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In this study, a comprehensive exergoeconomic analysis and a multi-objective optimization study are performed for four different types of fuel cell systems, in order to determine their maximum power production capacities, exergy efficiencies, and minimum production costs, by use of a genetic algorithm method. The investigated fuel cell types are Polymer Electrolyte Membrane (PEMFC) and Direct Methanol (DMFC) for low temperature fuel cells, and Solid Oxide (SOFC) and Molten Carbonate (MCFC) for high temperature fuel cells. The selected fuel cell systems are modeled exergetically and exergoeconomically. After modeling, the cases are studied parametrically with various available operating conditions, such as temperature, pressure, surrounding temperature and pressure, current density, and relative humidity, using the developed computer program MULOP (Multi-Objective Optimizer). For the low temperature fuel cells it is observed that the efficiencies are in the range of 10–30% and the costs are around $3–4/kW. On the other hand, for the high temperature fuel cell systems, efficiencies are in the range of 15–45% and the costs seems to be $0.003–0.01/kW. The results show that high temperature fuel cells operate more effectively for large scale applications. [ABSTRACT FROM AUTHOR]

During the last years, special attention has been paid to renewable polygeneration technologies, able of simultaneously producing thermal, cooling, electrical energy and desalinated water from seawater. This paper focuses on an innovative polygeneration system driven by renewable energy sources, including the following technologies: hybrid photovoltaic/thermal collectors, concentrating parabolic trough (CPVT), a biomass heater, a single-stage absorption chiller and a multiple-effect distillation desalination system. The system is designed to cover the base load of an isolated small community. In previous papers, the dynamic simulation model about plant operation is discussed. In this paper, a detailed exergy, economic and environmental analysis of the plant is presented. In addition, the plant was optimized using different objective functions, applying the Design of Experiment (DoE) methodology which evaluates the sensitivity of the different objective functions with respect to the selected design parameters. The results show that an increase of the storage volume is generally negative, whereas increasing the solar field area involves an increase of the exergy destruction rate, but also an improvement of the CPVT exergy output provided; the final result is an increase of both the exergy efficiency and the economic profitability of the polygeneration system. [ABSTRACT FROM AUTHOR]

In this paper we perform an exergoeconomic analysis to a PEM (proton exchange membrane) vehicular fuel cell system used in the latest generation of environmentally friendly cars. Two alternative configurations of a fuel cell system are considered (with and without an expander), and two alternative design concepts for each configuration: BoL (Begin of Life) and EoL (End of Life). The system including an expander generates additional power from the exhaust gases leaving the fuel cell stack, which might increase the system efficiency. However the total investment costs for this case are higher than for the other system configuration without an expander, due to the investment costs associated with the expander and its accessories. The fuel cell stack area in the EoL-sized systems is larger than in the BoL-sized systems. A larger stack area on one hand raises the investment costs, but on the other hand decreases the fuel consumption due to a higher cell efficiency. In this paper, exergoeconomic analyses have been implemented to consider a trade-off between positive and negative effects of using an expander in the system and to select the proper design concept. The results from the exergoeconomic analysis show that (a) an EoL-sized system with an expander is the most cost effective system, (b) the compression and humidification of air are very expensive processes, (c) the stack is by far the most important component from the economic viewpoint, and (d) the thermodynamic efficiency of almost all components must be improved to increase the cost effectiveness of the overall system. [ABSTRACT FROM AUTHOR]

Exergy analysis and exergoeconomics are often used to evaluate industrial energy systems performance from the thermodynamic and economic points of view. While the classical exergy analysis can be used to recognize the sources of inefficiency and irreversibilities, so called advanced exergy analysis is convenient for identifying real potential for thermodynamic improvements of the system by splitting exergy destruction into avoidable and unavoidable parts. In this paper, the advanced exergy analysis is used to identify performance critical components and the potential for exergy efficiency improvement of a complex industrial energy supply plant. This plant is a part of a rubber factory and its role is to provide steam, compressed air and cooling water to the production facilities, as well as hot water for space heating and sanitary use. The plant is first analyzed as is and the avoidable (and the unavoidable) part of exergy destruction is identified for each observed component. Then, the measures for removing the avoidable destruction are defined. Finally, the plant is analyzed as if the measures were implemented and avoidable losses eliminated. Numerical analysis is based on real data, some of which are collected during on site measurements. Large system of nonlinear and linear equations is defined and solved numerically using the Engineering Equation Solver. Results of the presented analysis show the difference in thermodynamic and economic operational parameters of the plant for the cases without and with the efficiency measures implemented, i.e. the current state and the state with the avoidable irreversibilities eliminated. Beside obvious increase of exergy efficiency and enhancement of other thermodynamic parameters, certain improvement in the economy of the plant could be achieved. [ABSTRACT FROM AUTHOR]

This paper presents the findings from a multi-objective genetic algorithm optimization study on the design parameters of an underwater compressed air energy storage system (UWCAES). A 4 MWh UWCAES system was numerically simulated and its energy, exergy, and exergoeconomics were analysed. Optimal system configurations were determined that maximized the UWCAES system round-trip efficiency and operating profit, and minimized the cost rate of exergy destruction and capital expenditures. The optimal solutions obtained from the multi-objective optimization model formed a Pareto-optimal front, and a single preferred solution was selected using the pseudo-weight vector multi-criteria decision making approach. A sensitivity analysis was performed on interest rates to gauge its impact on preferred system designs. Results showed similar preferred system designs for all interest rates in the studied range. The round-trip efficiency and operating profit of the preferred system designs were approximately 68.5% and $53.5/cycle, respectively. The cost rate of the system increased with interest rates. [ABSTRACT FROM AUTHOR]

A comparative exergoeconomic analysis is reported for waste heat recovery from a gas turbine-modular helium reactor (GT-MHR) using various configurations of organic Rankine cycles (ORCs) for generating electricity. The ORC configurations studied are: a simple organic Rankine cycle (SORC), an ORC with an internal heat exchanger (HORC) and a regenerative organic Rankine cycle (RORC). Exergoeconomic analyses are performed with the specific exergy costing (SPECO) method. First, energy and exergy analyses are applied to the combined cycles. Then, a cost-balance, as well as auxiliary equations are developed for the components to determine the exergoeconomic parameters for the combined cycles and their components. The three combined cycles are compared considering the same operating conditions for the GT-MHR cycle, and a parametric study is done to reveal the effects on the exergoeconomic performance of the combined cycles of various significant parameters, e.g., turbine inlet and evaporator temperatures and compressor pressure ratio. The results show that the GT-MHR/RORC has the lowest unit cost of electricity generated by the ORC turbine. This value is highest for the GT-MHR/HORC. Furthermore, the GT-MHR/RORC has the highest and the GT-MHR/HORC has the lowest exergy destruction cost rate. [ABSTRACT FROM AUTHOR]

In this study, the results of conventional and advanced exergoeconomic analyses of the performance of a pilot scale air-source heat pump food dryer were compared for the first time. The contributions of the components of the drying system to the exergetic cost effectiveness of the dryer were evaluated, and the effects of changing the inlet drying temperature were determined. The most important system component was determined to be the heat recovery unit, followed by the condenser with respect to the reducing potentials for the total costs of the overall system. Decreasing temperature caused an increase in the cost performance of drying. The modification of the system components for improving the efficiency of the system can be effectively determined through advanced exergoeconomic approach by stating the realistic potential improvements and the priorities in the system. [ABSTRACT FROM AUTHOR]

Highlights: [•] The overall energy and exergy efficiencies of the plant is found to be 59.37% and 38.99% respectively. [•] Performance assessment of a cement plant indicates that the calcination process involves the highest portion of energy losses. [•] The specific exergetic cost cement produced by the cement plant is calculated to be 180.5USD/GJ. [•] The specific cement manufacturing cost is found to be 41.84USD/ton. [Copyright &y& Elsevier]

Highlights: [•] Energy, exergy and exergoeconomic analysis of a complete cement plant have been investigated. [•] The first and second law efficiencies based on the energy and exergy analysis are defined for the entire cement plant. [•] The specific energy consumption of the whole sections of the cement plant have been analyzed. [•] The specific manufacturing costs of farine, clinker and cement have been determined by the cost analysis. [Copyright &y& Elsevier]

In this study, exergy and exergoeconomic analyses of a heat pump tumbler dryer are carried out by using actual thermodynamic and cost data. The wet cotton fabric is used as the test drying material. The results show that the specific moisture extraction rate (SMER) and evaporation rate of dryer are equal to 1.08 kg/kWh and 0.018 kg/s, respectively. Also, the respective exergetic efficiencies of the heat pump and overall system are equal to 0.07 and 0.11. A parametric study is then conducted in order to investigate the system performance and costs of the components, depending on the operating temperature and mass flow rate of air. [ABSTRACT FROM PUBLISHER]

Abstract: In this study, the thermal management system of a hybrid electric vehicle is optimized using single and multi-objective evolutionary algorithms in order to maximize the exergy efficiency and minimize the cost and environmental impact of the system. The objective functions are defined and decision variables, along with their respective system constraints, are selected for the analysis. In the multi-objective optimization, a Pareto frontier is obtained and a single desirable optimal solution is selected based on LINMAP decision-making process. The corresponding solutions are compared against the exergetic, exergoeconomic and exergoenvironmental single objective optimization results. The results show that the exergy efficiency, total cost rate and environmental impact rate for the baseline system are determined to be 0.29, ¢28 h−1 and 77.3 mPts h−1 respectively. Moreover, based on the exergoeconomic optimization, 14% higher exergy efficiency and 5% lower cost can be achieved, compared to baseline parameters at an expense of a 14% increase in the environmental impact. Based on the exergoenvironmental optimization, a 13% higher exergy efficiency and 5% lower environmental impact can be achieved at the expense of a 27% increase in the total cost. [Copyright &y& Elsevier]

Abstract: An exergoeconomic analysis is reported for a combined system with a net electrical output of 299 MW in which waste heat from a Gas Turbine-Modular Helium Reactor (GT-MHR) is utilized by two Organic Rankine Cycles (ORCs). A parametric study is also done to reveal the effects on the exergoeconomic performance of the combined system of such significant parameters as compressor pressure ratio, turbine inlet temperature, temperatures of evaporators, pinch point temperature difference in the evaporators and degree of superheat at the ORC (Organic Rankine Cycle) turbines inlet. Finally the combined cycle performance is optimized from the viewpoint of exergoeconomics. The results show that the precooler, the intercooler and the ORC condensers exhibit the worst exergoeconomic performance. For the overall system, the exergoeconomic factor, the capital cost rate and the exergy destruction cost rate are determined to be 37.95%, 6876 $/h and 11,242 $/h, respectively. Also, it is observed that the unit cost of electricity produced by the GT-MHR turbine increases with increasing GT-MHR turbine inlet temperature but decreases as the other above mentioned parameters increase. [Copyright &y& Elsevier]

Abstract: This paper investigates the performance of a RO (reverse osmosis) desalination plant at different seawater salinity values. An energy recovery Pelton turbine is integrated with the desalination plant. Thermodynamic analysis, based on the first and second laws of thermodynamics, as well as a thermo-based economic analysis is performed for the proposed system. The effects of the system components irreversibilities on the economics and cost of product water are parametrically studied through the thermoeconomic analysis. The exergy analysis shows that large irreversibilities occur in the high pressure pump and in the RO module. Both thermodynamic and thermoeconomic performances of the overall system are investigated under different operating parameters. For the base case; the system achieves an exergy efficiency of 5.82%. The product cost is estimated to be 2.451 $/m3 and 54.2 $/MJ when source water with salinity of 35,000 ppm is fed to the system. [Copyright &y& Elsevier]

Abstract: A detailed exergoeconomic analysis is performed for a combined cycle in which the waste heat from the Gas Turbine-Modular Helium Reactor (GT-MHR) is recovered by an ammonia–water power/cooling cogeneration system. Parametric investigations are conducted to evaluate the effects of decision variables on the performances of the GT-MHR and combined cycles. The performances of these cycles are then optimized from the viewpoints of first law, second law and exergoeconomics. It is found that, combining the GT-MHR with ammonia–water cycle not only enhances the first and second law efficiencies of the GT-MHR, but also it improves the cycle performance from the exergoeconomic perspective. The results show that, when the optimization is based on the exergoeconomics, the unit cost of products is reduced by 5.4% in combining the two mentioned cycles. This is achieved with a just about 1% increase in total investment cost rate since the helium mass flow in the combined cycle is lower than that in the GT-MHR alone. [Copyright &y& Elsevier]

A residential photovoltaic (PV)-based hydrogen fuel cell (FC) system is analyzed using exergoeconomic methods, and its monthly performance is investigated. Mathematical models for predicting the power outputs of the PV and FC systems are presented. The results reported include the PV output and the shares attributable to the battery and the SOFC in supplying the electrical demand. Moreover, to study the performance of the hybrid system in supplying the daily demand, results are presented for two typical days in summer and winter. An exergoeconomic analysis is performed to determine the electricity unit cost over the system lifetime. The PV-electrolyzer system is not able to produce a sufficient amount of hydrogen during winter days, so seasonal hydrogen storage is required to feed the FC. Power penetrations of the PV and the battery systems are at maxima during the summer months, while the penetration of the FC system reaches 67% in January and December. Due to its low efficiency (16%), the maximum exergy destruction occurs in the PV modules (86%). The unit cost of electricity varies on a monthly basis, reaching a minimum of 0.26 $ kWh-1 in July and a maximum of 1.8 $ kWh-1 in January and December. [ABSTRACT FROM AUTHOR]

Abstract: CCGT (Combined-cycle gas turbines) are gaining an increasingly important role in power generation thanks to their high thermal efficiency, low installed cost and ready availability. Increasing natural gas prices, the optimization of CCGT operating parameters is becoming a topic of growing interest. In this paper two different methodologies for optimizing CCGTs are compared. The first aims to minimize the cost per unit of electricity generated, the second to minimize an objective function based on exergoeconomic principles accounting for the costs related with thermodynamic inefficiencies. Optimization results have been obtained considering different CCGT configurations, with single or multi-pressure HRSG (heat recovery steam generators), and varying the gas turbine technology, fuel price and plant capacity factor. A modular approach has been adopted to design a highly effective and flexible HRSG layout, in terms of number of pressure levels and arrangement of heat exchange sections along the flue gas path, together with the corresponding energy, exergy and cost balances, using an “interaction matrix”, with nodes between elementary components and towards the surrounding environment. [Copyright &y& Elsevier]

Abstract: In this part II of the study, three new trigeneration systems are examined. These systems are SOFC-trigeneration, biomass-trigeneration, and solar-trigeneration systems. This study reveals that the maximum trigeneration-exergy efficiencies are about 38% for the SOFC-trigeneration system, 28% for the biomass-trigeneration system and 18% for the solar-trigeneration system. Moreover, the maximum cost per exergy unit for the SOFC-trigeneration system is approximately 38$/GJ, for the biomass-trigeneration system is 26$/GJ, and for the solar-trigeneration system is 24$/GJ. This study reveals that the solar-trigeneration system offers the best thermoeconomic performance among the three systems. This is because the solar-trigeneration system has the lowest cost per exergy unit. Furthermore, the solar-trigeneration system has zero CO2 emissions and it is based on a free renewable energy source. [Copyright &y& Elsevier]

Abstract: This part I of the study presents the thermoeconomic optimization formulations of three new trigeneration systems using organic Rankine cycle (ORC): SOFC-trigeneration, biomass-trigeneration, and solar-trigeneration systems. A thermoeconomic modeling is employed using the specific exergy costing (SPECO) method while the optimization performed using the Powell’s method to minimize the product cost of trigeneration (combined, cooling, heating, and power). The results help in understanding how to apply the thermoeconomic modeling and thermoeconomic optimization to a trigeneration system. [Copyright &y& Elsevier]

Abstract: At a particular temperature range, heat sources are not hot enough to drive lithium bromide double effect absorption refrigeration systems efficiently and are too hot to be used for the single effect systems because of the risk of crystallization. A combined ejector-double effect absorption cycle is a good choice to make effective use of heat sources at this temperature range for refrigeration purposes. In this study, detailed exergoeconomic analyses are performed for series flow double effect and combined ejector double effect systems in order to investigate and compare the influence of various operating parameters on investment costs of the overall systems and product cost flow rates. In addition, the proportion of component costs in the overall systems costs and exergoeconomic results are obtained. The results show that the combined cycle operates more economically compared to the double effect system. [Copyright &y& Elsevier]

Compressed Air Energy Storage is recognized as a promising technology for applying energy storage to grids which are more and more challenged by the increasing contribution of renewable such as solar or wind energy. The paper proposes a medium-size ground-based CAES system, based on pressurized vessels and on a multiple-stage arrangement of compression and expansion machinery; the system includes recovery of heat from the intercoolers, and its storage as sensible heat in two separate (hot/cold) water reservoirs, and regenerative reheat of the expansions. The CAES plant parameters were adapted to the requirements of existing equipment (compressors, expanders and heat exchangers). A complete exergy analysis of the plant was performed. Most component cost data were procured from the market, asking specific quotations to the industrial providers. It is thus possible to calculate the final cost of the electricity unit (kWh) produced under peak-load mode, and to identify the relative contribution between the two relevant groups of capital and component inefficiencies costs. [ABSTRACT FROM AUTHOR]

Abstract: The exergoeconomic analysis is one of the most used exergy sub-methods that combine exergy analysis with economic analysis. Based on a previous exergetic analysis of a combined heat and power (CHP) system which has a total installed electricity and steam generation capacities of 11.52MW and 9.0tons/h at 140°C respectively, this study considers the thermoeconomic analysis in order to provide cost-based information and suggests possible locations for the CHP system improvement. The analysis is based on the Specific Exergy Costing (SPECO) approach and the results show that the specific unit exergy cost of electrical power produced by the CHP system is calculated as 4.48$/GJ. The capital investment cost, the operating and maintenance costs, and the total cost of CHP system as found to be 649$/h, 149.6$/h and 810.2$/h respectively. The exergoeconomic factor of the diesel engine, heat recovery exchanger, cooling tower exchanger, and cooling exchanger are 79.86%, 41.99%, 87.93%, and 55.58% respectively. The exergoeconomic factor of the compressor is 54.51% while this value is 88.3% for the turbine. The relative cost difference for lubrication oil cooler is calculated to be 57.60% which is the third lowest value after the charge air cooler. [Copyright &y& Elsevier]

Abstract: Cogeneration involves the production of both electricity and thermal energy generally in the form of steam or hot water, and it has a great potential of saving primary energy in comparison to separate generation technologies. The use of cogeneration provides high energy conversion efficiency, and it also lowers the emissions released to the environment. Exergy analysis is an effective tool which provides insights into the performance of energy conversion systems, and highlights the possible improvements. On the basis of exergy concept and economics, an exergoeconomic analysis provides useful information to understand the behaviour of an energy conversion system from the cost viewpoint. This study presents the exergoeconomic analysis of a cogeneration plant at ERDEMIR, TURKEY. The mass, energy and exergy balances were done, and the exergoeconomic analysis of the plant with a 39.5 MW electricity and 80 ton/h steam production capacity, was performed. [Copyright &y& Elsevier]

Abstract: Energy, exergy and exergoeconomic analysis are often used for assessing large energy conversion systems. However exergy and exergoeconomic analysis are rarely used when small or medium scale energy generation systems, such as community CHP/CCHP plants or microcogeneration systems are evaluated. In this study energy, exergy and exergoeconomic analysis of four Community Energy Supply (CES) systems has been carried out. Biomass Steam Turbine CHP (BST), Gas Turbine CHP (GT), Biomass Integrated Gasification Gas Turbine CHP (BIGGT) and Biomass Integrated Gasification Combined Cycle CHP (BIGCC) systems have been modelled. Modelling and energy/exergy analysis have been conducted using the computer programme Cycle-Tempo. Exergoeconomic evaluation of CESS has been performed using the Specific Exergy Costing (SPECO) approach. Exergy costs of the main products: heat and electricity, have been calculated. The analysis shows that gasification of biomass reduces overall system efficiency due to the exergy destruction in the thermo-chemical conversion process when air is used as an oxidizer. A GT using natural gas as a fuel and BIGCC are the most exergy efficient systems in this study with the lowest exergy cost of electricity and heat produced. The exergy cost of electricity generated in BST is the highest. [Copyright &y& Elsevier]

It may be argued that society is becoming increasingly demanding for the quality from any activity. Even if it is true it is not easy to assess the quality of various processes as popular economic criteria hardly comply with the concept of sustainable development. Exergy, as an objective indicator of used and transformed energy quality, is used for the evaluation of energy transformation processes in different areas, such as: biology, technology etc. It is not affected by inflation, devaluation, and crisis. The compromise of combination of exergy and economic criteria is defined by exergoeconomics. This paper presents theoretical basics of exergy and exergoeconomic analyses. The exergy and exergoeconomic analyses were performed for 20 MW thermal capacity combined-cycle cogeneration plant. The exergy analysis allowed the identification of elements where the largest exergy losses are formed. The exergoeconomic analysis was conducted to determine costs of such system imperfection economically. Additionally, costs of final products (e. g. heat and electricity) were calculated. [ABSTRACT FROM AUTHOR]

The present study aims to develop a thermoeconomic-based approach for optimization of steam levels in a steam production and distribution system by use of the specific exergy costing (SPECO) method for determining optimum steam levels to minimize the cost caused by exergy destruction. In the field of total site optimization, incremental cost of the utility system caused by exergy destruction has been selected as an objective function and the result is compared with the case that energy minimization has been selected as the prime objective. The steam levels are optimized considering steam demand at each level, output power generated by turbines, boiler duty, fuel and cold utility requirements as well as capital cost of equipments. The analysis showed that thermoeconomic (exergoeconomic) approach in optimization not only can change the optimum structure of steam levels but also may reduce the total cost of utility system up to 8%. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a modified exergoeconomic model is proposed for geothermal power plants using exergy and cost accounting analyses, and a case study is in this regard presented for the Tuzla geothermal power plant system (Tuzla GPPS) in Turkey to illustrate an application of the currently modified exergoeconomic model. Tuzla GPPS has a total installed capacity of 7.5 MW and was recently put into operation. Electricity is generated using a binary cycle. In the analysis, the actual system data are used to assess the power plant system performance through both energy and exergy efficiencies, exergy losses and loss cost rates. Exergy efficiency values vary between 35% and 49% with an average exergy efficiency of 45.2%. The relations between the capital costs and the exergetic loss/destruction for the system components are studied. Six new exergetic cost parameters, e.g., the component annualized cost rate, exergy balance cost, overall unavoidable system exergy destruction/loss cost rate, overall unavoidable system exergy destruction/loss cost rate, overall unavoidable system exergy production cost rate and the overall unavoidable system exergy production cost rate are studied to provide a more comprehensive evaluation of the system. [Copyright &y& Elsevier]

Abstract: In this paper, a conceptual hybrid biomass gasification system is developed to produce hydrogen and is exergoeconomically analyzed. The system is based on steam biomass gasification with the lumped solid oxide fuel cell (SOFC) and solid oxide electrolyser cell (SOEC) subsystem as the core components. The gasifier gasifies sawdust in a steam medium and operates at a temperature range of 1023–1423 K and near atmospheric pressure. The analysis is conducted for a specific steam biomass ratio of 0.8 kmol-steam/kmol-biomass. The gasification process is assumed to be self-thermally standing. The pressurized SOFC and SOEC are of planar types and operate at 1000 K and 1.2 bar. The system can produce multi-outputs, such as hydrogen (with a production capacity range of 21.8–25.2 kgh−1), power and heat. The internal hydrogen consumption in the lumped SOFC-SOEC subsystem increases from 8.1 to 8.6 kg/h. The SOFC performs an efficiency of 50.3% and utilizes the hydrogen produced from the steam that decomposes in the SOEC. The exergoeconomic analysis is performed to investigate and describe the exergetic and economic interactions between the system components through calculations of the unit exergy cost of the process streams. It obtains a set of cost balance equations belonging to an exergy flow with material streams to and from the components which constitute the system. Solving the developed cost balance equations provides the cost values of the exergy streams. For the gasification temperature range and the electricity cost of 0.1046 $/kWh considered, the unit exergy cost of hydrogen ranges from 0.258 to 0.211 $/kWh. [Copyright &y& Elsevier]

Abstract: Exergoeconomic analysis and optimization technique combine second law analysis with economics for cost effective thermal systems design. Most of the conventional exergoeconomic optimization methods are iterative in nature and require the interpretation of the designer. On the other hand, as an alternative to the conventional mathematical approaches, modern stochastic optimization techniques based on evolutionary algorithms (EAs) have been given attention by researchers due to their ability to find potential solutions. A powerful EA is the differential evolution (DE) algorithm. The DE algorithm has been used in many practical cases and has demonstrated good convergence properties. In this work, a cogeneration system is optimized using exergoeconomic principles and modified DE (MDE) approaches. Results shows that the minimum cost was obtained with MDE(3) having the minimum cost of 1272.23 ($/h) while MDE(5) presents the minor CPU mean time (s). It is possible to note that the properties obtained in this study are better than that obtained in previous study, exception that the increase in capital investment cost is higher at 14.9% in comparison to 10% in the previous study, nevertheless additional investment can be paid back in approximately 3 years. [Copyright &y& Elsevier]

Abstract: A comprehensive exergy, exergoeconomic and environmental impact analysis and optimization is reported of several combined cycle power plants (CCPPs). In the first part, thermodynamic analyses based on energy and exergy of the CCPPs are performed, and the effect of supplementary firing on the natural gas-fired CCPP is investigated. The latter step includes the effect of supplementary firing on the performance of bottoming cycle and CO2 emissions, and utilizes the first and second laws of thermodynamics. In the second part, a multi-objective optimization is performed to determine the “best” design parameters, accounting for exergetic, economic and environmental factors. The optimization considers three objective functions: CCPP exergy efficiency, total cost rate of the system products and CO2 emissions of the overall plant. The environmental impact in terms of CO2 emissions is integrated with the exergoeconomic objective function as a new objective function. The results of both exergy and exergoeconomic analyses show that the largest exergy destructions occur in the CCPP combustion chamber, and that increasing the gas turbine inlet temperature decreases the CCPP cost of exergy destruction. The optimization results demonstrates that CO2 emissions are reduced by selecting the best components and using a low fuel injection rate into the combustion chamber. [Copyright &y& Elsevier]

Abstract: A LNG re-liquefaction plant is optimized with a multi-objective approach which simultaneously considers exergetic and exergoeconomic objectives. In this regard, optimization is performed in order to maximize the exergetic efficiency of plant and minimize the unit cost of the system product (refrigeration effect), simultaneously. Thermodynamic modeling is performed based on energy and exergy analyses, while an exergoeconomic model based on the total revenue requirement (TRR) are developed. Optimization programming in MATLAB is performed using one of the most powerful and robust multi-objective optimization algorithms namely NSGA-II. This approach which is based on the Genetic Algorithm is applied to find a set of Pareto optimal solutions. Pareto optimal frontier is obtained and a final optimal solution is selected in a decision-making process. An example of decision-making process for selection of the final solution from the available optimal points of the Pareto frontier is presented here. The feature of selected final optimal system is compared with corresponding features of the base case and exergoeconomic single-objective optimized systems and discussed. [Copyright &y& Elsevier]

Abstract: In this study, we conduct an exergy, cost, energy and mass (EXCEM) analysis of a copper–chlorine thermochemical water splitting cycle driven by geothermal energy for hydrogen production. We also investigate and illustrate the relations between thermodynamic losses and capital costs. The results show that hydrogen cost is closely and directly related to the plant capacity and also exergy efficiency. Increasing economic viability and reducing the hydrogen production costs will help these cycles play a more critical role in switching to hydrogen economy. [Copyright &y& Elsevier]

Abstract: The plasma gasification process appears to be a relatively new technology due to its better efficiency, effectiveness and environmental friendliness. The process can essentially be used for sewage sludge treatment and energy production. In this paper, we investigate a plasma gasification process from the literature for hydrogen production analysis purposes. We use the specific exergy cost (SPECO) method to calculate exergy-related parameters and display cost flows for all streams and components. We also determine exergy destructions and their costs in a more specific form as avoidable and unavoidable exergy destructions. We consider six main components: a plasma gasification furnace, a gas cleaning, syngas compressor, two heat exchangers and a pressure swing adsorption (PSA). We calculate that the PSA has the largest exergy destruction rates with 11.66 MW, followed by the plasma gasification components with 6.55 MW. We also determine exergy efficiencies for these components. The lowest exergy efficiency is 4.43% for the PSA. It is found that the maximum exergy destruction cost rates are 338.75 and 46.92 $/h, for the PSA and plasma gasification furnace, respectively, while the unit cost of hydrogen is 208.6 $/h at the outlet of the PSA. We further investigate exergy destruction rates and investment cost rates through an extended exergy analysis and obtain that for the plasma gasification furnace, the avoidable destruction and investment costs are 15.36 and 8.06 $/h, respectively. [Copyright &y& Elsevier]

Abstract: Multi-objective optimization for design of a benchmark cogeneration system namely as the CGAM cogeneration system is performed. In optimization approach, Exergetic, Exergoeconomic and Environmental objectives are considered, simultaneously. In this regard, the set of Pareto optimal solutions known as the Pareto frontier is obtained using the MOPSO (multi-objective particle swarm optimizer). The exergetic efficiency as an exergetic objective is maximized while the unit cost of the system product and the cost of the environmental impact respectively as exergoeconomic and environmental objectives are minimized. Economic model which is utilized in the exergoeconomic analysis is built based on both simple model (used in original researches of the CGAM system) and the comprehensive modeling namely as TTR (total revenue requirement) method (used in sophisticated exergoeconomic analysis). Finally, a final optimal solution from optimal set of the Pareto frontier is selected using a fuzzy decision-making process based on the Bellman–Zadeh approach and results are compared with corresponding results obtained in a traditional decision-making process. Further, results are compared with the corresponding performance of the base case CGAM system and optimal designs of previous works and discussed. [Copyright &y& Elsevier]

Abstract: A typical 1000 MW Pressurized Water Reactor (PWR) nuclear power plant and two similar hybrid 1000 MW PWR plants operate with natural gas and coal fired fossil fuel superheater-economizers (Hybrid PWR-Fossil fuel plants) are compared exergetically and economically. Comparison is performed based on energetic and economic features of three systems. In order to compare system at their optimum operating point, three workable base case systems including the conventional PWR, and gas and coal fired hybrid PWR-Fossil fuel power plants considered and optimized in exergetic and exergoeconomic optimization scenarios, separately. The thermodynamic modeling of three systems is performed based on energy and exergy analyses, while an economic model is developed according to the exergoeconomic analysis and Total Revenue Requirement (TRR) method. The objective functions based on exergetic and exergoeconomic analyses are developed. The exergetic and exergoeconomic optimizations are performed using the Genetic Algorithm (GA). Energetic and economic features of exergetic and exergoeconomic optimized conventional PWR and gas and coal fired Hybrid PWR-Fossil fuel power plants are compared and discussed comprehensively. [Copyright &y& Elsevier]

Thermoeconomics is the cost analysis based on the cost and exergy calculations which are used to determine the potential of unproductiveness in all of the thermal systems. This approach is also defined as 'exergy cost' and is named as 'exergoeconomics'. In this study, the new methodology of exergoeconomic analysis created for thermal systems has been applied on the raw material process of a cement plant which consumes high energy. In this study, two sets of analyses have been conducted by using operation data of the process weekly: the thermodynamic analyses and the exergoeconomic analyses. At the end of these analyses, the average energy and exergy efficiencies of the mill have been found 82.9% and 18.44% respectively. The unit cost of the output product named 'farine' has been calculated and found between 0.00708 - 0.0 1078 s/kg. These costs have been compared with the farine costs of the cement plant, and the effects of exergy consumption on the cost have been evaluated. [ABSTRACT FROM AUTHOR]

Abstract: Energy conservation is a central concern of the current industrial world, where increasing efficient energy usage is the only way of reducing a high energy demand. In the present study the optimization of a pulp and paper mill with a cogeneration plant has been carried out. The optimization was realized with a methodology which includes exergy, exergoeconomics, thermoeconomics and pinch analysis. The proposed methodology was useful in determining not only the best plant operating conditions but also establishing the components or subsystems with the highest irreversibilities. As a result of the study, operation changes in the recovery boiler, the turbogenerator, the thermal treatment and the deaerator were realized. Due to the higher irreversibility in the actual evaporator line, a new line of evaporators was proposed. Also, an innovative heat recycling technology as to the use of heat transformers was proposed in order to reduce waste heat discharged to the atmosphere. The results obtained with the proposed methodology, which integrates the different optimization methods, allowed reaching higher efficiencies and lower operational costs than those obtained with the optimization methods working separately. [Copyright &y& Elsevier]

Abstract: The manner is investigated in which exergy-related parameters can be used to minimize the cost of a copper–chlorine (Cu–Cl) thermochemical cycle for hydrogen production. The iterative optimization technique presented requires a minimum of available data and provides effective assistance in optimizing thermal systems, particularly in dealing with complex systems and/or cases where conventional optimization techniques cannot be applied. The principles of thermoeconomics, as embodied in the specific exergy cost (SPECO) method, are used here to determine changes in the design parameters of the cycle that improve the cost effectiveness of the overall system. The methodology provides a reasonable approach for improving the cost effectiveness of the Cu–Cl cycle, despite the fact that it is still in development. It is found that the cost rate of exergy destruction varies between $1 and $15 per kilogram of hydrogen and the exergoeconomic factor between 0.5 and 0.02 as the cost of hydrogen rises from $20 to $140 per GJ of hydrogen energy. The hydrogen cost is inversely related to the exergoeconomic factor, plant capacity and exergy efficiency. The results are expected to assist ongoing efforts to increase the economic viability and to reduce product costs of potential commercial versions of this process. The impact of the results are anticipated to be significant since thermochemical water splitting with a copper–chlorine cycle is a promising process that could be linked with nuclear reactors to produce hydrogen with no greenhouse gases emissions, and thereby help mitigate numerous energy and environment concerns. [Copyright &y& Elsevier]

Abstract: Thermoeconomics, or exergoeconomics, can be classified into the three fields: cost allocation, cost optimization, and cost analysis. In this study, a new thermoeconomic methodology for energy systems is proposed in the three fields. The proposed methodology is very simple and clear. That is, the number of the proposed equation is only one in each field, and it is developed with a wonergy newly introduced in this paper. The wonergy is defined as an energy that can equally evaluate the worth of each product. Any energy, including enthalpy or exergy, can be applied to the wonergy and be evaluated by this equation. In order to confirm its validity, the CGAM problem and various cogenerations were analyzed. Seven sorts of energy, including enthalpy and exergy, were applied for cost allocation. Enthalpy, exergy, and profit were applied for cost optimization. Enthalpy and exergy were applied for cost analysis. Exergy is generally recognized as the most reasonable criterion in exergoeconomics. By the proposed methodology, however, exergy is the most reasonable in cost allocation and cost analysis, and all of exergy, enthalpy, and profit are reasonable in cost optimization. Therefore, we conclude that various forms of wonergy should be applied to the analysis of thermoeconomics. [Copyright &y& Elsevier]

Abstract: Exergoeconomics is also called thermoeconomics, and thermoeconomic analysis methodologies combine economic and thermodynamic analysis by applying the cost concept to exergy which accounts for the quality of energy. The main concept of thermoeconomics is the exergetic cost and it deals with cost accounting methods. This paper is a review on the exergoeconomic analysis and optimization of combined heat and power production (CHPP). A brief historical overview on the exergoeconomics analysis and optimization is given. The concept of exergetic cost and cost accounting methods are discussed. An application of relevant formulation is given using a diesel engine powered cogeneration system as an example. Main thermoeconomic methodologies available in literature are described and their advantages and disadvantages with respect to one another are compared and discussed through a well-known problem, namely CGAM. Important studies on thermoeconomic analysis and optimization of combined heat and power production are listed based on the methodology used and the type of system considered. [Copyright &y& Elsevier]

The influence of thermodynamics on the emerging transdisciplinary field of 'ecological economics' is critically reviewed from an interdisciplinary perspective. It is viewed through the lens provided by the 'bioeconomist' Nicholas Georgescu-Roegen (1906-1994) and his advocacy of 'the Entropy Law' as a determinant of economic scarcity. It is argued that exergy is a more easily understood thermodynamic property than is entropy to represent irreversibilities in complex systems, and that the behaviour of energy and matter are not equally mirrored by thermodynamic laws. Thermodynamic insights as typically employed in ecological economics are simply analogues or metaphors of reality. They should therefore be empirically tested against the real world. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the monitoring energy and exergy efficiency results of the last heating seasons of operation of the geothermal district heating systems (GDHSs) and their technical availability analysis and monitoring exergoeconomic parameters are presented. The case studies cover the actual system data taken from the systems in Afyon and Salihli GDHSs, Turkey. General energy, exergy, technical availability, and exergoeconomic analysis of the GDHSs are introduced. Furthermore, the average technical availability, real availability, capacity factor and energy and exergy efficiencies value of GDHSs have been analyzed. [Copyright &y& Elsevier]

Abstract: A typical 1000MW pressurized water reactor (PWR) nuclear power plant is considered for optimization. The thermodynamic modeling is performed based on the energy and exergy analysis, while an economic model is developed according to the total revenue requirement (TRR) method. The objective functions based on the thermodynamic and thermoeconomic analysis are obtained. The optimization process with ten degrees of freedom for plant under consideration is performed using the genetic algorithm (GA). Three levels of optimization including thermodynamic single-objective, thermoeconomic single-objective and multi-objective optimizations are performed. In multi-objective optimization, both thermodynamics and thermoeconomic objectives are considered, simultaneously. A series of optimum solutions namely as Pareto frontier are obtained. In the case of multi-objective optimization, an example of decision-making process for selection of the final optimal solution from the Pareto frontier is introduced. The results obtained using the various optimization approaches are compared and discussed. [Copyright &y& Elsevier]

A typical 1000 MW pressurized water reactor nuclear power plant is considered for optimization. The thermodynamic modeling is performed based on the energy and exergy analysis, while an economic model is developed according to the total revenue requirement method. The objective function based on the exergoeconomic analysis is obtained. The exergoeconomic optimization process with 10 decision variables is performed using a hybrid stochastic/deterministic search algorithm namely as genetic algorithm. The results that are obtained using optimization process are compared with the base case system and the discussion is presented. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This article presents the ecological supply chain (ESC) model and demonstrates its benefits. The causes that make an ESC vulnerable to disruption risks are analyzed; the objective is to balance the cost and the disruption risk. Also, it provides supply management strategies, demand management strategies, product management strategies, and information management strategies. Practice in China is reviewed. Based on exergoeconomics theory, the ESC is regarded as a huge energy system providing new perspective. The sustainability of the ESC system is discussed under the circumstances of exergoeconomics. The metric of “system negative environment effect” is introduced to measure ESC system performance. Finally, a real case example is used to illustrate the models and get some conclusions. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an application of an exergoeconomic model, through exergy and cost accounting analyses, to the Gonen geothermal district heating system (GDHS) in Balikesir, Turkey for the entire system and its components. This exergoeconomic model is used to reveal the cost formation process and the productive interaction between components. The exergy destructions in the overall Gonen GDHS are quantified and illustrated for a reference temperature of 4°C. The results indicate that the exergy destructions in the system occur primarily as a result of losses in the cooled geothermal water injected back into the reservoir, pumps, heat exchangers, and pipelines. Total exergy destruction and reinjection exergy of the cooled geothermal water result in 1010kW (accounting for 32.49%), 320.3kW (accounting for 10%) of the total exergy input to the Gonen GDHS, respectively. Both energy and exergy efficiencies of the overall Gonen GDHS are also investigated to analyze the system performance, as these efficiencies are determined to be 42% and 50%, respectively. It is found that an increase of the load condition leads to a decrease in the overall thermal costs, which will result in more cost-effective energy systems for buildings. [Copyright &y& Elsevier]