The Nonlinear Relationship between Energy Consumption and Economic Growth in Iran Based on Threshold Approach

This paper investigates the possibility of both linear and nonlinear effects of energy consumption on economic growth in Iran, using data for the period of 1959–2007 based on threshold regression. Some previous studies support the view that energy consumption may promote economic growth. However, the conclusion drawn from this study suggests that such relationship exists only where there is a low level of energy consumption in Iran. The evidence shows that, there are two break points (corresponding with three regimes) in economic growth function. For the low energy consumption regime (where per capita energy consumption is less than 5 barrels) we find that energy consumption has an important positive influence on economic growth with coefficient 0.09, which is not the case with the high or middle regime. In middle regime with per capita energy consumption between 5 and 8 barrels, the marginal effect of energy use on economic growth gets to 0.015. For the regime corresponding to per capita energy consumption above the threshold 8 barrels, the marginal effect of energy use is reduced to about zero. We show that a threshold regression provides a better empirical model rather than the standard linear model and policy-makers should seek to capture economic structures associated with different stages of economic growth.