Summary
Ethylene‐cracking furnace has the highest energy consumption of all the devices used in the ethylene industry. The accurate energy‐efficiency evaluation of an ethylene‐cracking furnace is ...therefore of great significance for energy saving and productivity gain in ethylene production. Traditionally, a data envelopment analysis (DEA) model has been used to evaluate the energy efficiency. However, ethylene‐cracking furnace also involves a multi‐index and multiworking‐condition energy‐efficiency evaluation problem that results from there being multiple material flows, multiple energy flows, and multiple production loads. Therefore, this paper proposes a new energy efficiency evaluation solution for an ethylene‐cracking furnace that is based on the integrated technique for order preference by similarity to ideal solution (TOPSIS)‐DEA model. First, from the perspective of material and energy flows, an energy‐efficiency vector (EEV) is designed and integrated into the DEA model to meet the demand for multi‐index evaluation. Second, to eliminate interference of changes in working condition on energy efficiency, double virtual energy‐efficiency benchmarks (DVEEBs) are built using the relationship between EEV, operating conditions, and nonoperational factors, based on the established cracking model. Finally, the rearranged values of the EEV is solved by the TOPSIS method and then evaluated by the DEA model. The actual numerical results show that the proposed solution can support energy‐efficiency evaluation of an ethylene‐cracking furnace subject to the multiple indexes and multiple working conditions. Specifically, the interference of changes in the working condition on the evaluation results can be reduced greatly which ensures the accuracy and objectivity of the energy‐efficiency evaluation results.
Display omitted
•A new theory named “crossover relaxor ferroelectrics” were reported.•Crossover relaxor 0.9BBNT-0.1SSN ceramic processes high Wrec of 2.02 J/cm3 and η of 90.18% at ...206 kV/cm.•0.9BBNT-0.1SSN ceramic exhibits strong chemical and electrical uniformity.•The excellent thermal stability, frequency stability, and cycle life stability have been achieved in 0.9BBNT-0.1SSN ceramic.
With a view to the rapid development of pulsed power capacitors, the demands for higher energy density, energy efficiency, and stability have increased significantly. A large amount of research has been devoted to the energy storage field of dielectric ceramics, however, scientific and effective strategy to design novel materials with excellent energy storage performance is still lacking. In this work, a new guideline was proposed that higher energy density and efficiency are easier obtained in crossover relaxor ferroelectrics, which is between normal ferroelectrics and relaxor ferroelectrics. Based on this theory, a series of lead-free (1-x)(0.65BaTiO3-0.35Bi0.5Na0.5TiO3)-xSr(Sc0.5Nb0.5)O3 ((1-x)BBNT-xSSN, x = 0, 0.05, 0.10, 0.15, 0.20) ceramics are designed and investigated. Optimal energy storage properties are achieved in 0.9BBNT-0.1SSN ceramic, with a large Wrec of 2.02 J/cm3 and a high η of 90.18% under a moderate electric field of 206 kV/cm. More importantly, both the Wrec and η of 0.9BBNT-0.1SSN ceramic show outstanding stability (including frequency, thermal, and cycle life stability) at 150 kV/cm, which is superior to other lead-free ceramics. These results demonstrate 0.9BBNT-0.1SSN ceramic is a promising candidate for practical energy storage applications.
Energy efficiency is a complex concept which is represented in diverse fields including engineering, economics, energy, computer sciences, environmental sciences, mathematics and physics. The social ...sciences literature on energy efficiency, however, remains significantly underrepresented, comprising just 2.6% of the total energy efficiency literature found in this study. Energy efficiency is an important energy policy strategy globally to reduce energy consumption, secure energy supply, and reduce greenhouse gas emissions. Despite this, however, evidence shows that on a global scale, energy demand is rising and climate mitigation targets are not being met. There is an acknowledgement by scientists that these challenges cannot be viewed as simply technical in nature but rather the product of collective social and cultural factors. Therefore, more social science research is needed to support an energy transition towards cleaner energy sources. Specifically, there is a need to further disentangle what is meant by energy efficiency from a social sciences perspective, including, critically, its conceptual foundations and practical applications. This review seeks to understand these issues by exploring how energy efficiency is conceptualized, both historically and today, by different actors. Research shows that the way that the concept of energy efficiency is applied to the physical, material world is a value judgement that brings with it societal trade-offs that are not fully understood. That is, that applying any given conceptualization or methodology of energy efficiency to physical processes can privilege certain interests over others, and affect society in different ways. For example, such tradeoffs include pollution displacement, lower than expected energy savings and an unfair cost burden on certain groups. Bringing together technical and qualitative insights from economics, energy, engineering, science and technology studies and history, this review builds on the work of efficiency and energy social scientists to illustrate what we need to do in order to bridge a conceptual gap in the energy efficiency literature, and in practice. The findings show a diversity of conceptualizations in the energy efficiency literature, highlighting the fact that energy efficiency can mean different things depending on how it is defined and applied. The review finds that greater efforts are needed to integrate energy efficiency discussions into sociological frames including ethics, equality, philosophy and history for more diverse, comprehensive and balanced research.
Characterising the energy efficiency grades of machining systems (MS) is an effective analytical methodology or management tool that helps to establish the high energy-efficient MS. However, the ...current MS energy efficiency approaches still lack scientific and practical formulation strategies to addresses this issue due to its multi-source and variable energy consumption characteristics. Focusing on this challenge, a new concept of inherent energy efficiency (IEE), which is formed in the design and formation phases of the MS, is proposed. Meanwhile, a novel energy efficiency grade evaluation (EEGE) approach based on IEE is also presented. The proposed EEGE approach not only can evaluate the MS energy efficiency grades, but also can reveal the MS high energy-efficient intervals. According to the analysis of IEE in MS, the EEGE approach is developed in three steps: (i) the establishment of IEE evaluating indicator system from both inherent energy utilisation (IEU) and inherent specific energy (ISE), (ii) the acquisition of the IEE, and (iii) the development of a quantitative method for the EEGE in MS. Finally, a case study of energy efficiency grade evaluation and analysis for an XK714D CNC milling machining centre is examined, illustrating the practicability of the proposed method.
•EU policy efforts on energy efficiency in buildings stared in the 1970s in response to the oil crisis.•The first comprehensive EU policy was the SAVE directive in 1992, introducing policy actions ...still relevant today.•A major step forward was the Energy Performance of Buildings Directive in 2002 and its subsequent amendments.•Mandatory energy performance standards are progressively converging towards near zero energy buildings.•Additional policies and financing are needed for the full decarbonisation of the building stock.
The reduction of energy demand in buildings through the adoption of energy efficiency policy is a key pillar of the European Union (EU) climate and energy strategy. Energy efficiency first emerged in the EU energy policy agenda in the 1970s and was progressively transformed with shifting global and EU energy and climate policies and priorities. The paper offers a review of EU energy policies spanning over the last half century with a focus on policy instruments to encourage measures on energy efficiency in new and existing buildings. Starting from early policies set by the EU in response to the Oil Embargo in the 1973, the paper discusses the impact of EU policies in stimulating energy efficiency improvements in the building sector ranging from the SAVE Directive to the recently 2018 updated Energy Performance of Buildings Directive and Energy Efficiency Directive. The review explores the progress made over the last 50 years in addressing energy efficiency in buildings and highlights successes as well as remaining challenges. It discusses the impact of political priorities in reshaping how energy efficiency is addressed by EU policymakers, leading to a holistic approach to buildings, and provides insights and suggestions on how to further exploit the EU potential to save energy from buildings.
The concept of energy-efficient networking has begun to spread in the past few years, gaining increasing popularity. Besides the widespread sensitivity to ecological issues, such interest also stems ...from economic needs, since both energy costs and electrical requirements of telcos' and Internet Service Providers' infrastructures around the world show a continuously growing trend. In this respect, a common opinion among networking researchers is that the sole introduction of low consumption silicon technologies may not be enough to effectively curb energy requirements. Thus, for disruptively boosting the network energy efficiency, these hardware enhancements must be integrated with ad-hoc mechanisms that explicitly manage energy saving, by exploiting network-specific features. This paper aims at providing a twofold contribution to green networking. At first, we explore current perspectives in power consumption for next generation networks. Secondly, we provide a detailed survey on emerging technologies, projects, and work-in-progress standards, which can be adopted in networks and related infrastructures in order to reduce their carbon footprint. The considered approaches range from energy saving techniques for networked hosts, to technologies and mechanisms for designing next-generation and energy-aware networks and networking equipment.
Direct Air Capture (DAC) is a promising technology to fight climate change by capturing carbon dioxide (COsub.2) from the air. For DAC to be a negative emissions technology, the captured COsub.2 must ...be removed permanently, but can also be used as a net-zero technology to produce sustainable chemicals, fuels or other materials. This review presents a comprehensive survey of recent advancements, challenges, and potential applications of DAC technology, with an emphasis on the recent rapid increase in the number of DAC developers, the majority of them being founded in the past 4 years. Through pilot projects and recent commercial deployments, several DAC companies have made significant advances and demonstrated their scalability. Cost and energy efficiency remain significant impediments to the wide deployment of DAC. Integration with emission-free energy sources and utilization of waste heat are being researched to boost the total energy efficiency of DAC systems. Further research of electrochemical technologies for regeneration or direct capture are needed, as well as the development of new, modified, or hybrid adsorbents for improved capture efficiencies. Moreover, favorable regulations and financial incentives are crucial for enhancing the viability of DAC projects and will need to substantially increase if Paris Agreement goals are to be achieved.
This paper empirically investigates factors driving the adoption of energy-efficiency measures by small and medium-sized enterprises (SMEs). Our analyses are based on cross-sectional data from SMEs ...which participated in a German energy audit program between 2008 and 2010. In general, our findings appear robust to alternative model specifications and are consistent with the theoretical and still scarce empirical literature on barriers to energy-efficiency in SMEs. More specifically, high investment costs, which are captured by subjective and objective proxies, appear to impede the adoption of energy-efficiency measures, even if these measures are deemed profitable. Similarly, we find that lack of capital slows the adoption of energy-efficiency measures, primarily for larger investments. Hence, investment subsidies or soft loans (for larger investments) may help accelerating the diffusion of energy-efficiency measures in SMEs. Other barriers were not found to be statistically significant. Finally, our findings provide evidence that the quality of energy audits affects the adoption of energy-efficiency measures. Hence, effective regulation should involve quality standards for energy audits, templates for audit reports or mandatory monitoring of energy audits.
► We empirically analyze barriers to the adoption of energy-efficiency measures in SMEs. ► We focus on firms participating in the German energy audit program for SMEs. ► The program overcomes information related barriers. ► High investment costs still impede the adoption even for profitable measures. ► Low audit quality also impedes the adoption of profitable measures.
‘Energy efficiency first’ is one of the key principles of the Energy Union, mainly due to it being the most cost effective way to reduce emissions, improving energy security, enhancing competitiveness ...and making energy consumption more affordable for all consumers. In light of the revised EU Energy Efficiency Directive, this paper discusses new developments brought by the EU together with the national case studies of Slovenia and Spain. Given that the paper has a specific focus on the industrial sector, it discusses the selected measures of the Energy Efficiency Directive, such as defined in Articles 7, 8, and 14, which are the most relevant to this sector. The paper also explores the newly issued integrated national energy and climate plans together with national measures and policies that support energy efficiency in industry, including the quantification of achieved and forecast energy savings in these two EU Member States.
•The revised EU Energy Efficiency Directive is the key driver of change in Member States.•More ambitious energy efficiency targets are projected in Slovenia and Spain for 2030.•The integrated National Energy and Climate plans inspired further national developments.•Both countries committed to continue their national measures/schemes on energy efficiency.
At present, China is transforming into a green development mode in all respects, and improving green energy efficiency is a key component of this transformation. Using panel data of 2011–2018, this ...research adopts the Super-SBM (Slack-Based Model) to calculate the green energy efficiencies of China's 29 provinces and a GML (Global Malmquist-Luenberger) index method to explain the efficiency changes. Empirical analysis draws the following conclusions: 1) China's green energy efficiency presented a slowly decreasing rather than increasing trend. 2) Technological progress was a major factor in efficiency improvement. However, its contribution was canceled by energy overuse. 3) Provinces with low green energy efficiency tend to geographically gather in the regions with rich energy resource endowment. Instead, provinces with high green energy efficiency are relatively geographically scattered, and most of them are China's most developed regions. 4) Green energy efficiencies among China's four major regions have significant differences. Generally, the mean level is east > northeast > west > central. 5) The key policy directions to improve China's green energy efficiency include using transfer payment to balance the regional development, breaking down the barriers among provinces to facilitate energy circulation, and refining energy price structure to mitigate rebound effects.
•Green energy efficiency of each province in China is measured by the Super-SBM.•A GML index method is used to decompose the efficiency changes.•China's green energy efficiency presented a slowly decreasing trend in 2011–2018.•Energy overuse hindered the improvement of China's green energy efficiency.•Transfer payment, breaking down provincial barriers, and refining energy price structure are suggested.
PDF
