Advanced Exergoeconomic Analysis Applied to a Complex Energy Conversion System

Author(s):  
F. Petrakopoulou ◽  
G. Tsatsaronis ◽  
T. Morosuk ◽  
A. Carassai

Exergy-based analyses are important tools for studying and evaluating energy conversion systems. While conventional exergy-based analyses provide us with important information, further insight on the potential for improving plant components and the overall plant as well as on the interactions among components of energy conversion systems are significant when optimizing a system. This necessity led to the development of advanced exergy-based analyses, in which the exergy destruction, as well as the associated costs and environmental impact are split into avoidable/unavoidable and endogenous/exogenous parts. Based on the avoidable parts of the exergy destruction, costs and environmental impact, the potential for improvement and related strategies are revealed. This paper presents the application of an advanced exergoeconomic analysis to a combined cycle power plant. The largest parts of the unavoidable cost rates are calculated for the components constituting the gas turbine system and the low-pressure steam turbine. The combustion chamber has the second highest avoidable investment cost, while it has the highest avoidable cost of exergy destruction. In general, most of the investment costs are unavoidable, with the exception of some heat exchangers of the plant. Similarly, most of the cost of exergy destruction is unavoidable with the exception of the expander in the gas turbine system and the high-pressure and intermediate-pressure steam turbines. In general, the advanced exergoeconomic analysis reveals high endogenous values, which suggest improvement of the total plant by improving the design of the components primarily in isolation, and lower exogenous values, which suggest that the component interactions are of lower significance for this plant.

Author(s):  
Fontina Petrakopoulou ◽  
George Tsatsaronis ◽  
Tatiana Morosuk ◽  
Anna Carassai

Exergy-based analyses are important tools for studying and evaluating energy conversion systems. Conventional exergy-based analyses provide us with important information on the design and operation of a system. However, further insight into the improvement potential of plant components and the overall plant, as well as into component interactions, is important when optimal operation is required. This necessity led to the development of advanced exergy-based analyses, in which the exergy destruction as well as the associated costs and environmental impacts are split into avoidable/unavoidable and endogenous/exogenous parts. Based on the avoidable exergy destruction, costs and environmental impacts potential and strategies for improvement are revealed. The objective of this paper is to demonstrate the application, the advantages, and the information obtained from an advanced exergoeconomic analysis by applying it to a complex plant, i.e., to a combined cycle power plant. The largest parts of the unavoidable cost rates are calculated for the components constituting the gas turbine system and the low-pressure steam turbine. The combustion chamber has the second highest avoidable investment cost and the highest avoidable cost of exergy destruction. In general, the investment cost of most of the components is unavoidable, with the exception of some heat exchangers. Similarly, most of the cost of exergy destruction is unavoidable, with the exception of the expander of the gas turbine system and the high-pressure and intermediate-pressure steam turbines. The advanced exergoeconomic analysis reveals high endogenous values, which suggest that improvement of the total plant can be achieved by improving the design of individual components, and lower exogenous values, which means that component interactions are in general of lower significance for this plant.


Author(s):  
F. Petrakopoulou ◽  
G. Tsatsaronis ◽  
T. Morosuk

Although conventional exergy-based analyses uncover a path towards plant improvement, they suffer from some limitations, which are addressed by advanced exergy-based analyses. Advanced exergy-based methods identify interdependencies among plant components, and reveal the potential of improvement both at the component and plant level. Thus, data obtained from these methods pinpoint strengths and weaknesses of energy conversion systems and are of great importance when complex plants with a large number of interconnected components are considered. In this paper an advanced exergoeconomic analysis is applied to an advanced zero emission plant (AZEP). The most important components, in terms of the total avoidable costs, are the components constituting the main gas turbine system, while of particular importance are also the components of the mixed conducting membrane reactor incorporated in the plant. It has been found that for the most influential components of the plant, the largest part of investment cost rates and costs of exergy destruction are unavoidable. Additionally, for both the investment cost and the cost of exergy destruction, the interactions among the components are in most cases of lower importance, since for the majority of the components, the endogenous parts of the costs (related to the operation of the components themselves) are significantly larger than the corresponding exogenous parts (related to the operation of the remaining components). Nevertheless, strong interactions have been found among the components of the mixed conducting membrane reactor.


2015 ◽  
Vol 12 (3) ◽  
pp. 283-300 ◽  
Author(s):  
S.O. Oyedepo ◽  
R.O. Fagbenle ◽  
S.S. Adefila ◽  
Md. Mahbub Alam

In this study, exergoeconomic analysis and performance evaluation of selected gas turbine power plants in Nigeria were carried out. The study was conducted using operating data obtained from the power plants to determine the exergy efficiency, exergy destruction, unit cost of electricity and cost of exergy destruction of the major components of a gas turbine engine in the selected power plants. The results of exergy analysis confirmed that the combustion chamber is the most exergy destructive component compared to other cycle components as expected. The total efficiency defects and overall exergetic efficiency of the selected power plants vary from 38.64 to 69.33% and 15.66 to 30.72% respectively. The exergy analysis further shows that the exergy improvement potential of the selected plants varies from 54.04 MW to 159.88 MW. The component with the highest exergy improvement potential is the combustion chamber and its value varies from 30.21 MW to 88.86 MW. The results of exergoeconomic analysis show that the combustion chamber has the greatest cost of exergy destruction compared to other components. Increasing the gas turbine inlet temperature (GTIT), both the exergy destruction and the cost of exergy destruction of this component were found to decrease. The results of this study revealed that an increase in the GTIT of about 200 K can lead to a reduction of about 29% in the cost of exergy destruction. From exergy costing analysis, the unit cost of electricity produced in the selected power plants varies from cents 1.99 /kWh (N3.16 /kWh) to cents 5.65 /kWh (N8.98 /kWh).


Author(s):  
Awaludin Martin ◽  
Nur Indah Rivai ◽  
Rahmat Dian Amir ◽  
Nasruddin

In this study, exergoeconomic analysis was carry out on a 21.6MW gas turbine power plant by using logbooks record Pekanbaru Unit. The exergy analysis was start to determine the exergy destruction of each component of the power plant based on the first and second laws of thermodynamics and in this study, exergy and economic analysis were combined and used to evaluate the accrued cost caused by irreversibility, including the cost of investment in each component. The exergy analysis results showed that the location of the largest destruction was in the combustion chamber with 21,851.18 kW, followed by the compressor and gas turbine with 8,495.48 kW and 3,094.34 kW, respectively. The economic analysis resulted that the total cost loss due to exergy destruction was 2,793.14$/hour, consisting of compressor 1,066.43$/hour, combustion chamber 1,561.46$/hour and gas turbine 165.25$/hour. The thermal and exergetic efficiency of gas turbine power plant were 24.51% and 22.73% respectively.


Author(s):  
G Bidini ◽  
C N Grimaldi ◽  
L Postrioti

Nowadays, the most common way to improve energy conversion efficiency is the integration of different systems, thus achieving a better exploitation of the available exergy potential (e.g. combined cycles, cogeneration, etc.). As a means of producing power in hydroelectric plants hydraulic energy is commonly considered to be almost completely exploited. The aim of this paper is to analyse the possible integration of hydraulic energy sources with conventional, fossil fuel based systems; in particular, power plants based on the combination of an hydraulic air compressor (HAC) and a gas turbine are considered. In an HAC, air is entrained in the water flow in a downcomer pipe and compressed. Once separated from the water in a ‘stilling chamber’ at the bottom of the downpipe, the compressed air is supplied to a combustion chamber and then to a conventional gas turbine expander. An attractive characteristic of HACs is the capability, in principle, to perform an isothermal air compression instead of an adiabatic one, as in conventional compressors. In the present work, a thermodynamic analysis is presented of HAC-gas turbine energy conversion systems, which are compared with conventional hydroelectric and gas turbine power plants. The calculated performance levels of such systems are comparable to those of combined cycle plants, making further technical and economical investigations quite interesting.


2020 ◽  
pp. 99-111
Author(s):  
Vontas Alfenny Nahan ◽  
Audrius Bagdanavicius ◽  
Andrew McMullan

In this study a new multi-generation system which generates power (electricity), thermal energy (heating and cooling) and ash for agricultural needs has been developed and analysed. The system consists of a Biomass Integrated Gasification Combined Cycle (BIGCC) and an absorption chiller system. The system generates about 3.4 MW electricity, 4.9 MW of heat, 88 kW of cooling and 90 kg/h of ash. The multi-generation system has been modelled using Cycle Tempo and EES. Energy, exergy and exergoeconomic analysis of this system had been conducted and exergy costs have been calculated. The exergoeconomic study shows that gasifier, combustor, and Heat Recovery Steam Generator are the main components where the total cost rates are the highest. Exergoeconomic variables such as relative cost difference (r) and exergoeconomic factor (f) have also been calculated. Exergoeconomic factor of evaporator, combustor and condenser are 1.3%, 0.7% and 0.9%, respectively, which is considered very low, indicates that the capital cost rates are much lower than the exergy destruction cost rates. It implies that the improvement of these components could be achieved by increasing the capital investment. The exergy cost of electricity produced in the gas turbine and steam turbine is 0.1050 £/kWh and 0.1627 £/kWh, respectively. The cost of ash is 0.0031 £/kg. In some Asian countries, such as Indonesia, ash could be used as fertilizer for agriculture. Heat exergy cost is 0.0619 £/kWh for gasifier and 0.3972 £/kWh for condenser in the BIGCC system. In the AC system, the exergy cost of the heat in the condenser and absorber is about 0.2956 £/kWh and 0.5636 £/kWh, respectively. The exergy cost of cooling in the AC system is 0.4706 £/kWh. This study shows that exergoeconomic analysis is powerful tool for assessing the costs of products.


Author(s):  
Kari Anne Tveitaskog ◽  
Fredrik Haglind

This paper is aimed at designing and optimizing combined cycles for marine applications. For this purpose, an in-house numerical simulation tool called DNA (Dynamic Network Analysis) and a genetic algorithm-based optimization routine are used. The top cycle is modeled as the aero-derivative gas turbine LM2500, while four options for bottoming cycles are modeled. Firstly, a single pressure steam cycle, secondly a dual-pressure steam cycle, thirdly an ORC using toluene as the working fluid and an intermediate oil loop as the heat carrier, and lastly an ABC with inter-cooling are modeled. Furthermore, practical and operational aspects of using these three machinery systems for a high-speed ferry are discussed. Two scenarios are evaluated. The first scenario evaluates the combined cycles with a given power requirement, optimizing the combined cycle while operating the gas turbine at part load. The second scenario evaluates the combined cycle with the gas turbine operated at full load. For the first scenario, the results suggest that the thermal efficiencies of the combined gas and steam cycles are 46.3% and 48.2% for the single pressure and dual pressure steam cycles, respectively. The gas ORC and gas ABC combined cycles obtained thermal efficiencies of 45.6% and 41.9%, respectively. For the second scenario, the results suggest that the thermal efficiencies of the combined gas and steam cycles are 53.5% and 55.3% for the single pressure and dual pressure steam cycles, respectively. The gas ORC and gas ABC combined cycles obtained thermal efficiencies of 51.0% and 47.8%, respectively.


2014 ◽  
Vol 35 (4) ◽  
pp. 83-95 ◽  
Author(s):  
Daniel Czaja ◽  
Tadeusz Chmielnak ◽  
Sebastian Lepszy

Abstract A thermodynamic and economic analysis of a GT10 gas turbine integrated with the air bottoming cycle is presented. The results are compared to commercially available combined cycle power plants based on the same gas turbine. The systems under analysis have a better chance of competing with steam bottoming cycle configurations in a small range of the power output capacity. The aim of the calculations is to determine the final cost of electricity generated by the gas turbine air bottoming cycle based on a 25 MW GT10 gas turbine with the exhaust gas mass flow rate of about 80 kg/s. The article shows the results of thermodynamic optimization of the selection of the technological structure of gas turbine air bottoming cycle and of a comparative economic analysis. Quantities are determined that have a decisive impact on the considered units profitability and competitiveness compared to the popular technology based on the steam bottoming cycle. The ultimate quantity that can be compared in the calculations is the cost of 1 MWh of electricity. It should be noted that the systems analyzed herein are power plants where electricity is the only generated product. The performed calculations do not take account of any other (potential) revenues from the sale of energy origin certificates. Keywords: Gas turbine air bottoming cycle, Air bottoming cycle, Gas turbine, GT10


Author(s):  
U. Desideri ◽  
P. Lunghi ◽  
F. Zepparelli

The present work aims at evaluating the environmental impact caused by fuel cell systems in the production of electric energy. The very low pollutant emission levels in fuel cells makes them an attractive alternative in ultra clean energy conversion systems. Actually, to truly understand the environmental impact related to fuel cells, it is necessary to study their “cradle-to-grave” life, from the construction phase, during the conversion of primary fuel into hydrogen, to its disposal. The tool used in this analysis is the Life Cycle Assessment approach; in particular the environmental impact of a fuel cell system has been simulated through the software SimaPro 5.0. Thanks to this approach, once the critical process regarding the production of energy by fuel cell system, (i.e. the production of hydrogen by natural gas steam reforming), has been determined, an analysis of the use of landfill gas as a renewable source to produce hydrogen was done. Finally, the production of electric energy by fuel cell systems was compared to that by some conventional energy conversion systems. A second comparison was done between the Molten Carbonate Fuel Cell (MCFC) fuelled by landfill gas and natural gas.


2021 ◽  
Author(s):  
Robert Godin ◽  
James R. Durrant

The energy cost of lifetime gain in solar energy conversion systems is determined from a breadth of technologies. The cost of 87 meV per order of magnitude lifetime improvement is strikingly close to the 59 meV determined from a simple kinetic model.


Sign in / Sign up

Export Citation Format

Share Document