کشش تقاضای برق و حرارت: شواهدی از رگرسیون انتقال آرام پانل با رویکرد متغیر ابزاری

This study applies a non-linear model, i.e. the recently developed panel smooth transition regression (PSTR) model, and takes into account the potential endogeneity biases to investigate the demand function of electricity for 24 OECD countries from the period 1978–2004. Our empirical results demonstrate that there is a strongly non-linear link among electricity consumption, real income, electricity price, and temperature, a result that is new to the literature. As real income rises, electricity consumption rapidly increases first, and after the level of real income exceeds approximately US$2500, its increasing rate turns slow down. An increase in electricity price has a negative or no influence on electricity consumption. Evidence of a U-shaped relationship between electricity consumption and temperature is supported, and the threshold value of temperature is approximately 53 °F, which is endogenously determined. Furthermore, the estimated elasticities of time dynamic indicate that electricity demand is income inelastic, price inelastic, and temperature inelastic. As time goes on, the absolute elasticities of electricity demand gradually decrease with respect to real GDP and electricity price, whereas they gradually increase with respect to temperature, suggesting that the impact of temperature on electricity demand is becoming more important in recent years.

Electricity plays an important role in economic development and technological progress in many countries. “No country in the world has succeeded in shaking loose from subsistence economy without access to the services that modern energy provides” (World Bank, 1996). For developed countries, Ferguson et al. (2000) indicate that there is a strongly positive correlation between wealth and energy (or electricity) consumption, and the correlation between electricity and wealth is stronger than the correlation between total energy and wealth. However, the process of electricity production and consumption may emit air pollution and greenhouse gasses. The long-run accumulated greenhouse gas emissions are an important factor for global warming, which accelerates unusual climate change in the world. Many countries have paid attention to greenhouse gas emissions and problems of global warming. In 2005 the Kyoto Protocol was drawn up and co-signing countries agreed to reduce greenhouse gas emissions by 5.2% from the level in 1990. Since the greenhouse effect and the reduction of pollution emissions are global concerns, one needs to clarify the determinants of electricity demand, which include real income, own price, climate change, and so on. Accurately estimating and analyzing the determinants of electricity consumption can provide some information for governments to discuss and anticipate the supply and demand of electricity, and then provide the basis of setting up appropriate environmental policies, i.e. pollution and energy taxes. Thus, in the framework of global data, it is more important to investigate electricity demand. The paper aims to make the following contributions to the electricity demand literature. First, we apply the panel smooth transition regression (PSTR) model of González et al. (2005) to investigate the relationship among electricity consumption, real income, electricity price, and temperature for 24 Organization for Economic Cooperation and Development (OECD) countries from the period 1978–2004. Which economic variables could possibly explain the transition from one regime to another? In order to find out the optimal threshold variable of the electricity demand model, this study carries out non-linear tests by way of the potential threshold variables (Fouquau et al., 2008 and Huang et al., 2008), which are real GDP per capita (Model (1)), electricity price (Model (2)), and temperature (Model (3)). Second, most studies in the literature focus on analyzing the demand elasticities of electricity with respect to electricity price and income, but they seldom consider the impact of climate change on electricity consumption. How significant is temperature for the rising electricity consumption? We enrich the existing literature by simultaneously examining the impacts of real income, electricity price and temperature on electricity consumption and take into account endogenous determination of the types of our PSTR models for electricity demand. Third, based on the characteristics of the PSTR model, we can consider the elasticity of electricity demand changes with country and time to analyze the elasticities of heterogeneous countries and the potential impacts of structural breaks (parameter instability) on the electricity demand's elasticities in the panel framework. The structural breaks are a common problem in macroeconomic series when they are usually affected by exogenous shocks or regime changes in environmental or economic events, i.e. economic development, energy crisis, global warming, the Kyoto Protocol, renewable energy technology, and so on (Lee and Chang, 2007 and Lee and Lee, 2009). Fourth and finally, many existing studies have found unidirectional causality from electricity consumption to real income and/or from real income to electricity consumption (Jumbe, 2004, Lee and Lee, 2010, Mozumder and Marathe, 2007 and Ouédraogo, 2010). On the other hand, greenhouse gas emissions may increase with electricity consumption and then lead to rising temperatures (global warming), whereas an increase in temperature also influences electricity consumption. Thus, the problem of potential endogeneity exists in the electricity demand model.1 To the best of our knowledge, none of the studies on electricity demand in the existing literature to date notice this problem. To consider the potential endogeneity biases, we apply the PSTR model with instrumental variables developed by Fouquau et al. (2008). The remainder of this study is organized as follows: In the next section, we discuss the reasons why it is important to test for nonlinearity in the energy demand model. Section 3 introduces the PSTR model with instrumental variables and illustrates the variables' definitions and data sources. Section 4 describes the data specification. Section 5 provides the empirical results, and a conclusion is offered in Section 6.

Electricity plays an important role in economic development and technological progress in many countries. Accurately estimating the determinants of electricity consumption can provide some information to discuss and anticipate the supply and demand of electricity and to set up appropriate environmental policies. Thus, it is important to examine the determinants of electricity consumption in the framework of global data. The empirical results of this study are summarized as follows. First, the results show that evidence is supported for a non-linear relationship among electricity consumption, real income, electricity price, and temperature. Naturally, such a non-linear result may explain why existing studies on electricity and economic growth appear to exhibit diversification and dissimilar results. Second, the estimated elasticities of the time dynamic (Table 5) indicate that electricity demand has inelastic income, inelastic price, and inelastic temperature. Besides, as time goes on, the elasticity of real income gradually decreases, whereas the elasticity of temperature gradually increases. It may be due to greenhouse gas emissions and global warming, and thus the impacts of temperature on electricity consumption turn from negative to positive and have become more important in the recent periods. A policy implication emerges that OECD countries should set up some appropriate environmental policies to decrease their greenhouse gas emissions and to avoid the phenomenon of global warming. Reliable estimates of the elasticities of demand for electricity are important information for governments when they formulate policies for restructuring the electricity sector and for electricity companies needing to regularly upgrade their demand management policies. Equally important, the feature that electricity demand is own price inelastic indicates that pricing policies as an instrument to encourage a more efficient use of energy may not be practical. It also shows that an electricity control policy based on only the use of a tax increase is, under current conditions, a very expensive option. Our findings imply that changes in electricity demand contribute to one of the factors that cause structural change in the relationship among electricity consumption, income, electricity price, and temperature. Therefore, this structural change due to the existence of a real income threshold should be taken into account when constructing estimation and prediction models of electricity demand in the case of OECD countries. The policy implications derived from this study are that before policy-makers adopt any strategy to conserve or promote electricity consumption, the role of electricity use should not be neglected in the non-linear relationship.