نشریه انرژی ایران
سال چهاردهم شماره 2 (پیاپی 51، تابستان 1390)

Recently, energy issues and global warming have gained serious attentions all around the world. In this regard, using renewable energy options are of great importance. Among numerous options, tri-generation systems with fuel cell can be a good candidate for this unique purpose. Trigeneration means to produce cooling, heating and power simultaneously with one source of input energy. The importance of using Tri-generation systems are both higher efficiency and lower environmental impacts. They can be used widespread in residential applications though. Tri-generation prime movers can be internal combustion engine, micro turbines, fuel cells or sterling engine. Among these various prime movers, fuel cellsare the best option due to their high efficiency, low pollution and high reliability. In this paper, by using an economic analysis the size and operation of the required fuel cell for the specific electricity, cooling and heating load of a typical building located in Tehran, Iran are selected. To carry out this analysis, an objective function has been introduced and maximized using developed mixed integer nonlinear method. The operation strategy and the payback period of the chosen system are also determined in this study. In addition, the results end up with finding an optimal capacity, optimal chiller capacity. The results show that using fuel cell is not economical now but for afuture by considering the cost of environmental impact it will be the best option. Finally, the sensitivity analysis is performed by changes in fuel cost, electricity cost and investment cost. The results show that theses parameters have significant effects on the system performance.

The limitation of fossil fuel resources and pollution associated problems, especially in urban areas, and moreover, low efficient traditional energy convertors are the reasons for tendency to use more efficient energy convertors and renewable resources. Using a photovoltaic system for producing hydrogen beside a fuel cell system to supply the electrical and heat demands will be attractive in the near future. in this paper The feasibility study on using a photovoltaic-fuel cell hybrid system to produce heat and electricity simultaneously has been carried out. The results show that the photovoltaic system is the most economical case nowadays, which decreases the electrical dependency on the network and furthermore it has no pollution consequences, but the fuel cell based systems are not justifiable. It’s expected that they will have economical benefit in the future with increasing the cost of energy carriers, also decreasing the capital and operation costs of such systems.

Micro CHP is a micro combined heat and power system that consumes natural gas or other types of fuel and produces heat and power. The growing worldwide demand for less polluting types of energy has led to a renewed interest in the use of Micro Combined Heat and Power technologies in the residential sector.During the process of increasingacceptance of Micro CHP systems,manufacturers and customers are interested to know what the optimum capacity of power generators for these devices is and if these systems are installed in the building, what strategies should be used to minimize the costs of supplying electricity and heat for households. In this paper, a mixed integer nonlinear programming model has been developed. The objective is to minimize annual cost of the energy system for a given residential customer equipped with the CHP plant, combining with a storage tank and a back-up boiler. The model reports the optimal CHP system capacities that customers could employ given their electricity and thermal requirements and minimize a customer’s cost to meet its electricity and heat requirements. Then, a sensitivity analysis is elaborated which indicates that optimal value of CHP capacity is sensitive to capital cost, energy prices, as well as the electricity buyback. An optimal storage tank can extent the operating time of the CHP plant, in addition a Time Of Use (TOU) tariff structure will almost always result in a larger cost saving ratio.

Limitedenergy resources are problematic challenge nowadays. Electricity is one of the most important clean energies that can have the effective role in a developing economy like Iran. In this study, a theoretical model has been designed on the basis of dualism and structural change theory that shows using electricity increases the share of industry and decreases the share of agriculture in economy and hence by making structural changes, economic development process will be facilitated empirical evidence from sector production functions of Iranian economy, confirms this result.

The increased needsof world for energy and dependence of Iran on oil revenues as the most important revenue of country causedThe necessity To implementvision of thepetroleum industry that is along with 1404 vision of I.I.R in current decades with critical condition. Then, some issue as a literature review for assessing strategy, vision and implementing them was studied. For solving the problem, research was done as a case study – descriptive and crosses - sectional survey. Data was gathered by distributing questionnaires among 110 of managers and experts in petroleum industry in Tehran and was studied bycronbach 0.921 which factor is most effective factor in implementing vision of petroleum industry.

One of the most important operational functions in todayenergy management system is environmental/economic dispatch (EED). The environmental issues that arise from the pollutant emissions produced by fossil-fueled electric power plants have become a matter of concern recently. This paper presents a multi-objective Gravitational Search Algorithm (MOGSA) for environmental/economic power dispatch (EED) problem.The EED problem is formulated as a nonlinear constrained multi-objective problem with competing and incommensurable objectives of fuel cost, emission and system loss. The proposed MOGSA approach adopts an external elitist archive to retain non-dominated solutions found during the evolutionary process. In order to preserve the diversity of Pareto optimality, a crowding entropy diversity measuring tactic is proposed. The crowding entropy strategy is able to measure the crowding degree of the solutions more accurately. IEEE30 and 118 bus test systems were studied. The effectiveness of the proposed approach are demonstrated by comparing its performance with other evolutionary multi-objective optimization algorithms such as NSGA, NPGA, SPEA, MOPSO and MODE. The comparison with reported results of other multi objective optimization algorithms reveals the superiority of the proposed MOGSA algorithm and confirms its great potential in handling the multi-objective problems in power systems.

Power generation by Pressure Retarded Osmosis (PRO) method is a reliable approach for future. In this method, water from feed (low-salt or clean water flow) permeates through a semi membrane into a consentrated solution or a high pressurized salinity flow, such as sea water causing additional increase in its pressure and flowrate. Then this high pressure flow passing through a water turbine causes rotation of generator shaft and generates electric power. In this paper, in addition to investigate PRO power plant performance considering working condition of Iran, a PRO model is studied to predict water flux and power density under specific teoritical conditions. Model is based on empirical estimation of membrane water permeability coefficient (A), the membrane salt permeability coefficient (B) and suspended particles in solution resistivity (K).Results show that the PRO method with optimized membrane has higher specific power and greater efficiency than previous models. So, there is a growing trend into producing power via this new approach.