The gradual change in the energy consumption pattern of the United States from 1860 to 1990 is illustrated in Fig. 1.1. In the mid-1800s, biomass, princi-

FIGURE 1.1 Historical energy consumption pattern for United States, 1860-1990.

pally woody biomass, supplied over 90% of U. S. energy and fuel needs, after which biomass consumption began to decrease as fossil fuels became the preferred energy resources. For many years, a safe illuminant had been sought as a less expensive substitute for whale oils. By the mid-1800s, distillation of coal oils yielded naphthas, coal oil kerosines, lubricants, and waxes, while liquid fuels were manufactured by the distillation of petroleum, asphalt, and bituminous shales. Coal slowly displaced biomass and became the primary energy resource until natural gas and oil began to displace coal. In 1816, the first gas company was established in Baltimore, and by 1859, more than 300 U. S. cities were lighted by gas. Natural gas was no longer a curiosity, but illuminating gas manufactured from coal by thermal gasification processes still ruled the burgeoning gas industry. Natural gas did not come to the fore until manufactured gas was widely adopted for cooking, space heating, water heating, and industrial uses. Installation of a nationwide pipeline grid system after World War II for transmission of natural gas eventually made it available in most urban areas.

After the first oil well was drilled in 1859 in Titusville, Pennsylvania, for the specific purpose of bringing liquid petroleum to the surface in quantity, produc­ing oil wells were drilled in many states. The installation of long-distance pipelines for transport of oil from the producing regions to the refineries and the natural gas pipeline grid signaled the end of coal’s dominance as an energy resource in the United States. As shown in Fig. 1.1, the percentage contributions

to total primary U. S. energy demand in the 1990s were about 70% for petroleum and natural gas and 20% for coal. Biomass, hydroelectric power, and nuclear power made up the balance. It is noteworthy that since the advent of nuclear power, its overall contribution to U. S. energy demand has remained rela­tively small.

Over the period 1860 to 1990, U. S. fossil fuel consumption correlated well with the growth in population (Fig. 1.2), but more revealing is the trend over the same period, in annual and per-capita U. S. energy consumption (Fig. 1.3). As technology advanced, the efficiency of energy utilization increased. Less energy per capita was consumed even though living standards were dramati­cally improved. Large reductions in per-capita energy consumption occurred from over 600 GJ/capita-year (102 BOE/capita-year) in 1860 to a level of about 200 GJ/capita-year in 1900. Per-capita energy consumption then remained relatively stable until the 1940s when it began to increase again. In the 1970s, energy consumption stabilized again at about 350 GJ/capita-year (59 ВОЕ/ capita-year). This is undoubtedly due to the emphasis that has been given to energy conservation and the more efficient utilization of energy and because of improvements in energy-consuming processes and hardware.

Because of the increasing efficiency of energy utilization, the energy con­sumed per U. S. gross national product dollar exhibited substantial reductions also over the period 1930 to the early 1990s (Fig. 1.4). The U. S. gross national

POPULATION, MILLION EJ/YEAR

300 100

GJ/CAPITA-YEAR

700

YEAR
-x — EJ/YEAR — s- GJ/CAPITA-YEAR

FIGURE 1.3 Annual and per-capita energy consumption for United States, 1860-1990.

GNP, TRILLION DOLLARS MJ/$ GNP

7 30

GNP TRILLION DOLLARS — s — MJ/ $ GNP

FIGURE 1.4 U. S. gross national product and energy consumption per dollar of GNP, 1994dollars.

product increased more than sixfold in 1994 dollars over this period, while energy consumption per dollar of gross national product decreased from about 26 MJ/$ GNP to 14 MJ/$ GNP.