Mr. Cook. The goods and services enjoyed or suffered by man represent applications of power through time, and their value is therefore related to the work done to produce them, at least as man values them in the marketplace.

In the case of nonrenewable natural resources, however, the enormous amount of work performed by nature in transforming and concentrating naturally disperse materials into deposits of iron ore, coal, petroleum, and other materials used by man does not appear on man's balance sheets. Neither does the work of uplift and erosion that makes many of them more accessible to man.

As a consequence, industrial man has been able to turn quick and very large profits on work he has not had to perform or pay for; on the basis of these easy profits he has expanded his population greatly and enhanced his style of living materially. I have used in my presentation an illustration from coal mining.

In 1900, the average daily energy consumption required to sustain a miner and his family probably was in the neighborhood of 200,000 Btu. Interest, amortization, and maintenance of mine equipment might have equaled another 50,000 Btu per miner, for a total of 250,000 Btu. He produced in a day about 125 million Btu or 500 times the energy required to maintain himself as a miner and to sustain his family.

In 1900, in the United States, a ton of coal represented the average daily energy consumption of 70 persons; in 6 days a miner produced energy representing the weekly consumption of 300 persons. The rate of energy consumption at the turn of the 20th century in this country was four times that required for an advanced agricultural society; the surplus came mainly from coal (Fig. 2) and was transformed rapidly into industrial capital, technology, and the production of goods. Energy from coal and later, oil, provided the tremendous subsidy required to transform an advanced agricultural nation quickly into an advanced industrial nation.

Figure 2.

Mr. Cook. For more than a century increases in the efficiency of energy use, represented by the substitution of coal for wood, the replacement of the steam locomotive by the diesel, and an impressive improvement in the heat rate (energy consumption per kilowatt-hour) for central electric generating plants, compounded the fossil-energy subsidy to the industrial economy.

During this happy century what economic man calls the "real cost" of nonrenewable resources was coming down and a deep faith developed in the everlasting ability of ingenious technological man to overcome the physical constraints of his terrestrial environment.

However, the stage of resource depletion in which increases in efficiency of energy use could stay ahead of increases in work expended was bound to come to an end, and it appears that we are now beginning to see the end of that stage in resource exploitation.

Real costs of the industrial metals as well as of the energy resources on which our economy depends are beginning to rise. They are rising because efficiencies are reaching economic limits, because ores are getting leaner, because mines and wells are getting deeper, because new deposits are harder to find and more expensive to exploit, because we are at last beginning to charge long-deferred environmental and social costs to production, and because we have many more vigorous competitors for limited resources than we used to have. These reasons for increasing costs are not all that different from the reasons for the skyrocketing meat prices throughout the world; meat is another energy

source.

The use of energy resources in the United States may illustrate some of these points.

Energy is available in several forms and in numerous guises and settings. (Fig. 3.) Each set or mix of form, guise and setting has a different inherent cost of utilization in terms of work required to make "natural" energy a true resource for man. Each applicable technology of discovery, concentration, processing, conversion, transport and application modifies the amount of energy consumption required to produce the work needed to make "natural" energy useful.

Mr. Cook. In each of these processes, but especially in converting thermal energy to one of the other forms, some of the original energy, although not truly consumed, loses the ability to do any more useful work and becomes low-grade thermal waste. (Fig. 4.) The aggregate efficiency of the U.S. energy system is now about 36 percent and is probably dropping after a steady rise over a period of more than 100 years. (Fig. 5.)

FIGURE