This paper studies the integration of heat pump units (HPUs) to enhance the thermal efficiency of a combined heat and power plant (CHPP). Different solutions of integrate the HPUs in a combined-cycle gas turbine (CCGT) plant, the CCGT-450, are analyzed based on simulations developed on “United Cycle” computer-aided design (CAD) system. The HPUs are used to explore low-potential heat sources (LPHSs) and heat make-up and return network water. The use of HPUs to regulate the gas turbine (GT) intake air temperature during the summer operation and the possibility of using a HPU to heat the GT intake air and replace anti-icing system (AIS), over the winter at high humidity conditions were also analyzed. The best solution was obtained for the winter operation mode replacing the AIS by a HPU. The simulation results indicated that this scheme can reduce the underproduction of electricity generation by the CCGT unit up to 14.87% and enhance the overall efficiency from 40.00% to 44.82%. Using a H... [more]

The process of material removal from a workpiece to obtain the desired shape is termed machining. Present-day material removal technologies have high spindle speeds and thus allow quick material removal. These high-speed spindles are highly exposed to vibrations and, as a result, the accuracy of the final workpiece’s dimensions is compromised. To overcome this problem, the motion of the tool is restricted, and multiple degrees of freedom are given through the motion of the workpiece in different axes. A machining bed configured as a parallel manipulator capable of giving six degrees of freedom (DOF) to the workpiece is proposed in this regard. However, the proposed six DOF machining bed should be energy efficient to avoid an increase in machining cost. The benefit of using the proposed configuration is a reduction in dimensional error and computational time which, as a result, reduces the energy utilization, vibrations, and machining time in practice. This paper presents kinematics, dy... [more]

We examine energy efficiency in the European Union (EU) using an integrated model that connects labor and capital as production factors with energy consumption to produce GDP with a limited amount of environmental emissions. The model is a linear output-oriented BCC data envelopment analysis (DEA) that employs variables with non-negative values to calculate efficiency scores for a sample of 28 EU member states in the period 2010−2018. We assume variable returns to scale (VRS) considering the natural inclination of countries to adopt technologies that allow them to produce higher outputs over extended periods of time, which we observed through the trends of increasing labor productivity and decreasing energy intensity over the analyzed period. The average EU inefficiency margin in the sample period is 16.0%, with old member states being significantly more efficient (4.2%) than new member states (29.5%). Energy efficiency management does not improve over time, especially in new member st... [more]

The strong interdependency between economic growth and conventional energy consumption have led to significant environmental impact, especially with respect to greenhouse gas emissions. Conventional energy-intensive industries release increasing quantities every year, which has prompted global leaders to consider new approaches based on sustainable consumption. The main purpose of this research is to propose a new energy index that accounts for the complexity and interdependences between the research variables. The methodology is based on Principal Component Analysis (PCA) and combines the key components determined into a score that allows for both temporal and cross-country comparisons. All data analyses were performed using IBM SPSS Statistics 25™. The main findings show that most countries improved their economic performance since 2014, but the speed of the improvement varies a lot from one country to another. The final score determined reflects the complex changes taking place in e... [more]

In the rapidly growing economies of Southeast Asia, energy consumption and energy costs in buildings continue to increase. Over the past decade, energy consumption from the commercial building sector in Thailand has increased at an average of 4% per annum and currently represents over 30% of total electricity consumption, second only to the industrial sector. Buildings that exist today will continue to represent most of both energy and greenhouse gas (GHG) emissions from the built environment, with newly constructed buildings representing only a small additional portion. This paper analyzes the environmental, technical, and financial characteristics of energy efficiency retrofit activities in commercial buildings in Thailand through detailed case studies of forty-two projects undertaken over the past 8 years. Our findings suggest that retrofits provide significant opportunities to reduce energy use, energy costs, and GHG emissions while also validating the economic feasibility of inves... [more]

On 4 November 2016, the historic Paris Climate Agreement of the United Nations entered into force, requiring signatory countries to maintain global warming at the level of 1.5−2 °C. According to the calculations of the Intergovernmental Panel on Climate Change (IPCC), to achieve this goal, a 2/3 reduction in greenhouse gas energy emissions into the atmosphere compared with gaseous energy-related emissions in 2019 (33.3 Gt) by about 2050 (1.5 °C) or by 2070 (2 °C) is required. According to the International Renewable Energy Agency (IRENA), this is only possible with the implementation of a great energy transition from the use of currently dominant fossil hydrocarbon fuels—coal, oil, and natural gas—to the predominant use of renewable energy sources (RES) by 2040−2050, when the share of renewable energy in the total energy balance will reach 40% and above. In this work, mathematical description of an upcoming energy transition has been carried out, including long-term scenario writing of... [more]

Resource use in point-to-point and point-to-multipoint communication emerges with the tremendous growth in wireless communication technologies. One of the technologies is wireless power transfer which may be used to provide sufficient resources for energy-constrained networks. With the implication of cooperative communication in 5G/B5G and the Internet of Things (IoT), simultaneous wireless information and power transfer (SWIPT)-assisted energy efficiency and appropriate resource use become challenging tasks. In this paper, multiple IoT-enabled devices are deployed to cooperate with the source node through intermediate/relay nodes powered by radio-frequency (RF) energy. The relay forwards the desired information generated by the source node to the IoT devices with the fusion of decode/amplify processes and charges itself at the same time through energy harvesting technology. In this regard, a problem with throughput, energy efficiency, and joint throughput with user admission maximizat... [more]

One of the major anthropogenic sources of greenhouse gases is the operation of building stock. Improving its energy efficiency has the potential to significantly contribute to achieving climate change mitigation targets. The purpose of this study was to roughly estimate such potential for the operation of the national building stock of Czechia to steer the national debate on the development of related national plans. The estimation is based on a simplified energy model of the Czech building stock that consists of sub-models of residential and nonresidential building stocks, for which their future energy consumptions, shares of energy carriers and sources, and emission factors were modeled in four scenarios. Uncertainties from the approximation of the emission factors were investigated in a sensitivity analysis. The results showed that the operation of the Czech building stock in 2016 totaled 36.9 Mt CO2, which represented 34.6% of the total national carbon dioxide emissions. The four b... [more]

Hydro-power plants are able to produce electrical energy in a sustainable way. A known format for producing energy is through generation scheduling, which is a task usually established as a Unit Commitment problem. The challenge in this process is to define the amount of energy that each turbine-generator needs to deliver to the plant, to fulfill the requested electrical dispatch commitment, while coping with the operational restrictions. An optimal generation scheduling for turbine-generators in hydro-power plants can offer a larger amount of energy to be generated with respect to non-optimized schedules, with significantly less water consumption. This work presents an efficient mathematical modelling for generation scheduling in a real hydro-power plant in Brazil. An optimization method based on different versions of the Coral Reefs Optimization algorithm with Substrate Layers (CRO) is proposed as an effective method to tackle this problem. This approach uses different search operato... [more]

The energy efficiency requirements of most energy-consuming sectors have increased recently in response to climate change. For buildings, this means targeting both facility managers and building users with the aim of identifying potential energy savings and encouraging more energy-responsible behaviors. The Information and Communication Technology (ICT) platform developed in Horizon 2020 FEEdBACk project intends to fulfill these goals by enabling the optimization of energy consumption, generation, and storage and control of flexible devices without compromising comfort levels and indoor air quality parameters. This work aims to demonstrate the real-world implementation and functionality of the ICT platform composed of Load Disaggregation, Net Load Forecast, Occupancy Forecast, Automation Manager, and Behavior Predictor applications. Particularly, the results obtained by individual applications during the test phase are presented alongside the specific metrics used to evaluate their per... [more]

This paper introduces a novel design of an electric vehicle (EV) fast charging station, consisting of a battery energy storage system (BESS) with reconfigurable cell topology. The BESS comprises two battery strings that decouple the power flow between EV and grid, to enable charging powers above the grid capacity. The reconfigurable design is achieved by equipping the battery cells with semiconductor switches and serves two main purposes. First, it aims at solving cell unbalance issues to increase safety, reliability, and lifetime of the battery. Second, it enables the BESS to actively control the EV charging process by changing its cell configuration in a real-time fashion, making a DC-DC converter redundant. The paper presents a modelling approach that captures the reconfigurable design including the controlling algorithm used for cell engagement. The simulation results show that the BESS is able to fulfil the EV request with sufficient accuracy for most of the fast charging process.... [more]

This article discusses the current state and trends in the development of the electric power industry in Kazakhstan. An analysis of the energy supply and energy intensity of Kazakhstan’s GDP is provided in this paper. The results of the foresight of the risks and opportunities of the energy industry are described. This study identifies the relationship between the traditional development of the energy industry and the development of alternative energy sources. In addition, the work examines the risks and consequences of various trends in the development of national and global energy. Previous studies have shown that government efforts are insufficient in developing an alternative energy sector in Kazakhstan. The research results show that there is a need to transform energy production from traditional sources towards greater efficiency and environmental friendliness, as well as the active involvement of the business community in the development of an alternative energy market. This is... [more]

The research explores the potential of digital-twin-based methods and approaches aimed at achieving an intelligent optimization and automation system for energy management of a residential district through the use of three-dimensional data model integrated with Internet of Things, artificial intelligence and machine learning. The case study is focused on Rinascimento III in Rome, an area consisting of 16 eight-floor buildings with 216 apartment units powered by 70% of self-renewable energy. The combined use of integrated dynamic analysis algorithms has allowed the evaluation of different scenarios of energy efficiency intervention aimed at achieving a virtuous energy management of the complex, keeping the actual internal comfort and climate conditions. Meanwhile, the objective is also to plan and deploy a cost-effective IT (information technology) infrastructure able to provide reliable data using edge-computing paradigm. Therefore, the developed methodology led to the evaluation of th... [more]

The Digital Product Passport (DPP) is a concept of a policy instrument particularly pushed by policy circles to contribute to a circular economy. The preliminary design of the DPP is supposed to have product-related information compiled mainly by manufactures and, thus, to provide the basis for more circular products. Given the lack of scientific debate on the DPP, this study seeks to work out design options of the DPP and how these options might benefit stakeholders in a product’s value chain. In so doing, we introduce the concept of the DPP and, then, describe the existing regime of regulated and voluntary product information tools focusing on the role of stakeholders. These initial results are reflected in an actor-centered analysis on potential advantages gained through the DPP. Data is generated through desk research and a stakeholder workshop. In particular, by having explored the role the DPP for different actors, we find substantial demand for further research on a variety of i... [more]

Nonequilibrium statistical mechanics or molecular theory has put the transport equations of mass, momentum and energy on a firm or rigorous theoretical foundation that has played a critical role in their use and applications. Here, it is shown that those methods can be extended to nonequilibrium entropy conservation. As already known, the “closure” of the transport equations leads to the theory underlying the phenomenological laws, including Fick’s Law of Diffusion, Newton’s Law of Viscosity, and Fourier’s Law of Heat. In the case of entropy, closure leads to the relationship of entropy flux to heat as well as the Second Law or the necessity of positive entropy generation. It is further demonstrated how the complete set of transport equations, including entropy, can be simplified under physically restrictive assumptions, such as reversible flows and local equilibrium flows. This analysis, in general, yields a complete, rigorous set of transport equations for use in applications. Finall... [more]

Worldwide increasing awareness of energy sustainability issues has been the main driver in developing the concepts of (Nearly) Zero Energy Buildings, where the reduced energy consumptions are (nearly) fully covered by power locally generated by renewable sources. At the same time, recent advances in Internet of Things technologies are among the main enablers of Smart Homes and Buildings. The transition of conventional buildings into active environments that process, elaborate and react to online measured environmental quantities is being accelerated by the aspects related to COVID-19, most notably in terms of air exchange and the monitoring of the density of occupants. In this paper, we address the problem of maximizing the energy efficiency and comfort perceived by occupants, defined in terms of thermal comfort, visual comfort and air quality. The case study of the University of Pisa is considered as a practical example to show preliminary results of the aggregation of environmental d... [more]

The problem of high power consumption in data centers is becoming more and more prominent. In order to improve the energy efficiency of data centers, cooperatively optimizing the energy of IT systems and cooling systems has become an effective way. In this paper, a model-free deep reinforcement learning (DRL)-based joint optimization method MAD3C is developed to overcome the high-dimensional state and action space problems of the data center energy optimization. A hybrid AC-DDPG cooperative multi-agent framework is devised for the improvement of the cooperation between the IT and cooling systems for further energy efficiency improvement. In the framework, a scheduling baseline comparison method is presented to enhance the stability of the framework. Meanwhile, an adaptive score is designed for the architecture in consideration of multi-dimensional resources and resource utilization improvement. Experiments show that our proposed approach can effectively reduce energy for data centers t... [more]

The reliability of pumping units at nuclear power plants (NPPs) is critical in terms of their energy efficiency and safety. Remarkably, WWER-1000 reactors at Ukrainian NPPs are equipped with outdated pumping units that have already served their full-service life. This fact leads to an urgent need to develop a new, more efficient pump. In the article, a promising pump, ACNA 600-35, was developed. It was designed to increase the energy efficiency of pumps TX 800/70/8-K-2E, applied at the holding pool and the industrial circuit of the nuclear reactor. Since these pumps should be imported from the monopoly suppliers, this affects both the energy efficiency of pumping equipment and the energy independence of Eastern Europe. The proposed pump ACNA 600-35 is characterized by an increased efficiency of up to 0.12−0.13 compared with the TX 800/70/8-K-2E pump. In general, the life cycle cost of the proposed pump is 15−20% lower than for the analog TX 800/70/8-K-2E. The design of the developed pu... [more]

The current geopolitical landscape of the European Union has made it clear that the energy sector must be a top priority in EU policy, especially in light of the sudden escalation of Russian−Ukrainian conflicts. Energy efficiency has been used as the first tool of EU policy to tackle energy and climate crises, given the issues surrounding energy vulnerability and the need to limit gas emissions that contribute to climate change. The white certificate mechanism in Italy has played a pivotal role in encouraging measures to achieve the country’s energy-saving goals. Given the high energy requirements of Wastewater Treatment Plants (WWTPs), especially for aeration in the biological section, this paper examines the replacement of the air distribution system for a large WWTP as a viable intervention. In order to provide economic perspective for the plant, both the discounted Payback Period (dPBP) and the Net Present Value (NPV) were calculated for the investment. When viewed through an econo... [more]

The European Union (EU) is a global leader in renewable energy, and it is working to maintain this position through setting high standards for itself as well as for its member states in this field. Among the goals set for 2030 in Directive (EU) 2018/2001 and changes published on 14 July 2021 is a 55% reduction in greenhouse gas (GHG) emissions (compared to 20% in 2020). The targets for individual countries vary and depend on the current level of development of renewable energy. This article focuses on evaluation of these targets in the Visegrad Group (V4) countries (Czech Republic, Hungary, Poland, and Slovakia). These are post-Communist countries that have undergone systemic transformations but still face challenges related to sustainable development in renewable energy. This article analyzes the 2030 goals and the prospects of their implementation. Evaluated criteria include greenhouse gas emissions, the share of renewable energy in energy consumption, energy consumption, energy effi... [more]

In this work, a comprehensive energetic and exergetic comparative assessment is presented for the simple solar organic Rankine cycle (SORC), regenerative solar organic Rankine cycle (RORC), and dual-loop solar organic Rankine cycle (DORC), considering parameters such as the net power produced, exergy destruction, exergy, and energy efficiency in four zones located in Colombia due to their high solar irradiation potential. The energetic and exergetic balances were applied for each system component, using toluene as the working fluid. The RORC system showed a 2% increase in efficiency over the SORC, while the DORC cycle was lower than the SORC (45.85%) and RORC (46.90%) systems. Finally, for the exergy analysis, the results revealed that the SORC (5.3%) and RORC (5.2%) systems had the highest efficiency compared to DORC systems. Additionally, the highest exergy destruction (89%) was related to the collector, followed by the evaporators (1−2%), pumps (0.1%), and turbines (1.12%).

In this paper, determination of optimized regenerative braking-torque function and application in energy efficient driving strategies is presented. The study investigates a lightweight electric vehicle developed for the Shell Eco-Marathon. The measurement-based simulation model was implemented in the MATLAB/Simulink environment and used to establish the optimization. The optimization of braking-torque function was performed to maximize the recuperated energy. The determined braking-torque function was applied in a driving strategy optimization framework. The extended driving strategy optimization model is suitable for energy consumption minimization in a designated track. The driving strategy optimization was created for the TT Circuit Assen, where the 2022 Shell Eco-Marathon competition was hosted. The extended optimization resulted in a 2.97% improvement in energy consumption when compared to the result previously achieved, which shows the feasibility of the proposed methodology and... [more]

Lithium-ion batteries (LIBs) have circumvented the energy storage landscape for decades. However, safety concerns about liquid−electrolyte-based LIBs have challenged their mobilization. Lithium polymer (LiPo) batteries have gained rising interest due to their high thermal stability. Despite an array of commercially available LiPo batteries, limited studies have ventured into modeling. Numerical simulations allow low-cost optimization of existing battery designs through parameter analysis and material configuration, leading to safer and more energy-efficient batteries. This work examined the electrochemical, thermal, and thermal runaway behavior of a lithium cobalt oxide cathode, graphite anode, and poly(vinylidene fluoride-hexafluoropropylene) electrolyte pouch-type LiPo battery using COMSOL Multiphysics®, and validated results with experimental data. The simulated potential curve exhibited strong agreement with experiment data, while the temperature profile during discharge displayed... [more]

Smart cities need energy-efficient and low-emission transportation for people and goods. Most studies focus on sustainable urban-transportation systems for passengers. Freight transportation in cities has increased significantly during the COVID-19 pandemic, leading to greenhouse gases emissions and negative externalities, such as traffic congestion. The purpose of this paper is to identify through a systematic literature review which innovations (hardware and software) applied by logistics service providers (LSPs) in sustainable urban freight (SUF) are suitable to support the transition to energy-efficient smart cities. We propose to classify the existing innovations in last-mile delivery for SUF into categories: (1) urban freight consolidation and/or trans-shipment; (2) the Consumer as a Service Provider (CaaSP); (3) choice of transportation modes. We introduce the concept of CaaSP as an innovative solution in last-mile delivery (LMD), where customers take over some transport operati... [more]

The public procurement system in Poland remains highly centralized, although thanks to European Community directives, it is part of European law. Therefore, it has established procedures for sustainable public procurement, including so-called green public procurement. In addition to the Public Procurement Law of 11 September 2019, other provisions introducing specific instruments (e.g., energy labels, environmental labels) should be taken into consideration, as such provisions make it easier for contracting authorities to take environmental aspects into account in tender procedures. Bearing in mind the existing legal regulations, this article features a diagnosis of the degree of use of measures to improve energy efficiency in public procurement procedures and models activities related to improving this situation. For this purpose, surveys were conducted for 120 entities applying the provisions of the Public Procurement Law. Taking into consideration the results obtained in the survey,... [more]