Vikram Janardhan - Energy Explained: Conventional Energy and Alternative

The World of Energy

T he collection of economic, environmental, and political forces that we know as the energy industry is one of the most complex and influential in the world. In fact, its not unreasonable to say that most of what we take for granted in our day-to-day lives would not be possible without a steady supply of affordable energy on a global scale.

Of course, it wasnt all that long ago we humans were rather preoccupied with chopping firewood, caring for draft animals, and making sure we had enough food to eat (i.e., tending to the engines that drove our survival). Over the past two hundred years or so, however, things have changed dramatically. Since the industrial revolution, human beings have used their smarts to get more done with less effort. From early steam engines to jet aircraft to photovoltaic cells, weve been on quite a tear.

Now it looks like we might be in for another dramatic change, and this time not necessarily for the better. The realities of climate change and environmental pollution have made us realize that it might not be possible to continue in the manner to which weve become accustomed.

If youre feeling a bit apprehensive at this point, dont worry. The first step in understanding the energy landscape is to admit that this subject is big, complex, and at times scary. Were talking about an industry that spans the globe and generates trillions of dollars of revenue every year.

Everything about energy is gigantic: Energy is measured and expressed in megawatts (of electricity) or billions (of barrels of oil) or gigatons (of carbon released into the air), and our electricity grid is the largest machine in the world. Energy has its share of drama, too. Monopolies have driven competition out of markets, blackouts have wiped out billions of dollars of productivity, and energy issues have fanned the flames of war.

The industry can also be rather opaque in that many aspects of how our energy systems work are not clear to the average person. It is quite likely that Joe Sixpack may be able to spout stats on his favorite sports team but not have a clue about what goes into the price of a gallon of gasoline.

This book attempts to demystify the intricacies of the energy world, and this opening part is sort of like an overture to a big, loud, and dramatic symphony. Well spend a little time first on why this subject has become so important in recent years. Next well take a quick look at the science and history of energy, and well finish up with some thoughts about where were headed. If we do our job right, youll finish this first part eager to dig into the others.

What Is Energy?

This is actually a rather difficult question to answer for most peopleit seems so obvious, and yet its hard to put into words. Its easier to talk about what energy is used to do. Animals use the energy in food to run all the bodily functions that keep them alive. Mick Jagger uses a great deal of energy strutting around the stage (even in his sixties!), and cars convert the energy in gasoline into mechanical motion that turns the wheels and takes us to work.

In science, energy is defined simply as the ability to do work, which in some situations refers to the movement of a mass over a certain distance. So, energy might be used to move a hockey puck from a players stick to the goalies glove, or perhaps the back of the net, in a happier scenario for the shooter. Even in a less obvious example like a growing plant, the principle is the same. The cell division process that drives growth still amounts to work, scientifically speaking, and so it requires energy.

In some ways, energy is like volume, weight or temperature in that it is simply another property of an objectits just that you cant see it, touch it or otherwise sense it directly. It also comes in many forms, as well see in the following section.

Evidence of Energy

Energy is divided into two broad categories, potential and kinetic. Kinetic energy is the one were most familiar withthats the kind used in the movement of objects. Potential energy is perhaps best described as energy that is stored. For example, if you pull a rubber band so it stretches out, and hold it there, the energy of that movement is now stored in the material. It is called potential energy because its just there, not doing anything. If you let go of one end of the rubber band and cause it to fly across the room and strike your classmate in the head, well then the potential energy in the rubber band has been changed into the kinetic energy of movement. Batteries also store energy in the form of chemical potential energy, which can be released when the battery is placed into an electric circuit.

Well talk more about energy storage later, but for most of this book well be concerned with the kinetic variety. Within that category, there are many kinds of energy:

n Thermal energy appears as heat.

n Chemical energy is derived from the bonds between molecules.

n Mass energyotherwise known as nuclear energycomes from the structure of atoms.

n Electromagnetic energy covers a range of forms from radio and TV waves to x-rays, infrared and visible light.

n Radiant energy or solar energy is a combination of electromagnetic energy (light, UV rays) and thermal energy (heat).

All of these forms of energy occur in different ways in nature, but they all share the same basic principle. That is, that some force acting on some object produces a change in that object, whether its location, temperature, chemical makeup, or luminosity (brightness).

Like matter, energy cannot be created or destroyed. It can only be changed from one form to another. Thats the heart of the Law of Conservation of Energy, one of the cornerstones of our understanding of the physical world. We talk about producing or generating energy in this book, but we should be clear about how were using these terms. When we say produce energy, in many cases we mean extract (as in oil producers extract crude oil from wells), or convert (as in power plants convert some of the energy contained in coal into electrical energy). For the record, were not rewriting the laws of physics. We simply want to use words that will convey what we need to explain in the simplest possible way.

Finally, there is another important distinction we should make, and that has to do with the difference between energy and power. In science, power is simply the rate at which energy is being used, and is expressed in units that mean essentially energy used per unit of time. People often use energy and power interchangeably in conversation, and weve done that in some parts of this book, again with the goal of conveying a larger concept.

So, our apologies to the physicists, engineers, and others who might bristle at our calculated misuse of scientific terms, but were on a mission for energy literacy here and you know what they say about omelets and breaking eggs.

The Prodigal Sun

All hail the sun, the source of (almost) all the energy resources on earth. It might not be immediately obvious, but with the exception of geothermal and nuclear energy, all of the energy we use can be traced back to our local star.

Solar power, obviously, converts the suns rays into electric energy and solar thermal panels can heat your homes supply of hot water. The sun also warms the earth as a whole, but not evenly, and the resulting movement of air is used to generate electricity by converting the kinetic energy of the wind into electrical energy. Even fossil fuels like oil, coal, and natural gas are simply concentrations of millions of years of the suns energy collected by plants. The wood you burn in your fireplace is the samea store of solar energy in the convenient form of a sturdy plant that can be converted to heat, light, and smoke with the help of a little kindling and a match.