone.

I'm glad you've already got your safety gear on.

Now we're going to head to the blast furnace to see what we do next.

Look at all the raw material!

There is heaps here and it all comes from the earth.

First, we need to mix the raw ingredients together -

the iron ore, the coke and the limestone -

in a blast furnace.

What is a blast furnace?

It's like a huge oven used to melt the ingredients for steel making.

What's interesting is we can never really turn the furnace off,

because, once it cools, it takes so long to heat up again.

-So it's on all year round.

-How does a blast furnace work?

I tell you what, we'll go outside and I'll show you, OK?

So this is one of the enormous blast furnaces

that melts the iron ore, coal and limestone -

the ingredients that make steel.

What happens is we put all the raw ingredients

into the top of the furnace, until the iron is melted down

into a white-hot pool of liquid iron at the bottom.

The furnace is so hot, we're not allowed anywhere near it.

-How hot is the furnace?

-Do you know how hot the water in a kettle is?

Well, a blast furnace is 20 times hotter than that,

so it's very, very hot.

How would you get it all out of the furnace?

Once the metal is collected, we have two drill a hole

into the bottom of the furnace.

The red-hot liquid drains into special containers

on trains called torpedoes, which will take the liquid

to the next part of the process - to turn it into steel.

The liquid metal, at this stage, is full of impurities,

so the next process is to clean it.

How do you clean it?

A special lance is lowered down to the surface of the liquid.

A really fast gas is blown onto the top of the liquid.

This makes all the impurities, and everything else

in the steel that we don't want, float to the surface so we can

scoop it away, then we're left with the steel that we need.

Once the steel is cleaned,

the next stage is to turn it from a liquid into a solid.

When does it start looking like steel?

First, we have to cool the red-hot liquid into a solid,

then we can roll it thinner. Shall we go and see what we do next?

The red-hot liquid steel is moulded into giant slabs

and then the next process is to roll it, to make thin sheets of steel.

The slabs from the steel plant are still too thick

to be made into biscuit tins,

so this is where we bring it to make it even thinner

and roll the slabs into steel sheets.

How do you turn those slabs into thinner sheets?

First, you have to reheat them.

The steel slabs need to be reheated in a very hot oven,

so they're soft enough to go through the rollers,

which make them thinner and longer.

Then we can cut them, trim them and roll them into big coils,

which look like giant toilet rolls,

which can sometimes be up to a kilometre long.

That does look like a giant toilet roll!

It also looks very, very hot.

-It doesn't look anything like biscuit tins.

-You're right.

First, we need to send them to another process

to make them even thinner again.

Then we can take it to the factory to make it into biscuit tins.

So, at the end of this process, the red-hot steel is cooled

and rolled even thinner.

It is then ready to be made into biscuit tins.

Chris is taking the children to see how this is done.

So here we are at the factory

where we take the steel and make it into biscuit tins.

As you can see,

the steel has been rolled really thin by the steel factory.

We cut it into small sections,

so we can put it through the machines.

The thin sheets of steel are loaded onto the machine

that cuts them into different sizes.

This way, you can make different-sized biscuit tins.

Once the sheets have been cut into the right sizes,

the biscuit tin designs are printed on them.

These have just come back from the printers.

As you can see, they've got the same design on them.

This will make about 15 biscuit tins.

Do you think it looks more like a biscuit tin now?

BOTH: Yes.

Next, the printed sheets are cut even smaller...

..and then pressed to make the biscuit-tin shapes.

Here, the cylinders are about to go into this machine.

This is where the bottom is put on to them.

And after one last check, the biscuit tins are finished.

They are now ready to be filled with biscuits.

Now, our lids and our cylinders make a finished biscuit tin.

-Thank you.

-One for you.

-And one for you.

-Whoa!

Hello, children, what did you find out?

First, we went to see the ingredients - coal,

iron ore and limestone.

They were mixed together and melted in huge furnaces

that look like big ovens.

The liquid was poured into a transporter called a torpedo.

This then cooled into big slabs.

The slabs get flattened and stretched.

They are then rolled and look like massive toilet rolls.

The steel rolls are made even thinner

and sent to the biscuit-tin factory.

That's where the rolls get shaped into tins.

It was brilliant.

Well done, children.

Now you know how steel is made and how a biscuit tin is made.

Excellent work.

See you next time. Bye for now.

BOTH: Goodbye, Curious Cat.

Goodbye, children.

-Hello, children.

-Hello, Curious Cat.

Thank you for switching the lights on. It was a bit dark in here.

It's a good thing we have lights,

but do you know what makes them work?

Is it electricity?

That's right, children.

Electricity is very important.

We use it every day in all sorts of gadgets and gizmos.

Electricity makes all sorts of things work,

from little things, like hairdryers...

..to big things, like all the lights in our houses and schools.

That's because it's a type of energy.

In the same way that you eat food to keep you going,

machines and gadgets eat electricity to keep them going.

But do you know how electricity is made

and how it gets to the sockets in your home?

BOTH: No.

Well, to find out, you will need to visit the electricity power plant.

-My friend Mark is waiting to show you round.

-Hurray!

Off you go!

Electricity is made in a place called a power station.

There are power stations all over the country

and each needs to be fed fuel to make it run.

Different power stations use different types of fuel.

Some use coal, some oil, and some even use rubbish.

All of these fuels are burned to get energy.

But we can also use energy from the wind and flowing water.

Even the sun can be used to make electricity.

This power station is fuelled by gas.

-Should we go and have a look?

-BOTH: Yes!

-Let's go.

These are the biggest pipes I've ever seen!

What you can see is the natural gas fuel

that comes into the power station.

The gas comes from deep underground

and, because it is colourless, you cannot see it.

That's why it has to travel into the power station

in these great big pipes.

It comes all the way through our pipework.

It goes through into our buildings and gets burned.

So the first stage of the process

is to burn the natural gas to create heat.

That heat then turns water into steam.

Steam like from a kettle. Very hot.

OK, from here, shall be going see where these pipeworks go

and see where the steam is made?

-Yes?

-BOTH: Yes!

-OK.

We are now in the steam turbine hall where steam comes together

and goes through the turbine.

It passes through the blades

and turns that turbine to help create energy.

As an example, I've got these two little windmills for you.

If you blow into them from the front, you can see they spin. Yes?

If you think of your breath pushing that windmill around,

it's just like steam turning round the turbine.

The blades inside the steam turbine are really big.

They can be up to a metre high or really small.

Here's one to show you.

So it's quite a bit different to what you've got in your hands.

It does the same job.

How can it turn around when it's so big and heavy?

The steam turbine can turn, although it's metal and heavy,

through the power from the steam coming through the blades

and turning them round.

I know that's hard to imagine -

steam so powerful to push those heavy blades,

so Mark has a demonstration, to show the girls how it all works.

OK, girls, I promised showing you electricity,

here's a demo of it.

At the power station, we have gas coming in

that's burned to create our steam.

Here we have a gas cylinder, which will be set light to.

It will heat up the water inside the kettle.

The steam from there will come through there

and out the spout to turn these spoons,

which is just like our steam turbine out on the plant.

Once this starts to turn, we can then generate electricity

through the cable to our houses and the streetlight.

Wow!

Wow!

That's amazing!

Once the kettle has boiled, the steam pushes out of the spout

and turns the turbine made of spoons.

So now we know that an electricity power plant

can use different types of fuel to make steam to spin a turbine.

But how does this actually make electricity?

The answer involves a magnet and a coil of wire.

You can see there's plenty of wire that's turned round this plastic.

You have one of these on your steam turbine.

If I put a magnet inside, and shake it, what can you see?

BOTH: The light.

Yes, that's right.

The turbine moves a magnet that spins inside some wires.

This generates electricity in the wires.

The electricity travels down the wire and lights up the lamp.

How much electricity do you make here?

The power station can provide enough electricity to power London.

-Shall I show you the control room?

-BOTH: Yes!

Wow, that is a lot of electricity!

This is where we control the electricity

going out to major cities, homes, towns, in the country.

Sometimes, we need a little,

sometimes we need a lot of power to go out there.

When do we need lots of electricity?

Early in the morning, when everybody is waking up,

so a lot of electricity is going to be used then, and, of course,

when we come home from school, from work,

that is another time when we need to provide a lot of power.

How does the electricity get to our homes?

If we go outside, I can show you.

OK, girls,

now you can see the end of the process.

Here, you can see these large cables going up to this pylon.

These long cables go all the way round the country

and take the electricity to towns, cities and your home.

What are the cables made of?

They are made of a metal material to conduct the electricity.

A conductor is a material that electricity can flow through easily.

When you put a plug into a socket,

the electricity travels through the metal pins

and not the plastic casing.

This is because metal is a good conductor and plastic is not.

That's why electrical wires are made of metal.

The pylons support the metal cables

and take the electricity across the country.

All the pylons and wires together are called the National Grid.

These pylons and wires are very dangerous

and you should not go anywhere near them.

This is how electricity gets to your homes.

How it powers your kettles, your toasters, your ovens,

the things you use on a day-to-day basis.

Hello, children, how was your journey?

-It was great.

-Yes.

What did you find out about electricity?

That electricity can be made out of different fuels, like coal and gas.

And it's made in a power plant, where it gets really hot,

and spins a turbine, which has a magnet

that spins in the middle of some wires.

This makes electricity in the wire.

The electricity goes through the wire

and is sent all over the country through cables

and ends up in our homes.

Wow! That's brilliant work.

You know all about generating electricity. Well done, you two.

Now, I think it's time to say goodbye.

Don't forget to turn the lights off on your way out! Goodbye.

BOTH: Goodbye, Curious Cat.

Goodbye, children.

Subtitles by Red Bee Media Ltd