Amazon.com Review
The energy of solar radiation reaching the earth clocks in at 5,500,000 exajoules, an exajoule being one watt per second taken to 10 to the 18th power. The energy used to strike a typewriter key is 20 millijoules, a millijoule being one watt per second taken to 10 to the negative 3rd power; that keyboard-striking energy is a full order of magnitude larger than the energy a flea expends in hopping from one spot to another. Such is the sort of information that geographer Vaclav Smil delights in presenting in his endlessly interesting handbook of the various energy technologies of nature and culture. "Energy is the only universal currency," Smil writes, but, he notes, it is little understood. Beginning with a grand tour of the solar system and the terrestrial biosphere, and taking into account such matters as the movement and latent heat of waves, Smil moves on to consider the energy of natural food chains, the efficiency of human growth, the energy requirements of agriculture, and the terrible force of modern weapons, among hundreds of other subjects. His heavily illustrated book is one of a kind, and it makes for both entertaining bedside reading and a highly useful reference.
--Gregory McNamee
From Scientific American
"Energy is the only universal currency: one of its many forms must be transformed to another in order for stars to shine, planets to rotate, plants to grow, and civilizations to evolve." Thus Smil begins his teeming cross-disciplinary book--"a hybrid," he calls it, "combining a quasi-encyclopedic sweep with the brevity of mini-essays," together with some 300 illustrations, old and new. The 82 essays are grouped under the headings of sun and earth, plants and animals, people and food, preindustrial societies, fossil-fueled civilization, and transportation and information; they cover a broad span of knowledge. Dip into the book anywhere, and you will find a bracing fact or connection. Examples: Total runoff of the earth's rivers averaged 38,000 cubic kilometers during the 1980s, which was more than 5 percent below the mean during the late 17th century. The relation between the energy cost of walking and speed has a clear U shape: the energy cost is highest at a bit less than one meter per second, lowest at about 1.6 and moderate at about 2.4; the energy cost of running, however, is basically constant for speeds between three and 5.5 meters per second. The theoretical capacity of windmills increases with the cube of the wind speed; this in turn is proportional to the height above the ground raised to the power of 0.14; in other words, for a given wind speed at the surface, a machine with a shaft 10 meters above the ground will be only about 60 percent as powerful as one with its shaft 30 meters above the ground. And so on, in a dazzling procession.