Power Hungry

by Robert Bryce

  One watt is equal to 1 joule per second. The corollary is just as important: 1 joule = 1 watt-second.6 With the notable exception of the United States, the entire world uses SI when discussing energy and power. Though SI units are valuable and laudable, it doesn’t mean that everyone who uses them comprehends them. Indeed, although the watt has become a standard unit for measuring power, horsepower continues to be part of our everyday discussions, particularly when we are talking about cars, chainsaws, and lawnmowers. Why? It’s a centuriesold metric that’s easy for most laymen to grasp. Everyone can imagine a horse pulling a plow or a carriage and the work that that job entails. So which metric makes more sense? During the course of writing this book, I asked dozens of people which term they understood better—watts or horsepower. Some people replied with a blank stare and chose neither. A handful (including nearly all of the engineers and scientists) preferred watts. But the majority preferred horsepower. Asked why, they said that they were more familiar with horsepower ratings on cars than they were with power ratings listed in watts. Men generally preferred horsepower. Women generally picked watts. Thus, my sample may have been skewed because the population I surveyed had more males than females.

  This book will use both horsepower and watts. Pick whichever unit you prefer—just remember that both are measures of power, not energy, and keep in mind that 1 horsepower is equal to 746 watts.

  Now that the mini-lecture on physics and SI is done, we must return to the task at hand: defining energy and power. One of the best explanations I’ve heard comes from my good friend Stan Jakuba, a whipsmart engineer who has spent decades advocating the virtues and simplicity of SI. “Energy has many forms,” he explains, “such as electricity, heat, work, kinetic energy, potential energy, chemical energy, nuclear energy, etc. Energy can be visualized as an amount of something. Power is the energy flow.”

  Jakuba’s vivid explanation underscores an essential concept: Energy is an amount, while power is a measure of energy flow. And that’s a critical distinction. Energy is a sum. Power is a rate. And rates are often more telling than sums.

  To illustrate that fact, let’s express energy and power in oil terms. Energy is measured in barrels. Power is measured in barrels per day. Suppose you have discovered an oil field containing 1 billion barrels of oil. That’s a lot of energy, sure. But that energy is worthless unless it can be brought out of the ground. And, generally speaking, the faster you can get it out, the better. Thus, an oil field that holds, say, 100 million barrels of oil that can produce 10,000 barrels per day is worth a whole lot more—we can even say it is more powerful—than one that produces 10,000 barrels per week.

  The key word here is “per.” When buying a car, we want to know the rates: How many miles per gallon does it get, how fast—in miles per hour—can it go?

  Yet another good analysis comes from Richard Muller’s 2008 book Physics for Future Presidents, in which he writes, “For power and energy, the kilowatt is the rate of energy delivery (the power) and the kilowatt-hour is the total amount of energy delivered.”7 Combining Muller’s explanation with Jakuba’s provides yet one more way to conceive of energy and power: The kilowatt-hour gives us a tally of the energy provided, whereas the kilowatt measures the rate of energy flow. And that rate of energy flow can be measured in watts, kilowatts, megawatts, gigawatts, terawatts, or, of course, in horsepower, thousands of horsepower, millions of horsepower, and so on.

  Energy doesn’t produce wealth. Energy use produces wealth, and the majority of the energy we use is fed into engines, turbines, and motors to produce power. It’s converting energy—of whatever type—into motion that gives it value. And that’s what engines do: They convert energy into mechanical motion that can be used for doing work. As Jakuba cleverly phrased it, the more we increase the energy flow through those engines, the more power we get. And the more power we have, the more work we can do.

  That leads to another key point: The very word “power” implies control. When it comes to doing work, we insist on having power that is instantly available. We want the ability to switch things on and off whenever we choose. And that desire largely excludes wind and solar from being major players in our energy mix, because we can’t control the wind or the sun. Weather changes quickly. A passing thunderstorm or high-pressure system can take wind- and solar-power systems from full output to zero output in a matter of minutes. The result: We cannot reliably get or deliver the power from those sources at the times when it is needed.

  Renewable energy has little value unless it becomes renewable power, meaning power that can be dispatched at specific times of our choosing. But achieving the ability to dispatch that power at specific times means solving the problem of energy storage. And despite decades of effort, we still have not found an economical way to store large quantities of the energy we get from the wind and the sun so that we can convert that energy into power when we want it.

  Which renewable sources can provide clean renewable power? One of the best is geothermal—which can provide a constant flow of predictable power that can be dispatched when needed. By October 2009, the United States had about 3,100 megawatts of geothermal production capacity. And geothermal promoters were predicting that they could triple that quantity to about 10,000 megawatts of baseload power capacity. 8 That could help, but it would still be a trifle when compared to the total U.S. generating capacity of 1 million megawatts.

  The hype over renewables can only be debunked by thoughtfully walking through the numbers and the terms. And the most important of the terms are the first two items of the Four Imperatives: power density and energy density.

  Power density refers to the amount of power that can be harnessed in a given unit of volume, area, or mass.9 Examples of power-density metrics include horsepower per cubic inch, watts per square meter, and watts per kilogram. (In Part 2, I will show why watts per square meter may be the most telling of these. Using watts per square meter allows us to make a direct comparison between renewable energy sources such as wind and solar and traditional sources such as oil, natural gas, and nuclear power.)

  Energy density refers to the amount of energy that can be contained in a given unit of volume, area, or mass. Common energy density metrics include Btu per gallon and joules per kilogram.10

  When it comes to questions about power and energy, the higher the density, the better. For example, a 100-pound battery that can store, say, 10 kilowatt-hours of electricity is better than a battery that weighs just as much but can only hold 5 kilowatt-hours. Put another way, the first battery has twice the energy density of the second one. But both of those batteries are mere pretenders when compared with gasoline, which, by weight, has about eighty times the energy density of the best lithium-ion batteries.

  As our society develops and urbanizes, we are seeking to use power in ever-greater quantities in ever-smaller places, and that is particularly true in our cities. Watt’s breakthroughs increased the efficiency of the steam engine. Put another way, he increased the power density of the engine by designing it to produce more power from the same amount of space and from the same amount of coal. Ever since Watt’s day, the world of engineering has been dominated by the effort to produce ever-better engines that can more quickly and efficiently convert the energy found in coal, oil, and natural gas into power. And that effort to increase the power density of our engines, turbines, and motors has resulted in the production of ever-greater amounts of power from smaller and smaller spaces.

  The evolution of power density can be visualized by comparing the engine in the Model T with that of a modern vehicle. In 1908, Henry Ford introduced the Model T, which had a 2.9-liter engine that produced 22 horsepower, or about 7.6 horsepower per liter of displacement.11 A century later, Ford Motor Company was selling the 2010 Ford Fusion. It was equipped with a 2.5-liter engine that produced 175 horsepower, which works out to 70 horsepower per liter.12 Thus, even though the displacement of the Fusion’s engine is about 14 percent less than the one in the Model T,
it produces more than nine times as much power per liter.13 In other words, over the past century, Ford’s engineers have made a nine-fold improvement in the engine’s power density.

  Now let’s consider energy density. An easy way to understand energy density is to consider the amount of energy contained in a 5-gallon bucket that is filled with gasoline. Now consider that same bucket filled with dried leaves. Obviously, the energy density in the bucket filled with gasoline is far greater than the energy density in the one filled with leaves. Or consider corn ethanol. Although farm-state politicians and agribusiness promoters have been able to foist their fuel on motorists in non-farm states, ethanol contains just two-thirds of the heat energy of gasoline, meaning that motorists who use ethanol-blended gasoline must refill their tanks more often.

  Our quest for power density provides another argument against a return to renewable energy sources. The kinetic energy of the wind and the solar radiation from the sun are diffused. Some companies, such as General Electric and Vestas, manufacture huge turbines to turn the diffused kinetic energy of the wind into highly concentrated energy in the form of electricity. Photovoltaic cells capture diffused light energy and concentrate it into electricity, which is then fed into wires. Concentrated thermal solar-energy systems employ huge arrays of mirrors to concentrate sunlight so that it can be used to heat a fluid that can then be used to run a generator. But with both wind and solar, and with corn ethanol and other biofuels, engineers are constantly fighting an uphill battle, one that requires using lots of land, as well as resources such as steel, concrete, and glass, in their effort to overcome the low power density of those sources.

  For millennia, humans relied almost completely on renewable energy. Solar energy provided the forage needed for animals, which could then be used to provide food, transportation, and mechanical power. Traveling on lakes, oceans, or canals was made possible by the wind, human muscle, or animal muscle. And though today’s wind turbines are viewed as the latest in technological achievement, land-based systems that captured the power of the wind have been recorded through much of human history. About 1,000 years ago, a visitor to Seistan, a region of eastern Iran, wrote that the wind “drives mills and raises water from streams, whereby gardens are irrigated. There is in the world (and God alone knows it) nowhere where more frequent use is made of the winds.”14 The use of hydropower, likewise, goes way back. The ancient Greeks used waterwheels; so did the Romans, who recorded the use of waterwheels in the first century B.C.15 The use of mechanical power from water continued to the beginning of the Industrial Revolution. And while solar, wind, and water power all provided critical quantities of useful energy, they were no match for coal, oil, and natural gas. Hydrocarbons provided huge increases in power availability, allowing humans to go from diffused and geographically dispersed power sources to ones that were concentrated and free of specific geographic requirements. Hydrocarbons were cheap, could be transported, and most important, had greater energy density and power density.

  That increasing availability of power has allowed us to do ever-greater amounts of work in less time. And because we need power for many different applications, we have lots and lots of engines, turbines, and motors. In fact, the engines of our economy are, in fact, just that: engines. And some of those engines are enormous.

  At its most basic level, the $5-trillion-per-year global energy sector—the world’s biggest single business—exists primarily to feed the engines that permeate our towns and cities. Big Oil, Big Coal, and the Big Utilities are servants of the world’s engines. Whether those engines are fueled with oil, coal, natural gas, or enriched uranium doesn’t really matter to consumers. What matters to them is that they continue to have a plentiful supply of fuel that can be fed into those engines so that the engines can continue to turn the heat energy in the various fuels into motion.

  In the process of turning that heat energy into motion, engines now generally lose about two-thirds of the heat content in the various fuels. But once again, that matters little to consumers, who are primarily interested in power that is cheap, abundant, always available, and as clean as possible. For someone living in midtown Manhattan or central Tokyo, the idea of using coal or firewood to cook dinner is absurd. The only fuels that meet the clean air standards of those urban settings are natural gas and electricity. Furthermore, the more cheap, abundant, clean power those consumers get, the more they use. The result: Over the past few decades, energy consumption among city dwellers has increased, a fact that can be proven by peeking inside the average apartment. Three decades ago, that apartment might have had the standard kitchen appliances—toaster, stove, refrigerator, and mixer. Today, that same kitchen will almost certainly have all of those appliances as well as a microwave oven, bread maker, coffeemaker, juicer, convection oven, dishwasher, and food processor. And a few steps away, where there once was only a small black-and-white television, there is now a giant-screen TV, a DVD player, and digital video recorder, as well as a laptop computer and ink-jet printer. In 1980, the average U.S. household had just three consumer electronic products. Today, it has about twenty-five of those devices.16

  PHOTO 2 This massive diesel engine, designed by Finland-based Wärtsilä, is used on large ships (see www.wartsila.com). Each cylinder has a diameter of about 1 meter and displaces about 1,800 liters. The Wärtsilä engines, which can turn about 50 percent of the thermal energy in diesel fuel into useful power, are among the most efficient engines ever produced.

  All those electronics have had a clear result: The amount of power that we are able to consume in our homes has dramatically increased. And that spike in power use is not just happening in Manhattan and Tokyo; it’s happening all over the world, accelerated by the ongoing worldwide migration toward city living. In 2008, according to the International Energy Agency, about half of the world’s population was living in cities. By 2030, that percentage is expected to rise to 60 percent.17 And that will mean a corresponding rise in demand for power, because city dwellers use more power than their rural counterparts.18

  The inexorable quest for power—whether in the form of computing power, a bigger engine in a new car or a better vacuum cleaner—will continue apace. Why? Because consumers and entrepreneurs are always seeking better, more efficient technologies that allow them to do more things faster. Computer makers such as Apple or Lenovo wouldn’t be in business for very long if they started selling computers that were slower and had less computing power than the ones they had built two years earlier. Or imagine what would happen if a carmaker such as BMW or Mercedes Benz announced that its newest convertible took longer to go from 0 to 60 miles per hour than the model it built the previous year. The company’s market share would vanish faster than Dick Cheney’s hunting partners.

  Power is like sex and Internet bandwidth: The more we get, the more we want. And that’s one of the biggest problems when it comes to energy transitions. We have invested trillions of dollars in the pipelines, wires, storage tanks, and electricity-generation plants that are providing us with the watts that we use to keep the economy afloat. The United States and the rest of the world cannot, and will not, simply jettison all of that investment in order to move to some other form of energy that is more politically appealing.

  Yes, we will gradually begin moving toward other forms of energy. But that move will be just that: gradual. And for those who doubt just how lengthy energy transitions can be, history offers some illuminating examples.

  Power Equivalencies of Various Engines, Motors, and Appliances, in Horsepower (and Watts)

  Saturn V rocket: 160,000,000 (120 billion W)19

  Boeing 757: 86,000 (64.1 million W)20

  Top fuel dragster: 7,500 (5.6 million W)21

  M1A1 tank: 1,500 (1.1 million W)22

  Formula 1 race car: 750 (560,000 W)23

  2009 Ferrari F430: 490 (365,000 W)24

  1999 Acura 3.2 TL sedan: 225 (168,000 W)25

  2010 Ford Fusion: 175 (130,000 W)26

  1908 Ford
Model T: 22 (16,000 W)27

  Average home air-conditioning compressor: 5.6 (4,200 W)28

  Honda Cub motorbike: 4 (3,000 W)29

  Average lawnmower: 3.5 (2,600 W)30

  Dyson vacuum cleaner: 1.68 (1,250 W)31

  Toaster: 1.67 (1,250 W)32

  Lance Armstrong, pedaling at maximum output: 1.34 (1,000 W)33

  Coffeemaker: 1.08 (800 W)34

  Cuisinart: 0.16 (117 W)35

  Human walking at a brisk pace: 0.14 (106 W)36

  20-inch iMac computer: 0.11 (80 W)37

  Ryobi 3/8-inch cordless drill battery charger: 0.07 (49 W)38

  60-watt lamp: 0.07 (54 W)39

  Table fan: 0.03 (25 W)40

  Recharging an Apple iPhone: 0.0013 (1 W)41

  CHAPTER 4

  Wood to Coal to Oil

  The Slow Pace of Energy Transitions

  GIVEN OUR CURRENT OBSESSION with Big Oil and Big Coal, it’s worth noting that the fuel source that has had the longest reign in the American energy business is plain old firewood. Wood’s reign as the most important fuel in the United States lasted longer than any other. For 265 years after the Pilgrims founded the Plymouth Colony, and for 109 years after the signing of the Declaration of Independence, wood was the dominant source of energy in America. It wasn’t until 1885—the year that Grover Cleveland was first sworn in as president—that coal finally surpassed wood as the largest source of primary energy in the United States.

  For the next seventy-five years, coal was king. During the first two decades of the twentieth century, coal was supplying as much as 90 percent of all the primary energy in the United States, fueling factories, heating homes, and providing boiler fuel for essentially all of the nation’s electric power plants. But coal’s dominance was not to last. Thanks in large part to the booming demand for kerosene for lighting, and more particularly, for gasoline to fuel automobiles, oil began whittling away at coal’s market share.