Environmental Engineering Reference
In-Depth Information
Until the late 1950s, the United States was able to meet its energy needs with domestic production. At the end
of that decade, however, energy consumption exceeded domestic production, and the United States began to
import energy, generally in the form of petroleum. Why was there a change in energy consumption? Because
prior to World War II, the United States was just coming out of the Great Depression and energy consumption
was comparably low. During the early stages of war, the United States increased the manufacturing of ships,
planes, and vehicles built to fight and transport American troops and ammunition for war. After the war, only
limited manufacturing remained during the Cold War, and other manufacturing was converted to peace time
activities. The shift from agricultural to industrial professions also continued during this time. In the 1930s, ap-
proximately 21 percent of the work force worked on farms. By the 1950s, that number had decreased to just
over 12 percent; it had decreased to 3.4 percent of the work force by the 1980s.
The average home size also began to get larger, from 938 square feet of floor space in 1950 to 2,266 square
feet in 2000, a 141.6 percent increase over 50 years. Larger homes require more energy for heating and cool-
ing. Additionally, the population began to shift toward warmer climates, requiring increased use of air condi-
tioning to cool homes, business, and public buildings. Even in temperate climates, people started using air con-
ditioners more often. Other energy-using appliances were developed, modified to become more automated re-
quiring more energy, or increased in size and, thus, energy consumption. For example, refrigerators were deve-
loped, became ubiquitous, and then became larger. TVs first appeared in the late 1940s, and by the late 1950s
became common household products, and then became larger. Washing machines, dryers, and dishwashers re-
placed hand washing and wringing, automating the cleaning of clothes and dishes. All these changes required
more energy.
Energy consumption is typically divided into four end users: industry, transportation, residential, and commer-
cial. Since 1950, industry has been the largest end-user of energy. Industry is defined as the production of eco-
nomic goods and services. This includes mining and refining; farming; construction; manufacturing; services
such as law and medicine; the distribution of manufactured goods; and, most recently, research, design, and the
development of technology.
The transportation of people and goods is the second largest consumer of energy. Types of transportation in-
clude air, rail, road, water, and pipeline. Transportation can be divided into three broad categories: infrastruc-
ture, vehicles, and operations. Infrastructure needed for transportation: roads, railways, airways, waterways,
pipelines, airports, rail, bus, warehouses, trucking terminals, and refueling depots. Vehicles include automo-
biles, bicycles, motorcycles, buses, trucks, trains, and aircraft. Operations include the financing, legalities, and
policies related to operating vehicles.
Residential energy use takes place in single-family homes, multifamily residences, and mobile homes. Multi-
family homes include apartments, condominiums, and town houses. Residential areas may include schools,
hospitals, and parks that are used by the residents.
Commercial end users of energy include the places where goods and services are exchanged for money.
