Lesson video

This lesson is called Power stations and is from the unit, Fuels and energetics.

Hi, there.

My name's Mrs. McCready and I'm here to guide you through today's lesson, so thank you very much for joining me today.

In our lesson today, we're going to describe how burning fuels can be used to generate electricity.

We're gonna see how that functions and some of the pros and cons about doing so.

So in our lesson today, we're gonna come across a number of keywords and they're listed up here on the screen for you now.

You may wish to pause the video to make a note of them, but I will introduce them to you as we come across them.

So in our lesson today, we're going to have a look at how power stations work before we evaluate power stations and see how they have benefits and also problems. So, are you ready to go? I certainly am.

So, let's get started.

Now, we use electricity pretty much every single day of our lives, whether directly by using it to run things, like lights and power equipment, like our phone or TV, microwave or oven, or whether we use it indirectly because it has been used to transport something to us or it has been used to make something that we are then using.

So, every day electricity plays a very important role in our modern lifestyle.

Now, electricity is used not just by us at home, but it's also used by businesses and industry.

It's used to transport things around the world and it's also really important to help us with communication.

And the national grid helps to supply electricity around the country.

It moves it from where electricity is being generated to where it is being used via wires hanging from pylons.

And you'll see these crossing the countryside and running through our towns and cities.

And this infrastructure is what is known as the national grid and allows electricity to be moved efficiently around the country.

Now, we can generate electricity in lots of different ways and in the UK, we use a range of different ways to produce the electricity that we need for all of the different things that we use it for.

So in the UK, we generate electricity through power stations using nuclear fuel.

We also use more sustainable and renewable sources, such as using the sun, the wind, and also falling water.

And if you have a look at the pie chart on the screen, you can see how most of our electricity, certainly more than half of it, in 2024 was generated using renewable resources such as the sun, wind, and falling water.

Nuclear power accounted for quite a small section, maybe about an eighth of all of the electricity that was generated and the rest was generated using power stations.

And that's what we're going to be looking at in our lesson today.

So, how is most of the electricity in the UK generated? By nuclear power, by power stations, or by the sun, wind, and water? I'll give you five seconds to decide.

Okay, so you should have said that most electricity in the UK is generated by the sun, wind, and water.

Well done.

Now, how is electricity generated? Well, it's quite complicated, but it's also quite straightforward.

And let's have a look and see if we can work it out.

So, an electric generator works like a motor.

So, what's going on inside a motor? Well, a motor spins around when it is connected to an electricity supply.

Let's take a quick look at that now.

(motor clanking) So, you saw in that video how when electricity was flowing through the wires, the motor span, but why was that? Well, the motor span, because it is sitting between two magnets and they're the grey parts on the diagram on the screen there.

And when electricity flows, it creates a magnetic field, as well as the electricity flowing.

And when the magnetic field interacts with the magnets on either side of the motor, it causes the motor to spin.

So by passing electricity through a motor which is sat between magnets, it causes the motor to spin and this is what's going on inside the engine of an electric car.

And as the motor spins, it turns the wheels and allows the car to drive on.

But how is that like an electric generator? Because what we want it to do is generate electricity and not use it.

Well, if we turn that motor it will generate electricity, because of the interaction between electricity and magnetism, because we're turning the motor through a magnetic field.

And when we do that, electricity will be generated.

So if we have something turning that motor, that dark blue paddle in the bottom image there of the picture, on the bottom of the screen, if we have something turning that, then we can generate electricity, provided that it is sitting between magnets.

And that is exactly how an electric generator works.

Now that's quite complex science, but if you can understand the gist of that, then you'll understand what's going on inside a power station.

Now, electric generators are found in lots of different places.

So, you might have an electric generator attached to your bike.

Now, an electric generator on a bike is called a dynamo and it close to the frame and touches the bike wheel.

And as you pedal, the wheels turn and that turns the turbine, which turns the generator, which generates electricity.

And the electricity is used to light up a light, which shows other people where you are.

Now, this is quite old fashioned technology.

My mom had one of these on her bike when she was a child in the 1950s, but they're a really good way of generating electricity for free, because they're generating electricity as you are cycling.

So, maybe you do have one attached to your bike.

Now if we scale that same technology up a bit, we'll find the same principles applying in a wind turbine.

But what is turning the generator in a wind turbine? Well, as you've probably thought, the wind is turning the turbine blades, which is turning the turbine, which is attached to the generator.

And so as the wind blows, the turbines spin and the generator generates electricity as it is turning inside the magnets.

So, that's in a wind turbine.

If we scale that up a little bit more and look at how a hydroelectric dam works, we'll see exactly the same principle.

So in a hydroelectric dam, water is stored up high behind the dam wall.

And when we want electricity to be generated, we let the water fall and it falls through turbine blades.

That spins the turbine, which turns the generator, which generates electricity.

So as the water is falling, electricity is generated in exactly the same way as the wind turbine and the dynamo does.

And if we scale that whole process up again, we'll see the same principles being used in power stations.

But instead of falling water or wind being used to turn the generator, the generator is being turned in a power station by moving steam.

So, water is heated up to the point that steam is generated.

And then that steam is pumped through turbine blades which turn the turbine, which turn the generator, and that generates electricity.

So, this same principle is being applied in all of these different ways of generating electricity.

In the power station, the electric generators are absolutely enormous and steam can be created in lots of different ways.

So, how can electric generators be turned so that they make electricity? Can they be turned by falling water, by moving air, or by a room full of steam? I'll give you five seconds to decide.

Okay, so you should have said that electric generators can be turned by falling water and by moving air.

Well done if you spotted both of those.

Now, UK power stations burn lots of different types of fuels in order to heat the water to make the steam that goes through the turbine blades, turning the turbine, which is turning the generator to generate electricity.

So, natural gas and oil are two of the old staples.

These have been used for a good number of years now, 50, 60 or more years, to generate electricity.

And we also use natural gas for cooking our food and heating our homes.

We used to burn coal in power stations, but it's a very dirty way of producing electricity.

So, we don't use coal fired power stations anymore.

Now, the problem with using coal, oil, and gas is that these are all fossil fuels.

And fossil fuels were formed many millions of years, years ago.

The problem is it took a very long time to make those fossil fuels and we use them up faster than they can be replenished.

And therefore, they are called non-renewable resources.

That's because we cannot replenish them.

So once we have used them up, that's it, they're gone.

Now, some power stations burn wood pellets instead of coal, oil, or gas, but the same principle applies.

By burning the wood pellets, we are generating heat.

That boils water, turns it into steam, and the steam can pass through the turbine, turning the generator to generate electricity.

Now if we grow trees as quickly as we are chopping them down and turning them into pellets, then we have a sustainable way of generating electricity because we are using upward, but replacing it at the same speed and so it is sustainable.

However, if we don't replace the trees as quickly as we are cutting them down, then that is not sustainable because the number of trees available has been reduced by us cutting them down and turning them into wood pellets.

So, we need to be quite careful if we are using wood pellets to fuel our power stations, how are we managing the growth of those trees in order to produce the wood that we need to burn.

Is it being done sustainably and if not, how can it be changed to be sustainable? So, I've said how fuel is burnt in power stations and that heats up water and turns it into steam.

And the steam is then pushed past turbines at high pressure and high speed and that spins the turbines, turning the generator to generate electricity.

I also said that these turbines are enormous.

And you can see there in the picture, a single turbine in a power station and the four stick figures standing alongside it, each on top of each other, shows that the turbine is more than four people tall.

So it is a really, really big item within a power station.

And there is not just one of these in a power station, there are many, many of them all generating electricity as steam passes by a turbine, which turns the generator to generate electricity.

Which statement best describes the use of fuel in a power station? Is it used for heating water into steam, for heating the turbine to generate electricity, or for heating steam to make it move? I'll give you five seconds to decide.

Okay, so you should have said that fuel is used in a power station for heating water and turning it into steam.

Well done if you chose that.

So, what I'd like you to do is to summarise this section of the lesson by putting the statements in order to describe how electricity is made in a power station.

So, read them through carefully and sort them into the correct order.

Pause the video and come back to me when you are ready.

Okay, let's check our work.

So, this first statement that you should have put was fuel is burned, followed by water is heated into steam.

Then the steam is pushed forwards because it expands.

The moving steam pushes the turbine around at high speed.

The spinning turbine turns the generator and the electrical generator produces electricity.

Well done if you put them in all in the correct order.

Do check over your work and re-sort anything that's in the wrong place.

Okay, let's go and have a look now at the benefits and the problems of using power stations to generate electricity.

So, we have been using power stations to generate electricity in the UK for more than 100 years.

So, they're really important part of our electricity supply.

And when we talk about power stations, we are really talking about those which are burning fossil fuels in order to generate electricity, because that's what most of them are still doing.

Now, there's several advantages to using fossil fuels to generate electricity.

Firstly, fossil fuels, so that's coal, oil, and gas, but nowadays, we don't burn coal.

So, that's oil and gas.

These fuels are readily available.

We've got quite a good supply of them here in the UK and so, we can come across them quite easily and supply our power stations without too much trouble at all.

So, they're readily available and therefore, a good reliable source.

They're also reliable, because we know how much electricity a unit of oil or gas will produce.

And because we can change the amount of fuel that we are using quite easily, we can change the amount of electricity that is being generated and therefore, respond to demand quite flexibly.

In addition to that, fossil fuels don't depend on a good sunny day or plenty of wind in order to generate electricity.

They will carry on regardless of what the weather is like.

And as I say, we can produce an enormous amount of electricity very, very quickly to meet the demands of the moment, be that boiling the kettle to generate lots of cups of tea and coffee in the, at the break of your favourite soap or a lower amount of energy use 'cause the day is sunny and people have turned their lights off and the heating off as well.

However, burning fossil fuels does have some disadvantages.

Firstly, fossil fuels are non-renewable.

We've already discussed that very briefly, how we are using them up faster than they can be replenished and so, they are non-renewable.

Also, when we are generating electricity using new fossil fueled power stations, this is generating electricity in a much more expensive way than it would be if we were to build a solar farm or wind farm instead.

So, building new fossil fuel power stations is now much more expensive than it is to build a solar or wind farm instead.

Also, of course, by burning fossil fuels, we are releasing greenhouse gases into the atmosphere.

Greenhouse gases are driving climate change by driving global warming.

And so burning fossil fuels is not a good environmental option.

Also, it produces a lot of air pollution and that is not good for our health or the health of the planet.

So, what are the advantages of using power stations that burn fossil fuels to generate electricity? Is it that there are no advantages? Is it that they work in all weather conditions, or they release greenhouse gases, or they use energy resources? I'll give you five seconds to decide.

So, the advantage of using power stations that burn fossil fuels to generate electricity is that they work in all weather conditions.

Well done if you spotted that.

Now, I've said that by burning fossil fuels in a power station, it releases pollutants into the atmosphere.

And you can see the smoke pouring out of the chimneys in this photograph of a power station.

And all of that grey colouring is caused by pollutants entering the atmosphere.

You can see how it differs in colour from the water vapour that's coming outta the cooling towers.

The water vapour looks like clouds, but the smoke is much denser than that.

And that's because smoke contains many tiny little pieces of soot, which is particles of carbon and some other fine particle residues left over from the fuel that was being burnt.

And these particles can be harmful to human health.

So, people who have got lung conditions, such as emphysema, COPD, bronchitis, and asthma have great difficulty coping with the pollutants in the atmosphere, because they irritate the lungs and cause the condition that they've already got to get worse.

Now, a lot of the pollution that power stations produce is invisible.

We can't see it.

For instance, carbon dioxide, sulphur dioxide, and nitrogen oxide are all colourless gases and that means that we can't see them.

They're present in the atmosphere, but they can't be seen.

They're invisible.

Now carbon dioxide, as we know, is a greenhouse gas.

This means that it is contributing to global warming, driving climate change.

Sulphur dioxide and nitrogen oxides are all chemicals that can make rain water more acidic.

And this has many problems as well.

It erodes buildings made of limestone and it also acidifies ponds, and rivers, and lakes.

And that's bad for the organisms, the plants and the animals, that are living in those places.

So, sulphur dioxide and nitrogen oxide are pretty unpleasant chemicals.

Sulphur dioxide is also an irritant to the lungs.

It can cause breathing difficulties.

And as you would probably expect if you've already got a lung condition, having something that makes it worse is not gonna be very pleasant at all.

So, people who have got a range of different lung conditions find pollution from power stations make their condition much worse.

Now, I said that these pollutants are invisible, but sometimes they turn into a cloud that we can see.

And when they turn into a cloud that we can see, we call it smog.

It's a smoke and fog.

If we fuse those two words together, smoke and fog, we get smog.

And that's exactly what this is.

So, you can see that smog clouding the top of the city, polluting it.

So, this is where the invisible pollutants have reacted using the energy from sunlight to form particles that we can now see and we call that smog.

Now, just like the particles were when they were invisible, they are also harmful to us when we can see them.

They cause breathing difficulties.

And so obviously, people who have already got underlying breathing problems I find that they get much, much worse in smog.

And smog is a really big problem for some cities.

So true or false, there is definitely no air pollution on a clear day.

So, you should have said that that is false.

And that's false because some kinds of air pollution are invisible and these, despite it being a clear day, may still be present in the atmosphere.

We just can't see them.

Well done if you said that.

So, this is about the pollutants that are created in fossil fuel power stations, which are burning coal, oil, or gas.

But I've said that some power stations burn wood pellets and these are used to generate electricity perhaps more sustainably if we're managing the wood supply well.

But the problem is that we're still burning fuel and by burning fuel, we are generating pollutants.

So whilst wood pellets may possibly be more sustainable if they're managed correctly, they do still release pollutants into the atmosphere.

However, if we manage the woodland that we are harvesting in order to generate the wood pellets in the first place and make sure we are growing at least the same number of trees that we are cutting down, if not more, then the new trees that are growing will absorb the carbon dioxide that the wood pellets have released into the atmosphere.

So at least, we can say that we would be carbon neutral at that point.

As much carbon dioxide is being extracted from the atmosphere by the new forest as was released into the atmosphere by the old forest, which has been converted into wood pellets.

We can also burn waste, household waste to generate electricity.

So instead of putting it onto landfill sites, we can send it off to a power station instead and burn that.

The problem with this is it is incredibly filthy.

The products that we are burning have an enormous number of different pollutants that get aerosolized and put into the atmosphere.

And so, this is a really dirty way of generating electricity and is the most polluting form that we have.

Now, we are developing all of the time new technologies in order to try and trap the pollutants before they get into the atmosphere.

Carbon capture is already in existence and there are quite a few different schemes that allow carbon capture to happen.

However, carbon capture, so capturing carbon dioxide, is an expensive thing to do.

And so the cost of electricity increases as carbon capture is deployed.

So whilst carbon capture is a really important process to be trying to do, it is certainly not the only thing that we can do in order to reduce the pollution that is created by burning fuels to generate electricity.

So, which of these produces the most pollution? A power station burning wood pellets, a power station burning waste, or a power station burning fossil fuels that uses carbon capture technology? I'll give you five seconds to decide.

So, you should have said that the most polluting form of power station is that which burns waste.

Well done if you chose that option.

So, what I'd like you to do now is to firstly complete the table with some advantages and disadvantages of burning fossil fuels in power stations.

So, think back to what we've been discussing in this lesson so far, and add as many good and bad things as you can.

Then, I'd like you to state your opinion on the use of fossil fuels in power stations.

So, what do you think and why do you think that? Now, there's a sentence starter there that you can use to help you write your opinion out and explain it.

And it doesn't matter what your opinion is, as long as you can explain why you have it.

So pause the video, take your time and come back to me when you are ready.

Okay, let's review your work.

So firstly, I asked you to complete the table with some advantages and disadvantages of burning fossil fuels in power stations.

So, the advantages include the fossil fuels are readily available and the power stations are therefore very reliable.

They are not dependent on the weather and they can produce a large amount of electricity quickly to meet demand.

Whereas the disadvantages include the fact that fossil fuels are non-renewable resources.

That means that we're going to use them up and we can't replace them.

Also, generating electricity with new fossil fuel power stations is much more expensive than with new wind farms or solar farms. And of course, they release greenhouse gases, which is bad for the climate.

They also release pollution into the air.

So, just check over your work.

Have you missed anything out that you need to add to your list? Please do so before we move on.

And then, I asked you for your opinion on the use of fossil fuels in power stations.

So, there are two examples here on the screen, one which agrees that they should be used and one which disagrees.

Which one matches your response, your opinion most closely? So if you agree that we should use fossil fuels in power stations, you might have written that I think we should burn fossil fuels in power stations, because it is a very reliable way to make a lot of electricity quickly, no matter the weather.

There is some pollution, but the convenience outweighs the pollution.

Whereas if you disagree, we should not be using fossil fuels in power stations.

You might have written, "I do not think we should burn fossil fuels in power stations because it produces lots of carbon dioxide, which is a greenhouse gas.

There are other cheaper and cleaner ways of making electricity that we can use instead." So, perhaps you've written something along those lines, one or the other.

Just review what you have written and see whether you have written it clearly enough that you've stated both your opinion and why you think that.

And well done, that was a really hard task.

Okay, we've come to the end of our lesson now and we've seen today how more than half of the electricity in the UK is generated from the sun, wind, and falling water and about a third is generated by power stations.

Now in the UK, many power stations burn natural gas and oil in order to heat water to turn it into steam.

And that steam is then pushed away from the water, because it expands and it pushes turbines around at high speed.

And when the turbines are pushed around, the generators that they are attached to produce electricity.

Now, natural gas, oil, waste, and wood are all examples of fuels fuel that produce greenhouse gases and a range of pollutants when they are burned.

Natural gas and oil are examples of non-renewable resources that are not replenished when they are used up.

So, I hope you found today's lesson interesting.

Thank you very much for joining me today and I hope to see you again soon.

Bye.