Energy Efficiency Evaluation Research Articles

Research on Energy Efficiency Evaluation and Optimization of Intelligent Plant Equipment Based on Data-driven

Research on Energy Efficiency Evaluation and Optimization of Intelligent Plant Equipment Based on Data-driven

A combined evaluation of energy efficiency, customer satisfaction and food waste in the healthcare sector by comparing cook-hold and cook-chill catering

The healthcare sector greatly impacts the environment through energy, transport, product use, disposal and food service. This requires significant interventions to reduce energy consumption and waste generation and increase customer satisfaction simultaneously. Considering the need to investigate food waste amounts and energy consumption in hospitals, the present research has a triple goal. First, it evaluates energy consumption and efficiency by comparing cook-hold and cook-chill catering. Second, it estimates the customer satisfaction of the served meals and third, it assesses the food waste quantities at lunch and dinner among hospital patients. Specifically, the research combines (a) the evaluation of the energy consumption, based on primary data collected in a cooking center with a production capacity of 1590 meals per production cycle; (b) the investigation of the consumers’ behavior among 984 patients located in nine different hospital units in Southern Italy; (c) the measurement of food waste based on questionnaire-survey data. Results highlight the reduction in diesel consumption (– 42%) and in electricity consumption (– 93%), as well as the reduction in food waste (– 85%) when comparing cook-hold with cook-chill catering. This research illustrates a guideline in the field of efficient catering. It helps identify sustainable pathways and interventions toward energy efficiency, customer satisfaction, and food waste minimization for policymakers, healthcare professionals, catering companies or patients.

Conceptual Design and Energy Efficiency Evaluation for a Novel Torque Vectoring Differential Applied to Front-Wheel-Drive Electric Vehicles

This paper presents a novel differential with lateral torque vectoring activated by an auxiliary motor, called motor-modulated lateral torque vectoring differential, or briefly, MLTD. Its architecture and kinematic characteristics are described, and the optimal cornering performance due to torque vectoring is evaluated using a steady-state vehicle dynamic model. Then, a conceptual design case of MLTD installed in a front-wheel-drive electric vehicle is conducted to assess its feasibility in terms of cornering, driving performances, and energy efficiency performance. The calculations show that an optimal distribution ratio between left and right torques for maximum lateral acceleration can be obtained for a specific cornering condition, further used for DM sizing in the preliminary stage. The simulations for energy consumption at constant-speed turning reveal that energy efficiencies of MLTD are lower than those of conventional differentials with evenly distributed torques. However, this deficiency may be paid off by moderately cutting down the rolling resistance of tire while the superior cornering performances brought by torque vectoring is still preserved. Accordingly, the newly proposed MLTD possesses greater flexibility to improve energy efficiency and driving range of electric vehicles without trading off against its desirable cornering performance and safe handling, and is thus worthy of further development.

Evidence-based numerical building model enhancement and building energy efficiency evaluation in the case of Morocco

This paper presents a framework for numerical building validation enhancement based on detailed building specifications from in-situ measurements and evidence-based validation assessment undertaken on a detached sustainable lightweight building in a semi-arid climate. The validation process has been undergone in a set of controlled experiments – a free-float period, and steady-state internal temperatures. The validation was conducted for a complete year with a 1-min time step for the hourly indoor temperature and the variable refrigerant flow (VRF) energy consumption. The initial baseline model was improved by three series of validation steps per three different field measurements including thermal transmittance, glazing thermal and optical properties, and airtightness. Then, the accurate and validated model was used for building energy efficiency assessment in 12 regions of Morocco. This study aims to assess the effect of accurate building characteristics values on the numerical model enhancement. The initial CV(RMSE) and NMBE have improved respectively from 14.58 % and −11.23 %–7.85 % and 1.86 % for the indoor temperature. Besides, from 31.17 % to 14.37 %–20.57 % and 9.77 % for energy consumption. The findings demonstrate that the lightweight construction with the use of a variable refrigerant flow system could be energy efficient in the southern regions of Morocco.

Energy efficiency evaluation and optimization of active distribution networks with building integrated photovoltaic systems

With the rapid development of building integrated photovoltaic (BIPV) technology, rooftop PV grid-connected systems face challenges in operation. When the consumption rate of BIPV systems is low, power reverse increases distribution network losses and decreases power supply quality. Traditional energy efficiency evaluations for distribution networks do not consider the impact of low BIPV consumption rates on network losses. This paper establishes an energy efficiency evaluation model for distribution networks with BIPV systems based on adversarial interpretive structural modeling and proposes an energy efficiency indicator system applicable to distribution networks with BIPV systems. The method was applied to eight distribution networks with BIPV systems, achieving accurate energy efficiency level rankings. Through single-factor sensitivity analysis of the indicator system, the primary factors affecting distribution networks with BIPV systems energy efficiency were identified. A reactive power optimization model based on multi-objective particle swarm optimization algorithm was established. After optimization, network losses decreased by 153 kW, PV consumption rate increased by 73 %, and node voltage drift was significantly enhanced. Corresponding loss reduction strategies were proposed for other indicators. This paper provides valuable references for planning and renovating distribution networks with BIPV systems.

Research on Energy Efficiency Evaluation Model of Substation Building Based on AHP and Fuzzy Comprehensive Theory

The traditional energy-saving evaluation method for industrial buildings is intended for all industrial buildings; however, substation buildings belong to a special category of industrial buildings, and their energy consumption characteristics are different from those of general industrial buildings. Consequently, it is necessary to establish an energy-saving evaluation system for substation buildings according to the characteristics of their energy consumption. In view of the issue that the energy consumption characteristics of substation buildings are different from those of other industrial buildings, an analytic hierarchy process (AHP) and fuzzy comprehensive evaluation (FCE) are used to establish a more comprehensive energy saving evaluation model that is more applicable to substation buildings. This paper determines 19 quantitative indicators and 13 qualitative indicators through the screening of relevant standards and norms, as well as the literature, and then determines the weight of each indicator by using AHP before finally establishing a secondary evaluation model based on FCE. In this paper, a substation in Shandong, China was selected as a case study to verify the proposed evaluation model, scoring 80.4 points, which falls within the “Good” grade. This method is of great significance for the future establishment of energy-saving evaluation system for substation buildings.

Energy Efficiency Evaluation for Battery Energy Storage Stations Based on AHP-TOPSIS

The development of energy storage is a necessary support for the realization of the green energy future. At present, battery energy storage stations (BESSs) consume large amounts of energy, the energy loss relationships between various devices in a station are complex, and there is a lack of energy loss analysis and statistical methods for BESSs. It poses challenges to the further development of BESSs in the power grid. To deal with this issue, this paper establishes the energy loss indicators and proposes the energy loss evaluation methods for BESSs. The simulation results verify that the proposed method can accurately reflect the overall energy loss level of the BESSs and the proposed method of energy loss estimation and analysis can support the development of energy saving and loss reduction.

A novel district heating system based on absorption heat exchange and water-heat combined supply

Considering the challenges posed by long transportation distances and poor heating economy in large-scale heating systems based on conventional steam extraction cogeneration in nuclear power plants, a novel district heating system is proposed. This novel system is based on absorption heat exchange and water-heat combined supply. It offers significant improvements in heating and transportation capacity, while reducing the required investment in pipelines and transportation power consumption. In this study, an example of an AP1000 nuclear power turbine unit was used to construct a novel system. Additionally, a comprehensive energy efficiency evaluation model was established for this system. A comparison with the conventional district heating system based on cogeneration revealed several notable advantages of the novel system: (1) the comprehensive equivalent electricity decreased from 45.3 kWh/GJ to 31.2 kWh/GJ, representing a 31.1% reduction; (2) the unit heating cost decreased from 51.1 CNY/GJ to 42.0 CNY/GJ, resulting in potential savings of 10,726.17 × 104 CNY during a heating season; and (3) the emissions of CO2, SO2, and NOx were reduced by approximately 117.78 × 104 tons, 3.55 × 104 tons, and 1.77 × 104 tons, respectively.

The Evaluation of Energy Efficiency and its Decoupling from Economic Growth under the Carbon Peak Target

Abstract The Global Malmquist-Luenberger index was used to measure the energy efficiency of 11 provinces and regions in eastern China from 2010 to 2019, the Tapio decoupling model was constructed to analyze the decoupling relationship between economic growth and energy consumption and energy use efficiency, and the prediction results of the carbon peak time of each province in the existing literature were combined to put forward suggestions for the provinces that were not ideal for the decoupling. The results show that: (1) The total average energy efficiency of the 11 eastern regions of China during the period from 2010 to 2019 was 0.911, showing an overall upward trend, while the energy efficiency changes in each region were different; (2) The decoupling of economic growth, energy consumption and energy efficiency in Hebei and Hainan provinces was not ideal, and the decoupling in other regions was getting better; (3) There will be a large gap in the time of carbon peak in 11 regions in eastern China. Beijing, Tianjin, Shanghai, Jiangsu, Zhejiang, Guangdong and Liaoning will achieve carbon peak in 2030 and before; There will be no peaks in Hebei and Hainan regions, while the peaks in Shandong and Fujian appear after 2030. JEL classification numbers: F06. Keywords: Carbon peak, Eastern region, Energy efficiency, Tapio decoupling model, Directional distance function, Global Malmquist-Luenberger index (GML).

Application of the novel three-stage DEA model to evaluate total-factor energy efficiency: A case study based on 30 provinces and 8 comprehensive economic zones of China

The carbon emissions issues majorly caused by energy consumption have become a public concern around the globe. As a major energy consumer and carbon emitter in the world, it is imperative for China to improve energy efficiency. Moreover, energy efficiency evaluation can provide evidence for policy formulating. This study measures and analyzes the total-factor energy efficiencies of China's provincial and comprehensive economic zones during 2008–2017 based on the novel three-stage Data Exchange Agreement (DEA)model, which is upgraded by introducing the super-efficiency Slacks-Based Measurement (SBM) model with the undesirable output into the traditional three-stage DEA model. The empirical results illustrate that environmental regulation, economic development, and technical innovation are significantly affect total-factor energy efficiencies. The total-factor energy efficiencies and their rankings of different provinces and eight comprehensive economic zones in China change significantly after removing the environmental variables and statistical noise. The energy efficiencies of eight comprehensive economic zones show a decreasing trend from “the east, the central to the west”, and the gap between them are also widening. This study provides policy implications and empirical evidence for China to improve energy efficiency, reduce carbon emissions and consequently, achieve the green sustainable development goals.

Quality and energy efficiency evaluation of Rosmarinus officinalis L. by intermittent and continuous microwave drying: Polyphenol composition, bioactive compounds quantification, antioxidant properties, physical characteristics, and energy consumption

AbstractImproper drying is one of the major causes of beneficial bioactive compounds' degradation in bio‐crops together with high energy consumption. Preservation of the compounds is crucial in retaining the bioactivities of the herbs with diverse industrial applications. Continuous microwave drying (CMD), despite being effective and efficient, has not merged with the industry as process intensification due to the challenges of overheating. This study investigates the application of intermittent microwave drying (IMD) on rosemary and its compounds, to address the issues of overheating and the subsequent loss of bioactive compounds resulting from CMD. This technology is implemented through the application of microwaves in a periodic on/off manner. Although CMD had the shortest drying duration (>20 min) and the highest drying rate (0.431 kg H2O/kg DB min), IMD had the highest effective diffusivities (1.292 × 10−10 m2/s) indicating better moisture kinetics and evaporation. CMD exhibited favorable physical characteristics of shrinkage (83.40%), bulk density (669.23 kg/m3), and rehydration capacity (34%). However, both methods displayed high antioxidant activity (90.36%–93.78% inhibition). Higher compound concentrations of Carnosic acid (4.85 mg/g), Carnosol (6.86 mg/g), and Rosmarinic acid (14.36 mg/g) were achieved using IMD. Lastly, IMD had a higher energy efficiency (1.70%) than CMD due to drying by residual heat generation and redistribution.Practical applicationDrying is a crucial first post‐harvest process to preserve aromatic and medicinal herbs and plants for downstream processing. However, the sensitive and diverse nature of bioactive compounds makes it practically impossible to implement one drying technology to process all. Microwave technology is highly favored by researchers as well as industries to replace traditional convective hot air drying due to its effectiveness and higher efficiency. Nevertheless, the overheating issue from the continuous microwave is still a challenge while processing delicate herbs and their bioactive compounds. Especially, herbs like rosemary which possesses thermolabile compounds. The current study implements microwave technology periodically to benefit from sustainable drying via microwave without overheating and subsequent loss of bioactive compounds. The outcome of this study demonstrated the effectiveness of the intermittent microwave technology which proved to be more energy efficient than continuous microwave while retaining higher bioactive compound concentration in rosemary leaves.

Simplified Multi-Life Cycle Assessment at the Urban Block Scale: GIS-Based Comparative Methodology for Evaluating Energy Efficiency Solutions

The Italian residential building stock consists of 12.2 million buildings, with 7.2 constructed post-World War II during the economic boom. These structures were designed without specific regulations for seismic safety, fire resistance, and energy efficiency, and today lies the current state of strong obsolescence. Therefore, energy refurbishment may not always be the best cost/benefit solution due to these intrinsic issues. Consequently, the transition to construction systems based on circular economy principles brings new opportunities and becomes key to proposing replacement interventions for this heritage. This paper presents a comparative GIS-based bottom-up approach to evaluate the lifecycle impact of residential building blocks, encompassing energy, environmental, and economic aspects. Two tools are introduced: one for measuring energy consumption and the other for quantifying the quantities of materials stored in buildings. This methodology permits comparing the new circular buildings and different refurbishment scenarios to identify the most suitable solution from an environmental impact and financial point of view. The application of a case study, a residential urban block in Bologna, built in 1945–1965, highlights how the demolition and reconstruction scenario based on circular economy principles presents the lowest environmental impacts and is economically competitive compared to standard deep renovation techniques.

ENERGY EFFICIENCY IN COLD CLIMATE, DESIGN STRATEGIES: A CASE STUDY OF SHUSHA CITY IN KARABAKH REGION OF THE REPUBLIC OF AZERBAIJAN

To combat climate change and ensure sustainable growth, energy efficiency is essential. This academic paper examines and evaluates energy efficiency programs in cold climates, with a focus on the cities of the Republic of Azerbaijan. The study evaluates the difficulties and opportunities that these cities confront and suggests ways to improve energy efficiency while considering local climate factors and regional peculiarities. This research seeks to contribute to sustainable energy planning and policymaking in Azerbaijan and serve as a reference for other regions with comparable climatic circumstances by examining various elements of energy usage and identifying potential improvements.

Comparison of the embodied and operating energy in agricultural greenhouses and in residential buildings

The increase of the energy efficiency in buildings and greenhouses is important for reducing the use of fossil fuels and the emissions of greenhouse gases. Energy efficiency evaluation requires the consideration of both the embodied and the operational energy. Many estimations regarding the embodied and the operational energy in various types of buildings have been reported so far. However, studies regarding the embodied energy in agricultural greenhouses are rare while there are many estimations regarding their operational energy. The goal of our study is the comparison of the embodied and the operational energy in residential buildings and in agricultural greenhouses. The embodied and operational energies are compared in greenhouses as well as in low-energy and in conventional residential buildings. Our results indicate that the ratio of embodied energy to life-cycle energy in low-energy residential buildings and in nearly-zero energy buildings varies in the range at 36% to 83% that is significantly higher than the ratio in conventional residential buildings which is in the range of 6% to 20%. The ratio of embodied energy to life-cycle energy in agricultural greenhouses, at 0.86% - 70.41%, varies significantly depending on many parameters. The importance of carbon emissions related to embodied energy in low-energy buildings, in net-zero energy buildings and in agricultural greenhouses is highlighted. Our work could be useful to policy makers who are willing to accelerate the green transition to a low carbon economy in the coming decades.

Thermal comfort and energy efficiency evaluation of a novel conductive-radiative Personal Comfort System

Personal Comfort Systems (PCSs) create a localized comfort situation satisfying individual needs. These devices have low power consumption, as they focus on local environment and thus reduce the energy consumption of main HVAC systems by extending ambient control setpoint ranges. This study focuses on assessing a new type of PCS: a warming desk. It uses the two most efficient and effective means of heat transfer for warming a person: conduction (hands) and radiation (lower and upper body parts facing the table). Two different desks were tested, both simultaneously heating upward and downward with different surface temperatures, one with a higher temperature downward and one with a higher temperature upward. The desks were tested by 30 subjects, inside a climatic chamber, kept at 17 °C air temperature. Both desks are capable of generating good overall (whole-body) comfort and thermal sensation, even leaning towards a slightly warm one for someone. Moreover, results showed that PCS based on direct contact with the skin surface temperature should be kept below 36°, while the surface warming by radiation can reach higher temperatures: personal control of power is critical, as not everyone preferred the same operative temperature. The PCS can “correct” the ambient temperature toward the neutral thermal sensation by about 7K, creating improved thermal comfort compared to centralized HVAC. In its current design, the heating surface required 170W, significantly lower than 500/1500W of a common portable electric heater. It is expected that in an optimized design, the power consumption could be reduced further to 30/40W.

Energy efficiency evaluation, technology gap ratio, and determinants of energy productivity change in developed and developing G20 economies: DEA super-SBM and MLI approaches

This study employed Slack-based measure (SBM), Meta-frontier analysis, and Malmquist–Luenberger index (MLI) approaches to measure energy efficiency (EE), production technology heterogeneity, and energy productivity variation and its main determinants in developed and developing G20 countries for the period 1995–2020. The study's findings are: (i) Average EE for G20 countries is 0.8577, but still has an improvement potential of 14.23 percent. (ii) Developed countries have a higher average EE than developing (0.8927 > 0.8290). Results further revealed that energy efficiency scores in Argentina, Australia, Brazil, France, Saudi Arabia, South Africa, the US, the UK, and Korea are>1. (iii) Technology gap ratio (TGR) value in developed countries is higher than in developing (0.9869 > 0.6801), indicating that developed countries have advanced energy technologies superiority. The average MLI is less than one, showing a decline in energy productivity mainly due to a decline in technical efficiency, as EC < TC. (iv) Developed G20 countries get 0.64 percent aggregate growth in energy productivity as their MLI score is 1.0064, mainly due to technological growth (TC = 1.0161). Developing G20 countries, on the other hand, witnessed a decline in their energy productivity during 1995–2020, as MLI = 0.9925 > 1, designating that, on average, there is a 0.75 % decline in MLI.

A bibliometric review on electric vehicle (EV) energy efficiency and emission effect research.

Electric vehicles have received extensive attention due to their unique energy efficiency and good emission reduction effects. While a large-scale of electric vehicles are gradually replacing traditional fuel vehicles, it is necessary to ensure the energy efficiency of electric vehicles and the effectiveness of their emission reduction effects. This study conducted a bibliometric analysis of scientific publications on energy efficiency and emission reduction effects of electric vehicles from 2003 to 2022, using a variety of bibliometric tools such as R Studio, biblioshiny and VOSviewer. The results showed the gradual elimination of traditional energy vehicles, where electric vehicles play an important role in connecting energy efficiency and emission control. The results also showed the top publication outlets, citations trackers, authors with thematic evaluation of energy efficiency and emission reduction effects of electric vehicles. The contribution of the study is manifold. The academic contribution of the present study is the bibliometric analysis which will help academicians to get a quick overview of the most popular journals, top collaborators, documents, authors, and scientific knowledge structure. Secondly, policy makers, environmentalists, researchers, and academician will definitely get a pathway how they should go for future research. Finally, this study suggests more researches trend to focus on the sales of electric vehicles, automobile exhaust emissions, sensitivity analysis of electric vehicles, energy storage analysis to improve the energy efficiency of electric vehicles, and V2G related to the energy efficiency of electric vehicle clusters.

Comprehensive energy efficiency analysis of ultra-supercritical thermal power units

At present, ultra-supercritical power plant is the most advanced technology, which can achieve ultra-low pollutant emissions and greatly improve the energy efficiency of power plant. In this paper, the key factors affecting the energy efficiency of thermal power unit are analyzed. Moreover, the way in which these factors affect the energy efficiency of thermal power unit is obtained. Besides, this study lay a solid foundation for subsequent improvements in the energy efficiency of thermal power unit. First, a mathematical mechanism model of ultra-supercritical thermal power units is established. In addition, Aspen Plus software is used to build a full process simulation model of thermal power unit. In addition, a methodology for energy efficiency analysis based on the exergy balance theory is presented, and energy efficiency evaluation indicators are defined. Finally, the TOPSIS method was used to rank the key factors affecting the energy efficiency of thermal power unit. Based on experimental analysis, this study found that in comparison to general unit, the ultra-supercritical thermal power units has improved boiler efficiency by approximately 2%, power generation efficiency by approximately 6.77%, carbon emissions by approximately 0.027 t/h and the exergy efficiency by approximately 2.91%, providing better energy efficiency and lower carbon emissions.

Research on a TOPSIS energy efficiency evaluation system for crude oil gathering and transportation systems based on a GA-BP neural network

As the main link of ground engineering, crude oil gathering and transportation systems require huge energy consumption and complex structures. It is necessary to establish an energy efficiency evaluation system for crude oil gathering and transportation systems and identify the energy efficiency gaps. In this paper, the energy efficiency evaluation system of the crude oil gathering and transportation system in an oilfield in western China is established. Combined with the big data analysis method, the GA-BP neural network is used to establish the energy efficiency index prediction model for crude oil gathering and transportation systems. The comprehensive energy consumption, gas consumption, power consumption, energy utilization rate, heat utilization rate, and power utilization rate of crude oil gathering and transportation systems are predicted. Considering the efficiency and unit consumption index of the crude oil gathering and transportation system, the energy efficiency evaluation system of the crude oil gathering and transportation system is established based on a game theory combined weighting method and TOPSIS evaluation method, and the subjective weight is determined by the triangular fuzzy analytic hierarchy process. The entropy weight method determines the objective weight, and the combined weight of game theory combines subjectivity with objectivity to comprehensively evaluate the comprehensive energy efficiency of crude oil gathering and transportation systems and their subsystems. Finally, the weak links in energy utilization are identified, and energy conservation and consumption reduction are improved. The above research provides technical support for the green, efficient and intelligent development of crude oil gathering and transportation systems.

Study on energy consumption characteristics of passenger electric vehicle according to the regenerative braking stages during real-world driving conditions

Electric vehicles are affected by various factors such as the ambient temperature, traffic conditions, driver behavior, vehicle weight, and route characteristics. This study evaluated the energy efficiency of an electric SUV with regenerative braking system under real-world driving conditions. Data were collected using a controller area network while driving on the same route at each regenerative braking stage. Chassis dynamometer tests were performed to verify battery consumption during acceleration and regenerative braking. From the real-world driving test, it was determined that as the regenerative braking stage increased, the battery consumption (excluding regenerative braking) and energy recovered. However, the net battery consumption decreased. In addition, as the speed increased, the energy consumption increased in the order of urban, rural, and motorway sections owing to the air resistance and rolling resistance. Although the energy efficiency tended to increase with the regenerative braking stage, we observed that the real-world driving environment also had an impact. Therefore, in energy efficiency evaluation research, it is essential to analyze the results that reflect the various influencing factors in real-world driving environments and to verify the characteristics of each regenerative braking stage through chassis dynamometer tests.