Harnessing Energy and How Fossil Fuels are Used
Any form of energy we use needs to fulfill certain criteria to be practical on a global scale. If you were assigned the task of designing the most efficient form of energy imaginable to use on our planet, what are some of the characteristics you would have to keep in mind?
Cheap is a must—the global economy is driven by the possession and control of sources of energy. (This is certainly one of the factors we seem to value most in an energy source, as demonstrated by the fact that very few people are prepared to switch from something cheaper such as fossil fuels to something more expensive, as greener sources of energy tend to be, even if it's better for the planet in other respects.) You would want it to be energy-dense, which refers to getting a lot of energy out of a small unit of volume. Otherwise, it would be difficult to use in objects that are mobile and carry their engines with them, such as cars and planes. And you would want it to be easy to store and transport since energy use is needed everywhere, not just where it was obtained in the first place. Finally, you would want to have an endless supply of it, with no possibility that it will run out anytime soon. Ideally, you would also want it to be clean without any adverse effects on either people or the environment. Here's a summary of the factors to consider in an ideal energy source:
• Easily stored
• Easily transported
• Endless supply
Fossil fuels such as gasoline and coal have many features on the list, in fact all but the last two. They are certainly cheap. The next time you are inclined to complain about the rising price of gasoline, think about it this way: the amount of energy you get from a gallon of gasoline is equivalent to what a human being can do with his or her bare hands in the form of manual labour in about 400 hours. (Think of how far that gallon of gasoline will take your family in a car, and now imagine pushing that car filled with your family the same distance by your own sheer brute strength!) At minimum wage, that gallon of gasoline is estimated to be worth more than $3,000 in man-hours. In that context, it's extremely cheap.
Fossil fuels are also energy-dense: the amount of energy you can get from a gallon of gasoline is significant for the volume it occupies. A battery would have to be much bigger in volume to contain the same amount of energy, at least with current battery technology. A windmill or a solar panel would have to be larger still. And fossil fuels are definitely easy to store and transport. Depending on where you live, you may not necessarily see too many oil pipelines, but trains carrying carloads of coal have likely held you at a railroad crossing at some point in your life, and if you live near a commercial seaway, you've probably seen cargo ships loaded with coal or oil go by.
Fossil fuels have the first four features listed that you would want in a source of energy, better than anything else we've come up with so far. But fossil fuels aren't renewable. Given the millions of years required to produce them, they will run out eventually based on our ever-increasing rate of consumption over the last few centuries. And of course, there are the adverse effects of using them, including air pollution, acid rain, respiratory health problems, and greenhouse gases (a topic discussed in much greater detail in the next chapter). To be fair, the human species decided long before you and I were born that fossil fuels would be the backbone of our global economy; also, the negative aspects of their use were not really understood when they were first being used, at least not to the extent that we understand these issues today.
Energy Sources in Days of Old
To understand how fossil fuels have transformed our world, first try to imagine living on Earth about 300 years ago. Think of any pioneer village you might have visited, perhaps on a school trip. In that bygone era, you likely would have lived on a farm because most people were agrarian at that time. Families had to be self-sufficient, little microcosms of civilization; producing your own food was essential. To do this you would have lived in a farmhouse that you built yourself, or perhaps your father or grandfather built with the intention that it be passed down from generation to generation. The women in the family would have sewn the clothes you and your family wore. (My apologies to those offended by any gender inequalities in that statement, but it was a simple fact of the times that the tasks requiring less physical strength were usually handled by the women of the family; this included cooking, cleaning, and sewing.) The heat needed to keep your farmhouse warm and for cooking would have come from wood-burning. The light needed at night would have come either from candles made out of animal fat or beeswax or possibly from oil-burning lamps, with plant oils such as olive oil commonly used.
Manual labour was the way that things got done on the farm in those days, so you would have milked the cattle, slaughtered the pigs, and shorn the sheep all by hand. If your farm was near a river, you might have had a waterwheel to help generate some additional energy for you and your family. You even might have had a windmill if you were fortunate enough to have access to some reasonable winds. You would have tilled your fields with the help of beasts of burden such as oxen. And if you wanted to travel to visit the nearest town, you would have used horses to get there, most likely riding horseback, although if you were a bit more aristocratic, you might have been able to go in style with a stagecoach.
The way you lived would have been much the same as it had been for those who came before you, literally for hundreds of years. Whether someone from the eighteenth century was a farmer eking out a living or the king of a vast empire, the energy available to the population at large came predominantly from people and animals, wood and plant oils, and to a lesser extent wind and water. Fossil fuels, so prevalent in today's society and on which our current social, political, and economic standards are based, were untapped resources back then. Coal was known, for sure, but no practical way of harnessing its power existed.
The Industrial Revolution
All of that changed with something known as the steam engine, invented nearly 250 years ago. The steam engine produces mechanical work such as an up-and-down or back-and-forth motion, with the energy from steam pushing on the engine's parts and making them move. Although there had been earlier versions, the one invented by James Watt around 1770 became the most successful, partly because it used the combustion of coal to produce the steam more efficiently than earlier models, and partly because it incorporated a modification that produced a rotary motion rather than simply back-and-forth or up-and-down. This was much better suited for use in factories.
The steam engine was able to extract the energy stored in fossil fuels on a wide scale for the first time in our civilization's history. The coal was burned in a combustion chamber and provided the heat to convert water into steam in a boiler. The expanded steam pushed against pistons, providing the energy to power the machinery and turn a wheel. The turning of a wheel produces a rotational energy similar to that created by wind turning a windmill or a moving river turning a waterwheel, but in this case the process was no longer dependent on a windy day or a raging river, both of which are far less reliable or consistent. Once the steam had cooled and used up most of its energy, it would no longer have enough pressure to be useful and would be vented into the atmosphere.