A review and assessment of the energy utilization efficiency in the Turkish industrial sector using energy and exergy analysis method

Exergy has been seen a key component for a sustainable society, and in the recent years exergy analysis has been widely used in the design, simulation and performance evaluation of thermal and thermo chemical systems. A particular thermo dynamical system is the society of a country, while the energy utilization of a country can be assessed using exergy analysis to gain insights into its efficiency and potential for improvements.Energy and exergy utilization efficiencies in the Turkish industrial sector (TIS) over the period from 1990 to 2003 are reviewed and evaluated in this study. Energy and exergy analyses are performed for eight industrial modes, namely iron–steel, chemical–petrochemical, petrochemical–feedstock, cement, fertilizer, sugar, non-metal industry, other industry, while in the analysis the actual data are used. Sectoral energy and exergy analyses are conducted to study the variations of energy and exergy efficiencies for each subsector throughout the years studied, and these heating and overall energy and exergy efficiencies are compared for the eight subsectors. The chemical and petrochemical subsector, and the iron and steel subsector appear to be the most energy and exergy efficient sectors, respectively. The energy utilization efficiencies for the Turkish overall industrial sector range from 63.45% to 70.11%, while the exergy utilization efficiencies vary from 29.72% to 33.23% in the analyzed years. Exergetic improvement potential for this sector is also determined to be 681 PJ in 2003, with an average increase rate of 9.5% annually for the analyzed years. It may be concluded that the methodology used in this study is practical and useful for analyzing sectoral and subsectoral energy and exergy utilization to determine how efficient energy and exergy are used in the sector studied. It is also expected that this study will be helpful in developing highly applicable and productive planning for energy policies.     

Estimating the energy and exergy utilization efficiencies for the residential–commercial sector: an application

The main objectives in carrying out the present study are twofold, namely to estimate the energy and exergy utilization efficiencies for the residential–commercial sector and to compare those of various countries with each other. In this regard, Turkey is given as an illustrative example with its latest figures in 2002 since the data related to the following years are still being processed. Total energy and exergy inputs in this year are calculated to be 3257.20 and 3212.42 PJ, respectively. Annual fuel consumptions in space heating, water heating and cooking activities as well as electrical energy uses by appliances are also determined. The energy and exergy utilization efficiency values for the Turkish residential–commercial sector are obtained to be 55.58% and 9.33%, respectively. Besides this, Turkey's overall energy and exergy utilization efficiencies are found to be 46.02% and 24.99%, respectively. The present study clearly indicates the necessity of the planned studies toward increasing exergy utilization efficiencies in the sector studied.     

Exergy analysis of the energy use in Greece

In this work, an analysis is being done on the concept of energy and exergy utilization and an application to the residential and industrial sector of Greece. The energy and exergy flows over the period from 1990 to 2004 were taken into consideration. This period was chosen based on the data reliability. The energy and exergy efficiencies are calculated for the residential and industrial sectors and compared to the findings of a previous study concerning the exergy efficiency of the Greek transport sector. The residential energy and exergy efficiencies for the year 2003 were 22.36% and 20.92%, respectively, whereas the industrial energy and exergy efficiencies for the same year were 53.72% and 51.34%, respectively. The analysis of energy and exergy utilization determines the efficiency of the economy as a whole. The results can play an important role in the establishment of efficiency standards of the energy use in various economy sectors. These standards could be utilized by energy policy makers.     

Turkey's sectoral energy and exergy analysis between 1999 and 2000

This study analyses sectoral energy and exergy utilization in Turkey between 1999 and 2000. Total energy and exergy utilization efficiencies are calculated to be 43.24 and 24.04% in 1999, and 44.91 and 24.78% in 2000, respectively. In order to calculate these efficiency values, Turkey is subgrouped into four main sectors, namely utility, industrial, transportation and commercial‐residential. The energy efficiency values are found to be 23.88, 30.10, 68.97 and 57.76% in 1999, and 23.71, 30.11, 68.81 and 57.05% in 2000 for transportation, utility, industrial and commercial‐residential sectors, respectively. Besides this, the exergy efficiency values are obtained to be 23.80, 30.28, 35.97 and 8.12% in 1999, and 23.65, 30.47, 35.51 and 8.02% in 2000 for the same order of sectors. The present study has clearly shown the necessity of the planned studies towards increasing exergy efficiencies in the sectors studied. Copyright © 2004 John Wiley & Sons, Ltd.     

A review on solar-hydrogen/fuel cell hybrid energy systems for stationary applications

There are several methods for producing hydrogen from solar energy. Currently, the most widely used solar hydrogen production method is to obtain hydrogen by electrolyzing the water at low temperature. In this study, solar hydrogen production methods, and their current status, are assessed. Solar-hydrogen/fuel cell hybrid energy systems for stationary applications, up to the present day are also discussed, and preliminary energy and exergy efficiency analyses are performed for a photovoltaic-hydrogen/fuel cell hybrid energy system in Denizli, Turkey. Three different energy demand paths – from photovoltaic panels to the consumer – are considered. Minimum and maximum overall energy and exergy efficiencies of the system are calculated based on these paths. It is found that the overall energy efficiency values of the system vary between 0.88% and 9.7%, while minimum and maximum overall exergy efficiency values of the system are between 0.77% and 9.3% as a result of selecting various energy paths. More importantly, the hydrogen path appears to be the least efficient one due to the addition of the electrolyzer, the fuel cells and the second inverter for hydrogen production and utilization.     

Engineering sustainability: thermodynamics,energy systems,and the environment

Thermodynamic concepts have been utilized 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. It has been argued that these consequences of human development are reflected in thermodynamic parameters and methods of analysis; they are said to mirror energy transformations within society. ‘Exergy’, a quantity which follows from the First and Second Laws of Thermodynamics, has been viewed as providing the basis of a tool for resource and/or emissions accounting. It is also seen as indicating natural limits on the attainment of sustainability. The more traditional use of the exergy method is illustrated by a number of cases drawn from the United Kingdom energy sector: electricity generation, combined heat and power schemes, and energy productivity in industry. This indicates the scope for increasing energy efficiency, and the extent of exergetic ‘improvement potential’, in each of these areas. Poor thermodynamic performance is principally the result of exergy losses in combustion and heat transfer processes. However, the application of such thermodynamic ideas outside the sphere of engineering has its critics. The link between the efficiency of resource utilization, pollutant emissions, and ‘exergy consumption’ is only indirect, and generally provides an insufficient basis for environmental appraisal. Methods of energy and exergy analysis are, therefore, evaluated as appropriate measures of sustainability in and beyond the energy sector. Copyright © 2004 John Wiley & Sons, Ltd.     

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.     

Energy and exergy analyses of energy consumptions in the industrial sector in South Africa

The energy-utilization over a 10-year period (1994–2003) has been analysed for the South African industrial sector, which consumes more primary energy than any other sector of the economy. Four principal sub-sectors, namely iron and steel, chemical and petrochemical, mining and quarrying, and non-ferrous metals/non-metallic minerals were considered in this study. Primary-energy utilization data were used to calculate the weighted mean energy and exergy efficiencies for the sub-sectors and then overall values for the industrial sector were obtained. The results indicate that exergy efficiency is considerably lower than energy efficiency in all the sub-sectors, particularly in mining and quarrying processes, for which the values were approximately 83% and 16%, respectively. The performance of exergy utilization in the industrial sector can be improved by introducing various conservation strategies. Results from this study were compared with those for other countries.     

Analysis of sectoral energy and exergy use of Saudi Arabia

This paper presents the analysis of sectoral energy and exergy utilization of Saudi Arabia by considering the energy and exergy flows for the 12 years between 1990 and 2001. Sectoral energy and exergy efficiencies are obtained for the subsectors and the devices used in each sector. Energy and exergy flow diagrams for Saudi Arabia are also presented, respectively, to illustrate the situation on how energy and exergy efficiencies vary in each sector. The residential sector appears to be the most energy efficient sector, and the industrial sector to be the most exergy efficient. It is believed that the current methodology is useful for analyzing sectoral energy and exergy utilization, which will help Saudi Arabia with energy savings through energy efficiency and/or energy conservation measures. It is also be helpful to establish standards to facilitate application in various sectors and processes for a sustainable energy planning. Copyright © 2004 John Wiley & Sons, Ltd.     

Enabling technologies for industrial energy demand management

This state-of-science review sets out to provide an indicative assessment of enabling technologies for reducing UK industrial energy demand and carbon emissions to 2050. In the short term, i.e. the period that will rely on current or existing technologies, the road map and priorities are clear. A variety of available technologies will lead to energy demand reduction in industrial processes, boiler operation, compressed air usage, electric motor efficiency, heating and lighting, and ancillary uses such as transport. The prospects for the commercial exploitation of innovative technologies by the middle of the 21st century are more speculative. Emphasis is therefore placed on the range of technology assessment methods that are likely to provide policy makers with a guide to progress in the development of high-temperature processes, improved materials, process integration and intensification, and improved industrial process control and monitoring. Key among the appraisal methods applicable to the energy sector is thermodynamic analysis, making use of energy, exergy and ‘exergoeconomic’ techniques. Technical and economic barriers will limit the improvement potential to perhaps a 30% cut in industrial energy use, which would make a significant contribution to reducing energy demand and carbon emissions in UK industry. Non-technological drivers for, and barriers to, the take-up of innovative, low-carbon energy technologies for industry are also outlined.     

Environmental performance evaluation of Beijing's energy use planning

In line with rapid economic development, urban energy consumption is increasing rapidly, resulting in environmental problems. After considering several methods to evaluate the environmental performance of energy use, including: energy ecological footprint, input–output analysis, emergy–exergy analysis, and multi-criteria decision-making, an environmental performance evaluation model is proposed, which combines the analytical hierarchy process, fuzzy extent analysis, and membership degree analysis. In the model, 18 sub-indicators of environmental performance from energy use planning are classified into four categories: structure of energy use and industry, technology and efficiency of energy use, environmental impacts caused by energy use, and the socio-economic benefits of energy use. Membership degree analysis is applied to each indicator. Three energy use scenarios which are, respectively, environment-friendly, technology-led, and economic policy-led are evaluated. The results show that the technology-led energy use planning is best. The sustainable energy use policies are proposed from three aspects, including optimizing the energy use and industrial structure, encouraging development of energy-saving and air pollution control technologies, and enhancing legislation on energy use management. The policies are helpful to optimize the trade-offs between economic growth and environmental protection in Beijing.     

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.     

Energetic and exergetic aspects of cotton stalk production in establishing energy policies

Exergy analysis is important for energy resource utilization, because exergy, which is a way to a sustainable future, is a part of the energy analysis. Exergy analysis starts to play a role in several countries in developing energy policy. This paper deals with the exergetic assessment of the cotton stalk (CS) production. In this regard, Turkey, which is one of the eight countries producing 85% of the world's cotton, is given as an application country first. Energy and exergy relations used in the analysis are then presented. Finally, the Turkish CS production in 2003 is evaluated using energy and exergy analyses method, while the results obtained are discussed. The values for the net energy and exergy gained are obtained to be about 49,146 and 59,395 MJ/ha, respectively. Turkey's total energy and exergy are estimated to be 75.45 and 81.87 PJ. It may be concluded that this amount of energy is equal to 7.77% and 2.38% of Turkey's primary energy production and consumption in the same year, respectively. The overall mean energy and exergy efficiencies of the cotton production in the year studied are found to be 33.06% and 33.12%, respectively. It is also expected that the results of this study will be helpful in developing highly applicable and productive planning for energy policies.     

Thermal modeling of a packed bed thermal energy storage system during charging

The process of charging of an encapsulated ice thermal energy storage device (ITES) is thermally modeled here through heat transfer and thermodynamic analyses. In heat transfer analysis, two different temperature profile cases, with negligible radial and/or stream-wise conduction are investigated for comparison, and the temperature profiles for each case are analyzed in an illustrative example. After obtaining temperature profiles through heat transfer analysis, a comprehensive thermodynamic study of the system is conducted. In this regard, energy, thermal exergy and flow exergy efficiencies, internal and external irreversibilities corresponding to flow exergy, as well as charging times are investigated. The energy efficiencies are found to be more than 99%, whereas the thermal exergy efficiencies are found to vary between 40% and 93% for viable charging times. The flow exergy efficiency varies between 48% and 88% for the flows and inlet temperatures selected. For a flow rate of 0.00164 m³/s, the maximum flow exergy efficiency occurs with an inlet temperature of 269.7 K, corresponding to an efficiency of 84.3%. For the case where the flow rate is 0.0033 m³/s, the maximum flow exergy efficiency becomes 87.9% at an inlet temperature of 270.7 K. The results confirm the fact that energy analyses, and even thermal exergy analyses, may lead to some unrealistic efficiency values. This could prove troublesome for designers wishing to optimize performance. For this reason, the flow exergy model provides the most useful information for those wishing to improve performance and reduce losses in such ITES systems.     

Assessment of the Turkish utility sector through energy and exergy analyses

The present study deals with evaluating the utility sector in terms of energetic and exergetic aspects. In this regard, energy and exergy utilization efficiencies in the Turkish utility sector over a wide range of period from 1990 to 2004 are assessed in this study. Energy and exergy analyses are performed for eight power plant modes, while they are based on the actual data over the period studied. Sectoral energy and exergy analyses are conducted to study the variations of energy and exergy efficiencies for each power plants throughout the years, and overall energy and exergy efficiencies are compared for these power plants. The energy utilization efficiencies for the overall Turkish utility sector range from 32.64% to 45.69%, while the exergy utilization efficiencies vary from 32.20% to 46.81% in the analyzed years. Exergetic improvement potential for this sector are also determined to be 332 PJ in 2004. It may be concluded that the methodology used in this study is practical and useful for analyzing sectoral and subsectoral energy and exergy utilization to determine how efficient energy and exergy are used in the sector studied. It is also expected that the results of this study will be helpful in developing highly applicable and productive planning for energy policies.     

A renewable energy based waste-to-energy system with hydrogen options

A pressurized gasification combined system is studied in a novel integration with geothermal energy to produce hydrogen-enriched syngas. This system utilizes dewatered sludge, which leaves the biological wastewater treatment facility during the wastewater treatment process and is used as a feedstock to produce hydrogen as a useful output. The hydrogen produced is transformed in a proton-exchange fuel cell to electricity for community use. This system also incorporates a wind farm with a hydrogen storage system to meet societies’ energy need when the energy demand fluctuates. The integrated system is then analyzed with thermodynamic-based energy and exergy approaches. The Greater Toronto area is chosen as the case study location and comprehensive thermodynamic analysis and simulation are completed on the Aspen Plus and Engineering Equation Solver softwares while the annual wind speed data are obtained from the RETScreen software. The daily total energy delivered to the community from this proposed system is recorded to be 2.1 GWh. In addition, the hydrogen production ratio at the gasification system is observed to be 0.12 through the sludge utilization where the energy and exergy efficiencies of the integrated gasification combined cycle were calculated to be 24% and 28%, in this order. The highest energy and exergy efficiency with 38.6% and 42.2%, respectively, are observed in January where the wind farm operated at a capacity of 41.7% and the average wind speed was 6.3 m/s for Greater Toronto Area. The overall energy and exergy efficiencies of this waste-to-energy system are calculated as 32.7% and 36.6%, respectively.     

Energy and exergy prices of various energy sources along with their CO2 equivalents

Various types of energy sources are used in the residential and industrial sectors. Choosing the type of sources is important. When an energy source is selected, its CO₂ equivalent and energy and exergy prices must be known for a sustainable future and for establishing energy policies. These prices are based on their energy values. Exergy analysis has been recently applied to a wide range of energy-related systems. Thus, obtaining the exergy values has become more meaningful for long-term planning. In this study, energy and exergy prices of various energy sources along with CO₂ equivalents are calculated and compared for residential and industrial applications in Turkey. Energy sources considered include coal, diesel oil, electricity, fuel oil, liquid petroleum gas (LPG), natural gas, heat pumps and geothermal, and their prices were obtained over a period of 18 months, from January 2008 to June 2009. For the residential and industrial sectors, minimum energy and exergy prices were found for ground source heat pumps, while maximum energy and exergy prices belong to LPG for both sectors.     

Exergy analysis on combustion and energy conversion processes

When we consider exergy analysis on combustion and thermodynamic processes, we introduce another concept against energy analysis, which is supported by an evaluation of its temperature level. When a higher temperature energy than that an ambient level is taken into consideration, it can be put for some domestic or industrial purpose. A medium temperature energy of 30–60 °C is used for domestic heating, and a high temperature of 200 °C and above is suitable for power generation or process heating. Therefore, we study exergy concept supported by temperature level. When we discuss power generation, a high temperature energy of 1500 °C and above in combined cycle has a higher conversion efficiency than that of 500–600 °C in steam cycle. If we try to apply high temperature air combustion, a preheated air temperature of 1000 °C and above can be produced by exhaust heat recovery from stack gas, which has been developed as a new technology of energy conservation. In this study, the authors present an exergy analysis on combustion and energy conversion processes, which is based on the above-mentioned concept of exergy and energy supported by temperature level. When we discuss high temperature air combustion in furnace, this process shows a higher performance than that of the ambient air combustion. Furthermore, when we discuss the power generation and heat pump processes, the minimum ambient temperature would already be known for each season, and the conversion performance can be estimated by the maximum operating temperature in their cycles. So, the authors attempt to calculate the exergy and energy values for combustion, power generation and heat pump processes.     

A distributed energy system integrating SOFC-MGT with mid-and-low temperature solar thermochemical hydrogen fuel production

Solar thermochemical hydrogen production with energy level upgraded from solar thermal to chemical energy shows great potential. By integrating mid-and-low temperature solar thermochemistry and solid oxide fuel cells, in this paper, a new distributed energy system combining power, cooling, and heating is proposed and analyzed from thermodynamic, energy and exergy viewpoints. Different from the high temperature solar thermochemistry (above 1073.15 K), the mid-and-low temperature solar thermochemistry utilizes concentrated solar thermal (473.15–573.15 K) to drive methanol decomposition reaction, reducing irreversible heat collection loss. The produced hydrogen-rich fuel is converted into power through solid oxide fuel cells and micro gas turbines successively, realizing the cascaded utilization of fuel and solar energy. Numerical simulation is conducted to investigate the system thermodynamic performances under design and off-design conditions. Promising results reveal that solar-to-hydrogen and net solar-to-electricity efficiencies reach 66.26% and 40.93%, respectively. With the solar thermochemical conversion and hydrogen-rich fuel cascade utilization, the system exergy and overall energy efficiencies reach 59.76% and 80.74%, respectively. This research may provide a pathway for efficient hydrogen-rich fuel production and power generation.     

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.