272 Energy andtransport for thefutureEnergy intensity and carbon intensity
An index that provides an indication of a country’s
energy efficiency is the ratio of annual energy con-
sumption to gross domestic product (GDP) known
as theenergy intensity. Figure 11.3 shows that
from 1971 to 1996 for Organisation for Economic
Co-operation and Development (OECD) countries
GDP increased by a factor of two while energy con-
sumption increased by about fifty per cent, the result
being a decrease in energy intensity of about twenty
per centor an average of about one percent per year.
Within the OECD there are substantial differences
between countries. Denmark, Italy and Japan have
the lowest energy intensities and Canada and the
USA the highest, with more than a factor of two
between the lowest and the highest.
Of importance too in the context of this chap-
ter is thecarbon intensity, which is a measure of
how much carbon is emitted for a given amount of
energy. This can vary with different fuels. For in-
stance, the carbon intensity of natural gas is twenty-
five per cent less than that of oil and forty per cent
less than that of coal. For renewable sources the car-
bon intensity is small and depends largely on that
which originates during manufacture of the equip-
ment making up the renewable source (e.g. during
manufacture of solar cells).Figure 11.3Energy intensity averaged over OECD countries 1971–96.
avoided. Scenarios of carbon dioxide emissions that would be consistent
with various stabilisation levels were presented there and arguments put
forward for a target level for atmospheric concentration of carbon dioxide
in the range of 450 to 500 ppm. How the world’s energy producers and
consumers can meet the challenge of this target is addressed by this
chapter.