An Energy Overview - Energy Use By Sector

Energy use can be classified into four main "end-use" sectors: residential, commercial, industrial, and transportation. Historically, industry has been the largest energy-consuming sector of the economy, followed by the transportation, residential, and commercial sectors, in that order. In 2003 industry used about 33 quadrillion Btu, compared to approximately 27 quadrillion Btu in the transportation sector, 21 quadrillion Btu in the residential sector, and 18 quadrillion Btu in the commercial sector. (See Figure 1.9.)

Within sectors, energy sources have changed over time. For example, in the commercial sector, coal was the leading energy source through 1953 but declined dramatically in favor of petroleum (through 1962) and then natural gas (since 1963). In 1990 energy in the form of electricity pulled ahead as the leading energy source. (See Figure 1.10.) Similarly, coal was the leading energy source in the residential sector in 1949. (See Figure 1.11.) Natural gas quickly took over, with petroleum in second place. In 1979 electricity took over second place from petroleum. Industry used more coal than natural gas or petroleum through 1957, but after that natural gas and petroleum took over as nearly equally preferred energy sources. (See Figure 1.12.) In transportation, reliance on petroleum has been increasing since 1949. (See Figure 1.13.)

Not included in the four main sectors of energy consumption is the electric power sector. This sector includes electric utilities that generate, transmit, distribute, and sell electricity for use by the public. The electric power generated by this sector is then consumed by the other four sectors

FIGURE 1.7

as noted in Figure 1.10, Figure 1.11, Figure 1.12, and Figure 1.13 and in the previous paragraph. To generate electricity that comes into homes, businesses, and industry, the electricity sector must harness energy from renewable sources such as the sun, the wind, water movement, and geothermal sources, or it must generate electricity from nuclear power or the burning of fossil fuels. Figure 1.14 shows that the electric power sector generates most of the electricity for the United States by burning coal. The electric power sector consumed approximately 20 quadrillion Btu of coal in 2003, a figure that has increased tenfold since 1949 and accounts for almost all coal usage in the United States. Nuclear power is the next most used fuel, followed by natural gas, renewable energy sources (hydroelectric, wood, waste, geothermal, solar, and wind), and petroleum. As Figure 1.14 shows, renewable sources are used very little to generate the nation's electricity.