Environmental Engineering Reference
In-Depth Information
improved the steam engine and developed internal combustion engines (Otto and
Diesel cycles), electric engines, and nuclear energy. Consumption per capita in in-
dustrialized countries reached more than 100 times the consumption of primitive
man.
Presently the world's average energy consumption is approximately 1.8 toe per
year (50,000 kcal/day). Energy consumption in the United States is approximately
six times higher (300,000 kcal/day) than the world average.
Until the late Middle Ages the main source of energy used by the human population
originated in biomass, or renewable and biologically based energy sources, namely,
agriculture and forestry. As a consequence, a large share of the European forests
was cut down for this fuel. However, with the growing population and consumption
of energy, humans explored new sources of primary energy besides fuel wood, such
as the rivers, which could supply hydraulic energy; coal for heating and generating
steam; oil and products derived from it by distillation (gasoline, diesel, oil, and fuel
oil) for moving internal combustion engines; and uranium for generating thermo-
nuclear power.
Figure 2.2
charts the enormous growth in the consumption of energy since the
beginning of the 20th century, as machines and new technology came into use. It
also shows the gradual increase of coal, oil, gas, nuclear, and renewable energies.
