Search

The Swedish pulp and paper industry (PPI) must increase energy efficiency to remain competitive on the global market, which has experienced entries from countries with cheaper energy and raw material supplies. Interactions among variables for energy use, production, energy management, electricity price and firm characteristics (FC), in different types of mills, i.e., pulp, paper and integrated mills, in Sweden from 2006 to 2015 indicate that correlations among the studied variables were different in different types of mills. This difference between types of mills seemed to originate partly from varying accessibility to production residue that could be used for energy. For all types of mills, variation of electricity prices did not correlate significantly with energy efficiency during the study period. The studied FC were firm's age, number of employees, number of companies in company group, net sales and profit for the year. Energy efficiency was more affected by the variables characterizing energy and production compared to the variables representing FC. This study also suggested presence of possible discrepancies between FC that were perceived as barriers to energy management towards energy efficiency, according to previous studies, and what was shown by the data combining variables representing energy use, production and FC. [ABSTRACT FROM AUTHOR]

This paper presents a comparison between four gasification-based biorefineries integrated with a pulp and paper mill. It is a continuation of 'Transportation fuel production from gasified biomass integrated with a pulp and paper mill - Part A: Heat integration and system performance'. Synthesis into methanol, Fischer-Tropsch crude or synthetic natural gas, or electricity generation in a gas turbine combined cycle, were evaluated. The concepts were assessed in terms of GHG (greenhouse gas) emissions and economic performance. Net annual profits were positive for all biofuel cases for an annuity factor of 0.1 in the year 2030; however, the results are sensitive to biofuel selling prices and CO 2,eq charge. Additionally, GHG emissions from grid electricity are highly influential on the results since all biofuel processes require external power. Credits for stored CO 2 might be necessary for processes to be competitive, i.e. storage of separated CO 2 from the syngas conditioning has an important role to play. Without CO 2 storage, the gas turbine case is better than, or equal to, biofuels regarding GHG emissions. Efficiency measures at the host mill prior to heat integration of a gasification process are beneficial from the perspective of GHG emissions, while having a negative impact on the economy. [ABSTRACT FROM AUTHOR]

Abstract With the revolution of the traditional economic and social pattern based on centralized fossil energy consumption, the regional integrated energy system (RIES) has gained rapid development in recent years for achieving higher energy efficiency. This paper expands the Demand Response (DR) concept to the RIES and presents an optimal operation model of RIES considering the DR mechanism on the energy price. In this paper, a comprehensive DR strategy combining energy price and different loads is firstly developed to exploit the demand flexibility of RIES in the DR model established. Based on the DR modeling of the RIES, an operation optimization model with environmental, economic benefits and energy supply reliability as objective functions has been firstly established in detail. Secondly, a complete scheduling scheme is built based on the energy consumption characteristics and system operation characteristic of the integrated energy system. The model presented could reduce the cost of system without causing a significant amount of environmental pollution, and improve the energy efficiency of the RIES efficiently. Besides, the scheduling strategy proposed could also provide support for the operation strategy of integrated energy system under the energy development. Hopefully, this paper will provide reference for future research and engineering projects on DR programs in the RIES. Highlights • The typical structure of the RIES is introduced. • A DR model suitable for the RIES considering different loads is established. • An optimal operation model of the RIES based on DR is established. • The load in the RIES is affected not only by energy price but also by other loads. [ABSTRACT FROM AUTHOR]

Combining cost-optimal solutions to reach nearly zero energy buildings (NZEBs) in compliance with European policies is an ongoing challenge. Energy consumption can be reduced evaluating different configurations at the design stage and implementing the most appropriate solutions according to the building and the location. This paper develops a simulation-based optimization framework of cost-optimal choices and energy efficiency measures for new buildings. It combines energy and cost simulations using a sequential search technique to find the most effective combination of energy efficiency and renewable energy measures starting from a base configuration. The model is applied to a residential building prototype, taking into consideration hourly climatic data, construction methods, cost data and energy consumption. A cost database and a library of potential measures, related to envelope, appliances and systems, have been established and used within the optimization process. The potential impact of climate change on the estimated cooling loads has been included in the calculations. The paper shows the feasibility of European requirements for new NZEBs located in different cities. It describes how to best achieve the NZEB design at the lowest cost in 14 locations across Europe. Results highlight how the cost-optimal measures vary with climate and how in each location final selected options differ. Insulation and building tightness appear essential in colder climates, while efficient appliances and lighting are key measures in warmer locations. A key finding of the research is that a source energy reduction of 90% and beyond is feasible for new constructions in all locations. Results also show how efficient lighting and appliances considerably impact the building energy performance. The importance of integrating renewables and energy efficiency measures is confirmed as crucial to reach the NZEBs target. [ABSTRACT FROM AUTHOR]

The paper addresses the issue of the transition from a traditional electrical system without automation to a newer active and smart system allowing the possibility of implementing Demand Side Management policies, for little islands not supplied by the main grid. In particular, the paper focuses on two main topics related to the definition of: • an effective control, monitoring and communication system as a tool for the full exploitation of the opportunities given by Demand Response policies; • some solutions for the automation of the end-users’ electrical installations, in order to offer to the utility flexibility to be used for the improvement of the generation and distribution efficiency. After a brief discussion on the international regulatory framework on automation and ICT applications for power systems, the paper presents a feasibility study, based on the characteristics of the island of Lampedusa, of a hierarchical architecture of a suitable control system and of some DSM enabling solutions for residential end-users. The proposed solutions are defined taking into account some main elements: • distribution grids in small islands are generally equipped with outdated and hardly automatable devices; • utilities in small islands have reduced budget for new investments; • not less important, the most of the inhabitants has low income and unfamiliarity with automation. Therefore, main features of the proposed DSM enabling technologies are low cost and ease of use. [ABSTRACT FROM AUTHOR]

Both energy and water are important resources for human and should be investigated in an integrated way. The paper examines the implications of improving energy efficiency for water resources to contribute to the understanding of energy-water nexus. The paper first develops a mathematical model to link energy efficiency and water withdrawals and consumption. Using the model and the UK energy and water data, the paper then investigates the implications of improving energy efficiency of thermal power technology for freshwater, tidal and sea water in the UK. Results show that when the energy efficiency increases averagely by 10%, the total water withdrawals decrease by 1.65 × 10 6 Megaliter (ML) per year, and the total water consumption reduces by 2.89 × 10 4 ML per year. The saved freshwater withdrawals account for 0.43% of total public water supply in England and Wales in 2013, and could support 138,462 households. The water resources have different sensitivity to the improvement of energy efficiency. The sea water withdrawals are the most sensitive to the improvement of energy efficiency, followed by tidal sea water withdrawals and freshwater withdrawals. Results provide significant informative implications for energy-water nexus, and suggests that it is time to consider improving energy efficiency to address the emerging energy and water challenges. [ABSTRACT FROM AUTHOR]

In this paper, economic and environmental impacts of energy efficiency programs associated with new and existing buildings are evaluated for the Kingdom of Saudi Arabia (KSA). In particular, the analysis considers optimized designs for new buildings as well as different energy retrofit programs for existing buildings are considered in the bottom-up analysis using archetypical building energy models located in five sites representing a wide range of KSA climates. In particular, the analysis presented in this paper provides specific estimations to the extent of the energy and demand savings that could be achieved in the building sector even under highly subsidized energy prices. It is found that even a basic energy retrofit program using low-cost energy efficiency measures implemented to the existing building stock can provide significant economic and environmental benefits. Indeed, a level 1 energy efficiency retrofit program targeting only the existing residential building stock could reduce electricity consumption by 10,054 GWh/year and peak demand by 2290 MW and carbon emission by 7.611 million tons/year. [ABSTRACT FROM AUTHOR]

Abstract: Heat transfer intensification for shell and tube heat exchangers is an efficient technique to increase energy saving when retrofitting heat exchanger networks (HENs). Such intensification has been widely studied in the process industry in recent years from the point of view of individual heat exchangers. By implementing intensified techniques in existing exchangers, higher heat transfer coefficients can be achieved, leading to higher heat exchange duties in the existing matches, which can improve the overall energy recovery without the necessity to change the HEN configurations [1–3]. The conventional intensification techniques include tube-side enhancements (internal tube fins, twisted-tape inserts, and coiled-wire inserts), and shell-side enhancements (external tube fins, and helical baffles). Combining several enhancement techniques can achieve higher energy saving compared with single technique implementing. However, existing papers rarely considered different intensification techniques in the same case to compare their performances and examine combinations. It is difficult to identify which intensification technique is more suitable in a certain exchanger, or which combinations of intensification techniques are expected to contribute the most positively to the compound augmentation. Thus, this paper focuses on the recent advances on tube-side and shell-side enhancement techniques, and investigates their performances to obtain substantial economic benefits in intensified heat exchangers. [Copyright &y& Elsevier]

Abstract: This paper discusses the opportunities and challenges of implementing District Heating (DH) in Canada, with focus on the network design and operation. We selected for case study an urban area in Ottawa. First, we proved that the medium-temperature district heating (MTDH) (70°C≤ T supply ≤90°C) had better energy delivery performance than high-temperature district heating (HTDH) (T supply >100°C), decreasing the heat loss by approximately 40%. The low-temperature networks (T supply <60°C) achieved even lower heat losses, but they required additional capital investment. The implementation of low-temperature district heating (LTDH) should be considered, thanks to the capability of including more renewable energy and excess industrial waste heat. Next, the simulations show that DH can be implemented to supply present heating loads with medium temperature DH, and operate in the future at low temperature, after energy saving measures have been implemented in the buildings. Areas having linear heat densities greater than 3MWh/(myr) could economically be supplied by DH. Areas with linear heat density below 1.5MWh/(myr) are considered not practically feasible with the current energy market situation in Canada. The paper discusses critical issues and quantifies the performance of design concepts for DH supply to low heat density areas. DH is a fundamental energy infrastructure and is part of the solution for sustainable energy planning in Canadian communities. [Copyright &y& Elsevier]

Abstract: This paper aims at providing an identification and an analysis of the most relevant barriers to energy efficiency that limit a widespread implementation of the Best Available Technologies and Practices (BAT/Ps) through the investigation of 128 non-energy intensive manufacturing Small and Medium-sized Enterprises (SMEs) in Northern Italy. The study, starting from the existing literature, performs an investigation of the operational difficulties occurring when it has been decided to undertake the process of investing resources in energy efficiency interventions. The most perceived barriers have been analyzed with respect to several important characteristics (among others, sector and firm’s size). This examination shows also that very much attention should be paid to avoid bundling together SMEs of different sizes and sectors, since different behaviors with respect to the perception of the barriers can be observed. The analysis of the sample presents some interesting trends considering the perception of the barriers with respect to previous experience of the enterprises on energy efficiency. The paper also explores, through a preliminary analysis, the correlations among questions in order to understand the dynamics and the possible effects of a given barrier with respect to others. Several suggestions for future research in this important area have been provided. [Copyright &y& Elsevier]

Abstract The overall energy efficiency level of ethylene production process not only is influenced by the input energy mediums and output products, but also closely dependent on the operation status of the internal phases in the process. Traditionally, the energy efficiency diagnosis strategies mostly regard the ethylene production process as a black box, and only care about the influence caused by input and output factors, regardless of the interactions effect resulted from the internal subprocess and equipment. Therefore, to improve the traditional energy efficiency diagnosis schemes and extract the potential energy-saving factors, the deep analysis of the internal operation phases is necessary. Considering the large-scale and multi-dimensional characters of ethylene production process, a multi-level and multi-granularity energy efficiency diagnosis scheme is proposed in this paper. First, based on the analysis of energy flow, the layer classification for diagnosis boundary is implemented and the key energy-consuming facilities are determined in ethylene production process. Then, the corresponding three-level energy efficiency indicator system is established for benchmarking the energy efficiency level. Finally, the hierarchical energy efficiency diagnosis models are constructed based on two-stage and network data envelopment analysis to study the internal operation phases and find out the energy-saving factors. A practical Chinese ethylene plant is used to demonstrate the effectiveness of the proposed scheme. Not only is the energy efficiency level evaluated, but also the specific reasons resulting in the low energy efficiency level are found out, which provides the suggestions for saving energy and improving energy efficiency to the decision makers. Highlights • A hierarchical energy efficiency diagnosis scheme is proposed. • A hierarchical energy efficiency indicators system is established. • The energy efficiency diagnosis is carried out in multiple granularities. • The advice of energy saving obtained by the proposed scheme is more targeted. [ABSTRACT FROM AUTHOR]

Abstract The European Union has set specific targets for reducing energy consumption, shifting the main focus of European energy policy towards a firm commitment to enhancing energy efficiency. In light of the limited progress reported in Greece's energy efficiency action plan, the objective of this paper is to help redesign the near-term national policy framework. In this respect, a risk-oriented optimisation model is developed to support the optimal budget allocation to energy efficiency measures, with a view to achieving the 2020 national targets. The transdisciplinary methodological framework initially builds on the Energy Efficiency Action Plans for Greece and involves stakeholder engagement, multiple-criteria decision making and portfolio analysis. The evaluation of the policy instruments is based on two criteria, namely energy savings and implementation risk, under a set of technical and financial constraints. Finally, the robustness of both the optimal policy portfolios and the individual policies composing these portfolios is assessed. The results indicate that, given the financial and technical constraints, the 2020 target cannot be achieved. By stochastically analysing the impact of external uncertainty, three policies emerge as the most robust, while portfolios achieving savings of more than 1000 kTOE until 2020 are found highly vulnerable to underlying uncertainties. Highlights • Greece strives to achieve its national energy efficiency targets in the near-term. • We propose a risk-oriented framework to support the redesign of the national policy. • Given the financial and technical constraints, the 2020 target cannot be achieved. • Three policies appear to be robust and contribute the most in the optimal portfolios. • Policy portfolios achieving more than 1000 kTOE are highly vulnerable to uncertainty. [ABSTRACT FROM AUTHOR]

Abstract While the empirical literature on energy intensity is focused mainly on reduced energy intensity, this study examines a case where energy intensity is increasing. The paper aims at identifying price and non-price determinants of Iran's energy intensity and analyzing their importance in dynamics of it. In order to answer the research question, LMDI decomposition technique as well as time series econometrics have been used to data analysis. Based on the results, both structural changes in economic activities and inefficiency of energy consumption have led to the increase in Iran's energy intensity, although the latter dominated the former. The elasticity of energy intensity with respect to total factor productivity, real energy prices, and industrial development is negative in the short-run and long-run. Additionally, per capita income has a positive linear relationship with energy intensity that implies a high income elasticity of energy demand. Furthermore, changes in TFP and energy prices contribute more than two-thirds of forecast error variance decomposition of energy intensity, which shows the importance of these factors in energy intensity dynamics. Hence, in order to change the increasing trend of energy intensity, it is important to consider the necessities of improving technology and productivity while realizing energy prices. Highlights • Iran's economy faced an average annual growth of 3.3% in energy intensity between 1974 and 2014. • Both inefficiency and structural effects led to the increase in energy intensity of Iran. • Relative energy price and total factor productivity have key roles in energy intensity dynamics. • Economic growth based on TFP improvement will lead to declining energy intensity. • Industrial development strategy can has a significant role in energy productivity in Iran. [ABSTRACT FROM AUTHOR]

Abstract In tropical climates, the energy consumed by ventilation and air conditioning can exceed 50% of the total consumption of a building. Demand for cooling is rising steadily, driven mainly by growing incomes in developing economies, and is expected to also increase with climate change. Tropical, coastal areas with narrow continental shelves are good sites for the implementation of Seawater Air Conditioning (SWAC), a renewable and low CO 2 emission cooling process. This paper presents the existing SWAC projects around the world and gives details on the technology. Data on ocean temperature profiles, ocean bathymetry and world surface temperature are processed with the intent of estimating the world potential of SWAC. The results present the required distance from coast to reach seawater with a temperature of 5 °C or less. This is combined with the potential demand for air conditioning, taking into account surface air temperature and a set SWAC design for cooling from 30 to 20 °C. The pipeline length, seawater depth and capacity factor are then used to estimate the costs of SWAC projects around the world. It is concluded that the locations with the highest potential for SWAC are intertropical islands and some continental locations. Highlights • This renewable source is ideal for tropical coastal areas with narrow continental shelves. • The energy in a m3/s of SWAC can be equivalent to 49 ha of solar PV or 42 MW of wind turbines. • A novel SWAC potential model is developed to identify the most promising sites worldwide. • Capacity factor, pipeline length, depth extraction and cost estimates are presented in detail. • The cheapest SWAC project costs $0.0185/KWh t and is located in Nauru, Pacific Ocean. [ABSTRACT FROM AUTHOR]

Abstract Street lighting is an indispensable feature for the night landscape of cities. It is important for road safety, users visual comfort, crime prevention and to augment the perceived personal safety. Realize and maintain an adequate street lighting service is very expensive for municipalities with significant impact on their budgets. For this reason, special attention should be paid to the design of new street lighting systems and to the refurbishment of existing ones, since many of them are inadequate. In light of this it is very important to implement street lighting designs that fulfil lighting requirements avoiding energy waste and light pollution and, at the same time, result economically sustainable for municipalities. In this paper, an original step by step methodology for the lighting, energy and economic analysis of street lighting refurbishment designs has been introduced and explained in detail. The methodology is suitable for use in cities of different sizes. As an applicative example, the methodology has been tested in the town of Pontedera (Italy) and the results are discussed, also providing a sensitivity analysis of the economic feasibility with respect to the variations of electricity prices and investment costs. Highlights • Typical critical issues of public street lighting in Italian towns are analysed. • A methodology for street lighting systems refurbishment in small/medium sized Italian towns is proposed. • A multi-objectives analysis (lighting, energy and economic parameters) is adopted for lighting design evaluation. • The case study of Pontedera town (Italy) street lighting refurbishment is discussed. • Benefits from the use of the adopted methodology are exposed. [ABSTRACT FROM AUTHOR]

Abstract: This editorial and overview of a Special Issue dedicated to the 11th Conference Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction – PRES 2008. Thirteen papers have been selected and after being peer-reviewed. Nine were accepted for publication covering important subjects of energy generation and usage. They are focusing on recent development of various features of heat integration which is an important methodology for increasing energy efficiency and saving. The complementary issues covered are emissions reduction and the security of energy supply. This issue of ENERGY is the fourth special journal issue dedicated to selected papers from PRES conferences. [Copyright &y& Elsevier]

Energy planning in many developing Asian countries has neglected the structure of energy demand and how it is likely to evolve as development takes its path. The limited availability of energy consumption data makes it very difficult to assess the energy savings potential at end-use level. Energy planning requires the formulation of a proper modelling framework that supports the definition of energy policies. From the different approaches available, Input - Output (I-O) models are particularly useful, since they allow considering different impacts that can be consistent with different energy policy options. This paper proposes a novel I-O modelling framework by introducing a bottom-up approach into an I-O model which is combined with technical data for the holistic assessment of energy efficient technologies in the residential sector, which can assist energy decision-makers of India on the appraisal of the future impacts of the current national energy saving targets. A large size platform of real data has also been gathered considering different data sources, namely the household building stock characterization, the number of operating days according to the climatic regions of India, the lifetime and the investment cost of equipment. Finally, the main results are discussed and future research opportunities are identified. [ABSTRACT FROM AUTHOR]

Sea shipping is one of the most widespread transport modes. Therefore, the improvement of energy efficiency and further curbing of Carbon Dioxide emissions by marine vessels is important both economically and environmentally. During the sixty ninth Marine Environment Protection Committee session in April 2016, the International Maritime Organization approved mandatory requirements for ships to report their fuel consumption, which is the first of the three-phase approach to derive a standardized measure for energy efficiency tracking of marine vessels. Under the International Maritime Organization Data Collection System, emphasis has been placed on verification of the collected fuel consumption data so that vessels' energy efficiency could be benchmarked and improved. To optimize the operational efficiency of marine vessels, this paper proposes the Real-Time Energy Efficiency Operating Index and the framework to implement it. The proposed scheme can be used to verify fuel consumption and carbon dioxide emission data reported by individual ships. It also provides an approach to automatically and remotely estimate the transport work in real time. The proposed architecture mainly relies on the Automated Identification System and a constructed vessel database. A proof of concept prototype is deployed that monitors the energy efficiency of vessels along the Singapore Strait. [ABSTRACT FROM AUTHOR]

Data centers seek solutions to increase energy efficiency and lower costs by novel methods. Waste heat utilization is considered to be one of the major trends in the near future, especially in the Nordic countries, where heat demand is high. In this paper, waste heat utilization was analyzed from the perspectives of both the data center and district heating network operators. Timing of the data center waste heat production was considered based on an existing data center load profile. For the district heating network operator, the system level effects of increased waste heat utilization were quantified by simulating district heating production in the city of Espoo, Finland, with actual plant and heat demand data for 2013 and 2015. Results showed that with high shares of waste heat in the district heating system, i.e. 20–60 MW, the system level operational cost savings were 0.6–7.3% in the case study. Utilizing waste heat decreased utilization hours of both combined heat and power plants and heat-only boilers. The analysis showed that pricing of the procured waste heat affects the utilization level of waste heat, but operational hours of waste heat utilization were over 95% in all scenarios. [ABSTRACT FROM AUTHOR]

Energy benchmarking has been recognized as an effective analytical methodology and management tool to improve energy efficiency and performance. Many approaches to energy benchmarking have been applied in various fields. Machining systems, which are widely distributed and consume large amounts of energy with low efficiency, possess considerable potential for reductions in energy consumption. However, current research regarding the use of energy benchmarking for machining systems is insufficient due to the complexity and variety of energy consumption processes used in these systems. This paper proposes the use of energy benchmarking to strengthen the evaluation of energy demand and achieve efficiency improvements for machining systems. First, it analyses drivers for energy benchmarking and their characteristics. Next, an energy benchmarking framework for machining systems is presented. Then the concepts of the static, dynamic, single-objective, multi-objective, product-based, and process-based energy benchmarking are discussed from three different perspectives: the motion, object and application level. This lays a theoretical foundation for further energy benchmarking research. Finally, methods for developing energy benchmarking are also addressed including the prediction method, statistical analysis and expert decision. The application of these methods to a real machining plant allows an analysis of the practicability of potentially saving energy through benchmarking. [ABSTRACT FROM AUTHOR]

Italian energy policy has determined important keystones in building energy efficiency regulations and their application throughout the country. However, there is still much work to be done in order to make sustainable societies and territories, especially in historical contexts that have the greatest potentiality of energy saving. In detail, in the framework of conservation, restoration, refurbishment, and retrofit actions, the debate among scientists, administrators and skilled people is still open due to the many aspects yet to be considered and solved. In this paper, the state of the art of Italian residential building heritage has been reviewed, while energy retrofit issues and viable solutions have been investigated by collecting literature examples and experiences, focusing on common retrofit measures on historical buildings per thematic area. Finally, the advantages and disadvantages of each action have been discussed. Anyway, two main aspects have to be solved yet: the high Payback Times and the restriction about Renewable Energy Sources installation on this kind of buildings. [ABSTRACT FROM AUTHOR]

Energy efficiency program (EEP) is one of the demand-side management programs that can solve the demand-side and network-side problems. In this paper, a new concept of energy efficiency (EE) on the microgrid considering economic and technical impacts is introduced. The impacts of EE are considered on sitting of green virtual resources such as EEP as well as wind and solar power plants. The EE consists of two terms, economic and technical terms that are introduced in this paper. New indexes such as the efficient reliability index (ERI) are introduced to evaluate the EE. The presented model is implemented on the IEEE standard 33-bus test system. The model of the problem is the mixed integer non-linear programming (MINLP) and the problem is solved by the genetic algorithm in the MATLAB software. The results show the effectiveness of the proposed method and the presented model. • The impacts of green virtual resources are investigated to manage energy scheduling. • A mathematical model of the energy efficiency programs is suggested. • Techno-economic indices for energy efficiency evaluation are presented. • Optimal status of GVRs aiming at economic efficiency maximization is determined. [ABSTRACT FROM AUTHOR]

Global demand for heating accounts for more than 50% of primary energy consumption. Thermal energy for such purposes is produced mainly by natural gas, electricity, biomass, geothermal, and solar thermal technologies. Solar energy is an abundant, but low density, resource which can be harvested with little environmental impacts. In order to achieve outputs suitable for commercial and industrial applications, optical concentrators are conventionally required to increase the temperature and efficiency of a solar thermal system's output. In this paper, we instead explore the potential for utilizing energy concentrators to boost the performance of solar thermal collectors. To determine the feasibility of this approach, engineering limitations are established for realistic energy concentrators. Our analysis reveals that maximum effective energy concentration ratios of 176 and 2208 are possible for passive and active energy concentrators, respectively. Overall, this study demonstrates the potential of this concept for solar thermal collectors and other low-grade sources of heat. [ABSTRACT FROM AUTHOR]

In this paper we compare the technical and economical performances of a high temperature proton exchange membrane fuel cell with those of an internal combustion engine for a 10 kW combined heat and power residential application. In a view of social innovation, this solution will create new partnerships of cooperating families aiming to reduce the energy consumption and costs. The energy system is simulated through a lumped model. We compare, in the Italian context, the total daily operating cost and energy savings of each system with respect to the separate purchase of electricity from the grid and production of the thermal energy through a standard boiler. The analysis is carried out with the energy systems operating with both the standard thermal tracking and an optimized management. The latter is retrieved through an optimization methodology based on the graph theory. We show that the internal combustion engine is much more affected by the choice of the operating strategy with respect to the fuel cell, in terms long term profitability. Then we conduct a net present value analysis with the aim of evidencing the convenience of using a high temperature proton exchange membrane fuel cell for cogeneration in residential applications. [ABSTRACT FROM AUTHOR]

The IHX (internal heat exchanger) is introduced in some refrigeration systems in order to achieve higher energy performances. Results obtained vary greatly depending on the refrigerant used and working conditions. This paper describes a drop-in analysis of IHX effects on the performance of a vapour compression system using R1234ze(E) and R450A (R134a/R1234ze(E) commercial mixture) as R134a low-GWP replacements. The tests were carried out in a completely monitored vapour compression system varying the condensing and evaporating temperature, with and without a counter-current flow tube-in-tube IHX. Because the cooling capacity rises and the power consumption remains similar, the conclusion is that the IHX has a positive influence on the energy efficiency for all refrigerants tested. The COP (coefficient of performance) gain using R1234ze(E) is the highest observed (overcomes the R134a COP for the same conditions). The R1234ze(E) and R450A discharge temperature increments are lower than those of R134a so does not reach dangerous values and the IHX pressure drops are also below than that of R134a. [ABSTRACT FROM AUTHOR]

Retrofit analysis toolkits can be used to optimize energy or cost savings from retrofit strategies, accelerating the adoption of ECMs (energy conservation measures) in buildings. This paper provides an up-to-date review of the features and capabilities of 18 energy retrofit toolkits, including ECMs and the calculation engines. The fidelity of the calculation techniques, a driving component of retrofit toolkits, were evaluated. An evaluation of the issues that hinder effective retrofit analysis in terms of accessibility, usability, data requirement, and the application of efficiency measures, provides valuable insights into advancing the field forward. Following this review the general concepts were determined: (1) toolkits developed primarily in the private sector use empirically data-driven methods or benchmarking to provide ease of use, (2) almost all of the toolkits which used EnergyPlus or DOE-2 were freely accessible, but suffered from complexity, longer data input and simulation run time, (3) in general, there appeared to be a fine line between having too much detail resulting in a long analysis time or too little detail which sacrificed modeling fidelity. These insights provide an opportunity to enhance the design and development of existing and new retrofit toolkits in the future. [ABSTRACT FROM AUTHOR]

The coordinated actions of the central and the provincial governments are important in improving China's energy efficiency. This paper uses a three-dimensional decomposition model to measure the contribution of each province in improving the country's energy efficiency and a small-sample hybrid model to forecast this contribution. Empirical analysis draws the following conclusions which are useful for the central government to adjust its provincial energy-related policies. (a) There are two important areas for the Chinese government to improve its energy efficiency: adjusting the provincial economic structure and controlling the number of the small-scale private industrial enterprises; (b) Except for a few outliers, the energy efficiency growth rates of the northern provinces are higher than those of the southern provinces; provinces with high growth rates tend to converge geographically; (c) With regard to the energy sustainable development level, Beijing, Tianjin, Jiangxi, and Shaanxi are the best performers and Heilongjiang, Shanxi, Shanghai, and Guizhou are the worst performers; (d) By 2020, China's energy efficiency may reach 24.75 thousand yuan per ton of standard coal; as well as (e) Three development scenarios are designed to forecast China's energy consumption in 2012–2020. [ABSTRACT FROM AUTHOR]

In this paper, we reported the current status of the energy sector and its future challenges in Morocco. Recent strategies deployed by the government for sustainable development were reviewed and discussed. These strategies put the transition to renewable alternatives on the top of the national policy implications for energy security and low-carbon economy. We have also suggested a methodological tool to prioritize energy alternatives for power generation. It was found that wind energy is the most appropriate power generation alternative in Morocco at the current level. [ABSTRACT FROM AUTHOR]

The Swedish energy audit program is a publicly financed program, mainly targeting small and medium-sized firms to help them finance energy audits. By examining suggested and implemented energy efficiency measures from the energy audits conducted in 241 firms in the program, the aim of this paper is to examine the energy efficiency implementation gap and the cost efficiency of the program. The audits show that the firms' average annual energy efficiency improvement potential is between 860 and 1270 MWh/year which corresponds to a total energy efficiency improvement potential of between 6980 and 11,130 MWh/firm. The implementation rate of the suggested energy efficiency improvement measures in the SEAP is 53%. The program has resulted in investments in energy efficiency improvements between €74,100and €113,000/firm. [ABSTRACT FROM AUTHOR]

The importance of technology heterogeneity in estimating economy-wide energy efficiency has been emphasized by recent literature. Some studies use the metafrontier analysis approach to estimate energy efficiency. However, for such studies, some reliable priori information is needed to divide the sample observations properly, which causes a difficulty in unbiased estimation of energy efficiency. Moreover, separately estimating group-specific frontiers might lose some common information across different groups. In order to overcome these weaknesses, this paper introduces a latent class stochastic frontier approach to measure energy efficiency under heterogeneous technologies. An application of the proposed model to Chinese energy economy is presented. Results show that the overall energy efficiency of China's provinces is not high, with an average score of 0.632 during the period from 1997 to 2010. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines the prediction of energy efficiency indices of driven wheels (i.e. traction coefficient and tractive power efficiency) as affected by wheel load, slippage and forward velocity at three different levels with three replicates to form a total of 162 data points. The pertinent experiments were carried out in the soil bin testing facility. A feed-forward ANN (artificial neural network) with standard BP (back propagation) algorithm was practiced to construct a supervised representation to predict the energy efficiency indices of driven wheels. It was deduced, in view of the statistical performance criteria (i.e. MSE (mean squared error) and R 2), that a supervised ANN with 3-8-10-2 topology and Levenberg–Marquardt training algorithm represented the optimal model. Modeling implementations indicated that ANN is a powerful technique to prognosticate the stochastic energy efficiency indices as affected by soil-wheel interactions with MSE of 0.001194 and R 2 of 0.987 and 0.9772 for traction coefficient and tractive power efficiency. It was found that traction coefficient and tractive power efficiency increase with increased slippage. A similar trend is valid for the influence of wheel load on the objective parameters. Wherein increase of velocity led to an increment of tractive power efficiency, velocity had no significant effect on traction coefficient. [Copyright &y& Elsevier]

Abstract: Energy efficiency plays an important role in mitigating energy security risks and emission problems. In this paper, energy efficiency resources are modeled as efficiency power plants (EPP) to evaluate their impacts on generation expansion planning (GEP). The supply curve of EPP is proposed using the production function of electricity consumption. A decision making framework is also presented to include EPP in GEP problem from an investor's point of view. The revenue of EPP investor is obtained from energy cost reduction of consumers and does not earn any income from electricity market. In each stage of GEP, a bi-level model for operation problem is suggested: the upper-level represents profit maximization of EPP investor and the lower-level corresponds to maximize the social welfare. To solve the bi-level problem, a fixed-point iteration algorithm is used known as diagonalization method. Energy efficiency feed-in tariff is investigated as a regulatory support scheme to encourage the investor. Results pertaining to a case study are simulated and discussed. [Copyright &y& Elsevier]

Abstract: This paper presents an innovative low-energy district heating (DH) concept based on low-temperature operation. The decreased heating demand from low-energy buildings affects the cost-effectiveness of traditionally-designed DH systems, so we carried out a case study of the annual energy performance of a low-energy network for low-energy houses in Denmark. We took into account the effect of human behaviour on energy demand, the effect of the number of buildings connected to the network, a socio-economic comparison with ground source heat pumps, and opportunities for the optimization of the network design, and operational temperature and pressure. In the north-European climate, we found that human behaviour can lead to 50% higher heating demand and 60% higher heating power than those anticipated in the reference values in the standard calculations for energy demand patterns in energy-efficient buildings. This considerable impact of human behaviour should clearly be included in energy simulations. We also showed that low-energy DH systems are robust systems that ensure security of supply for each customer in a cost-effective and environmentally friendly way in areas with linear heat density down to 0.20 MWh/(m year), and that the levelized cost of energy in low-energy DH supply is competitive with a scenario based on ground source heat pumps. The investment costs represent up to three quarters of the overall expenditure, over a time horizon of 30 years; so, the implementation of an energy system that fully relies on renewable energy needs substantial capital investment, but in the long term this is sustainable from the environmental and socio-economic points of view. Having demonstrated the value of the low-energy DH concept, we evaluated various possible designs with the aim of finding the optimal solution with regard to economic and energy efficiency issues. Here we showed the advantage of low supply and return temperatures, their effect on energy efficiency and that a DH design that relies on low-temperature operation is superior to a design based on low-flow operation. The total primary energy use in the best design was 14.3% lower than the primary energy use for standard, recently designed networks, and distribution heat losses were halved. Moreover, the exploitation of the entire available pressure by means of careful network design decreased the average pipe size required, which slightly lowers the investment costs for purchasing and laying the pipelines in the ground. This low-temperature DH concept fits the vision of the future energy-sustainable society. [Copyright &y& Elsevier]

Abstract: This paper introduces the Quick-E-Scan methodology that has been developed to achieve the operational energy efficiency of small & medium enterprises (SMEs), characterized by being scarcely disposed to long energy audits and by a limited budget for energy management programs. On one side, through dividing the firm into functional units – either service (lighting, HVAC, etc.) or production units – the main consuming areas are identified and a criticality index is defined; conversely, an enhancement index highlights the gap of each unit towards the best available techniques (BATs) in energy management programs. Finally, a priority index, created with the junction of the two indexes, points out the most profitable areas in which energy saving measures should be implemented. The methodology, particularly quick and simple, has been successfully tested in 38 SMEs in Northern Italy. [Copyright &y& Elsevier]