Journal of Economic Modeling Research

  Environmental Kuznets Curve ( EKC) theory has evolved over several decades from its initial intuitive conception to the complex theoretical models of today. Through successive steps of empirical and theoretical debate, a quadratic relationship between income and environmental degradation has been proposed, criticized, defended, and criticized again.

  Along the way, each finding have new look at the subject. Critic that is provided by Mazzanti et al. (2007) and Stern (1998) is that instead of attempting to gain insight into the underlying mechanics of an EKC theoretical foundation, there are undue focus on exploring empirical regularities among a large set of variables. These critics from opponent and supporter cause researcher to review their approach and take more concerns on details and methodology of EKC theory that make the way of theoretical works.

    This study aims at determining the optimal environmental tax policy in the context of a dynamic model. For this purpose, clean technology diffusion was added to the AK growth model and the theoretical model has been generalized to the open economy. The main feature of the economy is creating pollution in the process of economic growth and its negative impact on social welfare. The diffusion of clean technology reduces pollution emission and has a positive effect on environmental quality and social welfare.

  The Hamiltonian solution of the model indicates that the steady state growth rate and optimal tax pollution is affected by the consumer preference toward consumption and environmental quality, pollution elasticity with respect to production, clean technology diffusion, foreign growth rate, inverse elasticity of intertemporal substitution , depreciation rate of capital and trade parameters.

  The results show that the optimal tax rate in Iranian economy is about 15 percent. Furthermore, sensitivity analysis shows that the emission elasticity of pollution subject to the production and environmental preference parameters have larger impacts on optimal tax rate than foreign growth rate and trade parameters.

  The aim of this study is to calculate the marginal private and social costs of two thermal power plants in Isfahan region for a particular day in January 2010. For this purpose a nonlinear planning model with linear constraints has been used. The objective function (social cost) which is a twofold objective function is calculated by the summation of variable costs and external costs of power plants in the above mentioned region.

  The results of minimizing the objective function of private cost and also minimizing objective function of social cost indicate a significant difference between marginal social cost and marginal private cost. This difference is considered as marginal external cost in peak hours of electricity consumption and has had an obvious increase to the off-peak hours of electricity consumption in the region of the study. Taking into account the social costs of electricity generation, green power generation technologies can compete with thermal power plants.

In recent years, the sudden increase in environmental awareness has resulted in more attention to this sector. On this basis, the economic load distribution models, that previously observed merely the minimization of the cost of production and determination of optimal arrangement of producers based on minimization of the total cost, are now facing a fundamental change in execution and modeling. Based on this, the optimal arrangement of producers will now be determined based on two objectives of a minimum cost of production and a minimum environmental pollution. Obviously, with the situation in mind, the problem changes from a single- objective one to a multi-objective problem. The present study takes into account the question of optimal economic and environmental distribution, and its goal is to determine the optimal arrangement of producers in a situation where both the economic and environmental objectives are achieved. The model has been implemented by E-Constraint algorithm. The modeling in this study has been performed for the practical development in Esfahan Electricity Inc. market, in 2012. The results from this model show that the real performance of the market is different from the economic and environmental optimums. The results show the fact that because of the disregard for the environmental costs, the real deviation of performance from the optimum condition is practically much more serious and extensive in the environmental sector.

Environmental quality is affected by many factors such as economic and political inequality. The main purpose of this article is to investigate the effects of income and political inequality on the environment quality in the selected countries. Using the Generalized Method of Moments (GMM), the effects of gini coefficient, democracy index and income per capita, energy consumption and human development index on environmental quality are estimated for 57 countries during the period 2000 to 2012. The results show that income inequality and Political inequality significantly had a negative effect on environment quality. While the energy consumption has the negative effect on the quality of environment, improvement in human development index and the income per capita have a positive effect on the quality of environment. This finding might has important policy implication for policymakers and authorities to achieve sustainable development in different countries.

In this paper to assess the environmental efficiency of electric power companies two-stage approach has been used Which means that the first step is to calculate the environmental efficiency score of electric power companies with Slack-Based Measure during the period (2004-2014). Then, the second step various factors effects have been evaluated on environmental efficiency by using Tobit and Ordinary Least Squares models. The result of first step show that environmental performance of the electricity industry has seen a reduction in performance during the period of 2004 to 2006, While environmental performance had a rising trend between 2007 to 2009 and then it has had a considerable reduction in the period 2010-2014 (after the liberalization of energy prices). Finally, in 2004, the average efficiency of the industry is reached to lowest level (0.65). The result of second step show that factors affecting efficiency namely Size and Liberation dummy variables have negative effects but the proportion of electricity produced by the thermal power plants, the proportion of gas used in the fuel, capacity utilization rate and electricity exports have positive effects. The results show that importing electricity doesn’t have any significance effect on the efficiency. In the end, the results of adding a new variable (variable log of per capita GDP) showed that except for the proportion of gas used in the fuel, the explanatory variables has robust coefficient.