نشریه انرژی ایران
سال پانزدهم شماره 2 (پیاپی 55، تابستان 1391)

Following the restructuring of electricity industry, electricity markets in many countries segmented in three sectors of production, distribution and transmission, and the structure of the vertically integrated industry was abolished. In this context, power transmission and related issues in the design of the electricity market is of special importance. The main feature of competitive electricity markets, are non-discriminatory and poen access to the transmission system. Financial Transmission Rights to facilitate open and competitive access to the transmission system, play an essential role in the market design. Financial Transmission Rights protect the network users among the costs of transmission congestion and is supplied in both poin to point and flowgate forms in electicity markets. The pricing of these financial instruments is based on the Local Marginal Prices. In this article, we investigate the basic properties of Financial Transmission Rights, their pricing, trading and application in power industry, and review some world exercises in this subject.

In this paper, performance and microstructural properties of single Solid Oxide Fuel Cells (SOFCs) have been investigated by using experimental tests, Scanning Electronic Microscopic (SEM) and a performance modeling. These single-SOFCs were fabricated by tape casting and screen printing as economical mass-production processes which have been presented. Also, overpotential polarizations, such as: ohmic, activation, and concentration polarizations, are determined by an electrochemical model and microstructure characteristics for each layer. On the basis of the modeling results, anode, cathode activation and ohmic polarizations have the most effects to cause loss power density of the single cells. Thus, microstructural and geometric properties play main role in performance of the single-SOFCs. Because of large grain and pore sizes of the anode layer compared with the cathode layer cause more activation polarization than that of the cathode layer. Performance analysis can be used as a powerful tool to improve and optimize fabrication characteristics and processing of the single cell of the SOFC which are made by tape casting and screen printing techniques by using an electrochemical model in the future studies

Solar arrays are one of the most promising renewable energy technologies for energizing future building. For roof top solar panels installation, knowledge of the optimum tilt angle is important to have the maximum annual or seasonal energy yield. this is due to the fact that variation in tilt angle affects the amount of solar radiation reaching the panel surface. In this study, a mathematical model and data obtained from Typical Meteorological Year (that calculated of radiation data for 12 years (1994-2005) on horizontal surfaces in Karaj) is used to estimated the total (global) solar radiation on a tilt surface and to determine the optimum tilt angle for a solar panel in karaj, iran. The best orientation for solar arrays in Karaj is due south. It is found that the optimum tilt angle change between (May, June, July and August) and (January) throughout the year.in winter(December, January and February) the tilt should be, in spiring (March, April and May), in summer (June, July and August) and in autumn (September, October and November). the annual optimum tilt angle dependent on many factors such as the latitude of the location and weather condition. the yearly average of this value was found to be and this would be the optimum fixed tilt throughout the year

Energy demand management has very importance in economic security and planning. To identify the energy demand affecting factors and energy demand prediction can help Policy makers and activists in the energy market to improve market performance and better economic decisions and high fuel security. Recently, new techniques have been developed to economic variables prediction and modeling. Among these techniques Genetic algorithm and Particle Swarm Optimization are the best known and most widely used in literature including economy. Therefore, in this study the genetic algorithm and particle Swarm Optimization is used for energy demand estimation and prediction in the form of linear and exponential and then their performance in each of the models evaluated. The results indicate that accuracy and efficiency of the particle swarm optimization in both of exponential and linear forms is better than genetic algorithm. In addition, among the different forms the exponential form estimated with the particle swarm optimization is the best way to predict the future energy demand.

Economic and reliability issues are very important for consumers and effect consumer's decision making for electric power supplying. Also micro grid is new configuration of network for supplying consumer's energy demands. In this paper, four scenarios are compared to each other in case of economic issues and reliability. The four scenarios are providing energy by main grid, main grid and distributed generation resources, isolated micro grid and a micro grid connected to an upstream network. The proposed objective function has two dimensions. Economical dimension consists of the initial costs and operational costs. Reliability dimension includes non-delivered energy (NDE) for the consumers. The two dimensional objective function is optimized for four scenarios by using weighting method. Each scenario is considered in two cases for evaluating reliability. First, the loads on one feeder and second is the loads on separated feeders. The proposed method is compared with a similar method and the comparison results show that it is more efficient and applicable.

A hybrid hydro/wind/photovoltaic base on hydrogen storage system is designed to supply power demand of pump stations. The aim of this design is minimization of net present cost of the hybrid system. Optimization problem is subject to reliable supply of the demand. The system is investigated in the north west of Iran (Meshkinshahr) and the local data is applied. About 12 pump stations are found in the Sabalan dam and far remote areas, which makes the task of their electrification via grid system very difficult. The hydro potentials are analyzed with the help of GIS data of Iran. Meteorological data from renewable energy organization (SUNA) of Iran and other sources, such as NASA, is used for the estimation of solar and wind energy potentials. In this paper, hydro/PV/wind/ fuel cell hybrid system is compared with above system without hydro unit. An advanced variation of Artificial Bee Colony algorithm (ABC) and HOMER optimization software is used to solve the optimization problem. The algorithm developed is compared with HOMER software and the results show that ABC algorithm accuracy is better than HOMER software. Result reveals the impact of components outages on the reliability and cost of the system, so they are directly dependent on component’s reliabilities, i.e. Outages result in need for a larger generating system for supplying the load with the acceptable reliability. Different system types and their component sizes are identified having a cost of energy less than 0.3 $/KWh.

Conservation of energy resources are becoming a focus of attention in today’s world since there is a widely known concern over alarming scarcity of fossil fuels in near future. Exercising synthesis of gases through gasification of municipal garbage’s can help increase electricity and energy production as well as lessen municipal waste disposal costs. In this research a thermodynamic model has been examined on emission synthesized gas mixture, equilibrium temperature gasification, heating value of synthesized gas in downdraft gasifier and it is based on equilibrium constants of the main gasification reactions in order to evaluate the effects of moisture of waste obtained. The mixture of synthesized gas is validated on the basis of practical data. Tehran municipal waste is employed as an example. The obtained results show that with any increase in garbage moisture content there is a steady increase in hydrogen content and this value decrease after a point, carbon monoxide shows a decrease in amount and carbon dioxide as well as nitrogen content shows a boost. The effect of temperature on synthesized gas concentration and its mole fraction examined as well.