Worldwide Primary Supply by Fuel Type

Figure 10 shows the worldwide growth in the use of energy and electricity, while Figure 11 shows the fuels used to produce this energy. Type of fuel used is an important factor in emissions because fuels have significantly different ratios of CO₂ emissions per unit of energy consumed. Coal produces 21 percent more CO₂ than oil and 76 percent more CO₂ than natural gas per unit of energy consumption. Nuclear, solar, wind, hydroelectric, and biomass energy sources do not result in significant CO₂ emissions. Consequently, CO₂ emissions per unit of energy used are directly related to fuels and technologies in use, and assumptions about fuels and the rate of technological change play a significant role in emissions forecasts. (See Figure 9 in Box 2.)

Figure 11

Note: Renewable includes biomass, waste, geothermal, solar, and wind. Source: IEA, 2000b.