3.5 Energy efficiency, dependency, and emissions See Table 3.5 here

Commentary
About the data
Definitions
Data sources

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Energy is both a critical factor of production and, through its generation, a major source of pressure on the environment. The sustainability of energy supplies and the efficiency of energy use are therefore critical for countries aiming for environmentally sustainable development.

Carbon dioxide (CO2) emissions, largely a byproduct of energy generation and use, are the largest source of greenhouse gases associated with global warming. Thus understanding the links between economic activity and CO2 emissions has become increasingly important.

The ratio of real GDP to energy use provides a measure of energy efficiency. Differences in this ratio over time and across countries are influenced by:

Structural changes in the economy. Changes in the energy efficiency of particular sectors of the economy. Differences in fuel mixes.

Technological changes in energy-intensive industries help increase overall energy efficiency. Shifts to thermodynamically efficient fuels such as natural gas also can help. But the most important factor affecting energy efficiency is the rapid rise in energy use as countries approach middle-income status. The development of heavy industries and the large increase in private automobile ownership associated with income growth both increase demand for energy. Offsetting this tendency, especially for high-income economies, may be the growth of the less energy-intensive services sector. Growth in services also helps reduce oil-importing countries’ dependence on external sources of energy. In the past two decades this dependency has put heavy pressure on these countries’ foreign exchange earnings and has made their economies vulnerable to external shocks.

Anthropogenic CO2 emissions result primarily from fossil fuel combustion and the manufacture of cement. Because fossil fuel consumption tends to rise with income, high-income countries are the largest emitters per capita.

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The Carbon Dioxide Information Analysis Center (CDIAC), sponsored by the U.S. Department of Energy, calculates annual anthropogenic emissions of CO2.

Estimates do not include bunker fuels used in international transport because of the difficulty of apportioning these fuels among the countries benefiting from that transport. Although the estimates of world emissions are probably within 10 percent of actual emissions (as calculated using global average fuel chemistry and use), individual country estimates may have larger error bounds.

For information on energy use and production see the notes to table 3.4.

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• GDP per unit of energy use is the U.S. dollar estimate of real GDP (at 1987 prices) per kilogram of oil equivalent of commercial energy use (see notes to table 3.4 on energy use).

• Net energy imports are calculated as energy use less production, both measured in oil equivalents. A minus sign indicates that the country is a net exporter.

• Carbon dioxide emissions from industrial processes are those stemming from the burning of fossil fuels and the manufacture of cement. They include contributions to the carbon dioxide flux from solid fuels, liquid fuels, gas fuels, and gas flaring.

Underlying data on commercial energy use and production are primarily from International Energy Agency (IEA) and United Nations sources. Data on CO2 emissions are based on several sources as reported by the World Resources Institute. The main source is the Carbon Dioxide Information Analysis Center, Environmental Sciences Division, Oak Ridge National Laboratory, in the state of Tennessee in the United States. CDIAC calculations of CO2 emissions are based on data on the net apparent consumption of fossil fuels from the World Energy Data Set maintained by the United Nations Statistical Division and from data on world cement manufacture based on the Cement Manufacturing Data Set maintained by the U.S. Bureau of Mines.

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