Lesson video

This lesson is called Using Renewable Energy Resources, and it's 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 renewable energy resources can be used to generate electricity.

And we'll have a look at a wide range of them throughout the lesson.

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 a video to make a note of them, but I will introduce 'em to you as we come across them.

So in our lesson today, we're going to first of all have a look at how we generate electricity using a turbine before we consider how we can generate electricity using moving steam, and then we'll consider how we can produce electricity with solar panels.

So are you ready to go? I certainly am.

So let's get started.

Now, when we're talking about generating electricity with a turbine, we have to first of all consider what an electrical generator is because the turbine is only the front section of it and actually, where the electricity is being generated from is called the generator.

Now we find electrical generators in lots of different locations.

You may have a generator on your bike, it's called a dynamo, and the dynamo attaches to the frame of the bike and a little rotating section is placed against the wheel.

So as you cycle along, the dynamo is spun by the turning wheel and that generates electricity within the dynamo section itself, and that makes the lights turn on.

Now this is really old technology.

My mum had a dynamo on her bike when she was a child back in the 1950s, but it's a very effective way of producing electricity for lights.

And so you may well have a dynamo on your bike.

Now if we take that dynamo and scale it up a bit, then we'll see exactly the same technology appearing, but on a larger scale within wind turbines.

So instead of the wheel turning the spinner, turning the generator, the wind is turning the turbine blades and that is turning the generator.

And if we scale that process up even further, then we'll see exactly the same technology being used within a hydroelectric dam.

And as the water falls, the turbines in the dam get spun and that turns the electricity generator and that generates electricity.

So at all of these different scales, we have an electrical generator which is being turned by a turbine.

So let's have a look at an electrical generator in a little bit more detail.

What is an electrical generator? Well, an electrical generator is a coil of wire that can be made to spin around.

Now when you turn electric wire through a magnet, it generates electricity because electricity and magnetism are closely interlinked.

So if we turn that blue section of the diagram, the paddle, which has got the coil of wire in green around the outside of it, if we turn that through a magnetic field, so having magnets on either side of it, then we will generate electricity.

And this is the essence of what is going on inside a bike dynamo, inside a wind turbine, and inside the hydroelectric power plant as well amongst many other locations where we find this technology.

So we are spinning wire through a magnetic field and that is generating electricity because of this interplay between electricity and magnetism.

So what is needed to make electricity with a generator? A battery, a coil of wire, an electricity supply or magnets? I'll give you five seconds to decide.

Okay, so you should have said that to make electricity with a generator requires a coil of wire and magnets.

Well done if you chose those two options.

Electric generators are often attached to turbines, and we've seen examples of this in the wind turbine and the hydroelectric dam.

And a turbine is essentially like the propeller on a plane or a boat.

And it's shaped so that liquid or gas flowing over it will make it turn, will make it spin around.

And when it is connected to the electric generator, the electric generator will be spun through the magnetic field and electricity will be generated.

Now in a wind turbine, wind is used to push the turbine blades around.

And you can see this wind turbine has three blades and the big box sitting behind the turbine is where the electric generator is sat.

So the wind is turning the turbine blades and that is spinning the coil of wires through the magnetic field within the generator, and that generates electricity.

Now wind is a renewable energy resource and that is because it can be replenished quickly and it'll not run out.

And that's a really important statement to remember when we're talking about renewable energy resources, they will not run out.

So wind turbines are an example of a renewable energy resource and they have several pros and cons, benefits and issues.

Firstly, they are expensive to manufacture and instal, but once they are installed, they are very cheap to run.

Even the offshore ones are cheap to run and when they are generating electricity, they do not emit greenhouse gases or other pollutants.

So only in the production of them do greenhouse gases and pollutants get produced when they're actually in sight and working, then it is pollution free.

However, wind turbines cannot generate electricity if there is either too little wind or if the wind is too fast.

Now some people think that wind turbines are too noisy or they spoil the landscape or that they disturb wildlife, and therefore there are these other issues associated with wind turbines in addition to the other practicality issues that we've already discussed.

So what is an advantage of a wind turbine? Are they cheap to run? Do they disturb wildlife? Are they noisy or do they spoil the view? What's an advantage? I'll give you five seconds to decide.

Okay, so you should have said that an advantage of a wind turbine is that they are cheap to run.

Well done if you chose that.

So wind turbines are an example of something turning an electrical generator.

But falling water can also be used to turn turbines and these are incorporated within a dam.

So this is the Hoover Dam, this picture, and you can see the water stored in a reservoir behind the dam itself.

And at the bottom of the dam are the turbines, they're stored at the bottom.

And as water falls through the pipes in the dam wall, they then pass through the turbines in the dam and generate electricity because the turbines are spinning the coils of wire inside the magnets and that is generating electricity.

So electricity which is generated by falling water is called hydroelectricity, where the word hydro means water.

And hydroelectricity is also a renewable energy resource because the water levels are replenished by falling rain.

Now a hydroelectric dam can produce huge amounts of electricity very, very quickly and without any greenhouse gas emissions.

And the Hoover Dam, which is built near Las Vegas, can generate enough electricity for 8 million people.

However, building a dam is extremely expensive.

It requires an enormous amount of construction in order to build the dam.

You can see that by looking at the picture of the Hoover Dam, all that concrete reinforcement of the dam wall plus the back reinforcement where the river is being backed up and then all of the electricity infrastructure sitting around that as well.

And building all of that infrastructure requires the release of greenhouse gases during construction because of the types of technology that are being used in order to construct it.

Then of course there are only certain places in the world where dams can be built.

And if a dam can be built, the environmental consequences of building a dam need to be considered as well, because reducing the water flow downstream and backing up the water flow upstream will significantly impact habitats and change the way animals and plants can survive within those changed fundamentally changed environments.

So what is an advantage of generating electricity using falling water instead of wind? Is it that a reservoir has a big impact on the environment? Is it that no greenhouse gases are emitted or is it that electricity can be generated whatever the weather? So what is an advantage of generating electricity with falling water instead of wind? I'll give you five seconds to consider.

So an advantage of hydroelectricity over wind is that electricity can be generated whatever the weather.

Well done if you chose that.

Okay, let's summarise this part of the lesson by filling in the gaps describing how electricity can be generated from the wind or from falling water.

And you need to only use the words turbine or generator to fill in the gaps.

So pause the video and come back to me when you're ready.

Okay, let's check our work.

So a wind turbine can generate electricity from wind.

The turbine has three blades that are pushed around by wind.

Inside the box behind the blades is an electric generator.

The turbine spun around by the wind, makes coils of wire spin inside the generator.

Falling water can make a turbine spin inside a dam and an electric generator connected to it generates electricity.

So just check, you've got the words turbine and generator correct in all of those sentences.

Remember it's the turbine, which is the blades that's being pushed around by wind or water.

And the generator is where the electric wires and the magnets are that generates the actual electricity.

Well done if you've got all of those correct.

Okay, let's move on to look at how electricity can be generated by moving steam.

So we've seen how turbines can be turned by moving wind and moving water, but in power stations they are moved by moving steam.

So what has to happen is that steam is made so water is heated up until it turns to steam, and then that is pushed past turbine blades which spins coils of wire inside electric generators to generate electricity.

So usually power stations generate enough heat to boil water by burning oil or gas.

So oil or gas is burnt, that heats up the water, turns it to steam, and then the steam is pushed past turbine blades which turns the generator.

Now oil or gas are examples of non-renewable resources because we are using them up faster than they can be replenished.

But power stations can also make steam by burning other things such as biomass.

Now is plant material such as wood pellets or crops that have been grown specifically for the purpose of being burnt within a power station.

Now burning anything will produce greenhouse gases and other pollutants that is just the way it is.

Burning anything will always do this.

However, biomass could be a sustainable energy resource if it is grown at least as quickly as it is being used up.

And that's because it firstly can be burnt within existing power stations.

And although burning it produces greenhouse gases and other pollutants, growing biomass removes carbon dioxide from the atmosphere as the plant grows.

So the carbon dioxide that is being put into the atmosphere when the crop is burnt is being removed by the crop whilst it is growing.

And so it is carbon neutral or at least it can be if the crop is being grown as fast as it is being burnt.

However, the land that is being used to grow the crops for biomass cannot be used to grow crops for food production either for humans to eat or to feed to animals.

And then we eat the animals.

So it changes the use of the land from growing crops for food to growing crops for energy.

So there are a number of significant implications with growing biomass for fuel production that need to be considered.

So burning biomass to generate electricity produces pollution.

True or false? So you should have said that that is true and that is true because burning anything will produce greenhouse gases and other pollutants.

Well done if you got that.

Now we can generate steam by other hot things including very hot rocks.

So the inside of the Earth is extremely hot, hot enough to melt rock into its liquid form.

And we see that coming outta volcanoes in the form of lava.

But in some parts of the world that very hot rock is near enough to the Earth's surface for us to use that energy to generate steam.

Now this is only true in very specific parts of the world, such as Iceland for instance.

And you can see in the picture there a geothermal power station in Iceland, which is using very hot rocks to heat water into steam.

And once the steam has been heated, it can then be used in exactly the same way as it is in an oil, gas or biomass power station by turning the turbines which turns the electrical generator and generates electricity.

Now when hot rock is used to heat water into steam, it is called geothermal Geo meaning of the ground and thermal meaning heating.

So geothermal electricity is ground heating electricity, electricity produced when the ground heats water.

Now geothermal electricity is a renewable energy source because volcanic activity and the energy from the Earth itself is being used and that isn't going to run out anytime soon.

However, not many places across the world have hot rocks sufficiently close to the surface for them to be very easily usable.

The benefit of geothermal electricity is the production of electricity produces very few greenhouse gas emissions.

However, geothermal power stations have to be cited relatively far away from populated areas because the process of digging the ground in order to access the hot rocks can cause earthquakes.

And so we wouldn't want that to happen near a populated area.

So they have to be cited safely out of the way.

So geothermal electricity is renewable, but it has some restrictions on it.

So geothermal power stations can be built wherever there is space.

True or false? Okay, so you should have said that that is false and that is false because there are only a few places in the world with sufficiently hot rocks close to the surface that can be accessed for geothermal power stations.

So let's summarise this section of the lesson by matching each method for generating electricity on the left with the correct description on the right.

So pause the video and come back to me when you're ready.

Okay, let's check our work.

So you should have said that biomass is the burning of wood to produce moving steam to spin turbines that gas is burning non-renewable energy resources to generate electricity.

Geothermal is generating electricity using steam with very few greenhouse gas emissions.

Hydroelectric is electricity from falling water and wind is electricity from moving air.

Well done if you've got all of those correctly matched.

Do amend your work if you've made any mistakes, but make sure you do it neatly so that it's still obvious which word matches with which correct description and well done.

Okay, let's move on to the last section of our lesson now, which is about producing electricity using solar panels.

So solar panels produce electricity without the need for an electric generator.

So this is a completely different type of energy generation.

And solar panels contain instead of little turbines that get spun, they contain lots of semiconductor crystals.

And what happens is that the radiation from the sun produces a voltage across each of those semiconductor crystals.

And because there are lots of crystals within each solar panel and lots of solar panels can be connected together, a large enough electric current can be produced in order to provide electricity for that building.

Now other aspects of a solar panel need to be incorporated to make sure that that electricity is being used as efficiently and completely as possible.

So as well as the semiconductor crystals which are converting radiation into electricity, there is also a device called an inverter.

And this converts the current from the solar panels into main's electricity, which can be used in the home.

And that means that the electricity that is being produced by the solar panel can usefully be used in all of the electrical devices within the house because it's using the electricity at a current and voltage that is suitable for all of those devices just as main's electricity is.

In addition to this, solar panels can also store electricity in batteries.

So the electricity that is being generated by the solar panels, if it's not being used immediately within the home, can be used to charge batteries instead.

And that provides a backup supply of electricity for when it isn't sunny enough or when it is dark.

Now those batteries that are storing charge are like the batteries that we find within electric vehicles and you can see those in the picture there.

These batteries just like little batteries that power little devices are just stores of electricity in a chemical form.

And then the electricity is able to be converted using the inverter back into main's electricity that can run through the electricity supply within the house.

So if the electricity is being used straight from the panels, it goes straight to the devices that are needing it.

But if it's not needed immediately it can be stored in the batteries instead and used at a later date and that means that it's not wasted.

Alternatively, it can be sold back to the main's grid and used in somebody else's house or business.

Now there have been rapid advances in solar panel technology over the last 20 years or so because the demand for them has increased and so there's been more investment available to advance that technology.

And that has meant that solar panels are much less expensive than they were and they are much more efficient.

They're also being used in large solar farms. So instead of growing crops, some farmers are converting their fields to solar panels instead.

And that's able to produce large quantities of electricity, which can supply many homes or businesses via the national grid via the main electricity supply.

And this means that electricity can be produced by solar panels throughout the year.

However, electricity from solar panels cannot be produced when it is dark unless electricity is produced on cloudy or dull days.

However, producing electricity using solar panels does not emit greenhouse gases or other pollutants.

Except when the solar panels are being manufactured and installed in the first place.

So true or false? Solar panels can be used to provide electricity to a house during the night.

So this is true and it is true because solar panels can be used to charge batteries that then provide electricity when the sun is set.

So let's summarise this last section of our lesson by considering these statements about solar power.

And I'd like you to decide whether you are sure this is correct, whether you think it's correct, whether you think it's incorrect or whether you are sure it is incorrect.

So read the statements, make up your mind, pause the video and come back to me when you're ready.

Okay, let's review your work.

So for the first statement, radiation from the sun is a renewable energy resource.

You should have said that that is correct.

For the second statement, solar farms can help reduce greenhouse gas emissions.

You should have said that that is correct.

And for the third statement, every home can have solar panels installed.

You should have said that that is incorrect.

Well done if you got all of those answered correctly.

Good work.

Okay, we've reached the end of our lesson today.

And in our lesson we have seen how an electrical generator is a machine that generates electricity by spinning electrical coils through a magnetic field.

Now a turbine is a series of angled blades on a shaft that can be used to turn the electrical generator in order to generate electricity.

Now electricity can be generated using wind, falling water or radiation from the sun.

And these are all examples of renewable energy resources because they are being replenished faster than they are used up.

So none of them will run out.

Biomass can be burned to make steam, which can be used to turn a turbine and it is a sustainable energy resource if it can be replaced as quickly as it is used up.

Whereas gas and oil can also be used to make steam when they are burnt.

But these are non-renewable energy resources because they cannot be replenished and they will run out.

So I hope you found our lesson today interesting.

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

Bye.