As the 20th century draws to a close, both individual countries and the world community face challenging problems related to the supply and use of energy. These include local and regional environmental impacts, the prospect of global climate and sea level change associated with the greenhouse effect, and threats to international relations in connection with oil supply or nuclear proliferation.
For developing countries, the financial costs of providing energy to provide basic needs and fuel economic development pose an additional burden. To assess the magnitude of future problems and the potential effectiveness of response strategies, it is important to understand how and why energy use has changed in the past and where it is heading.
This requires study of the activities for which energy is used, and of how people and technology interact to provide the energy services that are desired. The authors of this report and their colleagues have analyzed trends in energy use by sector for most of the world’s major energy-consuming countries.
The approach they use considers three key elements in each sector: the level of activity, structural change, and energy intensity, which expresses the amount of energy used for various activities. At a disaggregated level, energy intensity is indicative of energy efficiency, but other factors besides technical efficiency also shape intensity.