Extended Exergy Research Articles

Sustainability analysis and exergy return on investment of a dual-chamber solar PV-powered evaporative cooling system based on conventional and extended exergy approach

Sustainability analysis and exergy return on investment of a dual-chamber solar PV-powered evaporative cooling system based on conventional and extended exergy approach

Designing a sustainable municipal solid waste management system over multiple periods using extended exergy accounting method – a case study of Shanghai

Waste-to-energy technologies can significantly alter urban metabolism and sustainability. This article proposes a multicriteria analysis framework based on the extended exergy accounting method to assess and plan a sustainable municipal solid waste management system from urban metabolism perspective. This framework includes three components. Firstly, an accounting model that integrates material, energy, social, economic, and environmental criteria was developed to identify the contribution of municipal solid waste management system to urban sustainability and to decide whether it is sustainable. Then, a multiperiod municipal solid waste management system planning model was developed to provide the optimal strategy for waste-to-energy facilities deployment and municipal solid waste allocation for different periods. Finally, multidimensional indicators were proposed for a sustainability comparative analysis in overdeployment, pressure on urban ecosystem and urban resource conversion efficiency. The proposed method was applied to the case study of household solid waste management in Shanghai and two scenarios were considered. Our comparison showed that the hybrid scenario (in which various waste recycling technologies were applied together) theoretically performs significantly more sustainable than the incineration scenario in terms of material investment, emissions, economic performance, resource depletion, and recovery. Sensitivity analysis of three parameters—the maximum deployment number of each unit waste-to-energy facility ([Formula: see text]), the minimum utilization rate ([Formula: see text]), and the capacity budget ([Formula: see text])—were carried out. The proposed hybrid method was found to be sensitive to [Formula: see text], but less sensitive to [Formula: see text] and [Formula: see text]. Lessons learnt can be used to plan similar waste-to-energy strategies in other countries.

Exergy Analysis of a Sugarcane Crop: A Planting-to-Harvest Approach

The objective of this study was to conduct an exergy analysis of sun–plant interactions in sugarcane using mathematical models, aiming to estimate plant production and exergy flows and describe their photosynthetic efficiency during sugarcane cultivation. Sugarcane productivity was determined based on the Brazilian BRCANE model. The efficiency of this crop was evaluated through a simple control volume, where the exergy of solar radiation serves as the sole energy input, and the exergy of the culms and straw represents the useful exergy. The findings revealed an average second-law efficiency of 5% for sugarcane photosynthesis production from solar radiation, with an estimated harvest of approximately 16.29 kWh/m2 of useful extended exergy after a year, and an estimated water consumption of 111.2 m3/ton of harvested stalks. Moreover, this study highlights that exergy efficiency varies significantly in response to seasonal changes. The method developed here can be utilized in future studies to estimate mass and energetic flows and exergy analyses.

Ecological accounting of the Chinese society 2012–2020 based on extended exergy

China's social system has undergone unprecedented economic transformation in the past decade. It is essential that the relationship between the country's socio-economic development and natural ecosystem be revealed, thereby revealing the evolutionary trajectory of its biophysical sustainability. The extended exergy accounting (EEA) method offers a thermodynamics-based tool to evaluate the structure and function of a social system and objectively estimate the impacts of human activities on sustainable development and broader ecosystems. This study aims to perform extended exergy analysis to trace the flows of resources, labor, capital, and environmental remediation exegetics in China's society from 2012 to 2020. During the accounting period, the average annual growth rate of total extended exergy (TEE) was just 1.2%. The TEE in the conversion and tertiary sectors ew noticeably faster than those in other sub-sectors, while the TEE in the extraction and agriculture sectors showed a declining trend. The TEE in 2020 reached 764.50 EJ, of which 179.13 EJ were attributed to Cumulative Exergy Consumption, 74.89 EJ were attributed to labor, 68.85 EJ to capital, and 441.63 EJ to environmental remediation costs. The indicator assessment reflects an enhancement in the sustainability of the Chinese social system, particularly the rapid improvement in labor and capital-related indicators. Comparing the results with other countries demonstrates that the gap between China and developed nations has narrowed, with China's indicators for balancing resource production and capital flows rivaling those of the U.S. and the U.K. The objective revelation of the developmental and transitional trajectory of Chinese society, based on the EEA approach, provides valuable insights for other developing countries in achieving sustainable development.

Application of net zero extended exergy buildings concept for sustainable buildings analysis

Different Zero-Energy Building (ZEB)-related definitions considering its four main dimensions, such as zero energy, zero carbon, zero exergy and zero cost, have been proposed by different investigators. Among these, exergy-based definitions are relatively low in numbers. In this regard, the main objective of this present study is to propose net zero extended exergy buildings as a new concept, which combines extended exergy and net zero exergy building concepts and is a measure of the exergetic footprint. This concept setups a balance between extended exergy accounting of electricity from the grid and electricity generated in building. The proposed methodology is applied to a building available in the literature for heating and cooling seasons. Results show that 450Wp peak power and 44.181 kWh electrical energy must be obtained for meeting the electricity demand of the building. Another novel result is that the extended exergy accounting of the electricity generated by PV panels is bigger than the extended exergy of the electricity taken from the gird meaning that exergetic footprint of the electricity generated by PV panels is bigger. However, this result must be interpreted for the whole life time of the system.

Advanced, extended and combined extended-advanced exergy analyses of a novel geothermal powered combined cooling, heating and power (CCHP) system

In this study, not only conventional and advanced exergies, but also advanced exergoeconomic, extended exergy and combined extended-advanced exergy analyses are firstly applied to the novel ejector-based CO2 transcritical Combined Cooling, Heating and Power (CCHP) system powered by geothermal energy. It is found that the evaporator and domestic water heater (DWH) components should be focused to increase system efficiency. For the vapor generator (VG), evaporator (EV) and DWH, avoidable exergy destruction rates are found as 26.334 kW, 0.323 kW and 8.288 kW, while their unavoidable exergy destruction rates are 11.206 kW, 0.276 kW and 1.410 kW, respectively. The extended avoidable exergy destruction rates are determined as 89.068 kW, 5.174 kW and 12.385 kW, while their unavoidable exergy destruction rates are 36.846 kW, 3.079 kW and 1.992 kW for the VG, EV and DWH, respectively. Improvement potential of VG, EV and DWH are endogenous, it means they should be focused on these components themselves. DWH is strongly connected to condenser which has important role on exergy destructions of it and condenser should be focused on improving DWH. According to mexogenous exergy destruction results, the condenser's exergy destruction is equal to −0.468, which means DWH's exergy destruction can be reduced.

Environmental sustainability and exergy return on investment of selected solar dryer designs based on standard and extended exergy approaches

ABSTRACT Different solar dryer designs are available in the literature. However, it is essential to understand how the performance of the dryer designs contributes to environmental sustainability by reducing waste in the exergy-loop and mitigate CO2 emission into the atmosphere. The exergy-based sustainability indices include waste exergy ratio, lack of productivity (LOP), sustainability index, environmental destruction coefficient and exergy recovery ratio. The paper also introduces exergy return on investment (ExRoI) by applying an extended exergy accounting approach with the inclusion of exergy influx of material resources, capital and labor in the exegetic computations of the sustainability index. Four solar dryers consisting of an indirect solar-cabinet dryer, mix-mode solar dryer, hybrid solar dryer and a double-partitioned single-pass-collector solar dryer with a wind generator were used as a case study. Comparatively, the ExRoI is lower than the standard exergy-efficiency for the four dryers by 6.87 to 91.61%. In contrast, the standard exergy-based sustainability index was higher by 5.4 to 61.2%. Total invested exergy ranged from 0.04TJ to 0.081TJ. The values of waste exergy ratio, LOP, ERR, EDC, and carbon credit ranged from 0.47 to 0.79, 0.566 to 16.45, 5.44 × 10−4 to 1.37 × 10−1, 1.57 to 17.45 and 231.45 to $2908, respectively.

Energy, exergy, economic, environmental, advanced exergy and exergoeconomic (extended exergy) analysis of hybrid wind-solar power plant

Aiming to net-zero emissions, hybrid power generation through renewable means has gained substantial attention across the globe. Considering the stochastic nature of renewable energy resources, a comprehensive performance assessment is a must prior to project development. Present work is a novel multidimensional 6E analysis (energy, exergy, economic, environmental, advanced exergy, and exergoeconomic) to evaluate the performance of hybrid wind-solar energy systems. The analysis is performed using long-tern (41 years) high-resolution ERA5 reanalysis resource data and the mathematical modeling by means of MATLAB R2018a computation software. The long-term data facilitates reliable and precise predictions of resource availability, power generation, and system performance during the lifespan of the project. The performance of HWSES in terms of capacity factor and exergy efficiency is computed to be 9.6–35.5% and 4.7–10.4% respectively, whereas the extended exergy efficiency lies in the range of 3.39–5.79%. Hybridizing wind power projects with solar power enhances the overall system capacity factor, exergy efficiency, and extended exergy efficiency by 3.46%, 5.12%, and 2.87% respectively. Hence, the hybridization leads to superior year-round system performance with smaller power fluctuations than the standalone systems. Further, wind, solar and hybrid systems would annually reduce the Specific Emission Reduction of 1128 tone/kW, 1685 tone/kW, and 1407tone/kW respectively. The present research will be helpful to the policy-makers and the project developers in the project feasibility study of hybrid energy systems.

Extended exergy analysis of a photovoltaic-thermal (PVT) module based desiccant air cooling system for buildings

In this paper, a photovoltaic-thermal (PVT) module based desiccant air-cooling system for buildings is analyzed by extended exergy analysis. Extended exergy analysis contains all information about material, energy, capital, labor, and environmental flows. The results show that the extended exergy analysis gives different results from conventional exergy analysis in terms of exergy destruction and exergy efficiency. The maximum exergy efficiencies of the system are 0.84 and 0.18 by considering the conventional and extended exergy analyses, respectively. Another important change is shown in the exergy destruction owing to the increase from 5085.50 kJ to 98029.50 kJ in maximum values for conventional and extended exergy analyses, respectively. When extended exergy items are taken into account, it is seen that exergy equivalent of the capital has the biggest portion. This is mostly resulted from the great expenses of the electricity consumption. That’s why, either electricity consumption needs to be decreases by using efficient systems or electricity should be generated via renewable energy. These methods would be useful to increase in exergy efficiency and decrease in exergy destruction.

An improved extended exergy accounting method for assessing the sustainability of the Chinese society

This study presents an ecological accounting for the Chinese society using improved extended exergy accounting method. Based on the input–output table of China, we capture the economic linkages of societal labor and capital fluxes, and improve the equivalent exergy metrics of labor and capital to be consistent with the Chinese situation. Material and externalities-equivalent exergy structures are examined by the quantitative estimation and indicator assessment. Results show that the total resource consumption of the Chinese society amounted to 151.6 EJ in 2012, while the total equivalent exergetic values of labor, capital and environmental remediation cost were estimated at 67.0 EJ, 69.1 EJ and 411.5 EJ, respectively. The national total capital and labor input was close to its resource consumption, but only equal to one third of the environmental remediation cost, highlighting the contribution of ecosystem products and services. An overall system diagram covering major extended-exergy inflows and outflows within the society was designed to display the complex metabolism process and network relationship of resource use, economic production and environmental externalities in an integrative way. Exergy and extended exergy analyses of the Chinese society for a benchmark year contributes to understanding the operation of a socio-economic system from a biophysical perspective and establishing effective regulatory strategies of production and consumption activities to accelerate a shift towards sustainability.

A contribution to the search for a thermodynamics-based sustainability indicator: Extended Exergy Analysis of the Italian system (1990–2012) and comparison with other indicators

Sustainable growth is one of the major challenges of the XXI century; the antagonism between the needs of “development” and finiteness of natural resources is more and more evident, forcing international Agencies to endorse a “2030 Agenda for Sustainable Development” to promote, among other goals, a responsible management of natural resources. The key issue here is the lack of a consistent sustainability indicator to assess whether a country is moving in the right direction: for over seventy years, the Gross Domestic Product (GDP) has been the main parameter to verify the “health” of a Society, but this is a controversial issue in the scientific community. The main concern expressed by Economists and Energy experts is that the GDP was conceived to evaluate the “marketable part” of a society being in contrast with either a sustainable development and a responsible exploitation of natural resources. According to its critics, developmental scenarios built on the GDP might in fact be unsustainable and extremely harmful for future generations. Against this background, several indicators were developed with the intention of replace or supplement such a purely monetary quantifier, but these efforts enjoyed little success, so that the GDP is still the tool of choice for governments and most international Agencies. The aim of the paper is to assess whether it is possible to use a sustainable indicator based on the Extended Exergy Analysis (EEA), a Second Law-based accounting method that includes a novel internalization of Externalities (Capital, Labour and Environmental Cost). The present study proposes a structured method to perform an Extended Exergy Analysis of a whole country, starting with a very disaggregated database that ensured higher accuracy. A numerical application to the “System Italy” is implemented over a period of 22 years (1990–2012). The results lead to a complete divergence between the trends of GDP and EEA. Quite on the contrary, the EEA results are consistent with those generated by other sustainability indicators and contain a higher information content.

Extended exergy analysis of a solar driven water production plant via reverse osmosis

• Novel small scale solar desalination plant provides a solution for water scarcity. • Proposed desalination plant using solar energy studied via extended exergy analysis. • Extended exergy analysis evaluates solar plant performance and sustainability. • Labor and capital exergy equivalents are 42.68 MJ/workhour and 12.09 MJ/Euro. • Products having much higher specific exergy content could be produced. Water scarcity and contamination of available water are becoming one of the most complex problems worldwide and they compromise economic development, global sustainability, and human supply, among others. Water is required in almost all human activities and also for planet equilibrium in terms of biodiversity. In this research a new home scaled water desalination plant, using a reverse osmosis technology and driven with solar energy is analyzed via extended exergy analysis, which is one of the most accurate methods for evaluating both energy performance and sustainability. The proposed system, that is presented and analyzed, consists of a solar concentrator having 1000 concentrating rate, a Photon Enhanced Thermionic Emitter, a Dye-Sensitized Solar Cell for the electricity generation and a Reverse Osmosis Desalination Plant (RODP) for water purification using the produced electricity. This system allows water desalination in small scale plants requiring low density energy sources and can produce sustainable water for multiples uses, such as domestic use or agricultural, among others. The most important results are labor and capital exergy equivalents, 42.68 MJ/workhour and 12.09 MJ/Euro , respectively, and an exergy destruction of 389.700 GJ for all the system annually. The proposed technology can be extended and used in different locations and the Extended Exergy Analysis can be used as a powerful tool for both design and optimization.

Novel combined extended-advanced exergy analysis methodology as a new tool to assess thermodynamic systems

In this study, a novel combined extended-advanced exergy analysis method is developed for assessing thermodynamic systems. The method is established by combining extended exergy analysis with advanced exergy analysis and the so-called extended-advanced exergy analysis. The methodology used in the novel analysis method is different from only extended exergy analysis and only advanced exergy analysis, but the criteria are the same to reach the goal. This proposed method is applied to a gas turbine system as a case study to show its variability. The gas turbine system considered consists of a combustion chamber, a compressor and turbine units. The conventional (Fuel-Product approach), advanced and extended exergy analyses are separately applied to the case study system for the comparison with the novel combined extended-advanced exergy analysis. It is seen that the combined extended-advanced exergy analysis results of the case study are not exactly the same with the advanced and extended exergy analyses’ results. The reason for this is its comprehensive joint of various thermodynamic analysis methodologies integrating all materials, capital, labor, energy and environmental effect instead of the relation between components and their improvement potentials in one analysis. But it is assessed that the novel analysis tool is able to apply all of those analyses into one simple methodology. The exergy efficiencies of the case study are 28% and 31% by considering the conventional and extended exergy analyses, respectively. This means that all input parameters including labor, capital and environment are used with better efficiency. Also, the exogenous exergy destruction rate (159 kW) is higher for the combined extended-advanced exergy analysis (384 kW). This shows that the relations between other components are increased for the turbine. Another important change is shown in avoidable exogenous exergy destruction rate for the turbine, increasing from 374 kW to 833 kW. This new combined method is useful to those, who wish to apply advanced and extended exergy analyses through a new practical assessment way.

Comparative thermo-economic and advanced exergy performance assessment of wind energy for distributed generation in four sites in Nigeria

Electricity access and reliability in Nigeria is poor due to obsolete power distribution infrastructure. This could be improved by deploying wind energy resources. The present research assessed the thermo-economic, advanced and extended exergy analysis of deploying wind turbine for distributed generation in four Nigerian locations. The air temperature and wind speed of the sites was used together with Weibull statistical parameters to mathematically model the thermodynamic performance of selected wind turbine for the sites. The results show that the energy and standard exergy efficiency of the sites ranges from 0.16 – 0.44, 0.05 – 0.37, 0.23 –0.39, 0.26 – 0.37 and 0.12 –0.33, 0.04 – 0.25, 0.17 – 0.28, 0.18 – 0.28 respectively for Enugu, Kaduna, Katsina and Jos. The exergy efficiency based on the extended exergy analysis (EEA) approach was found to be much lower than the standard exergy efficiency for all the sites. Based on EEA, Enugu, Kaduna, Katsina and Jos has exergy efficiency of 1.05, 0.73, 2.52 and 3.22 % respectively. Economic performance results showed that Jos is the best site with least monthly average COE value of 0.15 $/kWh which compares closely with global average COE value of 0.14 $/kWh for households. Katsina and Enugu have a COE value of 0.19 and 0.84 $/kWh respectively while Kaduna is the worst in performance with highest COE value of 1.13 $/kWh.

A new systematic decision support framework based on solar extended exergy accounting performance to prioritize photovoltaic sites

Determining locations is important for researchers and policymakers involved in developing photovoltaic (PV) plants. Here, solar extended exergy accounting performance is proposed as a new systematic decision support framework for prioritizing PV sites from environmental, technical, financial, and social viewpoints. The space-time solar extended exergy accounting performance of a 500 kW grid-connected PV system is determined for different Iranian climates as an example to show how the proposed tool can enhance site selection for PV power systems. The simulations are carried out for all 12 months of the year using the actual climatic, technical, economic, environmental, and social databases. Results for January, April, July, and October, representing winter, spring, summer, and autumn, respectively, are discussed in detail. The outcomes of the proposed method are compared with those for total irradiance, solar irradiance exergy, power generation, and exergy efficiency. In addition, several space-time ‏maps are developed for facilitating comparison among PV installation priorities obtained using various criteria. The average monthly total irradiance and solar irradiance exergy in Iran respectively varies in the range 120–184 kWh/m2/month and 112–172 kW/m2/month, respectively. The average monthly power generation, exergy efficiency, and extended exergy accounting performance of the developed plant are respectively found to be in the range of 45.3–66.0 MWh/month, 13.6‒14.8%, and 9.46–10.5% for different Iranian climates. Overall, southeast, central, and northwest cities of Iran are shown to be promising candidates for solar PV power systems based on the extended exergy accounting approach. The outcomes show that the proposed tool can be much more helpful than conventional methods for ranking candidate locations for building PV plants. The proposed extended exergy accounting performance framework can be applied for other stand-alone and hybrid renewable energy systems for various environmental and climatic conditions.

Research on Extended Carbon Emissions Accounting Method and Its Application in Sustainable Manufacturing

Carbon-Emission Accounting (CEA) is an important assessment method for sustainable manufacturing, which mainly focuses on raw materials, energy and waste disposal factors but ignores labor and capital factors. However, the generation process of labor and capital inevitably produce Carbon Dioxide Emissions (CDE). Referring the Extended Exergy Accounting method, the calculation model of extended carbon dioxide emissions factors of capital and labor is established based on the standard CDE per capita, total population, annual working hours, intermediate money M2 and total annual wage S, etc. Then the Extended Carbon-Emission Accounting (ECEA) method is proposed based on the current CEA method, accounting labor, capital, raw materials, energy and all other environmental related factors. Comparatively analyzing on grinding and hard-turning process of a lathe spindle part is studied, the result shows ECEA method is more reasonable and suitable for sustainable manufacturing than CEA method.

An integrated full cost model based on extended exergy accounting toward sustainability assessment of industrial production processes

Existing methods for the sustainability assessment of industrial production processes have considered the values of natural resource use and ecosystem services. However, these methods mainly focus on monetary measures of natural capital cost and ignore some other costs, including human health effects, biodiversity loss and indirect exergy consumption in labor employment. The integrated ecological cumulative exergy consumption accounting method was proposed to improve the existing extended exergy model and provide a comprehensive perspective of the full cost of production including natural resources, human resources and environmental cost. The improved model is illustrated by its application for the steel-making process in China. Of the total cost of the steel-making process, the human resources cost (investment) accounts for only 9.7%. Contrary to the traditional cost evaluation, the result of this case study shows that classical economic assessment cannot reflect an overall ecological sustainable level of the steel-making process. The integrated method framework can be used to assess sustainability in a different spatial scale.

Energy, exergy, economic and advanced and extended exergy analyses of a wind turbine

Energy, exergy, economic, advanced exergy, and extended exergy analyses are reported of a Bergey Excel-S wind turbine with nominal power of 10 kW in two cities: Tehran (medium wind potential) and Manjil (high wind potential). The results show that the energy efficiency of the wind turbine is higher in Manjil (3.33%) than Tehran (1.08%). The exergy efficiency in these areas is lower. This means that the exergy efficiency in Manjil is 10.8% but in Tehran is 6.43%. The cost of electricity generated by the wind turbine in Tehran is 0.23US$kWh. This cost is reduced to 0.73US$kWh in Manjil. The advanced exergy analysis demonstrates that the avoidable exergy destruction percentage of the wind turbine increases with wind speed. The extended exergy analysis shows that, in windy areas, the highest exergy percentage is exhibited by the system’s input and output exergy flows and power production (88.7%), while, in areas with medium wind speed potential, the exergy is equal to is the equivalent extended exergy content of the influx of capital cost (58.9%).

Exergy-based ecological indicators: From Thermo-Economics to cumulative exergy consumption to Thermo-Ecological Cost and Extended Exergy Accounting

This paper presents a summary of the conceptual development and the practical applications of exergy-based Environmental Indicators. After a brief historical introduction, the two most popular methods are presented and discussed: the Exergo-Environmental Analysis (here TEA, as a memento of Jan Szargut's original denomination “Thermo-Ecological Analysis”, currently adopted also by Valero's school) and the Extended Exergy Accounting (EEA). Both emerged from Szargut's idea of the existence of a consumption index, the Cumulative Exergy Consumption (CExC), which can be used to quantify the consumption of primary resources “embodied” in a final product or service. The extension introduced by both methods with respect to CExC consists in the explicit inclusion in the exergy budget of one or more of the Externalities, lumped in the original CExC formulation into the exergetic material contents of the single commodities. The differences between the three formulations are obviously reflected in the numerical values of the resulting indicators. The Thermo-Ecological Cost (TEC) and the CExC differ because of the inclusion in the former of the exergetic resources that reflect the “penalty” in the use of primary non-renewable consumption caused by the anthropic intervention. The CExC index and the Extended Exergy Cost EEC differ because the latter explicitly includes in the calculation a “Labour and Capital equivalent exergy consumption” that allows for the survival of the individuals in a given region according to the respective life standards (variable in space and time). Another difference is the way the Environmental Externality is computed: while TEA takes an ex-post assessment, EEA introduces a calculation of the -ideal or real-remediation costs.

The Way Forward in Quantifying Extended Exergy Efficiency

Extended exergy accounting (EEA) is a methodology which estimates the extended exergy cost (EEC) of a product or a service or the extended exergy efficiency (EEE) of a country or economic sector taking into account materials, energy, labour, capital, and environmental impact. The use of EEA results for policy or planning purposes has been hampered by: (1) the lack of data to quantify the EEC of most of the inputs, making it almost impossible to quantify the EEC of a product or service and (2) the lack of a conceptual framework to quantify in a consistent way the exergy of labour and capital. In this paper, we make a review of past studies to identify, synthesize, and discuss the different EEA methods. We identified 3 different EEA methods, that we further compare using the Portuguese Agriculture, Forestry, and Fishery (AFF) sector from 2000 to 2012. The equivalent exergies of labour and capital estimated for the AFF sector vary widely among the three EEA methodologies. We propose and test a new EEA methodology to estimate EEE which accounts for these fluxes in a more restricted scope but more consistently and that includes the Environmental Benefit (EB) that represents the capability of the forestry to capture carbon dioxide. Results show that the EEE of the Portuguese AFF sector has increased by 32% from 2000 to 2012.