Video: Methods of Energy Production

In this lesson, we will learn how to describe which energy sources are renewable and which energy sources are non-renewable.


Video Transcript

In this video, we’re talking about methods of energy production. As we’ll see, energy can be produced in all kinds of different ways. And the various methods have different biproducts, things that are produced from that energy production method. These biproducts become of interest when we consider the Earth and its overall environment. As we get started, let’s first consider this question of just what we mean when we say energy production. Energy, after all, is not something that’s necessarily tangible to us. It’s not something we can feel or see or hear. So, how is it we go about producing this thing called energy?

We can recall that, in general, energy is the ability to do work. In other words, it’s the capacity to exert some amount of force over some amount of distance. So, if we produce energy, that means we’re creating the capacity for something to do work. In general, there are lots of different kinds of energy. There’s mechanical energy. There’s heat energy. There’s electrical energy. But of all the energy types, in this video, we will focus on electrical energy production. That’s the form of energy that’s most commonly useful on a large scale.

So, for our purposes, when we talk about energy production, we’re talking about the ability to produce electrical energy. When it comes to the particular methods we could use to generate electrical energy, those methods generally divide into two categories. The first category is called renewable energy production. Renewable energy sources are sources that are not depleted when they’re used. Examples of renewable sources of energy are the wind. When we consider the operation of a windmill, we see that the turning of the rotors of a windmill doesn’t diminish the wind at all.

Or another source of renewable energy is the sun, solar energy. And we see this from the fact that if we set out a big array of solar panels devices to capture sunlight, the energy produced by those panels in no way diminishes the sun’s energy. This is what it means then for an energy source to be renewable. And we see that another example of this is hydropower, energy acquired from the movement of water. So, that’s one category of methods for producing energy, using renewable sources, or sources that don’t run out as they’re being used.

And then, the other category for methods that produce energy use what are called nonrenewable sources. These are sources that do run out while they’re being used. And they include things like oil, gas, coal, and nuclear fuel. So, for example, say that we have a chunk of coal and then we burn this coal in order to release energy. Burning this lump of coal indeed does that. And that energy is able to be converted to electrical energy. But in the process, this coal that we’re using burns up; it’s used up. So, we can see how this is different from the renewable sources, such as wind and sunlight, that are also used to generate energy.

And just as coal is used up as it’s burned and energy is released from it, so the same thing happens to gas and oil. Now, nuclear energy may seem a bit different because there’s no burning in that process. Instead, nuclear energy is produced by the process of nuclear fission, the splitting of atomic nuclei into smaller pieces. But because the nuclear fuel that goes into generating energy indeed does break down by splitting apart, we can say that nuclear fuel is nonrenewable as well. That’s because getting energy out of this source changes the source; it diminishes it.

Now, when it comes to renewable and nonrenewable energy sources, there are other sources besides the ones we’ve listed here. What we’re seeing here is just a sampling of these different types of energy sources. Along with the difference between these two types of sources that we understand from their names, there’s yet another difference between them. While renewable energy sources typically don’t emit gases or other biproducts when they’re used to generate energy, nonrenewable sources generally do.

For example, going back to our chunk of burning coal, in the process of combusting, of burning up, gases including carbon dioxide — we can represent that as CO₂ — are released into the environment. And it turns out that it’s not just burning coal that releases carbon dioxide, but burning oil or gas does the same thing. Nuclear sources, when they’re used to generate energy, do not give off gases like oil, gas, and coal do. But one thing it does do is create nuclear waste, radioactive material that needs to be stored and carefully shielded for long periods of time.

So, we see that while renewable sources are able to create electricity without generating significant biproducts, nonrenewable sources are different. They do generate electricity, but also some other things that we might not want. When it comes to these undesired biproducts, some of them fall into a particular category called greenhouse gases, of which carbon dioxide is an example. As we consider this phrase, greenhouse gases, let’s first consider just what a greenhouse is and how it works.

Say that we had some plants, and we wanted these plants to be able to grow and flourish even in cold temperatures, say, through the winter season. To help the plants to do that, we might put them in what’s called a greenhouse, which is literally an enclosure made of glass. The glass is transparent so that when sunlight shines on it, it’s able to go straight through the glass and to the plants or the floor of the greenhouse. The sun heats up the interior of the greenhouse, and that heat is radiated back outward.

Now, if it weren’t for the greenhouse, that is, it weren’t for these glass walls and roof, that heat would just radiate out into the atmosphere and be lost. But because the glass is there, the heat bounces off the glass back into the greenhouse and is able to keep the interior warm. The construction of a greenhouse is such that light can come in but heat can’t escape. So, the heat generated by the sunlight is able to be kept inside the house. This raises the temperature inside the greenhouse and lets the plants thrive even in colder weather.

So, we’ve seen that a greenhouse lets sunlight in but keeps heat from escaping. So, if we then consider what a greenhouse gas is, to understand this, we’ll need to think in terms of the entire Earth, as well as the layer of atmosphere surrounding the Earth. Now, just like with a greenhouse, when sunlight comes in, greenhouse gases let that light pass through and then it reaches the surface of the Earth. The Earth heats up a bit and radiates some of that heat back into the atmosphere.

That radiated heat would have no problem continuing on leaving Earth’s atmosphere and letting the Earth cool down to its original temperature, we could say. Unless there’s a gas in the atmosphere that blocks this radiated heat from escaping. When a gas like this is present, the radiated heat actually reflects back to the Earth. We see how this is like the effect of a greenhouse and, therefore, how such a gas gets the name greenhouse gas.

Overall these gases prevent infrared radiation or heat energy from escaping Earth’s atmosphere. They trap that energy in the system, which contributes to warming up the system overall. When it comes to specific greenhouse gases, gases that prevent heat from escaping Earth’s atmosphere, by far the most common is water vapor H₂O. The next most common greenhouse gas is carbon dioxide CO₂. Then, comes methane and then a gas called nitrous oxide than ozone and so forth and so on.

From this list, we can see that some of our nonrenewable energy sources, oil, gas, and coal, for example, give off a greenhouse gas in the process of extracting energy from them. Knowing this helps us better understand the effects of using these energy sources. Let’s get a bit of practice now using these ideas of renewable and nonrenewable energy sources as well as greenhouse gases and how they work through an example exercise.

Which of the following are greenhouse gases? a) Carbon dioxide. b) Oxygen. c) Nitrogen. d) Argon. e) Methane.

As we get started answering this question, let’s remind ourselves just what a greenhouse gas is. If we consider the system of our Earth and the atmosphere surrounding it, then there’s a normal thermal process that goes on as sunlight reaches the Earth. As light comes from the sun and lands on the surface of the Earth, the Earth heats up in response. This heat is then radiated off the surface of the Earth and back out through the atmosphere and then into space. This is how the process would work unless there’s something in the atmosphere that blocks the heat from escaping.

It’s possible for there to be certain gases in the atmosphere so that exactly this happens. The heat that normally would escape from the Earth out into space is reflected back towards Earth. These gases, because they let sunlight pass through them but they block heat trying to escape, are known as greenhouse gases. That is, they work very much the same way that a greenhouse works for keeping plants warm. So, a greenhouse gas is an atmospheric gas that’s responsible for blocking the radiation of heat.

When we think about Earth’s atmosphere, the most common gases in that atmosphere are, in order, nitrogen, then oxygen, and then argon. None of these gases are responsible for trapping heat inside Earth’s system. On the other hand, the gas carbon dioxide, symbolized CO₂, is the second most common greenhouse gas after water vapor. And then, answer option e, methane, is also a known greenhouse gas. It’s a gas that effectively traps heat inside Earth’s atmosphere. So, in answer to our question, we choose answer options a and e; carbon dioxide and methane are both greenhouse gases.

Let’s look now at a second example exercise.

Which of the following types of power station release carbon dioxide into the atmosphere? a) A nuclear power station. b) A coal power station. c) A gas power station. d) A solar farm. e) A wind farm.

Okay, so, considering these five different types of power station, we want to know which ones release this gas, carbon dioxide, into the atmosphere in the process of generating power. Now, the fact that we’re talking about releasing a gas into the atmosphere as a biproduct of power generation means that we’re talking about a certain category of power generation. We can think in terms of the broad categories of renewable energy sources and nonrenewable energy sources. The difference between these is that if a source is renewable, that means that it is not depleted as it generates energy, whereas nonrenewable sources are depleted as energy is extracted from them.

So, for example, if we had an array of solar panels, panels that take in sun energy and convert it to electrical energy, we can see that the generation of energy by this process in no way depletes or diminishes the energy of the source, the sunlight. Generating energy by solar means, then, is an example of using a renewable source. This distinction between renewable and nonrenewable energy sources is important when we realize that the release of carbon dioxide that the problem statement talks about is a result of a process of combustion, that is, something burning.

The two standard products of combustion are carbon dioxide, CO₂, and water. Whatever types of power station release carbon dioxide into the atmosphere will be types that involve some sort of burning, some combustion process. So, among our answer options we’ll look for sources that require combustion for extracting their energy. As we go down our list, then, considering a, b, c, d, and e, we can see that both options d, a solar farm, and option e, a wind farm, are renewable sources.

The sunlight and wind that generate energy in these farms, respectively, is not depleted by being used up to generate electricity. Moreover, getting energy from these sources does not involve combustion, and as a result, they don’t release carbon dioxide into the atmosphere. So, we’ll cross out options e and d from our list of candidates.

Considering option a, a nuclear power station, we know that this kind of source uses nuclear fission to generate energy. It’s not a burning or combustion process, but rather a splitting process, where larger atoms split into smaller ones, that’s responsible for the generation of power from this type of power station. Since no combustion is involved in nuclear power generation, we’ll cross off this possibility as a type of power station that can release CO₂.

This leaves us with coal and gas power stations. For both of these types, there is combustion that goes on; the coal is burned and the gas is burned to generate energy. As these fuels are burned, they release the products of combustion, carbon dioxide and water. And therefore, both these types of power station release CO₂, carbon dioxide, into the atmosphere.

Let’s take a moment now to summarize what we’ve learned about methods of energy production. Starting off, we saw that energy is the ability to do work, that is, to exert some amount of force over some distance. We saw further that energy is produced by two types of sources. Renewable sources, which are not depleted with use. Examples of this include solar power or wind power. And nonrenewable sources, which are depleted as they’re used. These are sources such as oil, coal, or gas, or nuclear fuel.

Additionally, we learned that greenhouse gases are gases in the atmosphere that block heat from leaving the atmosphere and reflect it back to Earth. Lastly, we saw that the most common types of greenhouse gases are, in order, water vapor, carbon dioxide, and methane.

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