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In view of the energy transition, it is important that engineering students are familiar with the concept of exergy and the added value of exergy analysis compared to energy analysis. Exergy analysis tells the truth about energy efficiency and exergy is directly related to sustainable development. This paper focuses on teaching exergy to students at the Delft University of Technology (TU Delft), but the contents are valuable to other engineering students as well. To encourage the teaching of exergy, the basics of exergy and exergy analysis are presented, as well as examples and ideas for teaching exergy to BSc students that are related to the topics of their BSc programme. It is recommended that the contents of this paper be discussed with many teachers of BSc programmes, especially teachers of BSc programmes that do not yet seem to include the teaching of exergy, and that attention be paid to teaching exergy to MSc students as well., Energie and Industrie, Reservoir Engineering

The Netherlands is known for its high penetration of natural gas use in households and industry, but the threat of climate change and earthquakes in the province of Groningen, caused by natural gas production, stimulate the search for alternatives, such as hydrogen gas. Various ways of producing and supplying hydrogen have the attention of scientists, companies and policy makers. This study compares the following three ways of green hydrogen production: 1) a photovoltaic system in Africa is used to produce hydrogen from sea water, followed by pipeline transport to Rotterdam, Netherlands, 2) electricity generated by the offshore Borssele 1&2 wind farm in the Netherlands is used for the offshore production of hydrogen from sea water followed by pipeline transport to Rotterdam, or 3) the electricity generated by this offshore wind farm is transmitted to Rotterdam where it is used for onshore production of hydrogen from sea water. The sustainability of the three systems is assessed from a life cycle point of view. The environmental LCA resulted in ReCiPe 2016 endpoint indicators and the midpoint indicators GWP, land use and water consumption. The exergetic sustainability assessment applied the Total Cumulative Exergy Loss (TCExL) method. The preferred system according to the results of the environmental LCA and the exergetic sustainability assessment is the wind energy system including offshore hydrogen production. The results are not unanimous as to which system is the second-best. The three systems need to be investigated in more detail before firm conclusions can be drawn. It is recommended that attention also be paid to the economic and social pillars of sustainability, and to the exergetic sustainability of technological systems in general, as exergetic assessment results are independent of changing and subjective models, weighting factors and other variables., Energie and Industrie

Energy conversion systems have assumed a crucial role in current society. The threat of climate change, fossil fuel depletion and the growing world energy demand ask for a more sustainable way of electricity production, eg, by using renewable energy sources, by improving the conversion efficiency and/or by controlling power plant emissions. Despite the relationship between exergy and sustainability stated in literature, exergy losses are usually not considered when comparing systems and energy sources for power generation. The exergetic sustainability assessment method named Total Cumulative Exergy Loss (TCExL) has been used to assess several systems for electricity production, ie, a coal-fired power plant, a coal-fired power plant including carbon capture and storage, a biomass-fired power plant, an offshore wind farm and a photovoltaic park. The results of the TCExL method have been compared with an environmental sustainability indicator, ie, the overall ReCiPe endpoint indicator and the economic indicator named Present Worth Ratio. The offshore wind farm is the best system from the exergetic and environmental point of view. The photovoltaic park is the system with the second-best scores. However, from the economic viewpoint including subsidy by the Dutch government, the photovoltaic park performs better than the wind farm system and the system that performs best is the biomass-fired power plant. Without subsidy, only the coal-fired power plant without carbon capture and storage is profitable. The exergetic sustainability scores of the coal-fired and biomass-fired power plants are similar, but from the environmental sustainability viewpoint, the biomass-fired power plant performs better than both coal-fired power plants. As the results of environmental and economic sustainability assessments strongly depend on models, weighting factors, subsidy, market prices, etc, while the results of the exergetic sustainability assessment do not, it is recommended that the e, Energy & Industry, Petroleum Engineering

Power generation from biomass is mentioned as a means to make our society more sustainable as it decreases greenhouse gas emissions of fossil origin and reduces the dependency on finite energy carriers, such as coal, oil and natural gas. When assessing the sustainability of power generation from biomass, it is important to consider the supply chain of the used biofuel by conducting a life cycle assessment of the system. Besides regular sustainability assessments, such as the calculation of the environmental sustainability, attention should be paid to exergy losses, i.e. the loss of 'energy quality', caused by the system as a whole, because every process and activity is accompanied with the loss of exergy and because the amount of exergy on earth can only be replenished by capturing new exergy from solar and tidal energy. This research compares the use of livestock manure and verge grass for power generation by assessing the systems from an environmental as well as an exergetic life cycle point of view. The assessed systems are the following: combustion of bioethanol from the fermentation of verge grass, combustion of substitute natural gas from anaerobic digestion of cow and pig manure and combustion of substitute natural gas from supercritical water gasification of cow and pig manure. The environmental sustainability is assessed by calculating ReCiPe endpoint indicators and the exergetic sustainability is assessed by applying the relatively new Total Cumulative Exergy Loss (TCExL) method. The TCExL method considers all exergy losses caused by a technological system during its life cycle, i.e. the internal exergy loss caused by the conversion of materials and energy, the abatement of emissions and the exergy loss related to land use. In addition to comparing the three systems as well as both assessment methods, the influence of taking into account the system's by-products as 'avoided products' and via 'allocation' on the assessment results is investigated. The bi, Energy & Industry, Energy Technology, Petroleum Engineering

Energy conversion systems have assumed a crucial role in current society. The threat of climate change, fossil fuel depletion and the growing world energy demand ask for a more sustainable way of electricity production, eg, by using renewable energy sources, by improving the conversion efficiency and/or by controlling power plant emissions. Despite the relationship between exergy and sustainability stated in literature, exergy losses are usually not considered when comparing systems and energy sources for power generation. The exergetic sustainability assessment method named Total Cumulative Exergy Loss (TCExL) has been used to assess several systems for electricity production, ie, a coal-fired power plant, a coal-fired power plant including carbon capture and storage, a biomass-fired power plant, an offshore wind farm and a photovoltaic park. The results of the TCExL method have been compared with an environmental sustainability indicator, ie, the overall ReCiPe endpoint indicator and the economic indicator named Present Worth Ratio. The offshore wind farm is the best system from the exergetic and environmental point of view. The photovoltaic park is the system with the second-best scores. However, from the economic viewpoint including subsidy by the Dutch government, the photovoltaic park performs better than the wind farm system and the system that performs best is the biomass-fired power plant. Without subsidy, only the coal-fired power plant without carbon capture and storage is profitable. The exergetic sustainability scores of the coal-fired and biomass-fired power plants are similar, but from the environmental sustainability viewpoint, the biomass-fired power plant performs better than both coal-fired power plants. As the results of environmental and economic sustainability assessments strongly depend on models, weighting factors, subsidy, market prices, etc, while the results of the exergetic sustainability assessment do not, it is recommended that the e, Energie and Industrie, Reservoir Engineering

Power generation from biomass is mentioned as a means to make our society more sustainable as it decreases greenhouse gas emissions of fossil origin and reduces the dependency on finite energy carriers, such as coal, oil and natural gas. When assessing the sustainability of power generation from biomass, it is important to consider the supply chain of the used biofuel by conducting a life cycle assessment of the system. Besides regular sustainability assessments, such as the calculation of the environmental sustainability, attention should be paid to exergy losses, i.e. the loss of 'energy quality', caused by the system as a whole, because every process and activity is accompanied with the loss of exergy and because the amount of exergy on earth can only be replenished by capturing new exergy from solar and tidal energy. This research compares the use of livestock manure and verge grass for power generation by assessing the systems from an environmental as well as an exergetic life cycle point of view. The assessed systems are the following: combustion of bioethanol from the fermentation of verge grass, combustion of substitute natural gas from anaerobic digestion of cow and pig manure and combustion of substitute natural gas from supercritical water gasification of cow and pig manure. The environmental sustainability is assessed by calculating ReCiPe endpoint indicators and the exergetic sustainability is assessed by applying the relatively new Total Cumulative Exergy Loss (TCExL) method. The TCExL method considers all exergy losses caused by a technological system during its life cycle, i.e. the internal exergy loss caused by the conversion of materials and energy, the abatement of emissions and the exergy loss related to land use. In addition to comparing the three systems as well as both assessment methods, the influence of taking into account the system's by-products as 'avoided products' and via 'allocation' on the assessment results is investigated. The bi, Energie and Industrie, Energy Technology, Reservoir Engineering

It is difficult to decide which power generation system is the most sustainable when environmental, economic and social sustainability aspects are taken into account. Problems with conventional environmental sustainability assessment methods are that no consensus exists about the applied models and weighting factors and that exergy losses are not considered. Economic sustainability assessment methods do not lead to results that are independent of time because they are influenced by market developments, while social sustainability assessment methods suffer from the availability and qualitative or semi-quantitative nature of data. Existing exergy analysis methods do not take into account all exergy losses and/or are extended with factors or equations that are not commonly accepted. The new Total Cumulative Exergy Loss (TCExL) method is based on fundamental thermodynamic equations and takes into account all exergy losses caused by a technological system during its life cycle, i.e. internal exergy losses, exergy losses caused by emission abatement and exergy losses related to land use. The development of the TCExL method is presented as well as the application of this method and environmental, economic and social sustainability assessment methods to two case studies: power generation in combination with LNG evaporation and Fossil versus renewable energy sources for power generation. According to the results of the assessments, large differences exist between the environmental sustainability assessment and TCExL methods in the sense that different parts of the systems contribute most to their overall scores. It is concluded from the case studies that involving the TCExL method in choices between power generation systems with the same energy sources has no consequences, i.e. it does not result in a different ranking of the systems, but can lead to the choice of a system that has a lower economic sustainability if the assessed systems use different energy sources. Howev, Energy & Industry, Petroleum Engineering

It is difficult to decide which power generation system is the most sustainable when environmental, economic and social sustainability aspects are taken into account. Problems with conventional environmental sustainability assessment methods are that no consensus exists about the applied models and weighting factors and that exergy losses are not considered. Economic sustainability assessment methods do not lead to results that are independent of time because they are influenced by market developments, while social sustainability assessment methods suffer from the availability and qualitative or semi-quantitative nature of data. Existing exergy analysis methods do not take into account all exergy losses and/or are extended with factors or equations that are not commonly accepted. The new Total Cumulative Exergy Loss (TCExL) method is based on fundamental thermodynamic equations and takes into account all exergy losses caused by a technological system during its life cycle, i.e. internal exergy losses, exergy losses caused by emission abatement and exergy losses related to land use. The development of the TCExL method is presented as well as the application of this method and environmental, economic and social sustainability assessment methods to two case studies: power generation in combination with LNG evaporation and Fossil versus renewable energy sources for power generation. According to the results of the assessments, large differences exist between the environmental sustainability assessment and TCExL methods in the sense that different parts of the systems contribute most to their overall scores. It is concluded from the case studies that involving the TCExL method in choices between power generation systems with the same energy sources has no consequences, i.e. it does not result in a different ranking of the systems, but can lead to the choice of a system that has a lower economic sustainability if the assessed systems use different energy sources. Howev, Energie and Industrie, Reservoir Engineering

The selection of power generation systems is important when striving for a more sustainable society. However, the results of environmental, economic and social sustainability assessments are subject to new insights into the calculation methods and to changing needs, economic conditions and societal preferences. Researchers active in the field of exergy and sustainability claim that exergy losses and sustainability are related. The Total Cumulative Exergy Loss method and the exergy replacement costs of minerals are used to assess and compare power generation systems that make use of fossil and renewable energy carriers. These power generation systems are the following: an ultrasupercritical coal power plant, a power plant that co-fires coal and biomass, a wind farm, and a combined cycle power plant that uses bioethanol originating from the fermentation of verge grass. Furthermore, environmental, economic and social sustainability assessment methods are applied to assess the four power generation systems as well. On the basis of the results of the assessments, it is concluded that the wind farm system is preferred from the environmental, social and exergetic sustainability points of view, but not from the economic sustainability viewpoint. The advantage of the exergetic sustainability assessment method is that its results are not influenced by choices like whether verge grass should be considered a waste product or not. The influence of the exergy replacement costs on the results of the exergetic assessment is small, because less than 5 per cent of the exergy input of the systems during construction, operation and commission is of mineral origin. When looking at the infrastructural part of the systems only, the influence of the exergy replacement costs is larger because about 25 to 40 per cent of the exergy input is of mineral origin., accepted authors manuscript, Energy & Industry, Petroleum Engineering

The selection of power generation systems is important when striving for a more sustainable society. However, the results of environmental, economic and social sustainability assessments are subject to new insights into the calculation methods and to changing needs, economic conditions and societal preferences. Researchers active in the field of exergy and sustainability claim that exergy losses and sustainability are related. The Total Cumulative Exergy Loss method and the exergy replacement costs of minerals are used to assess and compare power generation systems that make use of fossil and renewable energy carriers. These power generation systems are the following: an ultrasupercritical coal power plant, a power plant that co-fires coal and biomass, a wind farm, and a combined cycle power plant that uses bioethanol originating from the fermentation of verge grass. Furthermore, environmental, economic and social sustainability assessment methods are applied to assess the four power generation systems as well. On the basis of the results of the assessments, it is concluded that the wind farm system is preferred from the environmental, social and exergetic sustainability points of view, but not from the economic sustainability viewpoint. The advantage of the exergetic sustainability assessment method is that its results are not influenced by choices like whether verge grass should be considered a waste product or not. The influence of the exergy replacement costs on the results of the exergetic assessment is small, because less than 5 per cent of the exergy input of the systems during construction, operation and commission is of mineral origin. When looking at the infrastructural part of the systems only, the influence of the exergy replacement costs is larger because about 25 to 40 per cent of the exergy input is of mineral origin., accepted authors manuscript, Energie and Industrie, Reservoir Engineering

It is difficult to decide which power generation system is the most sustainable when environmental, economic and social sustainability aspects are taken into account. Problems with conventional environmental sustainability assessment methods are that no consensus exists about the applied models and weighting factors and that exergy losses are not considered. Economic sustainability assessment methods do not lead to timeless results because they are influenced by market developments, while social sustainability assessment methods suffer from the availability and qualitative or semi-quantitative nature of data. Existing exergy analysis methods do not take into account all exergy losses and/or are extended with factors or equations that are not commonly accepted. The new Total Cumulative Exergy Loss (TCExL) method is based on fundamental thermodynamic equations and takes into account all exergy losses caused by a technological system during its life cycle, i.e. internal exergy losses, exergy losses caused by emission abatement and exergy losses related to land use. The development of the TCExL method is presented as well as the application of this method and environmental, economic and social sustainability assessment methods to two case studies: Power generation in combination with LNG evaporation and Fossil versus renewable energy sources for power generation. According to the results of the assessments, large differences exist between the environmental sustainability assessment and TCExL methods in the sense that different parts of the systems contribute most to their overall scores. It is concluded from the case studies that involving the TCExL method in choices between power generation systems with the same energy sources has no consequences, but can lead to the choice of a system that has a lower economic sustainability if the systems use different energy sources. However, it must be noted that the economic sustainability changes over time, while the results of t, Engineering, Systems and Services, Technology, Policy and Management

It is difficult to decide which power generation system is the most sustainable when environmental, economic and social sustainability aspects are taken into account. Problems with conventional environmental sustainability assessment methods are that no consensus exists about the applied models and weighting factors and that exergy losses are not considered. Economic sustainability assessment methods do not lead to timeless results because they are influenced by market developments, while social sustainability assessment methods suffer from the availability and qualitative or semi-quantitative nature of data. Existing exergy analysis methods do not take into account all exergy losses and/or are extended with factors or equations that are not commonly accepted. The new Total Cumulative Exergy Loss (TCExL) method is based on fundamental thermodynamic equations and takes into account all exergy losses caused by a technological system during its life cycle, i.e. internal exergy losses, exergy losses caused by emission abatement and exergy losses related to land use. The development of the TCExL method is presented as well as the application of this method and environmental, economic and social sustainability assessment methods to two case studies: Power generation in combination with LNG evaporation and Fossil versus renewable energy sources for power generation. According to the results of the assessments, large differences exist between the environmental sustainability assessment and TCExL methods in the sense that different parts of the systems contribute most to their overall scores. It is concluded from the case studies that involving the TCExL method in choices between power generation systems with the same energy sources has no consequences, but can lead to the choice of a system that has a lower economic sustainability if the systems use different energy sources. However, it must be noted that the economic sustainability changes over time, while the results of t, Engineering, Systems and Services, Technology, Policy and Management

Several options exist for power generation, but it is difficult to determine which option is the most sustainable. When assessing the sustainability of an option or system, it is important to consider the environmental, economic and social aspects of sustainability and to take a life-cycle point of view. According to literature, a relationship exists between exergy and sustainability, but it is not common use to apply exergy analysis for improving sustainability. In this research, three options for power generation in combination with LNG evaporation are assessed, i.e. using the waste heat from a coal-fired power plant for LNG evaporation, integrating an oxy-fuel power plant with an air separation unit and an LNG terminal, and a separate power plant plus an LNG terminal combined with an Organic Rankine Cycle. The results of environmental LCA, environmental Life Cycle Costing, social LCA and the Cumulative Exergy Loss (CExL) method of the three options have been compared. The oxy-fuel option is preferred according to the results of the environmental, economic and exergetic assessment methods. The difference in the outcomes of the social assessment is too small to choose between the three options. From studying the three options in more detail, it became clear that the processes that contribute most to the overall score of a method are different. E.g., the natural gas production process is responsible for about 70 per cent of the LCA score, but causes only 2 to 3 per cent of the CExL., Infrastructures, Systems and Services, Technology, Policy and Management

Infrastructures, Systems and Service, Technology, Policy and Management

A thorough investigation of literature about the relation between exergy and sustainability was conducted in September 2010. An overview of opinions and methods in the field of exergy analysis and sustainability is briefly presented. Exergy analysis has several advantages compared to energy analysis, but a careful underpinning of the relation between exergy and sustainability has not yet been found. Sustainability consists of environmental, economic and social sustainability. Especially the social aspect of sustainability is not, or just minimally, taken into account in the methods found in literature. During future research, the consequences of involving exergy analysis in decisions regarding future energy supply will be investigated with respect to the three aforementioned aspects of sustainability., Technology, Policy and Management

Numerous LNG (Liquefied Natural Gas) import terminals are under construction to fulfil the growing demand for energy carriers. After storage in tanks, the LNG needs to be heated and evaporated, also called ‘regasified’, to the natural gas needed in households and industry. Several options exist for providing the required heat. In the interest of sustainable development it is important to decide carefully upon which technology to apply for LNG evaporation. In this research, three options for LNG evaporation have been investigated: using the waste heat from a power plant, integrating the LNG terminal with an air separation unit and an oxy-fuel power plant, and combining the evaporation process with an Organic Rankine Cycle to produce electricity. The research consisted of an environmental life cycle assessment, calculation the life cycle costs, conducting a social life cycle assessment and determining the cumulative exergy extracted from the natural environment (CEENE). The option in which the LNG terminal is integrated with an air separation unit and an oxy-fuel coal power plant appeared to be preferable. This research is part of a study after the effects of involving exergy analysis in decisions regarding future energy supply on the environmental, economic and social aspects of its sustainability., Infrastructure Systems & Services, Technology, Policy and Management

A thorough investigation of literature about the relation between exergy and sustainability was conducted in September 2010. An overview of opinions and methods in the field of exergy analysis and sustainability is briefly presented. Exergy analysis has several advantages compared to energy analysis, but a careful underpinning of the relation between exergy and sustainability has not yet been found. Sustainability consists of environmental, economic and social sustainability. Especially the social aspect of sustainability is not, or just minimally, taken into account in the methods found in literature. During future research, the consequences of involving exergy analysis in decisions regarding future energy supply will be investigated with respect to the three aforementioned aspects of sustainability., Technology, Policy and Management

Numerous LNG (Liquefied Natural Gas) import terminals are under construction to fulfil the growing demand for energy carriers. After storage in tanks, the LNG needs to be heated and evaporated, also called ‘regasified’, to the natural gas needed in households and industry. Several options exist for providing the required heat. In the interest of sustainable development it is important to decide carefully upon which technology to apply for LNG evaporation. In this research, three options for LNG evaporation have been investigated: using the waste heat from a power plant, integrating the LNG terminal with an air separation unit and an oxy-fuel power plant, and combining the evaporation process with an Organic Rankine Cycle to produce electricity. The research consisted of an environmental life cycle assessment, calculation the life cycle costs, conducting a social life cycle assessment and determining the cumulative exergy extracted from the natural environment (CEENE). The option in which the LNG terminal is integrated with an air separation unit and an oxy-fuel coal power plant appeared to be preferable. This research is part of a study after the effects of involving exergy analysis in decisions regarding future energy supply on the environmental, economic and social aspects of its sustainability., Infrastructure Systems & Services, Technology, Policy and Management

The worldwide demand for Liquefied Natural Gas (LNG) is growing, which results in numerous LNG import terminals being under construction. In the interest of sustainable development, it is important to decide carefully upon which technology to apply for evaporating the LNG to natural gas. Three options for the evaporation of LNG have been investigated and analysed: a system that uses the waste heat from a coal-fired power plant to evaporate LNG, an integrated system consisting of LNG evaporation, air separation and a coal-fired oxy-fuel power plant, and a system in which LNG evaporation is combined with electricity production through a thermodynamic cycle. The oxy-fuel option appeared to be preferable with regard to the results of the exergy analysis, but it is not yet sure whether this option is the most sustainable of the three options. A more detailed analysis is needed before conclusions can be drawn upon the effects of involving exergy analysis in the choice between the three options for LNG evaporation., Technology, Policy and Management

The worldwide demand for Liquefied Natural Gas (LNG) is growing, which results in numerous LNG import terminals being under construction. In the interest of sustainable development, it is important to decide carefully upon which technology to apply for evaporating the LNG to natural gas. Three options for the evaporation of LNG have been investigated and analysed: a system that uses the waste heat from a coal-fired power plant to evaporate LNG, an integrated system consisting of LNG evaporation, air separation and a coal-fired oxy-fuel power plant, and a system in which LNG evaporation is combined with electricity production through a thermodynamic cycle. The oxy-fuel option appeared to be preferable with regard to the results of the exergy analysis, but it is not yet sure whether this option is the most sustainable of the three options. A more detailed analysis is needed before conclusions can be drawn upon the effects of involving exergy analysis in the choice between the three options for LNG evaporation., Technology, Policy and Management

A thorough qualitative investigation of the relation between exergy losses and environmental problems has been conducted. Environmental effects being taken into account include climate change, acidification, eutrophication, disposal and dissipation. It is concluded that almost all environmental effects can be taken into account by studying the waste of feedstocks and energy caused by technological activities, like processes, and the emission and dispersion of pollutants. To underpin the qualitative investigation two case studies have been conducted: the production of aluminium and polystyrene. On the basis of the results of the case studies it can be made plausible that exergy losses and environmental impact are related. Exergy losses are a kind of environmental impact, whereas environmental impact is related to exergy loss. It is concluded that exergy loss is at least a qualitative measure that can be used in environmental policy making regarding technological processes. According to literature, exergy losses should be minimized to obtain a more sustainable development. During a follow-up study the relation between exergy and sustainability will be investigated in more detail, partly based on basic principles borrowed from nature. Apart from environmental impact also others aspects of sustainability, like economic and social aspects, will be taken into account., Technology, Policy and Management

A thorough qualitative investigation of the relation between exergy losses and environmental problems has been conducted. Environmental effects being taken into account include climate change, acidification, eutrophication, disposal and dissipation. It is concluded that almost all environmental effects can be taken into account by studying the waste of feedstocks and energy caused by technological activities, like processes, and the emission and dispersion of pollutants. To underpin the qualitative investigation two case studies have been conducted: the production of aluminium and polystyrene. On the basis of the results of the case studies it can be made plausible that exergy losses and environmental impact are related. Exergy losses are a kind of environmental impact, whereas environmental impact is related to exergy loss. It is concluded that exergy loss is at least a qualitative measure that can be used in environmental policy making regarding technological processes. According to literature, exergy losses should be minimized to obtain a more sustainable development. During a follow-up study the relation between exergy and sustainability will be investigated in more detail, partly based on basic principles borrowed from nature. Apart from environmental impact also others aspects of sustainability, like economic and social aspects, will be taken into account., Technology, Policy and Management

Applied Sciences, Applied Sciences

Applied Sciences, Applied Sciences