Published by Elsevier
JTHERGAS is a versatile calculator (implemented in JAVA) to estimate thermodynamic information from two dimensional graphical representations of molecules and radicals involving covalent bonds based on the Benson additivity method. The versatility of JTHERGAS stems from its inherent philosophy that all the fundamental data used in the calculation should be visible, to see exactly where the final values came from, and modifiable, to account for new data that can appear in the literature. The main use of this method is within automatic combustion mechanism generation systems where fast estimation of a large number and variety of chemical species is needed. The implementation strategy is based on meta-atom definitions and substructure analysis allowing a highly extensible database without modification of the core algorithms. Several interfaces for the database and the calculations are provided from terminal line commands, to graphical interfaces to web-services. The first order estimation of thermodynamics is based summing up the contributions of each heavy atom bonding description. Second order corrections due to steric hindrance and ring strain are made. Automatic estimate of contributions due to internal, external and optical symmetries are also made. The thermodynamical data for radicals is calculated by taking the difference due to the lost of a hydrogen radical taking into account changes in symmetry, spin, rotations, vibrations and steric hindrances. The software is public domain and is based on standard libraries such as CDK and CML.
This study presents new adiabatic laminar burning velocities of diethyl ether in air, measured on a flat-flame burner using the heat flux method. The experimental pressure was 1 atm and temperatures of the fresh gas mixture ranged from 298 to 398 K. Flame velocities were recorded at equivalence ratios from 0.55 to 1.60, for which stabilization of the flame was possible. The maximum laminar burning velocity was found at an equivalence ratio of 1.10 or 1.15 at different temperatures. These results are compared with experimental and computational data reported in the literature. The data reported in this study deviate significantly from previous experimental results and are well-predicted by a previously reported chemical kinetic mechanism.
Due to growing environmental concerns and diminishing petroleum reserves, a wide range of oxygenated species has been proposed as possible substitutes to fossil fuels: alcohols, methyl esters, acyclic and cyclic ethers. After a short review the major detailed kinetic models already proposed in the literature for the combustion of these molecules, the specific classes of reactions considered for modeling the oxidation of acyclic and cyclic oxygenated molecules respectively, are detailed.
The objective of this study is to examine practical and cost constraints on where riblets, a new drag-reduction technology, might be used in internal flows. The broad categories of internal flow considered were HVAC ducting, gas pipelines, oil pipelines, water pipes, steam pipes, and pipes in refrigeration or air-conditioning machinery. Each category was first examined for practical constraints, which might complicate or exclude the use of riblets. Second, the potential power savings and the resulting cost effectiveness of adding riblets were estimated. For the more promising categories of internal flow, we then discuss what major questions must still be researched, and what technical developments might improve prospects.
To what extent have quantitative models been used in the formulation of policy? The author addresses this question by examining two issues confronted by the Ninety-fourth Congress, oil price decontrol and synthetic fuels commercialization. He describes the influence of results from the large-scale models used to analyze the proposed policies and identifies conditions that apparently accounted for the successful use of these models.
The electrolytic decomposition potential of ZnO has been studied in a solar furnace in the temperature range 1200–1675 K. The electrolyte consisted of various mixtures of CaF2 and Na3AlF6. The measured potentials were close to the thermodynamically predicted values for the reaction ZnO(s) → Zn(g) + 0.502(g). The zero current overvoltages, surprisingly, increased with increasing temperature and the concurrent change in composition. The specific conductances of the electrolytes were estimated in the temperature range 1200–1500 K. They increased with increasing temperature and the concurrent change in composition. Various materials were tested for use as electrodes and crucibles. Some of our experiences and our experimental techniques are described.
Reactive ceramics are investigated for potential use in a rotary-type solar reactor. The two-step water-splitting process, which consists of O2-releasing (MOoxidized=MOreduced+1/2O2) and H2-generation (MOreduced+H2O(g)=MOoxidized+H2) reactions with yttria-stabilized zirconia (YSZ)-iron oxide solid solutions prepared by co-precipitation and solid-state reaction, is examined at temperatures of 1623 K for O2 release and 1273 K for H2 generation. The YSZ-iron oxide solid solutions with a single phase are obtained at mole ratios lower than 15% and 20% of iron ions to total cations (Fe3+, Zr4+, Y3+) by co-precipitation and the solid-state reaction, respectively. The two-step water-splitting process using YSZ-iron oxide solid solutions prepared by both preparation methods are repeated successfully. The amount of O2 gas evolved per weight of the sample (ml/g) is observed to increase with the iron content of the YSZ-iron oxide solid solution because of the high reactivity of iron ions in the solid solution. The maximum amounts of H2 and O2 gases evolved in the two-step water-splitting process with the YSZ-iron oxide solid solution were 0.89 and 1.2 ml/g, respectively.
Dichlorodifluoromethane (CFC-12) is the major contributor to ozone depletion. The new refrigerant tetrafluorethane (HFC-134a), which is a leading candidate to replace CFC-12 in refrigeration and air-conditioning applications, has been investigated from the standpoint of thermodynamic performance. For this purpose, a computer program is written to calculate the thermodynamic properties of HFC-134a, which can be used as a reference for analyses. A comparison has also been made for CFC-12 and HFC-134a refrigerants, which indicates that CFC-12 may be replaced by HFC-134a without a significant loss in overall thermal performance. It is found that the volumetric refrigerating effect of HFC-134a is less than that of CFC-12 for the same operating conditions. Thus, a larger compressor will be required for the same refrigeration capacity with HFC-134a.
CO2 separation from wet and dry synthetic biogas has been investigated using adsorption on 4A and 13X molecular sieves in dynamic conditions, flowing through fixed beds in an adsorption column connected with an IR detector. The adsorption of CO2 has also been investigated by IR spectroscopy over pressed disks of the zeolites in static dry and wet conditions. 13X molecular sieve has significant adsorption capacity of CO2 from dry biogas, which is further increased by the presence of moisture. This is due to the change of the adsorption mode of CO2 due to the copresence of water. Over wet 13X zeolite adsorption of CO2 mostly occurs in the form of bicarbonate ions interacting with coadsorbed water, while over the dry surface several different kinds of carbonate ions are formed together with molecular adsorbed species. The adsorption capacity of CO2 from biogas is definitely lower over 4A molecular sieve, where coadsorption of methane is also significant. However, regeneration of 4A by purging with nitrogen at r.t. is faster than that of 13X. Over 4A coadsorption of water do modifies the adsorption state of CO2 but has little effect on adsorption capacity.
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Formally adopted in 1996 by the International Organization of Standardization, ISO 14000 represents a new voluntary international environmental standard, which will likely be adopted by the vast majority of corporations. Its major focus is on the structure, implementation, and maintenance of a formal environmental management system. While the literature is clearly divided in its assessment of ISO 14000, an underlying common theme is that the decision to achieve ISO 14000 certification constitutes a major undertaking for most firms. Such an undertaking, it is argued, does not take place in a vacuum. Rather, it is a response to a number of factors or influences. However, no research to date has empirically identified these factors and explained how they can be leveraged into a competitive advantage. In this article, we use qualitative case studies to identify which factors affect the decision to attain ISO 14000 certification and we also explain how these factors can influence the level of success achieved during the certification process.
Energy is a fundamental factor of industrial production. The industrial process consists of work performance and information processing, in terms of which the production factors and the output can be defined and aggregated. The equation of growth relates the growth of output Q to the growth of the production factors capital K, labor L, and energy flow E. It can be solved in zero order approximation with respect to time, if one assumes that the characteristic properties of the industrial system are not changed by human creativity and that the economy is far from its thermodynamic limits to growth. Then Q must be a unique function of K, L and E. The integrability conditions result in three differential equations for the elasticities of production. They are solved subject to asymptotic boundary conditions. The integral of the equation of growth with the calculated, factor-dependent elasticities of production yields the production function q = e × exp }}a0[2 − (l + e)/k] + a0ct(l/e − 1){{, with q, k, l and e being the relative values of Q, K, L, and E; a0 and ct, are the two free parameters of the theory. For given factor inputs, the GNP and the output of the industrial sector of West Germany and the output of the sector “Industries” of the United States are calculated for the years 1960–78. Deviations of theory from reality are generally less than 5%. The slump during the energy crisis (1973–75) and the subsequent recovery are well reproduced. The influence of energy prices on factor inputs and growth is discussed. An assessment of future economic developments is given, including a calculation of the impact on U.S. industrial growth of solar power satellites from space manufacturing facilities.
This article reconstructs the history of electric power uses in the US from 1900 to 1998 from a number of different sources of data. The uses are grouped into functional categories, viz. lighting, electrolysis, high temperature heat (electric furnace applications), low temperature heat (space heating and hot water), motor drive and electronics (radio, TV and information processing). Motor drive accounts for by far the largest absolute share of consumption, while low temperature heating is by far the most rapidly increasing application. We were able to subdivide motor drive into transportation applications (very important in the early years), air-conditioning and refrigeration, and ‘other’, but a further breakdown has not been possible, based on available data. The article also estimates the efficiency of conversion from electric power to ‘secondary work’ for each application, based on historical data (where available) and our estimates. Finally, we develop an estimate of the overall conversion efficiency of electricity to secondary work. Surprisingly, the overall efficiency has remained almost constant during the past century, even though all individual applications have become more efficient, because the least efficient applications (low temperature heat and fractional horsepower motors) have sharply increased their share.
Conventional economic growth theory assumes that technological progress is exogenous and that resource consumption is a consequence, not a cause, of growth. The reality is different and more complex. A ‘growth engine’ is a positive feedback loop involving declining costs of inputs and increasing demand for lower priced outputs, which then drives costs down further, thanks to economies of scale and learning effects. In a competitive environment prices follow. The most important ‘growth engine’ of the first industrial revolution was dependent on coal and steam power. The feedback operated through rapidly declining fossil fuel and mechanical power costs. The advent of electric power, in growing quantities and declining cost, has triggered the development of a whole range of new products and industries, including electric light, radio and television, moving pictures, and the whole modern information sector. The purpose of this paper is to reformulate the idea of the ‘growth engine’ in terms of the service provided by energy inputs, namely ‘useful work’, defined as the product of energy (exergy) inputs multiplied by a conversion efficiency. We attempt here to reconstruct the useful work performed in the US economy during the twentieth century. Some economic implications are indicated very briefly.
The history of waste energy utilization in Germany during the 20th century is the story of alternately significant developments and significantly missed opportunities. In spite of three waves of remarkable progress during this period, there were economic, political, scientific and societal obstructions which prevented further development and implementation of this promising energy resource.
Numerous coal gasification studies have been found in the literature those employed various kinds of gasifying agents such as steam and carbon dioxide. These studies are featured with wide variations in the parametric conditions and the usage of equipments. Steam is frequently employed as a gasifying agent, however, in several studies carbon dioxide has also been used as a gasifying agent either pure or in combination with other gasifying agents (H2O, O2, CO, H2). This paper is a brief review of the coal gasification with CO2 as a diluent. Different factors were studied over the coal gasification with CO2 such as coal rank, pressure, temperature, gas composition, catalyst and the minerals present inside the coal, heating rate, particle size, and diverse reactor types. It also deals with the application of the gas–solid models developed in the literature and the combustion and gasification mechanisms for O2/CO2 streams. Moreover, it reviews the kinetics and the reaction rate equations (Arrhenius and Langmuir–Hinshelwood types) for coal-char gasification both in the reaction kinetic control region (low temperature) and the diffusion control region (high temperature) and at both low and high pressures.
Trends in energy intensities for 31 countries are evaluated, over the period from 1950 to 1988, using a purchasing power parity-based GDP measure and United Nations energy statistics. With non-commercial energy included, the energy intensities of low income countries are similar to those of high income countries. Energy intensities have decreased for 15 out of the 31 countries studied. The analysis indicates that there is a level of energy intensity, between 0.25 and 0.5 toe per 1000 (1980) international dollars, to which many countries are converging. Energy use per capita increases with higher incomes, but cross-country comparisons can be misleading and inappropriate due to large differences in, for example, economic structure and climate. Electricity appears to be the energy carrier of choice for advanced economies, leading to increased use of electricity relative to other energy carriers. Electricity intensities for eight industrialized countries are evaluated. In four countries, electricity intensities have decreased in recent years. This result suggests that electricity intensities may develop similarly to how energy intensities have developed as economic structure and energy end-use efficiency continue to change.
The total energy requirements of household consumption of all goods and services have been calculated. Source for consumption data is the 1972–1973 Bureau of Labor Statistics (BLS) Consumer Survey. These are converted to energy terms using input-output energy intensities. The dependence of household energy use on expenditures, number of household members, degree of urbanization, and other demographic-economic factors, has been investigated graphically and statistically. The major factor determining energy requirement is expenditure level, but this can be affected by up to about 15% by variation in the other factors. In agreement with previous work based on the 1960–1961 BLS Survey, we find that 1.(1) the dependence of total energy requirements on expenditures shows a tendency to saturation;2.(2) about one-half of the total energy of the average household is a result of the purchase of fuels and electricity while the other half results from the purchase of non-energy commodities. Application to the analysis of an energy tax and rebate program is discussed briefly.
We evaluate those economically-traded forms of energy which are consumed in the home in New Zealand, either directly as fuel or indirectly embodied in the goods and services that add up to material lifestyle. The methodology involved using data from our energy analysis of the N.Z. economy, and household expenditure survey data from the N.Z. Department of Statistics. Over the period of the survey (1974–1980), average per household consumption of energy decreased by 19% and per capita consumption by 11%. In any year, household energy consumption (both direct and indirect) was closely related to after-tax household income; gasoline consumption was the only area of expenditure that increased faster than income. The principal conclusion of this study is that, even without improvements in the technology of energy use, the overall demand for consumer energy for direct or indirect household consumption in N.Z. is likely to increase at a much slower rate than increases in real income and significantly more slowly than in the past.
We examine the economic reforms in China's electric power industry during the 1980s, describe China's pre-reform economy and show how investment and price reforms affected the power industry. Despite notable gains in economic and energy efficiencies following the introduction of market-oriented policies, some reform measures produced undesirable side-effects for the power industry. Using a simple economic model, it is possible to show that the multiple-price system adopted in the mid-1980s for paying power producers results in the underutilization of China's newest and most energy-efficient plants. We provide an estimate of the fuel losses which may have resulted from this pricing policy and suggest alternative pricing rules which will reduce efficiency losses in the power industry.
This is an updated version of a study on solid waste management. It deals with state legislation that is developing rapidly and also includes summaries of factual information that is required to assess current and future problems related to solid waste management in the U.S. An integrated solid waste management system that includes waste-to-energy conversion and can dispose of solid waste in an environmentally responsible manner is discussed.
An extensive financial analysis of the entire Greek State wind parks is carried out taking into account the life-long variation of every wind power installation techno-economic parameter. This investigation is based on a well-elaborated and integrated cost–benefit model developed by the authors and properly adapted to the local market situation. On top of that, the time-evolution of the local market financial parameters is included, using official data. In this context, the payback period and the corresponding benefit to cost ratio (BCR) values of all wind power installations analyzed are computed. As a general conclusion, one may clearly declare that the Greek State wind power program leads to substantial financial loss, despite the existing advantageous conditions. The main reason for this unexpected financial behavior is the unexpected low energy production of most wind power plants along with their long-term failures. In conclusion, the future of every State wind park may be redefined in view of the attempted European electricity market deregulation.
This study examines the primary energy consumption and energy-related CO2 emissions in Argentina, Brazil, Colombia, Mexico and Venezuela during the period 1990–2006. It also reviews important reforms in the energy sector of these countries as well as the promotion of energy efficiency (EE) and renewable energy sources (RES). Using a decomposition analysis, results indicate that even though significant reductions in energy intensity have been achieved in Colombia, Mexico and in a lesser extent in Brazil and Argentina, the reduction of CO2 emissions in these countries has not been significant due to an increased dependence on fossil fuels in their energy mix. Although the Latin American region has an important experience in the promotion of EE programs and renewable sources, the energy agenda of the examined countries focused mostly on the energy reforms during the analyzed period. The policy review suggests that further governmental support and strong public policies towards a more sustainable energy path are required to encourage a low carbon future in the region.
We present an analysis of the retooling decision of a full-line automobile manufacturer facing large uncertainty in the price of gasoline. The paper focuses on the appropriate mix of five car classes to be produced in 1990. By calculating the severity of a possible market mismatch problem with different retooling decisions, we show the effect of different strategies that could minimize the adverse effects of world oil price uncertainty. The manufacturer's retooling decision is considered with 1.(1) no competition,2.(2) competition from another full-line company, and3.(3) competition from another full-line company and a limited-line foreign manufacturer. Of particular interest is whether the market risks are so great that government intervention is required to assist the manufacturers in planning for an uncertain future. Specifically, we question whether the corporate average fuel efficiency standards should be extended past 1985 to encourage automobile manufacturers to retool for increased fuel efficiency in the face of highly uncertain gasoline prices.
This paper deals with the decomposition analysis of energy-related CO2 emissions in Greece from 1990 to 2002. The Arithmetic Mean Divisia Index (AMDI) and the Logarithmic Mean Divisia Index (LMDI) techniques are applied and changes in CO2 emissions are decomposed into four factors: income effect, energy intensity effect, fuel share effect and population effect. The period-wise and time series analyses show that the biggest contributor to the rise in CO2 emissions in Greece is the income effect; on the contrary, the energy intensity effect is mainly responsible for the decrease in CO2 emissions. A comparison of the results of the two techniques gave an insight in the intricacies of energy decomposition. Finally, conclusions and future areas of research are presented.
Living means consuming, and consuming requires producing consumer items which causes depletion of non-renewable energy resources and emissions of greenhouse gases. Thus, in addition to direct energy use, households indirectly require energy and greenhouse gases that are embodied in their purchases of consumer items. This study deals with the requirements for energy and greenhouse gases in Australia during 1993/94 for different aspects of living and how these amounts vary with changing household characteristics.
Energy and exergy utilization in Turkey have been analysed. We have evaluated the conversion sector and end uses for transportation, industrial, residential and commercial applications. Energy efficiencies are about 15% for transportation, 45% for thermal and hydropower plants, 55% for residential and commercial uses and 58% for industrial applications. The exergy efficiencies are about 6% for residential and commercial uses, 15% for transportation, 33% for industrial applications and 45% for the utility sector. Overall averages are 35% for energy and 13% for exergy utilization.
The Weatherization Assistance Program (WAP) is a federal block grant program established in 1976 to assist low-income households in reducing their energy bills and improve their health and safety through a variety of weatherization and related services. The manner in which WAP funding is distributed among states has been a contentious issue since the inception of the program, and in 1995, the Department of Energy developed a new allocation mechanism. The purpose of this paper is to describe the 1995 WAP funding formula and to provide an empirical analysis of alternative formulae. The central tenet of the paper is that it is not possible to define the need for weatherization assistance in a unique manner, and this ambiguity and confusion is one of the primary reasons why a distribution “formula” cannot be derived to satisfy the main stakeholder groups. The purpose of this discussion is not to “refute” or “validate” the WAP funding formula, but rather, to demonstrate the main assumptions implicit in the procedure and to point out methodological issues and the choices and trade-offs inherent in any formula development.
This paper develops a thermodynamic input–output (TIO) model of the 1997 United States economy that accounts for the flow of cumulative exergy in the 488-sector benchmark economic input–output model in two different ways. Industrial cumulative exergy consumption (ICEC) captures the exergy of all natural resources consumed directly and indirectly by each economic sector, while ecological cumulative exergy consumption (ECEC) also accounts for the exergy consumed in ecological systems for producing each natural resource. Information about exergy consumed in nature is obtained from the thermodynamics of biogeochemical cycles. As used in this work, ECEC is analogous to the concept of emergy, but does not rely on any of its controversial claims. The TIO model can also account for emissions from each sector and their impact and the role of labor. The use of consistent exergetic units permits the combination of various streams to define aggregate metrics that may provide insight into aspects related to the impact of economic sectors on the environment. Accounting for the contribution of natural capital by ECEC has been claimed to permit better representation of the quality of ecosystem goods and services than ICEC. The results of this work are expected to permit evaluation of these claims. If validated, this work is expected to lay the foundation for thermodynamic life cycle assessment, particularly of emerging technologies and with limited information.
Life Cycle Assessment (LCA) is not widely used as a decision-supporting tool in Italy, despite recent European Commission policies fostering its adoption to achieve an energy- and resource-efficient economy. In this paper, an LCA of waste management system of the 1st Macrolotto industrial area is presented. The aims of the study were to identify the environmental critical points of the system and to evaluate opportunities and problems in applying this methodology at industrial area level. After a description of the waste management system of the 1st Macrolotto industrial area, the main assumptions of the study and some elements of the system modelling are presented. Results confirmed that door-to-door separated collection and packaging recycling are successful strategies for reducing the use of natural resources. The cooperation of the waste management company, which was part of the area management structure, was strategic for the completion of the analysis. Country-specific databases and models should be developed for a widespread application of the LCA methodology to waste management in Italian industrial areas.
Using an uninsulated Beijing apartment house of standard design as a base case, the DOE-2.1A energy analysis program is used to study the cost-effectiveness of more energy-efficient designs. Two measures have attractive simple payback times; reduced infiltration (1–2 yr payback) and insulation of the north wall (6 yr). The cost of conserved coal for the insulation measure is less than half the international price of coal. This insulation adds only 0.6% to the first cost of the building, yet, combined with more attention to infiltration, it reduces annual heat load from 230 to 130 MJ/m2. Furthermore, the first cost of these two measures may be offset by savings from downsizing the heating plant. In Shanghai, reduced infiltration and insulation are justified not on the basis of saving fuel, but because they make dwellings more comfortable.
This paper presents an engineering-economic approach for developing energy demand models. The approach combines the economic theory of production with engineering process data. We review the economic theory of production, the Constant Elasticity of Substitution (CES) function, and the Logit function. Using the Oak Ridge Industrial Model (ORIM) as a case study, we show how the Logit function can be used to specify a fuel share model and how the CES function can be used to specify an energy conservation model. Shephard's lemma is a key result of the economic theory of production. The lemma can be used to derive input-output coefficients from a cost function. We use CES cost functions because they have good global properties. To obtain more flexibility, we use nested CES cost functions. To identify the parameters in a nested CES structure, we assume that the multilevel cost function corresponds to a multistage production process. When input-output coefficients are derived from a cost function, the tradeoffs between the factors satisfy the law of diminishing returns. Energy conservation occurs when capital, labor, or materials are substituted for energy service. In most cases, the substitution obeys the law of diminishing returns. Thus, a CES cost function can be used to specify an energy conservation model. Normally, perfect substitutes do not obey the law of diminishing returns. Since we include all of the costs for each option (the options use fuel and provide energy service) in ORIM, the options are perfect substitutes and do not satisfy the law of diminishing returns. Since the options are perfect substitutes, we use the Logit function to specify the ORIM fuel share model.
Accounting and end-use models were developed in industrialized countries in the early seventies. Since then they have become rather popular and are now widely used all over the world. These models are directly derived from the so-called technico-economic analysis of energy demand.Based on the concepts of applied system analysis, this approach aims at identifying all economic, social, technical and political factors which are related to energy demand and also at understanding how these factors explain changes in energy demand in the medium and long term. Focusing on the long term, this methodology is above all, a prospective approach which enables an analysis of all possible energy demand patterns in the long range instead of trying to predict just one in particular.
This paper furnishes an overview of the development status, economic viability, and environmental aspects of a select group of newer coal-burning technologies that are likely to augment or replace today's conventional modes of generating electricity possibly as early as the mid-to-late 1990s. An analysis of current fuel choice economics in the power and industrial sectors is also reviewed, to set the basis for the thermal coal demand and supply outlook to 2000.World thermal coal demand growth is expected to average almost 2.5% per year over this time period, with internationally traded coal rising by 6% annually. However, surplus industry production capacity is expected to persist until about 1990. With the large world-wide reserve base, industry need develop only high-quality, low-cost reserves to compete in the international marketplace.Large-scale coal-mining project management is a key technology that must be mastered in order to be competitive. Exxon's 15 million-tonne, $3 billion Cerrejon development in Colombia is being brought to market on time and within budget, with the help of some advanced project management technology.
The extraction, conversion, and use of energy carriers and materials in the Norwegian society in 2000 were investigated by Sciubba's method of extended-exergy accounting (EEA). In this method, extended-exergy (EE) values are assigned to labor and capital fluxes in addition to thermomechanical and chemical exergy values. The interchange of resources and products was quantified in terms of energy and exergy between seven sectors of the society and between the sectors and other countries. The extraction of resources from the environment and the discharge and deposit of waste were also included in the analysis. In the extraction sector, the exergy and EE conversion efficiencies both were 95%, and in the conversion sector both were approximately 76%. These two sectors are, respectively, dominated by oil and gas extraction and hydropower conversion. The third sector—agriculture, forestry, the fisheries, and food industry—had a lower exergy output to input ratio, 45%, whereas the EE conversion efficiency was 62%. A fourth sector, manufacturing industry, was dominated by paper, metal, and also chemical industry, and the efficiencies were 50 and 69%, respectively. In the transportation and service sectors, the labor and capital fluxes dominated the EEA, giving EE efficiencies of 63 and 75%, respectively, whereas the exergy efficiencies were 19 and 26%, respectively. In the seventh sector, the domestic sector (i.e. households), there was a close to zero energy and exergy output in this approach, since no products or resources were transferred to the other sectors except waste for re-circulation. However, the EE output of this sector was greater than the input, since labor is supplied from this sector to the other sectors.
This paper presents the highlights from a study of “reliability-focused energy-efficiency programs” implemented for the summer of 2001. We define these types of programs as those that were specifically designed, modified, or rapidly enlarged to address electric system reliability concerns. After first describing the methodology of the project, we present the results of a 50-State Screening Survey, followed by a description of 22 reliability-focused energy efficiency programs identified and selected as “case studies” in this project. We then discuss examples of three other different types of energy efficiency policy responses that were taken to address reliability concerns. Finally, we conclude by providing some preliminary aggregate impact estimates and outlining some lessons learned during the 2001 experience.
This editorial introduces and provides an overview of a Special Issue dedicated to the 9th conference of Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction—PRES 2006. It contains 11 selected papers covering various fields of energy related issues focusing on recent developments and includes energy resources, management and use, heat integration, heat pumps, emission treatment and waste to energy. The selected papers include interesting applications in the power generation, food industry, building materials production, oil refining, district heating, waste treatment and hydrogen production.
This editorial introduces and provides an overview of a Special Issue dedicated to the jubilee 10th Conference Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction—PRES’07. It contains nine selected papers covering various fields of energy-related most recent developments. The papers deal with carbon footprint (CFP) and CO2 emissions minimisation during energy generation, integration of fuel cell combined cycles and micro-CHP systems. They are supplemented by studies on power management strategies, gas and liquid fuel burners assessment and two industrial case studies: energy efficiency in pulp and paper Kraft mills and energy saving in reactive distillation.
Recent estimates and forecasts of the oil, gas, and coal resources and their reserve/production ratio, nuclear and renewable energy potential, and energy uses are surveyed. A brief discussion of the status and prospects of fossil, nuclear and renewable energy use, and of power generation (including hydrogen, fuel cells, micropower systems, and the futuristic concept of generating power in space for terrestrial use) is given. Ways to resolve the problem of the availability, cost, and sustainability of energy resources alongside the rapidly rising demand are discussed. The author's view of the promising energy R&D areas, their potential, foreseen improvements and their time scale, and last year's trends in government funding, are presented.
Recent estimates and forecasts of the oil, gas, coal resources and their reserve/production ratio, nuclear and renewable energy potential, and energy uses are surveyed. A brief discussion of the status, sustainability (economic, environmental and social impact), and prospects of fossil, nuclear and renewable energy use, and of power generation (including hydrogen, fuel cells, micropower systems, and the futuristic concept of generating power in space for terrestrial use), is presented. Comments about energy use in general, with more detailed focus on insufficiently considered areas of transportation and buildings are brought up. Ways to resolve the problem of the availability, cost, and sustainability of energy resources alongside the rapidly rising demand are discussed. The author’s view of the promising energy R&D areas, their potential, foreseen improvements and their time scale, and last year’s trends in government funding are presented.
High heating value (HHV) is an important property which characterises the energy content of a fuel such as solid, liquid and gaseous fuels. The previous assertion is particularly important for vegetable oils and biodiesels fuels which are expected to replace fossil oils. Estimation of the HHV of vegetable oils and biodiesels by using their fatty acid composition is the aim of this paper. The comparison between the HHVs predicted by the method and those obtained experimentally gives an average bias error of −0.84% and an average absolute error of 1.71%. These values show the utility, the validity and the applicability of the method to vegetable oils and their derivatives.
With the liberalization of energy markets and the introduction of an emission trading system, electricity production by gas combined cycle power plants has significantly increased in the European Union in recent years. Reasons for the significant increase include the short construction time for gas power plants and the favourable investment costs. One further advantage is the relatively low CO2 emissions of gas power plants. Thus, a key option for reducing emissions is seen in the increased use of gas for power production. Model calculations from various models show that an increase of gas power production is expected. In general, however, the interdependencies of the different markets (gas, electricity and CO2) as well as the country-specific gas supply options, determined by pipelines and liquefied natural gas (LNG), are neglected. As the competitiveness of gas power plants mainly depends on the availability of gas and the gas price, a novel model that integrates electricity, gas, and CO2- emission markets assuming perfect competition will be presented. The objective of this paper is to analyse the long-term relevance of the gas market for the electricity sector in the European Union in the context of CO2-emission reduction targets.
This paper provides an overview of the IEA's 1998 edition of the World Energy Outlook. It discusses the likely developments in global energy demand for the period to the year 2020. Special attention is paid to the power generation sector. Prospects for electricity generation are discussed in detail for 10 world regions, followed by a description of the model that was used to produce these projections. Finally, the paper discusses the main uncertainties surrounding the projections presented here.
Increasing use of petroleum, coupled with concern for global warming, demands the development and institution of CO2 reducing, non-fossil fuel-based alternative energy-generating strategies. Ethanol is a potential alternative, particularly when produced in a sustainable way as is envisioned for sugarcane in Brazil. We consider the expansion of sugarcane-derived ethanol to displace 5% of projected gasoline use worldwide in 2025. With existing technology, 21 million hectares of land will be required to produce the necessary ethanol. This is less than 7% of current Brazilian agricultural land and equivalent to current soybean land use. New production lands come from pasture made available through improving pasture management in the cattle industry. With the continued introduction of new cane varieties (annual yield increases of about 1.6%) and new ethanol production technologies, namely the hydrolysis of bagasse to sugars for ethanol production and sugarcane trash collection providing renewable process energy production, this could reduce these modest land requirements by 29–38%.
The objective of this study is to examine the potential for a full transition to domestically produced biofuels in the Stockholm County transport system in 2030, without exceeding the proportional share of national bioenergy assets. This target is chosen in order to test the potential of biofuel assets in Sweden, facilitating the transition to renewable fuel systems, and to display the potential of transport energy demand at macrolevel under tighter conditions on the energy market after fossil oil production has peaked. The distribution of bioenergy to the transport sector, including conversion losses and relationships to other energy sectors, is analysed explicitly. State-of-the-art traffic forecasting models, complemented with a specially designed energy quantification model, are applied to assess energy quantities needed at different vehicle efficiency levels and mobility patterns. The purpose is not to determine the most energy-efficient transport system possible, or to forecast the optimal distribution of bioenergy set aside for the transport sector in the future. Rather, we try to visualise, at a more conceptual level, energy demand as dependent on principle transport strategies, future technological developments and a type of planning that takes technological interlinkages between evolving components into strategic account. This work highlights the importance of implementing both demand and supply-side policies in order to reduce energy use and greenhouse gas emissions in all energy sectors before making assessments of reasonable distributions of bioenergy between energy sectors and other biomass usage.
This paper presents the methodology and results of the overall energy system analysis of a 100% renewable energy system. The input for the systems is the result of a project of the Danish Association of Engineers, in which 1600 participants during more than 40 seminars discussed and designed a model for the future energy system of Denmark. The energy system analysis methodology includes hour by hour computer simulations leading to the design of flexible energy systems with the ability to balance the electricity supply and demand. The results are detailed system designs and energy balances for two energy target years: year 2050 with 100% renewable energy from biomass and combinations of wind, wave and solar power; and year 2030 with 50% renewable energy, emphasising the first important steps on the way. The conclusion is that a 100% renewable energy supply based on domestic resources is physically possible, and that the first step towards 2030 is feasible to Danish society. However, Denmark will have to consider to which degree the country shall rely mostly on biomass resources, which will involve the reorganisation of the present use of farming areas, or mostly on wind power, which will involve a large share of hydrogen or similar energy carriers leading to certain inefficiencies in the system design.
A mineral deposit is a natural resource whose exergy can be calculated from a defined reference environment (RE). This RE can be compared to a thermodynamically dead planet, where all materials have reacted, dispersed and mixed. Like any substance, a mine is characterized by its quantity, chemical composition and concentration (ore grade). The mine’s exergy measures the minimum (reversible) energy to extract and concentrate the materials from the RE to the conditions in the mine. And the mine’s exergy replacement cost accounts for the actual exergy required to accomplish this, with available technologies. The exergy assessment of the natural resource wealth of the Earth defined from a RE is named as exergoecology. The aim of this paper is to prove the usefulness of these two indicators for assessing the degradation of mineral deposits over history. As an example, the exergy decrease of US copper mines due to copper extraction throughout the 20th century has been determined. The results indicate that the exergy decrease was 65.4 Mtoe, while the exergy replacement cost 889.9 Mtoe. During the past century, the US extracted the equivalent of 2.5 and 1.2 times of its current national exergy reserves and base reserve of copper, respectively.
We present an overview of likely sources of needed United States energy supplies for the 21st century.
This paper illustrates the role that integrated energy systems, also known as ‘energyplexes’, could play in supplying energy demands in the long term. These systems could enable a multi-fuel, multi-product strategy with both economic and environmental benefits. They could increase the adaptability and robustness of energy-services companies in the marketplace, providing them with flexibility in meeting demands in different market segments while achieving lower production costs and, reducing the risks of reliance on a single feedstock. In addition, with the possibility of achieving high conversion efficiencies and low polluting emissions and facilitating carbon capture, they could deliver high-quality energy services in a cost-effective way while meeting stringent environmental requirements. Their potential is highlighted here using the case of coal-fired, synthesis-gas-based gasification systems that allow co-producing hydrogen, electricity and liquid fuels, i.e. Fischer–Tropsch liquids and methanol, and could be a key building block in a clean-coal technology strategy. Co-production, also known as poly-generation, strategies may contribute to improve the economics of the system and exploit potential synergies between the constituent processes. However, the technical feasibility and economic viability of poly-generation schemes have to be examined carefully on a case-by-case basis.
This paper presents results of performance tests for R-22 and four alternative fluids (R-134a, R-32/134a (30/70%), R-407C, and R-410A) at operating conditions typical for a residential air conditioner. The study was performed in an experimental breadboard water-to-water heat pump in which a water/ethylene glycol mixture was used as the heat transfer fluid. The heat exchangers representing the evaporator and condenser were counter flow and cross flow, respectively. In tests performed at the same capacity, R-410A had the highest coefficient of performance. Test results for the system and data characterizing the performance of the heat exchangers and compressor are presented. The impact of the wide variations in the different alternative fluid properties on the system's operation and performance is particularly noted. The benefit of the liquid-line/suction-line heat exchange cycle is also addressed.
A method for setting up a reference year of reduced temperature data, proposed by Klein and Erbs, has been applied by us to 29 European locations for which an official test-reference year is available. This reference year of reduced temperatures may be utilized in computer programs for analysis of the thermal behaviour of buildings. The effectiveness of the method has been tested by calculating the annual energy demand in 29 European locations for three modules with different thermophysical characteristics.
Top-cited authors
Henrik Lund
  • Aalborg University
Brian Vad Mathiesen
  • Aalborg University
Wei-Hsin Chen
  • National Cheng Kung University
Andrea Lazzaretto
  • University of Padova
Boqiang Lin
  • Xiamen University