مصرف انرژی و رشد اقتصادی: دیدگاه جدید در رابطه هم انباشتگی

This paper examines the long-run relationship between energy consumption and real GDP, including energy prices, for 25 OECD countries from 1981 to 2007. The distinction between common factors and idiosyncratic components using principal component analysis allows to distinguish between developments on an international and a national level as drivers of the long-run relationship. Indeed, cointegration between the common components of the underlying variables indicates that international developments dominate the long-run relationship between energy consumption and real GDP. Furthermore, the results suggest that energy consumption is price-inelastic. Causality tests indicate the presence of a bi-directional causal relationship between energy consumption and economic growth.

The question of whether or not energy conservation policies affect economic activity is of great interest in the international debate on global warming and the reduction of greenhouse gas emissions. Although the causal relationship between energy consumption and economic growth has been widely studied, no consensus regarding this so-called energy consumption-growth nexus has yet been reached. The direction of causality is highly relevant for policy makers. For instance, if causality runs from energy consumption to economic growth, energy conservation policies that have the aim of reducing energy consumption may have a negative impact on an economy's growth. The literature proposes four different hypotheses regarding the possible outcomes of causality (Apergis and Payne, 2009a and Apergis and Payne, 2009b).1 The growth hypothesis suggests that energy consumption is a crucial component in growth, directly or indirectly as a complement to capital and labour as input factors of production. Hence, a decrease in energy consumption causes a decrease in real GDP. In this case, the economy is called ‘energy dependent’ and energy conservation policies may be implemented with adverse effects on real GDP. By contrast, the conservation hypothesis claims that policies directed towards lower energy consumption may have little or no adverse impact on real GDP. This hypothesis is based on a uni-directional causal relationship running from real GDP to energy consumption. Bi-directional causality corresponds with the feedback hypothesis, which argues that energy consumption and real GDP affect each other simultaneously. In this case, policy makers should take into account the feedback effect of real GDP on energy consumption by implementing regulations to reduce energy use. Finally, the neutrality hypothesis indicates that reducing energy consumption does not affect economic growth or vice versa. Hence, energy conservation policies would not have any impact on real GDP. In consideration of such a pure statistical causality analysis with a few variables it should be noted that the policy implications of causality between energy consumption and real GDP are not straightforward. Energy conservation policies cannot sensibly be constituted without considering economic or environmental factors such as energy supply infrastructure, energy efficiency considerations or institutional constraints (Mahadevan and Asafu-Adjaye, 2007). Hence, the formulation of an efficient energy policy is more complicated than empirical results might suggest. For instance, energy conservation policies accomplishing a reduction in energy consumption due to an improved energy efficiency may raise the productivity of energy consumption, which in turn may stimulate economic growth. Thus, a shift from less efficient energy sources to more efficient and less polluting options may establish a stimulus rather than an obstacle to economic growth (Costantini and Martini, 2010). The other way around, bad energy supply infrastructure or other supply side disruptions decreasing energy consumption could indeed induce an adverse impact on economic growth. Further, high substitutability between energy and other input factors on the production side can explain possible economic growth without a considerable increase in energy consumption. Therefore, the empirical results of causality analyses should be interpreted with caution. Our analysis of the relationship between energy consumption and economic activity is based on a sample of 25 OECD countries from 1981 to 2007 and uses recently developed panel-econometric methods. We explore an additional channel of causality by introducing energy prices. As energy prices have been neglected in many previous studies, the long-run parameters and the evidence of causality may be biased, see Masih and Masih, 1997 and Asafu-Adjaye, 2000. But in contrast to these two studies, we examine the original energy price index rather than the consumer price index (CPI) as a proxy. Income and price elasticities provide policy makers a suggestion of the extent to which prices need to increase, in the form of energy taxes, in order to reduce energy consumption and the potential for the market to conserve energy (Lee and Lee, 2010). Additionally, energy companies need this information to design their demand management policies. But only a few papers have estimated income and price elasticities for energy consumption in a panel framework. Furthermore, the long-run equilibrium relationship is studied in both directions, i.e. with either energy consumption or real GDP as a dependent variable (Costantini and Martini, 2010). The innovative contribution of our paper is to determine the long-run relationship between energy consumption, real GDP and energy prices in more detail. In contrast to other studies concerning the energy consumption-GDP growth nexus, we distinguish between national and international trends as potential drivers of the long-run equilibrium between energy consumption, real GDP and energy prices. To analyse these issues, each variable is decomposed into common and idiosyncratic components. The idiosyncratic component is the part of a variable that is driven by national developments, whereas the common component represents international trends in the evolution of the variables. These might, however, have a different relevance for individual countries. Taking this decomposition as a starting point, cointegration between the common components means that the common components of energy consumption, real GDP and energy prices move together in the long run and do not deviate permanently from one another. Hence, cointegration between the common components suggests that the relationship between these variables depends to a great extent on international developments. Instead, cointegration between idiosyncratic components refers to developments relevant exclusively on the national level (Dreger and Reimers, 2009). Depending on the results of the cointegration tests, this distinction has important implications for policy makers. If the common components cointegrate, national energy policies may not have a large impact on economic growth. Indeed, this paper delivers empirical evidence that energy consumption, real GDP and energy prices are cointegrated in their common factors, but not in their idiosyncratic components. The remainder of this paper is organised as follows. Section 2 briefly reviews the literature related to the causal relationship between energy consumption and economic growth. Section 3 presents the data, discusses the econometric methods and presents the empirical results. Section 4 provides conclusions and policy implications.

In our contribution, we study the causal relationship between energy consumption and economic growth for 25 OECD countries from 1981 to 2007, explicitly taking into account the role of energy prices. We provide new empirical insights into the long-run relationship among these variables by applying factor decomposition to distinguish between common factors and idiosyncratic components as potential drivers of this relationship. The distinction between common factors and idiosyncratic components has important policy implications. Cointegration between the common components suggests that international developments dominate the long-run relationship whereas cointegration between idiosyncratic components relates to developments relevant on the national level. Hence, national energy policies may not have a large impact if international developments dominate the relationship between energy consumption, economic growth and energy prices. Indeed, our main empirical finding is that only the common components of energy consumption, economic growth and energy prices are cointegrated. This result highlights the relevance of international developments to explain energy demand in OECD countries. Hence, policy makers should take into account the international impact on energy demand when designing efficient energy policies. Additionally, energy companies need accurate information concerning energy demand in order to be able to predict the future requirements and to take account of the necessary capacity to satisfy future energy consumption. In contrast to our finding, in non-OECD economies which are less integrated and not such closely connected to international markets as OECD countries national particularities may play a more important role than international developments. But even if a economy is less open at least the energy consumption will be affected by international developments such as changes in the world market price of oil. The strength of the international impact certainly depends on the energy intensity of the specific economy. Further analysis of the cointegration relationships suggests that energy consumption is relatively price-inelastic. This underlines the theoretical expectation that energy use is mostly a necessity. The established long-run causality in the energy demand equation means that energy consumption readjusts after a shock towards an international rather than a national equilibrium relationship. In this light, national energy policies may have only a limited impact on energy consumption. The same holds for economic growth, such that national energy conservation policies may not have a large impact on economic growth either. What is more, bi-directional causality between energy consumption and economic growth in the long run suggests that no variable leads the other. An increase in energy consumption leads to an increase in economic growth and vice versa. Hence, it seems that OECD countries exhibit a kind of energy-dependence in the sense that an adequately large supply of energy seems to ensure higher economic growth (Lee and Lee, 2010). The bi-directional causal relationship indicates that the feedback hypothesis holds. This suggests that energy consumption and economic growth are interrelated. If this is true, the design of efficient energy conservation policies should imply the consideration of the direct impact of energy consumption on economic growth and the feedback effect of economic growth on energy consumption. One further conclusion regarding the empirical result of causality from energy to GDP could be that energy policies devoted to a reduction in greenhouse gas emissions should emphasise the use of alternative energy sources rather than exclusively try to reduce overall energy consumption in order to ease the trade-off between energy consumption and economic growth. But the finding that energy consumption causes economic growth does not necessarily mean that energy conservation will harm economic growth if energy-efficient production technologies are used. In fact, a reduction in energy consumption due to improvements in energy efficiency may raise productivity, which in turn may stimulate economic growth. Thus, a shift from less efficient and more polluting energy sources to more efficient energy options may establish a stimulus rather than an obstacle to economic development (Costantini and Martini, 2010). One main task of energy policy is the conservation of energy which means a more efficient use of energy and a reduction in greenhouse gas emissions using alternative energy options. In order to achieve these ambitious objectives, it should be noted that efficient energy conservation policies cannot be designed without considering other economic and environmental factors than the underlying variables in our study. Furthermore, according to the results of our study, not only national factors such as energy supply infrastructure, energy efficiency considerations or institutional constraints, but also international developments should be taken into account in the future.