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.
