Industrial energy analysis,thermodynamics and sustainability

Thermodynamic methods of (energy and exergy) analysis are employed to illustrate energy use in industry. The scope for increasing energy efficiency, and the extent of exergetic ‘improvement potential’ are examined. Poor thermodynamic performance is principally the result of exergy losses in combustion and heat-transfer processes. The late Professor Willem van Gool (a distinguished Dutch physical chemist) was at the forefront of the development and application of energy and exergy methods. He also explored the link between energy and economics. The work of van Gool and others researchers who laid down the foundations of industrial energy analysis are reviewed. These contributions are placed in the broader context of the modern paradigm of sustainable development, and their implications for the future direction of European Union energy and environmental strategies are discussed. Thermodynamic concepts have been utilised by practitioners in a variety of disciplines with interests in environmental sustainability, including ecology, economics and engineering. Widespread concern about resource depletion and environmental degradation are common to them all. Van Gool was instrumental in stimulating a dialogue across the economic and physical sciences. Some researchers view thermodynamic parameters as mirroring energy transformations within society. However, it is argued (after Hammond GP. Engineering sustainability: thermodynamics, energy systems, and the environment. Int J Energy Res 2004;28:613–639.) that they may simply reflect a weak analogy or metaphor, rather than representing thermodynamic limits in a physical sense.     

A longitudinal analysis of the UK transport sector, 1970–2010

This paper presents an overview of the resource consumption and environmental impact of the United Kingdom's transport system for the period between 1970 and 2010. For the purpose of this analysis the concept of exergy has been employed both to quantify and aggregate the energy used and the atmospheric emissions arising from the sector. Our analysis illustrates and elucidates the disproportionate increase of the overall exergy consumed by the transport sector when compared to that of other UK economic sectors. Furthermore, its environmental impact and, in particular, the trends in the emission of the main ambient air pollutants and greenhouse gases is discussed. Exergy efficiency and intensity time series are also calculated and recommendations are made in order to minimize the sector's environmental impact and to facilitate a shift towards a more sustainable transport system.     

Is bioethanol a sustainable energy source? An energy-, exergy-, and emergy-based thermodynamic system analysis

Biofuels are widely seen as substitutes for fossil fuels to offset the imminent decline of oil production and to mitigate the emergent increase in GHG emissions. This view is, however, based on too simple an analysis, focusing on only one piece in the whole mosaic of the complex biofuel techno-system, and such partial approaches may easily lead to ideological bias based on political preference. This study defines the whole biofuel techno-system at three scales, i.e., the foreground production (A), the background industrial network (B, including A), and the supporting Earth biosphere (C, including B). The thermodynamic concepts of energy, exergy and emergy measure various flows at these three scales, viz. primary resources, energy and materials products, and labor and services. Our approach resolves the confusion about scale and metric: direct energy demand and direct exergy demand apply at scale A; cumulative energy demand and cumulative exergy demand apply at scale B; and energy is applied at scale C, where it is named emergy, while exergy also can be applied at scale C. This last option was not examined in the present study.The environmental performance of the system was assessed using a number of sustainability indicators, including resource consumption, input renewability, physical benefit, and system efficiency, using ethanol from corn stover in the US as a technology case. Results were compared with available literature values for typical biofuel alternatives. We also investigated the influence of methodological choices on the outcomes, based on contribution analysis, as well as the sensitivity of the outcomes to emergy intensity. The results indicate that the techno-system is not only supported by commercial energy and materials products, but also substantially by solar radiation and the labor and services invested. The bioethanol techno-system contributes to the overall supply of energy/exergy resources, although in a less efficient way than the process by which the Earth system produces fossil fuels.Our results show that bioethanol cannot be simply regarded as a renewable energy resource. Furthermore, the method chosen for the thermodynamic analysis results in different outcomes in terms of ranking the contributions by various flows. Consequently, energy analysis, exergy analysis, and emergy analysis jointly provide comprehensive indications of the energy-related sustainability of the biofuel techno-system. This thermodynamic analysis can provide theoretical support for decision making on sustainability issues.     

Energy and environmental sustainability assessment of a crude oil refinery by thermodynamic analysis

This study presents the assessment of energy and environmental sustainability metrics for a crude oil refinery consisting of three distillation columns. The assessments of the current operation and the retrofits for possible improvements are suggested by the thermodynamic analysis and energy analyzer. The main objective is to explore the scope of reducing the thermal energy consumption and CO₂ emissions for a more sustainable refinery operation. Thermodynamic analysis is carried out by using the thermal analysis capability of ‘column targeting tool’ to address the ‘energy intensity metrics’ and the ‘energy analyzer’ to design and improve the performance of the heat exchanger network system for process heat integration. Environmental pollution impact metrics are estimated from the ‘carbon tracking’ options with a selected CO₂ emission data source of US‐EPA‐Rule‐E9‐5711 and using crude oil as a primary fuel source for the hot utilities. The results indicate that column targeting tool, energy analyzer, and carbon tracking can estimate the energy and environmental sustainability metrics of an existing design and determine the scope of considerable improvements for reducing the costs of thermal energy required and emissions of carbon dioxide in a crude oil refinery operation. Copyright © 2015 John Wiley & Sons, Ltd.     

The energy and environmental implications of UK more electric transition pathways: A whole systems perspective

Electricity generation contributes a large proportion of the total greenhouse gas emissions in the United Kingdom (UK), due to the predominant use of fossil fuel (coal and natural gas) inputs. Indeed, the various power sector technologies [fossil fuel plants with and without carbon capture and storage (CCS), nuclear power stations, and renewable energy technologies (available on a large and small {or domestic} scale)] all involve differing environmental impacts and other risks. Three transition pathways for a more electric future out to 2050 have therefore been evaluated in terms of their life-cycle energy and environmental performance within a broader sustainability framework. An integrated approach is used here to assess the impact of such pathways, employing both energy analysis and environmental life-cycle assessment (LCA), applied on a ‘whole systems’ basis: from ‘cradle-to-gate’. The present study highlights the significance of ‘upstream emissions’, in contrast to power plant operational or ‘stack’ emissions, and their (technological and policy) implications. Upstream environmental burdens arise from the need to expend energy resources in order to deliver, for example, fuel to a power station. They include the energy requirements for extraction, processing/refining, transport, and fabrication, as well as methane leakage that occurs in coal mining activities – a major cotribution – and from natural gas pipelines. The impact of upstream emissions on the carbon performance of various low carbon electricity generators [such as large-scale combined heat and power (CHP) plant and CCS] and the pathways distinguish the present findings from those of other UK analysts. It suggests that CCS is likely to deliver only a 70% reduction in carbon emissions on a whole system basis, in contrast to the normal presumption of a 90% reduction. Similar results applied to other power generators.     

Assessing energy technologies and environmental impacts with the principles of thermodynamics

Many suggest that the environmental impact of energy resource use and the achievement of increased efficiency are best addressed by considering the thermodynamic property exergy. This paper reports on the use of the principles of thermodynamics via exergy to evaluate energy systems and technologies as well as environmental impact. Exergy is described and its use as a tool to improve efficiency illustrated. The environmental implications of exergy are discussed, and the ties between exergy and economics described. It is concluded that thermodynamics, and particularly exergy, has a significant role to play in evaluating energy technologies and environmental impact. The results indicate that exergy methods should prove useful to engineers and scientists, as well as decision and policy makers. To increase the acceptance of exergy, further research is needed to better define its role in the area of environmental impact.     

Exergy as the confluence of energy,environment and sustainable development

The exergy of an energy form or a substance is a measure of its usefulness or quality or potential to cause change. A thorough understanding of exergy and the insights it can provide into the efficiency, environmental impact and sustainability of energy systems, are required for the engineer or scientist working in the area of energy systems and the environment. Further, as energy policies play an increasingly important role in addressing sustainability issues and a broad range of local, regional and global environmental concerns, policy makers also need to appreciate the exergy concept and its ties to these concerns. During the past decade, the need to understand the connections between exergy and energy, sustainable development and environmental impact has become increasingly significant. In this paper, a study of these connections is presented in order to provide to those involved in energy and environment studies, useful insights and direction for analyzing and solving environmental problems of varying complexity using the exergy concept. The results suggest that exergy provides the basis for an effective measure of the potential of a substance or energy form to impact the environment and appears to be a critical consideration in achieving sustainable development.     

Environmental and Exergetic Aspects of Geothermal Energy

Geothermal energy is already in the form of heat, and from the thermodynamic point of view, work is more useful than heat because not all heat can be converted to work. Therefore, geothermal resources should be classified according to their exergy, which is a measure of their ability to do work. In recent years there has been a remarkable growth of interest in environmental issues—sustainability and improved management of development in harmony with the environment. Environmental impact assessment is one of the most widely used tools in environmental management. In this study, the environmental and exergetic aspects of geothermal energy, namely the rapid impact assessment matrix method, and, specific exergy index, were studied first. They were then applied to the Tuzla geothermal field in Canakkale and Balcova geothermal field in Izmir, Turkey, respectively. Finally, the results obtained are given and discussed.     

Energy,exergy, environmental and sustainability assessments of jet and hydrogen fueled military turbojet engine

In this study, energy, exergy, environmental and sustainability assessments of jet and hydrogen (H₂) fueled J79-GE-17 turbojet engine are done. The results are compared for hydrogen and JP-8 fueled modes. It is found that aviation performance metrics are better for hydrogen utilization mode. By using hydrogen fuel instead of JP-8 fuel; the specific thrust and power rates reduce 1.037%, the specific fuel consumption decreases 63.987% the energy efficiency of the turbojet engine reduces from 30.293% to 29.979%, the exergy efficiency of the combustion chamber component increases 10.581%, and the turbojet engine exergy efficiency rises from 28.54% to 30.73%. The sustainability of the hydrogen fuel utilization for the J79-GE-17 turbojet engine is higher than JP-8 fuel utilization mode. The hydrogen utilization decreases the emission index as 73.36% and the environmental impact as 99.05% comparing to JP-8 usage mode. As a result, hydrogen fuel utilization in this engine is a better choice for emissions and environment, while it can be used as effective as JP-8 fuel.     

High‐temperature latent heat storage technology to utilize exergy of solar heat and industrial exhaust heat

Latent heat storage (LHS) using phase change materials is quite attractive for utilization of the exergy of solar energy and industrial exhaust heat because of its high‐heat storage capacity, heat storage and supply at constant temperature, and repeatable utilization without degradation. In this article, general LHS technology is outlined, and then recent advances in the uses of LHS for high‐temperature applications (over 100 °C) are discussed, with respect to each type of phase change material (e.g., sugar alcohol, molten salt, and alloy). The prospects of future LHS systems are discussed from a principle of exergy recuperation. In addition, the technologies to minimize exergy loss in the future LHS system are discussed on the basis of the thermodynamic analysis by ‘thermodynamic compass’. Copyright © 2016 John Wiley & Sons, Ltd.     

An entropy generation metric for non-energy systems assessments

Processes in non-energy systems have not been as frequent a subject of sustainability studies based on Thermodynamics as have processes in energy systems. This paper offers insight into thermodynamic thinking devoted to selection of a sustainability energy-related metric based on entropy balancing of a non-energy system. An underlying objective in this sustainability oriented study is product quality involving thermal processing during manufacturing vs. resource utilization (say, energy). The product quality for the considered family of materials processing for manufacturing is postulated as inherently controlled by the imposed temperature non-uniformity margins. These temperature non-uniformities can be converted into a thermodynamic metric which can be related to either destruction of exergy of the available resource or, on a more fundamental level of process quality, to entropy generation inherent to the considered manufacturing system. Hence, a manufacturing system can be considered as if it were an energy system, although in the later case the system objective would be quite different. In a non-energy process, a metric may indicate the level of perfection of the process (not necessarily energy efficiency) and may be related to the sustainability footprint or, as advocated in this paper, it may be related to product quality. Controlled atmosphere brazing (CAB) of aluminum, a state-of-the-art manufacturing process involving mass production of compact heat exchangers for automotive, aerospace and process industries, has been used as an example.     

On the thermodynamics of cogeneration

Cogeneration of various energy forms in a single piece of equipment has the potential of saving primary energy in comparison to separate generation. The amount of energy saving depends on the thermodynamic parameters of the systems to be compared and can be presented in a closed formula. For the particular case of cogeneration in a steam turbine a thorough thermodynamic analysis on the basis of exergy losses reveals the reasons for the higher efficiency. It is due to the facts that on producing the useful heat a transfer of this heat over the temperature difference between the heat intake of the cycle and the temperature of the heat demand is replaced by a power cycle and that separate power production is avoided altogether. This leads to a rational allocation of primary energy and in turn of emissions to the coupled energy forms.     

Sustainability assessment of cogeneration sector development in Croatia

The effective and rational energy generation and supply is one of the main presumptions of sustainable development. Combined heat and power production, or co-generation, has clear environmental advantages by increasing energy efficiency and decreasing carbon emissions. However, higher investment cost and more complicated design and maintenance sometimes-present disadvantages from the economical viability point of view. As in the case of most of economies in transition in Central and Eastern Europe, Croatia has a strong but not very efficient co-generation sector, delivering 12% of the final energy consumption. District heating systems in the country's capital Zagreb and in city of Osijek represent the large share of the overall co-generation capacity. Besides district heating, co-generation in industry sector is also relatively well developed. The paper presents an attempt to assess the sustainability of Croatian co-generation sector future development. The sustainability assessment requires multi-criteria assessment of specific scenarios to be taken into consideration. In this respect three scenarios of Croatian co-generation sector future development are taken into consideration and for each of them environmental, social and economic sustainability indicators are defined and calculated. The assessment of complex relationships between environmental, social and economic aspects of the system is based on the multi-criteria decision-making procedure. The sustainability assessment is based on the General Sustainability Index rating for different cases reflecting different criteria and their priority. The method of sustainability assessment is applied to the Croatian co-generation sector contributing to the evaluation of different strategies and definition of a foundation for policy related to the sustainable future cogeneration sector development.     

Constructing a network of the social-economic consumption system of China using extended exergy analysis

The prominent conflict between consumption and environmental resources is acknowledged as a significant force in affecting the social-ecological community balance. The whole process of resource allocation, utilization, efficiency and outcome are crucial clues in uncovering the structural and functional characteristics in complex consuming systems. Herein, network relationship provides a system-oriented modeling technique for examining the structure as well as flow of materials or energy from an input–output perspective. Meanwhile, extended exergy, the only currently available thermodynamic based metric for social-economic environmental impacts associated with energy consumption, manpower and monetary operation as well as environmental emission, is an extension of the labor theory of value and a possible sustainability metric. The core purpose of this research is to construct a network of the social-economic consumption system of China using extended exergy analysis to explain the interrelationship among different sectors within a thermodynamic metric. Therefore, we firstly make a database of extended exergy accounting in the Chinese consumption system. Data are available for 2007, which can be divided into seven sectors based on the reclassification of the regularly published 42-sector Input–Output Table, namely, (1) Agriculture, (2) Extraction, (3) Conversion, (4) Industry, (5) Transportation, (6) Tertiary, and (7) Domestic sectors. Then we will construct an extended exergy network to gain insight into the thermodynamic distribution within sectoral criterion. Lastly, the network results and indicator analysis are explained for China's social metabolism maintained by a large quantity of energy, resources, and labor, as well as the environmental costs, within an exergy foundation.     

Energy,exergy, and sustainability a novel comparison of conventional gas turbine with fuel cell integrated hybrid power cycle

In this paper, six novel modified exergy relations are explored to determine the precise estimation of exergy destruction and to identify which component has the most improvement potential. For this, three power generation cycles are considered, i.e., simple gas turbine (SGT), recuperated gas turbine (RGT), are compared with a novel hybrid system (SOFC-RGT: Solid Oxide Fuel Cell-RGT), which operates with fuel flexibility as well as enhanced work-output and thermal efficiency. For energy, exergy, and sustainability studies, numerical modeling is conducted using MATLAB. At r_p = 4, TIT = 1250 K, an exclusive comparison has been made between proposed configurations based on thermodynamic modeling and exergy-based sustainability index. It is found that with the inclusion of a recuperator and a fuel cell in the proposed cycles, the thermal and sustainability performance tend to increase significantly. Whereas, exergy destruction increases but has minimal impact on comparing thermal performance and sustainability index. In terms of sustainability, RGT is 30.76% more sustainable than SGT, while SOFC-GT is 63.39% more sustainable than RGT.     

Exergy, exergoeconomic and environmental analyses and evolutionary algorithm based multi-objective optimization of combined cycle power plants

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

Thermo-economic and thermo-environmental assessment of hydrogen production,an experimental study

Nowdays, the topic involvement of green hydrogen in energy transformation is getting attention in the world. The current research examined, thermo-economic and thermo-environmental analyses of the organic Rankine cycle (ORC) system and the hydrogen production system integrated into the solar collector with medium temperature density are investigated. The presented study is a holistic evaluation of experimentally solar-assisted electricity and hydrogen production. The studied model is comprised of an evacuated tube solar collector for thermal energy generation, ORC system for electricity generation and proton exchanger membrane electrolyzer (PEMe) for hydrogen production. According to the results of the thermodynamic analysis, the energy and exergy efficiency of the whole system are calculated as 39.01% and 17.37%, respectively. Also exergoenviroeconomic and exergoenviromental analysis of the whole system is found as 71.48 kgCO₂/kWh and 0.139 $/kgCO₂, respectively. In addition, the sustainability index of the presented system is obtained as 1.21. In this study, in addition to thermodynamic analysis, parameters such as energy and exergy affecting environmental and economic efficiency, are explained. Ambient temperature plays a prominent role in energy-based environmental analysis. On the contrary, the ambient temperature did not cause a significant change in the exergy-based environmental analysis.     

带压缩空气储能的冷热电联产系统的

对一种带压缩空气储能的冷热电联产系统进行了热力学(火用)分析,得到了各主要部件和整个系统的(火用)损失及(火用)效率的变化规律.分析结果表明空气透平绝热效率的提高对系统(火用)效率的贡献大于压缩机效率同样提高的功效;在其它参数确定时,存在最佳压比,可使系统的(火用)效率在该条件下达极值;高温换热器是新型冷热电联产系统中产生(火用)损失的主要部件,而循环水量的大小是影响高温换热器(火用)效率的主要因素.     

Evaluation of a new geothermal based multigenerational plant with primary outputs of hydrogen and ammonia

Increasing environmental concerns and decreasing fossil fuel sources compel engineers and scientists to find resilient, clean, and inexpensive alternative energy options Recently, the usage of renewable power resources has risen, while the efficiency improvement studies have continued. To improve the efficiency of the plants, it is of great significance to recover and use the waste heat to generate other useful products. In this paper, a novel integrated energy plant utilizing a geothermal resource to produce hydrogen, ammonia, power, fresh water, hot water, heated air for drying, heating, and cooling is designed. Hydrogen, as an energy carrier, has become an attractive choice for energy systems in recent years due to its features like high energy content, clean, bountiful supply, non-toxic and high efficiency. Furthermore in this study, hydrogen beside electricity is selected to produce and stored in a hydrogen storage tank, and some amount of hydrogen is mixed with nitrogen to compound ammonia. In order to determine the irreversibilities occurring within the system and plant performance, energy and exergy analyses are then performed accordingly. In the design of the plant, each sub-system is integrated in a sensible manner, and the streams connecting sub-systems are enumerated. Then thermodynamic balance equations, in terms of mass, energy, entropy and exergy, are introduced for each unit of the plant. Based on the system inputs and outputs, the energy and exergy efficiencies of the entire integrated plant is found to be 58.68% and 54.73% with the base parameters. The second part of the analysis contains some parametric studies to reveal how some system parameters, which are the reference temperature, geothermal resource temperature and mass flow rate, and separator inlet pressure in the geothermal cycle, affect both energy and exergy efficiencies and hence the useful outputs.     

Thermodynamic analysis of a hybrid geothermal heat pump system

A thermodynamic analysis of a hybrid geothermal heat pump system is carried out. Mass, energy, and exergy balances are applied to the system, which has a cooling tower as a heat rejection unit, and system performance is evaluated in terms of coefficient of performance and exergy efficiency. The heating coefficient of performance for the overall system is found to be 5.34, while the corresponding exergy efficiency is 63.4%. The effect of ambient temperature on the exergy destruction and exergy efficiency is investigated for the system components. The results indicate that the performance of hybrid geothermal heat pump systems is superior to air-source heat pumps.