Thermo-ecological Cost Research Articles

Thermoecological analysis of an oxy-fuel combustion power plant integrated with a CO2 processing unit

The paper presents a mathematical model of assessing the indices of thermoecological costs concerning an oxy-fuel combustion power plant integrated with a CO2 processing unit. Thermoecological cost is the measure of depletion of non-renewable natural resources. It expresses the cumulative consumption of exergy charging the production processes leading to the analyzed useful product. The additional consumption of exergy compensating the negative impact of harmful emissions has also been taken into account. The proposed model has been developed making use of “input–output analysis” which is an effective tool in modeling of large energy systems. The example of the analysis of thermoecological costs has been elaborated for three variants of an integrated power plant operating with oxy-fuel combustion (basic variant, ultra-supercritical steam parameters and advanced oxygen production) and one reference power plant without CO2 capture. The analysis of the degree of sustainable development has been realized in these four cases.

Thermo-ecological assessment of CCHP (combined cold-heat-and-power) plant supported with renewable energy

The current energy policy requires a constant technology development towards more sustainable energy transformation systems. Cogeneration and the use of renewables are two important solutions available to achieve this goal. If cogeneration is applied locally, e.g. as CHP (combined heat-and-power generation) modules with internal combustion engines, it leads to additional advantageous effects due to the decrease of energy transmission losses. To analyse such systems from the point of view of resource efficiency, the pure energy analysis is not sufficient since the quality of particular energy carriers is not evaluated.The paper presents the exergo-ecological analysis using the concept of TEC (thermo-ecological cost) for a selected CCHP (combined cold-heat-and-power) trigenaration system consuming both renewable and non-renewable resources. The analysed CCHP system is equipped with a photovoltaic plant, an internal combustion engine fired with biogas and an adsorption chiller. The peak demand for electricity is covered from the grid, and the peak demand for heat is covered by a gas boiler. The seasonal availability of renewable sources (solar radiation and biogas) is taken into account.It has been demonstrated that the obtained TEC depends on the type of generated carrier (electricity/heat/cold), on internal process irreversibility and the emitted pollutants, and on the type of primary energy supplied to the analysed systems. The values of TEC range between 0.22 for electricity generated in the photovoltaic plant and 4.72 for the cooling agent generated in the adsorption chiller.

An exergy-based approach to the joint economic and environmental impact assessment of possible photovoltaic scenarios: A case study at a regional level in Italy

Most energy conversion systems, and especially electricity generation plants, do not operate at nominal conditions throughout their useful life: periodic, semi-periodic and stochastic changes in the availability of the resource affect solar (thermal and PV), wind, hydraulic, and geothermal plants, which in reality operate at off-design conditions for most of their life. To a smaller extent, fossil-fuelled plants may also be plagued by fuel availability problems and no longer easily predictable demand oscillation. In spite of the ever growing net connectivity, since the demand curve in even larger geographic regions displays a typical quasi-sinusoidal shape, fleet load modulation is unavoidable. Naturally, off-design operation and load cycling affect the cost of the generated kWh.This paper presents a general thermoeconomic method to evaluate the economic and environmental effects of energy system integration, taking into account life cycle concerns (supply chains) and the effect of inefficiencies due to off-design operation of the systems. The method here is applied to a realistic case study of an Italian regional utility: an analysis of the implications of the variation of the productive mix between a photovoltaic power plant (PV) and a standard commercial, non-cogenerating gas turbine plant (GT) on the final cost of the electrical kWh. The demand curve is prescribed, and the effect of different mixes is assessed, both on the monetary and on the exergy cost of the electricity.The economic cost assessment is performed by standard thermoeconomic techniques, whereas the exergy costs are evaluated using both the Extended Exergy Accounting (EEA) and the Thermo-Ecological Cost (TEC) methods. The results show that a purely monetary cash flow accounting and thermo-economics lead to contrasting results, and also that the EEA and TEC cost indicators generate different rankings among the studied alternative GT/PV mixes.

Environmental Quality Evaluation of Hard Coal Using Lca and Exergo-ecological Cost Methodology

The world’s global economy is based on the access to energy. The majority of useful energy is still produced by combustion of fossil fuels that belongs to non-renewable natural resources. Besides the depletion of non-renewable resources there is also a problem related to release of waste substances into the natural environment. Moreover, efficient power and energy sector is one of the factors determining the competitive management of countries or regions. Often the improvement of energy management is focused on power technologies or effectiveness of final production processes. However, some improvement can be found in the stage of extraction, processing and transportation of fuels. To evaluate chains of the processes inside the system the ecological analysis such as Life Cycle Assessment (LCA) or Thermo-Ecological Cost (TEC) analyses is necessary. LCA in association with characterization factors is commonly used; however, TEC which is based on second law of thermodynamics is not so widespread. In the papers fundamentals of both TEC and LCA methods are described. The example results of TEC and LCA application in the case of extraction of hard coal from Polish coal mines are presented.

System approach to the analysis of an integrated oxy-fuel combustion power plant

Abstract Oxy-fuel combustion (OFC) belongs to one of the three commonly known clean coal technologies for power generation sector and other industry sectors responsible for CO2 emissions (e.g., steel or cement production). The OFC capture technology is based on using high-purity oxygen in the combustion process instead of atmospheric air. Therefore flue gases have a high concentration of CO2. Due to the limited adiabatic temperature of combustion some part of CO2 must be recycled to the boiler in order to maintain a proper flame temperature. An integrated oxy-fuel combustion power plant constitutes a system consisting of the following technological modules: boiler, steam cycle, air separation unit, cooling water and water treatment system, flue gas quality control system and CO2 processing unit. Due to the interconnections between technological modules, energy, exergy and ecological analyses require a system approach. The paper present the system approach based on the ‘input-output’ method to the analysis of the: direct energy and material consumption, cumulative energy and exergy consumption, system (local and cumulative) exergy losses, and thermoecological cost. Other measures like cumulative degree of perfection or index of sustainable development are also proposed. The paper presents a complex example of the system analysis (from direct energy consumption to thermoecological cost) of an advanced integrated OFC power plant.

Application of life cycle thermo-ecological cost methodology for evaluation of biomass integrated gasification gas turbine based cogeneration

Biomass integrated gasification cogeneration is nowadays considered as one of the most attractive technologies for CO2 emission reduction and non-renewable fuel savings. The paper presents application of the Thermo-Ecological Cost (TEC), which expresses the cumulative consumption of non-renewable exergy, for examination of energy and environmental benefits of biomass energy conversion plant based on gasification technology and medium scale recuperative gas turbine. To express the total effect of considered energy conversion systems the TEC is supplemented with the data resulting from Life Cycle Analysis (LCA). Different available gasification technologies and configurations of a cogeneration plant are investigated. Atmospheric fluidized bed gasification (AFB), pressurized fluidized bed gasification (PFB) and allothermal gasification using pure steam as gasification agent (FICFB) are taken into account as well as simple and combined power cycles with the Mercury 50 Solar gas turbine. The results reveal that simple cycle with gas turbine and waste heat recovery water boiler offers better effects than combined cycle configuration. The best performance has been reported for pressurized gasification technology.

Thermo-ecological and exergy replacement costs of nickel processing

In this paper, an exergy analysis of nickel processing is performed through the application of two methodologies: TEC (thermo-ecological cost) and ERC (exergy replacement cost). The merging of both methodologies allows to have a complete assessment of non-fuel mineral processing. TEC evaluates the cumulative consumption of non-renewable exergy required to produce a unit of useful product from the raw materials contained in natural deposits, i.e. from the cradle to the market. It further splits the results into the fuel, mineral and emission components so as to show the exergy consumption resulting from each part, thereby identifying the types of resources that are being consumed in each step of the overall production process. A problem detected with the TEC was that the exergy associated with the mineral component was small compared to that of fuels. This is because the TEC traditionally uses the chemical exergy of substances in their assessment and fossil fuels eclipse any other raw material. In order to overcome such issue, the TEC has been complemented with the ERC. The latter accounts for the exergy required to produce minerals from a completely dispersed state to the original conditions in which they were originally found in nature, i.e. the exergy that one would consume to restore minerals from the grave to the cradle. Through ERC, the aim is to account for the dispersion problem associated with minerals, because the scarcer a mineral, the more exergy is associated with its replacement. Results show that when ERC is embedded into the TEC infrastructure, the impacts associated with mineral consumption are significantly greater. Accordingly, the inclusion of ERC into TEC allows for a more comprehensive consumption of non-fuel mineral resources, thereby providing better indications as to the achievement of a more sustainable production.

Exergo-ecological evaluation of adsorption chiller system

Technological processes in food industry require chilling agent. System of chillers can be driven by non-renewable or renewable sources. In the group of renewable sources solar collectors seem to be an attractive solution both as the basic or the auxiliary power source for adsorption refrigerators. The common tool for the evaluation of the refrigerator systems used in practice is the energy effectiveness expresses as the COP (coefficient of performance). In the case of energy systems with energy fluxes of different parameters or supplied partly with renewable and non-renewable sources such evaluation is not enough. The authors proposed the method of exergetic evaluation. In the paper the comparison of the exergetic effectiveness and thermoecological cost of an example refrigeration system existing in Polish food industry supplied with heat alternatively from boiler house, cogeneration system and heat from solar collectors is presented.

Depletion of the non-renewable natural resource reserves in copper, zinc, lead and aluminium production

Depletion of the world's copper, zinc, lead and aluminium resources is examined using Cumulative Exergy Consumption (CExC) and thermo-ecological cost concepts. Due to a short projected term of availability of the copper, zinc and lead resources (20–30 years) and unavoidable consumption of primary energy (oil, coal, natural gas) the problem of efficiency and economics of the currently used and future technologies is important. It is important that the metallurgy industry is efficient because it can be a significant contribution to Gross National Product and energy consumption in countries where metal production occurs. For example, to get the maximum value from copper deposits, the proper and most efficient technology (of many) should be chosen. The authors proposed a minimum value of Cumulative Exergy Consumption (CExC) as the criterion for the recommended technology. Based on this criterion we conclude that, for example, pure copper cathode production by flash smelting technology is the best technology.

Thermoecological cost of electricity production in the natural gas pressure reduction process

The paper presents a novel concept for thermodynamic evaluation of a selected energy system. The presented method has been developed by integration of the Thermo-Economic Analysis with the theory of Thermo-Ecological Cost. It can be applied as a thermodynamic evaluation method of rational resources management within any production system. It takes into account both the interrelation of irreversibility within the analyzed system and its influence on the global effects related to the depletion of non-renewable natural resources. The proposed method has been applied to evaluate the production of electricity in the process of natural gas transmission at pressure reduction stations. The expansion system is based on an existing plant integrated with a CHP module, characterized by a performance ratio of 89.5% and exergy efficiency of 49.2%. Within the paper, this expansion plant is supplied with natural gas transported from a natural deposit through a case-study transmission system with 4 compressor stations. The TEC (thermoecological cost) method was applied in conjunction with thermoeconomic analysis. As a result, TEC of the electricity generated in the expanders was determined at 2.42 kJ/kJ, TEC of electricity from the CHP module is 1.77, and the TEC of medium-pressure natural gas distributed to consumers is 1.022.

Thermodynamic evaluation of biomass-to-biofuels production systems

Biomass is a renewable feedstock for producing modern energy carriers. However, the usage of biomass is accompanied by possible drawbacks, mainly due to limitation of land and water, and competition with food production. In this paper, the analysis concerns so-called second generation biofuels, like Fischer–Tropsch fuels or Substitute Natural Gas which are produced either from wood or from waste biomass. For these biofuels the most promising conversion case is the one which involves production of syngas from biomass gasification, followed by synthesis of biofuels. The thermodynamic efficiency of biofuels production is analyzed and compared using both the direct exergy analysis and the thermo-ecological cost. This analysis leads to the detection of exergy losses in various elements which forms the starting point to the improvement of conversion efficiency. The efficiency of biomass conversion to biofuels is also evaluated for the whole production chain, including biomass cultivation, transportation and conversion. The global effects of natural resources management are investigated using the thermo-ecological cost. The energy carriers' utilities such as electricity and heat are externally generated either from fossil fuels or from renewable biomass. In the former case the production of biofuels not always can be considered as a renewable energy source whereas in the latter case the production of biofuels leads always to the reduction of depletion of non-renewable resources.

Application of life cycle assessment and exergy to environmental evaluation of selected polymers

This paper presents LCA (Life Cycle Assessment) and exergy analysis for the environmental evaluation of selected polymers: PE, PP, PVC, PS and PET. In the analysis, damages to human health and ecosystem quality as well as resource consumption were considered, also global warming potential and cumulative energy use were determined. As a result of exergy analysis the sustainable development index and thermo-ecological cost of selected polymers were evaluated. The results from LCA study were compared with those obtained using exergy analysis and the impact of the production of selected polymers on the consumption of non-renewable natural resources was assessed. A life cycle assessment was conducted using three methods: Ecoindicator 99, IPCC and CED.

Fuel part and mineral part of the thermoecological cost

The thermoecological cost, expressing the cumulative consumption of nonrenewable exergy per unit of the considered useful product, may be divided into the fuel part and the mineral part. The fuel part may be eliminated by the utilization of renewable exergy carriers. The mineral part cannot be eliminated. The depletion of mineral resources leads to the necessity of utilization of more and more lean natural resources. The equation system determining both parts of the thermoecological cost is formulated. Two numerical examples are included. The first one is a simple demonstration example, the second is detailed and relates to the Polish energy system.

Fuel part and mineral part of the thermoecological cost

Fuel part and mineral part of the thermoecological cost

Environmental externalities and their effect on the cost of consumer products

Economic activities generate pollution, which causes damages to the society and the environment. It is possible to estimate the quantities of emitted pollutants from energy conversion systems using thermodynamic principles combined with empirical techniques. The indices of direct emission are often not sufficient to show the entire environmental load because production processes are interconnected. The methodology of determination of cumulative exergy consumption was proposed by Szargut as the thermo-ecological cost (TEC). Recently, Szargut and Stanek published the methodology of cumulative CO2 emission determination called thermo-climatic cost (TCC). The main objective is to show that the TCC can be extended to evaluation of emission of any harmful substance. To achieve that, the new index of cumulative emission (CEm) is proposed. Two different methods of evaluating the cost of emission are presented; physical (exergy) used to investigate the influence of emission on the depletion of natural resources; and economic (monetary) used to show the influence of externalities on the market prices of consumer goods.

Thermodynamical motivation of the Polish energy policy

Abstract Basing on the first and second law of thermodynamics the fundamental trends in the Polish energy policy are analysed, including the aspects of environmental protection. The thermodynamical improvement of real processes (reduction of exergy losses) is the main way leading to an improvement of the effectivity of energy consumption. If the exergy loss is economically not justified, we have to do with an error from the viewpoint of the second law analysis. The paper contains a thermodynamical analysis of the ratio of final and primary energy, as well as the analysis of the thermo-ecological cost and index of sustainable development concerning primary energy. Analyses of thermo-ecological costs concerning electricity and centralized heat production have been also carried out. The effect of increasing the share of high-efficiency cogeneration has been analyzed, too. Attention has been paid to an improved efficiency of the transmission and distribution of electricity, which is of special importance from the viewpoint of the second law analysis. The improvement of the energy effectivity in industry was analyzed on the example of physical recuperation, being of special importance from the point of view of exergy analysis.

Comparison of five exergoenvironmental methods applied to candidate energy systems for rural villages in developing countries

This paper tackles the environmental impact assessment of different energy systems for rural communities in developing countries. Ten systems are proposed, modelled, and assessed by five published methods: ReCiPe indicator combined with exergy, exergy wasted, thermo-ecological cost, extended exergy accounting, and extended thermoeconomics. All the methods constitute life cycle assessment (LCA) and mathematically take a similar form, combining an environmental impact assessment with exergetic analysis. Despite the inevitable difference of weighting between methods, most showed clear benefits to using responsibly grown Jatropha oil (rather than diesel) to generate electricity and all showed clear benefits of biogas over solar thermal or fuelwood heat. Analyses of error and sensitivity are presented at the end of the results and discussion section.

Thermo-ecological optimization of a solar collector

The depletion of non-renewable natural exergy resources (the thermo-ecological cost) has been accepted as the objective function for thermo-ecological optimization. Its general formulation has been cited. A detailed form of the objective function has been formulated for a solar collector producing hot water for household needs. The following design parameters have been accepted as the decision variables: the collector area per unit of the heat demand, the diameter of collector pipes, the distance of the pipe axes in the collector plate. The design parameters of the internal installation (the pipes, the hot water receiver) have not been taken into account, because they are very individual. The accumulation ability of hot water comprising one day has been assumed. The objective function contains the following components: the thermo-ecological cost of copper plate, copper pipes, glass plate, steel box, thermal insulation, heat transfer liquid, electricity for driving the pump of liquid, fuel for the peak boiler. The duration curves of the flux of solar radiation and absorbed heat have been elaborated according to meteorological data and used in the calculations. The objective function for economic optimization may have a similar form, only the cost values would be different.

Optimization of the design parameters aiming at the minimization of the depletion of non-renewable resources

The thermo-ecological cost, expressed by means of the cumulative consumption of non-renewable natural resources of exergy, has been applied as a criterion of the selection of technical solutions. This criterion differs from the classical economical one. The general formulation of the objective function of thermo-ecological economy is presented. A detailed formulation of the objective function is demonstrated my means of the optimization of the parameters of a heat exchanger. It indicates the difficulties appearing when determining the influence of the design parameters on the consumption of exergy in fabrication process. Other concepts of the economical application of exergy have been discussed.

On the transition of fatigue crack growth from stage I to stage II in a corrosive environment: Humano, R. Metall. Mater. Trans. A (1996) 27A, 471–476

Depletion of the world's copper, zinc, lead and aluminium resources is examined using Cumulative Exergy Consumption (CExC) and thermo-ecological cost concepts. Due to a short projected term of availability of the copper, zinc and lead resources (20–30 years) and unavoidable consumption of primary energy (oil, coal, natural gas) the problem of efficiency and economics of the currently used and future technologies is important. It is important that the metallurgy industry is efficient because it can be a significant contribution to Gross National Product and energy consumption in countries where metal production occurs. For example, to get the maximum value from copper deposits, the proper and most efficient technology (of many) should be chosen. The authors proposed a minimum value of Cumulative Exergy Consumption (CExC) as the criterion for the recommended technology. Based on this criterion we conclude that, for example, pure copper cathode production by flash smelting technology is the best technology.