Note: This is the first of a series of blog posts I will be writing that discuss the different types of energy we use in our society and how the various methods of energy extraction and use affect our planet and society.
You can’t turn on a news channel or visit a news media website without finding a discussion about energy use in our society. This could take the form of political debates in Washington about whether we should build the Keystone Pipeline (see argument against it here, which I happen to agree with) , or reports about the newest, most efficient solar cell, or the effect of burning coal on global warming and climate change. No matter the topic, it is clear that energy plays a central role in the operations of our society. But why is that? What is energy, why do we need it, and how do we extract it?
These are basic questions, but important ones that begin our journey to learn about energy in our society. We all take energy for granted: turning on a light switch, mowing the lawn, tending a garden. But it turns out that how you get the electricity required to turn on your light or how that gasoline for your lawn mover was extracted has huge consequences on the planet, not to mention the global economical landscape. For this reason, it seems important for all citizens to understand the basics of what goes into energy extraction and dissemination. Beyond the social reasons, it is a fascinating topic that will take us to the ends of the universe, to stars bubbling with nuclear reactions, to the smallest of the small where electrons behave unlike any object you’ve ever seen, and to the limits of human ingenuity that push our energy use into a new, cleaner era. I hope you will join me on this series of blog posts exploring the ways we interact with the planet to access energy, and see how important it is to mindfully and scientifically choose methods that reduce our impact on the local ecology and climate to preserve a sustainable future for our children.
What is Energy?
Ask anyone on the street what energy is and I’m sure the first response will be hesitation. We all have a sense of it, but to actually define it in some concrete sense quickly becomes difficult. This is because energy is the chameleon of the physics world, easily changing forms that look nothing alike but still maintaining the same potential to be used. Put simply, energy is responsible for all processes you could ever possibly see in the universe. For example, it’s responsible for this supernova remnant:
And the chaotic, fiery nature of stars, including our Sun (which is extremely important to us!):
But also on the smaller scale, it is responsible for this, the inner workings of your digestive system:
Without energy, your food wouldn’t be digested, fusion reactions wouldn’t convert hydrogen to helium in the Sun, electrons would stand still (ignoring quantum effects) in a circuit, and you couldn’t even make your body move! So how can the concept of energy possibly be applied to completely different phenomena? The rawest physics definition of energy is the capacity of a system to do work. Well, this just creates more questions: first, what is a system? A system is defined as simply the part of the world we want to investigate. Everything else not included is called the environment. For example, if we want to examine the supernova above, the system is the supernova, and the environment is the rest of space and all the particles and objects in it that surround the supernova. In the case of digestion, the system would be all the parts of the body involved in digestion. Defining the system allows us to then account for all the particles within a certain boundary, and then we can keep track of these particles or objects in detail and see what they do and how they interact within the system. The system can also interact with the environment, but since we haven’t been keeping track of the details of the environment, we can’t say as much about this interaction.
Okay, so we find some set of particles we’re interested in and define them as our system. Then energy is the capacity for these particles to do work. So what is work? Physicists define work using a simple equation: Work = Force * Distance. There are some finer details within this equation, but the main idea is that with lots of energy, you can do lots of work, which lets you either use a lot more force to move a short distance, or use a little force to move a much longer distance (based on the rules of multiplication). Either way, the key point is that energy allows us to manipulate everything around us by applying forces. Without energy, this just isn’t possible.
Wherever you are reading this, look out your window. What do you see? Maybe some leaves on a tree blowing in the wind? In this case, we define our system as the wind and the leaves. The leaves are moving (technically, accelerating) in different directions, so this means that they must be feeling some force, which in this case is from the wind. This in turn means that the wind must have energy (this is the basis for wind energy devices such as the giant windmills being erected across the plains of the Midwest). But here’s another important point: as the wind moves the leaves, it loses some of its energy, giving it to the leaves so they can move. Energy cannot be created nor destroyed, but it can be transformed. And that transformation is the key to all the dynamics and diversity of the universe as well as to all our energy technology. In this case, the energy was contained in the movement of all the air particles in the wind, but as soon as they hit the leaves, this energy transfers to the leaves and transforms into the movement of the particles in the leaves. This is a fairly mundane example, but we will explore much more exciting types of energy transformation related to energy technology, such as energy found in the bonds between atoms being transformed into electricity we can harness!
So, to recap, the energy of a system is its capacity to do work, which allows that system to apply forces and change parts of other systems around it. Energy is the most fundamental and flexible part of our universe. Without energy, we or anything else wouldn’t be able to change anything in our environment. We wouldn’t be able to stand up, open a door, swing a baseball bat, write a love letter, dream, or shoot rocket ships to the moon. For this reason, energy is the physical cornerstone of any society, but for us things become more complicated because we have specific reasons to use energy to apply specific forces to do specific things. The random motions of wind pushing leaves around doesn’t help us. We want to use energy to push electrons through a circuit to make a light bulb glow. Or, we want to move a car along a highway (notice in any example, there is always a force being applied – to electrons, to pistons that turn the car wheels, to something always!). So the crucial goal of energy technology is devising novel ways to find sources of energy, extract it in controlled ways, and then apply it with purpose to manipulate our environment in a helpful way. This has a host of consequences on the environment, either based on how we extract energy or how we use it, which is most often ignored in a capitalistic society when considering energy costs. But this will be a central focus of this blog.
And What Type of Energy Are You?
A final point to make is that energy can take varying forms based on its usefulness. The two major types of energy are potential energy and kinetic energy. Potential energy can take many forms, but in terms of energy use, it is helpful because it is easily stored. Examples include chemical potential energy stored in chemical bonds as in this CH4 molecule:
or the gravitational potential energy stored in any object at a high height that feels the force of gravity (think of a water wheel):
Now, if we consider this water wheel, we can think about the water at the top of the wheel being stationary but with a lot of a potential energy. As gravity pulls it down, this potential energy transforms into kinetic energy of the wheel (and a bit in the water that’s now falling faster – remember, energy is conserved but fluidly transfers between objects. In this case, some of the water’s potential energy transforms to its own kinetic energy as well as the wheel’s kinetic energy). So, we had this one type of energy – potential energy – stored in the water that is now making the water wheel move. Whenever energy is associated with motion of an object, or, in physics-speak, the velocity of the object, then we say that it is kinetic energy. So here, the potential energy stored in the water at a high height is converted to kinetic energy in the wheel, which now spins and is probably connected to gears inside that do something useful, like milling flour, perhaps.
But here’s the rub, and one of the reasons why so much money and effort goes into improving technology for energy extraction and use. Remember, the water has a lot of potential energy stored in it sitting at the top of the wheel. Now, one can ask, is ALL the energy stored in the water transferred to the wheel. That is, can we use all the energy to do work by moving the water wheel at a high velocity and applying forces to the gears in the mill? The answer is ALWAYS NO. There will always be some energy lost that does not go into the useful work done – this could be energy transformed into sound (you hear the water splashing against the wheel) or heat from friction (probably not much in this case, but a little between the water and wheel), or other sources. And even more so, depending on the type of technology used, more or less energy is wasted – so it is a central goal of technology to find devices that provide us energy that create as little waste energy as possible. We will return to this idea time and time again, but in the energy business, it is known as efficiency, and is intimately connected to a deep physical concept known as entropy.
And where does this waste energy go? This waste energy can take many forms, as we will see, some of which could be very harmful to the surrounding environment. This is what we mean by clean energy sources: it is those sources by which energy extraction and the conversion between forms of energy does not create waste products that damage the surrounding ecosystem (and the impacted ecosystem could be quite large, if we consider weather patterns and how far pollutants from waste can travel!).
Where Do We Go From Here?
This was a lot of introductory information, and hopefully not too dry, but I promise that this is a foundation that takes us to exciting places! We’ll continue to apply these basic concepts to very cool technologies as we explore all the possible ways we harness the energy around us. The key points to remember are:
1) Energy is the capacity to do work and is the source of all movement and change in our universe. It’s truly difficult to imagine a universe without energy, but it would completely static. And therefore, to the human mind, excruciatingly boring.
2) Energy is a chameleon – it can never be created or destroyed (i.e., conservation) but it can be transformed into many colors that at first glance seem completely different. But it’s all still energy.
3) Energy can be stored in forms of potential energy and transformed into kinetic energy associated with motion which can be used to do work. You can never directly transform all your stored energy into useful work – some is always lost as waste. We are always looking for better devices and tools that minimize the amount of waste energy created.
4) As a society that values technology that improves our quality of life or simply gives us pleasure, energy is the foundation that allows us to manipulate our environment (through applying forces) to make it more amenable for our basic needs and lifestyle choices.
5) The area of energy technology is about finding the most cost-effective, efficient ways to extract and apply energy from sources on the planet. The sustainable movement, which I absolutely endorse, believes this is not enough; we must also extract and use sources of energy in a way that minimizes its impact on the planet.
In the next post in this series, we’ll take a look at why all this energy is available to us (hint: the giant ball of energy in our sky!) in the first place and what forms it takes – this will lead us into discussing the possible energy sources available to our society. Stay tuned!