Table 1.

Variable indices.

Variable	Definition	Variable	Definition
i	Area	j	Fuel
G	Gross domestic product	ggi	Province structure: GDP share of area i
Gi	Gross domestic product of area i	igi	Investment intensity: share of fixed asset investment in GDP of area i
Ii	Fixed asset investment of area i	rii	R&D intensity: share of R&D Expenditure in fixed asset investment of area i
Ri	R&D expenditure of area i	gri	R&D efficiency: GDP per unit of R&D expenditure in area i
Ei	Gross energy consumption of area i	egi	Energy intensity: gross energy consumption per unit of GDP in area i
Eij	Consumption of fuel j in area i	eeij	Energy structure: share of Consumption of fuel j in gross energy consumption in area i
Cij	Carbon emission by fuel j in area i	ceij	Carbon emission coefficient: carbon emission per unit of fuel j in area i