44
geography and the structure of the economy. Consequently, changes in the ratio over
time are influenced by factors that are not related to changes in energy efficiency
(such as changes in economic structure). It is thus important
to supplement the energy
use per GDP indicator with energy intensities disaggregated by sector, since these
disaggregated indicators are a better representation of energy efficiency
developments.
Comparisons among countries of the ratio of energy use to GDP are complicated by
geographical factors.
Large countries, for example, tend to have high levels of freight
transportation, as many goods are distributed nationwide. Compared with countries
with moderate climates, cold countries might consume considerably
more energy per
capita due to demand for space heating. Countries with hot climates might use more
energy per capita as a result of demand for air conditioning. Countries with economies
that depend mainly on raw-material industries might use larger quantities of energy
per unit of manufacturing output compared with countries that import processed
materials owing to the high energy intensity of raw-material processing. Canada, for
example, has a high
ratio of energy use to GDP, resulting in part from the fact that it
is a large country with relatively cold weather and an economy that depends on a large
raw-material processing sector. In Japan, the climate is milder,
raw materials are
limited, and the high population density results in smaller residential units and less
distance travelled, contributing to a lower ratio of energy use to GDP.
Interpreting the ratio of energy use to GDP in terms of environmental impact or
sustainability is also complicated by differences in environmental impacts among
energy options. Canada, for example,
has substantial hydropower, nuclear power and
natural gas, which are energy sources that have lower environmental impacts than
coal or oil with respect to air pollution and climate change.
Given the large number of factors that affect energy use, the ratio of total energy use
to GDP should not be used alone as an indicator of energy efficiency
or sustainability
for policy-making purposes.
Dostları ilə paylaş: