Lesson 3C: The Future Is Green

Teacher: Lately, there has been a lot of talk about renewable sources of energy. But, before we say something more about them, we’re going to talk about the non-renewable ones. Okay? Do you know of some examples of non-renewable energy sources?

Students: Oil… Coal…

Teacher: That’s right: first we have oil. People pump oil from deep underground. We use it to make electricity, and as fuel in our cars. There are many everyday products made from oil, including plastic bags, paint and crayons! But did you know that producing electricity from oil is more expensive than from other fossil fuels, such as coal or gas? Also, burning oil produces carbon dioxide.

Then there’s gas. People pull natural gas out of the ground. We usually use it for cooking and heating. It’s relatively cheap and easy to transport gas through pipes, so people still use it a lot. But it also has some downsides: burning gas produces carbon dioxide!

I also heard someone mention coal: well done! People mine coal from the ground. When we burn it, it produces heat. It is also relatively cheap, and there are still many coal reserves. But coal is the worst pollutant we have. As is the case with oil and gas, burning coal also produces carbon dioxide.

Teacher: Now that we’ve discussed non-renewable energy, we can move on to renewable types of energy. Do you know of some renewable energy sources?

Students: Sun… Waves…

Teacher: Well done! You already know that there are several types of renewable energy sources. But now I’ll tell you a bit more about each of them, so you can understand them better.

Let’s start with solar energy. As you know, this type of renewable energy comes from the sun. People use solar panels to turn sunlight into electricity. We use this collected energy to get light, to charge our smartphones, to power many different electric devices that we use every day, and to keep our homes warm or cool. But sunlight can only be collected during the day, when it is sunny. It can be stored, but the process is quite expensive.

Then there’s wind power. You know that wind turbines can be seen in areas with strong winds. A group of wind turbines is called a wind farm. These turbines convert wind energy into electricity. The problem with them is that, if there’s no wind or if it isn’t strong enough, then they can’t produce enough power. Wind turbines can also cause noise pollution, because they can be very, very noisy.

Next we have hydropower. This is a type of energy that is produced by the movement of water. In short: dams block a river, and when the water is released, the huge pressure turns turbines in the dams and produces electricity. The negative side to this energy source is that dams can change and destroy habitats near rivers.

The last renewable type of energy that you will learn about today is geothermal energy. This is actually heat from under the Earth’s surface. A geothermal power plant turns the heat from hot water, two or three kilometres deep in the Earth, into energy. The negative side of this energy source is that toxic gas below Earth’s surface can get into the atmosphere.