I learned about energy efficiency in a very painful and embarrassing way. Many years ago, I entered the famous Western States 100-Mile Endurance Run, which follows tortuous old gold-miners’ trails over the Sierra Nevada Mountains. I had calculated that I’d burn about 130 calories per mile, which meant I’d need about 13,000 calories to get through that run. So, I planned to consume about 80 PowerBars along the way. The first few hours went easily enough, but by the time I reached a major aid station at 54 miles, I was deathly sick and severely dehydrated -- yet could no longer stand the sight of either food or water. How on earth were the other runners able to keep going? Only later did I learn that evolution has created a kind of bodily ecology that with training enables very small amounts of carbohydrate to interact with small amounts of fat to generate a far more efficient propulsion than I’d thought possible. Energy efficiency, it turned out, was a far bigger factor than energy supply in determining a man or woman’s ability to run over rough terrain all day and all night.
As I later discovered, in my work as an editor at the Worldwatch Institute, the mistake I’d made as an individual in my abortive 100-mile effort was almost identical to a mistake the United States had made as a nation. It began with a widespread misunderstanding of what energy efficiency really is. A salesman for gas-fired hot-water heaters, for example, might tell a customer his product has 85-percent efficiency because only 15 percent of the heat is lost “up the stack,” and therefore 85 percent is going into the water. But a physicist would point out that the gas flame is much, much hotter than the water coming out, so a lot of the work that could have been done by that flame has been wasted. In other words, it’s the work output or loss, not energy output or loss, that should be measured. According to the first law of thermodynamics, energy itself can’t be used up or lost.
In 1972, a government consultant, using the same unscientific logic as the water-heater salesman, presented a report to the U.S. Congress asserting that the country as a whole was using energy at a rate of 50-percent efficiency, which he assured the politicians was so high that no further gains from efficiency could be relied on and therefore the country would need to build hundreds of new nuclear power plants by the end of the 20th century. It was the same kind of thinking that had led me to think I’d need lots and lots of PowerBars.