In the literature, different decomposition techniques are available and these techniques are broadly grouped into those based on the Divisia index and those based on the Laspeyres index. The method applied in this study is a simple complete decomposition based on the Laspeyres index (Sun,1996). The factors behind the change in CO2 emissions from fuel combustion is based on the partition presented in the following equation: CO2 ¼ CO2
The first factor (CO2/TPES) in the equation refers to CO2 emission intensity of entire energy system; the second factor (TPES/FED) refers to efficiency of energy transformation system; the third factor (FED/GDP) refers to energy intensity; the fourth factor (GDP/POP) refers to per capita GDP; and the fifth factor (POP) refers to population. For different decomposition techniques used in energy modeling studies see Ang (2004), Ang and Zhang (2000), and Rose and Casler (1996).