Environmental Engineering Reference
In-Depth Information
creased demand for buildings and transportation required more energy. However,
the “explosion” in energy growth per capita really began with the development of
machines such as the steam engine, which opened the way for railroads and a great
expansion in commerce and transportation—and the building of the great cities.
The discovery of electricity at the end of the 19th century opened the way to mod-
ern technologies such as refrigerators, washing machines, radio, TV, and telecom-
munications, all of which revolutionized our consumption patterns and produced a
corresponding increase in per capita consumption.
Income growth is an aspiration of most people and is usually associated with devel-
opment. A higher per capita income means that individuals can afford more materi-
al possessions—such as cars, domestic appliances, and better houses—all of which
require more energy to build and use. However, the relationship between income
per capita and energy consumption is a complex one.
Figure 2.4
plots the gross domestic product (GDP) per capita of a number of
countries against commercial energy consumption per capita (in toe) per year. GDP
is measured in power purchasing parity dollars of the year 2000.
Coal, oil, natural gas, and electricity are all commercial types of energy. Non-
commercial energy or traditional energy includes locally collected and unprocessed
biomass-based fuels such as crop residues, wood, and animal dung.
It is obviously a gross simplification to assume a linear relationship among these
two indicators, although this is a concept that has been used repeatedly (and con-
tinues to be adopted) as a planning tool in many countries.
There are at least three reasons why energy consumption and income are not
linked or linearly related.
We can first look at the historical evidence: in the United States between 1850
and 1950, or the initial phase of the industrialization in that country, energy con-
sumption per capita grew more rapidly than income per capita. From 1950 on, the
opposite happened, with income growing more rapidly than energy consumption.
This occurred due to a shift from infrastructure building to services, which involve
less intensive use of energy.
Second, we can compare industrialized countries: in the United States consump-
tion per capita is 40% higher than in Sweden for the same income per capita despite
the harsher climate. This is due basically to the fact that Sweden has better insu-
lated homes and smaller and more efficient automobiles.
