نشریه انرژی ایران
سال شانزدهم شماره 1 (پیاپی 58، بهار 1392)

Greenhouse gas emissions are considered as the main cause of climate change. Investigation of economic dimensions of greenhouse gas emissions and its environmental effects especially in a situation where the volume of greenhouse gas increasingly is rising is very important. In this paper، the relationship between greenhouse gas emissions i. e. carbon dioxide and GDP per capita and energy consumption in Iran during the years 1370 to 1387 using the Environmental Kuznets Curve has been studied. Due to the fact that in this study the relationship between the dependent and independent variables is equivocal Fuzzy regression models were used to estimate this relationship. Fuzzy regression estimates an interval of possible values for the output variable while the classical regression calculates a value for the output variable. Results from the fuzzy regression model show an incomplete Kuznets model in Iran. The results of the maximum and minimum amount of carbon dioxide emissions in 1387 are approximately 269،000 and 204000 kt respectively. Knowledge about the relationship between energy consumption and carbon dioxide emissions can be substantial in the overall energy sector planning policies، provide useful guidance.

Economic growth is one of the most important indicators of economic performance of governments. The OPEC member countries which have abundant oil resources endeavor to use it for improving of their economic growth. Therefore، evaluation of how the impact of oil revenues on economic growth is essential. The present study examines the relationship between oil revenues and economic growth in selected OPEC member countries، including Algeria، Ecuador، Iran، Kuwait، Nigeria، Qatar، Saudi Arabia، United Arabic Emirates and Venezuela، during the period of 1981- 2010; based on an error components model using panel data. The main hypothesis of this research is that oil revenues caused economic growth. The results of this research ultimately reject the hypothesis above for all countries and also show that the effect of oil revenues is not same in different countries. In the case of Iran and Saudi Arabia، more growth in oil revenues even causes a decrease in economic growth that this is a confirmation upon theory of natural resource curse.

Conventionally، providing energy services in most developing countries has been the responsibility of public sector monopoly. The deficient management in facilities and government budjet constraints has inclined developing countries to finance their services provision through international markets. The growing demand for energy and higher interest rates in these countries attract investors and lenders to this new business position. Following power production sector privatization، governments have changed their roles from main financer، manager and operation to facilitator and regulator in services supply process by private sector. Increasing private sector activity in developing countries، risk should be distributed among the project partners- public and private. This study is concentrated in general trends of private power market، risk management and different project invironment in the developing world and Iran. Attention to project participant role such as sponsers، fuel and equipment suppliers، construction contractors and operation and maintanence corporations for risk management، risk effect on project development، government protection and guaranteed level against special risks and mechanism of risk reduction is necessary.

Distributed generation (DG) using a parallel battery pack with photovoltaic (PV) system has been presented in this paper. For this aim، first modeling of a photovoltaic package has been illustrated. Then، a DC/DC converter has been considered as the PV power controller and a battery pack has been connected to its output. Considering a two level inverter and a three phase’s transformer، a local load will supplied by the DG and connected power grid. The DG has been connected to the high voltage network via a filter and a distribution power station. Since the power capacity of PV system is depended to both temperature and irradiance، a Nero-Fuzzy network has been designed for estimation of maximum power ability of PV. To producing of obtained power by the PV system، the connected DC/DC converter has been controlled relatively. So، the power management between the PV system and the battery pack can be confirmed. In the other hand، another controller has been design for control of transferred power between the power network and DG system that can control the battery pack power indirectly. Finally، a series of simulation results shows the effectiveness of proposed method for some various conditions such as different temperature، difference irradiations and also various state of charge of battery pack.

Power generation systems by renewable energy can reduce primary energy consumption and harmful emissions. Organic Rankine Cycles (ORC)، together with solar energy as a heat source، is a possible solution for producing power. In these cycles water is replaced with organic working fluids. This study uses a thermodynamic simulation for performance analysis of ORC، choosing a suitable working fluid for these Cycles. In this study، Parabolic Trough collector as a heat source with temperature of 260°C has been considered. The system defined generated 10kW of electrical power. The effects of the properties of twelve different working fluids، on the overall cycle efficiency have been investigated. The thermodynamic and physical properties، environmental impacts، safety، availability and cost are among the important considerations when selecting a working fluid. N-decane presents the best cycle efficiency، resulting in the minimum collector surface area. However، this fluid has the highest saturated vapor specific volume (resulting in a larger condenser) and the lowest condenser saturation pressure (higher infiltration of non-condensable gases). The best candidates for the cycle regarding all the considered aspects considered are: R113، R123 and Isopentane. Comparing these three fluids، R113 presents the highest efficiency and with highest impact in environment but good fluid from safety point of view. Isopentane presents the smallest cycle efficiency and biggest vapor specific volume، but is the fluid with super-atmospheric saturation pressure and higher flammability. R123 presents the high efficiency and with low impact in environment.

Phase change materials are organic or inorganic compounds which can absorb and save a great deal of energy in form of latent heat. This ability enables the designers to delay the heat transfer to the building for few hours in peak load energy consumption. Using phase change materials in buildings has been introduced from last decades but in our country is a new problem. The goal of this paper is ti introduce phase change materials and to present some applicable suggestions for using them in buildings.

Along with photovoltaic systems which produce electrical energy from solar radiation، a photovoltaic/thermal system simultaneously produce electricity and heat. In this research، a photovoltaic/thermal system was designed using a series of thermosyphons (gravity assisted heat pipes) to cool the photovoltaic panel. Because of high vapour pressure، methanol was used as the working fluid in the thermosyphons. During the experiments، the filling ratio as one of the most important parameters affecting the thermosyphon performance، varied at different values. At the optimal filling ratio e. g. 50%، 5. 67 percent more electrical power in average was produced from the photovoltaic/thermal system compared to the photovoltaic one. Additionally، the photovoltaic/thermal system had 16. 35 percent thermal efficiency in average.