(pages 18 -19)
If you follow the FDA guidelines and burn 2000 calories per day inside, your personal power output averages 100 W. Not that long ago, when almost all of us lighted our houses with heat-until-they-glow incandescent light bulbs, everyone understood Watts—a turned-on big light bulb was using 100 W. (With modern compact fluorescents, 100 W is four or five bright light bulbs.) {2/11} If you’ve ever touched a 100 W incandescent light bulb that had been turned on for a while, you know that it was hot! So, you shouldn’t be surprised that you and the light bulb are using energy at about the same rate. You may be using 150 or even 200 W during part of the day, then idle down while sleeping, but your average will be in the neighborhood of 100 W. A Tour de France bicycle racer may eat 10,000 calories per day, to average 500 W. A whole lot of that goes into waste heat, but at the very highest level for a human, an elite bicycle racer may put close to 500 W into moving the bicycle up a mountain stage. The rest of us can only dream about that, so when we consider amounts of energy, just remember that the energy you generate is 100 W. {2/12}
Recently, total energy usage in the United States has been running notably higher than the personal burning inside of us. In fact, if you take the total energy use in the US in a day, and divide by the number of people, you end up with approximately 240,000 calories per person per day, or somewhat over 10,000 W for each person. {2/13} This is the equivalent of each of us having over 100 people doing our bidding—100 energy “servants” apiece. We’re really better off than that, though. If you actually had 100 people to do your bidding, you wouldn’t get this much work out of them, because most of their time and most of their energy would be used keeping themselves fed and clothed and bathroomed and otherwise alive.
Some people find the challenges described later in this book to be so big that these people get discouraged. Giving up is just wrong, though. If you start to get discouraged, just remember this: Abraham Lincoln ran his mind and body on the same amount of energy as a single heat-till-it-glows lightbulb. You, and Einstein, and Beethoven, and Michaelangelo, taken together, use or used less energy than a single chandelier. The careful mathematics of science yield the same answer that we teachers learn from our students—we have more than enough brainpower to figure out how to power our brains!
2/11 2000 calories per day is actually about 97 Watts. But many Americans eat more than 2000 calories per day, especially if they are serious athletes or else planning to be fatter in the future. In round numbers, if you leave a 100 Watt light bulb running for a day, it will have used up about 2000 calories in that day, or just over 8 million Joules. In the US, the electric company that sells you the power converts to still another set of units. If you use 1000 Watts for one hour, you have used 1000 Watt hours or 1 kilowatt hour or 1 kwh. Thus, a 100 Watt light bulb running for 10 hours, or ten 100 Watt light bulbs running for 1 hour, will use 1 kwh. During one day that you are alive and the 100 Watt light bulb is turned on, each of you uses 2.4 kwh.
2/12 For Lance Armstrong’s energy output of almost 500 W that actually went into moving the bicycle up a mountain stage, see “Super, Sure, But Not More than Human”, Gina Kolata, New York Times, July 24, 2005, calculated using a racing weight for Mr. Armstrong of 74 kg or 162 pounds. In the 2005 race, Floyd Landis, former teammate of Armstrong’s, rode with a device on his bicycle that measured his power output through the bicycle—the heat his body put into the air around him was not measured. For the entire race, Mr. Landis averaged 232 Watts, but he maintained an average of 379 Watts over 75 minutes in the final time trial, in which he finished sixth, as reported by Mark McClusky, “Powering through the Tour, July 27, 2005, Wired,, accessed October 19, 2009. Neither Mr. Armstrong nor Mr. Landis is probably the best comparison to use for typical humans, so we will stick with 100 W in this book.

11,600 Watts per person is closer to correct, but we’ll round off for convenience here.