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A liquid nitrogen wash based novel system is proposed for electricity generation and LNG production. This system utilizes cold energy of methane rectification for power generation, and realizes the LNG production through methane recovery from exhaust gas. Effects of operational parameters on net generation capacity (NEG) and energy efficiency are studied. Exergy destruction/efficiency and exergy cost are obtained. Advanced exergy/exergo-economic analyses are conducted to clarify the improvement potential and improvement strategy. Finally, the optimal solutions are obtained in multi-objective optimization. Results show that propane could be used as the organic working medium and the maximum NEG is 675.95 kW and the energy efficiency is 19.34 %. As 88.8 % of the system investment cost is for the equipment, reduction on exergy destruction cost of equipment should be considered. Advanced analysis indicates that 27.27 % of the exergy destruction, 30.02 % of the exergy cost and 7.20 % of the investment cost can be avoided. The thermodynamic optimization shows that the highest energy efficiency is 67.26 %, the highest exergy efficiency is 76.95 % and the lowest exergy cost per unit is 28.45 $/GJ. The economic optimization shows that exergy efficiency is improved by 2.83 % and NEG is improved by 47.95 % when increasing the investment cost for 6.13 %. • A liquid nitrogen wash based system is proposed for electricity and LNG production. • Advanced exergy/exergo-economic analyses are conducted for the system evaluation. • 27.27 % of exergy loss, 30.02 % of exergy cost and 7.20 % of investment can be avoided. • The highest energy efficiency and exergy efficiency are obtained as 67.26 % and 76.95 %. • Optimal operation of this cogeneration system is achieved using the genetic algorithm. [ABSTRACT FROM AUTHOR]

Photovoltaic/thermal (PV/T) system could convert solar energy to high-grade electrical and thermal energy, which has significant application value in various aspects such as energy, environment, lifestyle, and economy. The new-developed micro heat pipe PV/T(MHP-PV/T) has excellent potential for combined heat and power generation in cold regions. To elevate the combined thermoelectric performance of MHP-PV/T through heat transfer enhancement ulteriorly, it is of great necessity to research the impacts of working fluids on the performance of MHP-PV/T systems. Two sets of MHP-PV/T systems were constructed, using R141b and Acetone micro heat pipes. We compared their comprehensive performance in terms of electrical and thermal properties using a combination of theoretical and experimental analysis. The performances of two sets of MHP-PV/T systems were compared when the panel inclination angles were 35°, 40°, 45°, and 50° and flow rates of circulating water pump were 5.6 L/min and 7.6 L/min respectively. The results showed that R141b MHP-PV/T systems exhibited higher performances than the acetone MHP-PV/T under all working conditions. When the panel inclination angle was 45°, the average thermal power, average electrical power, average thermal efficiency, and average electrical efficiency of R141b MHP-PV/T were 341.8W, 125.8W, 34.1 %, and 12.0 % , which were 58.5W, 50.0 W, 6.8 % and 4.4 % higher than those of acetone MHP-PV/T respectively. In summary, the performance differences of working fluids were systematically compared between acetone and R141b in MHP-PV/T and the results are of great significance to the future application of PV/T in cold regions. • The performances of MHP-PV/T with acetone and R141b were disclosed respectively at different tilt angles and flow rates. • R141b is more suitable for new-developed MHP-PV/T than acetone. • Systematical comparison of performance differences of MHP-PV/T with acetone and R141b as working fluids. [ABSTRACT FROM AUTHOR]

This paper focuses on the determination of the optimal operating scenario of an Externally-Fired Micro-Gas turbine utilizing syngas produced by biomass gasification. Biomass exploitation can contribute to the achievement of the net-zero emissions target in 2050. This can be boosted by the advancement of externally-fired technology. In this study, a dual-objective optimization process, including a validated thermodynamic model, is combined with preliminary cost insights to assist the decision-making process. The resulting performance is compared with the actual data-based performance of a reference natural-gas-fired Micro-Gas Turbine. The performance comparison is performed through an exergetic analysis, identifying the main losses contributors. The optimization results in an externally-fired performance of 77.9 kW el electrical power and 20.3% efficiency, improved by 31.5% compared to the average current externally-fired demonstrated efficiencies. Yet, there is still room for improvement to reach natural-gas-fired Micro-Gas Turbine efficiency. The study highlights an unavoidable efficiency decrease of at least 4.0 percentage points due to the use of syngas itself instead of natural gas, which conversely increases heat recovery potential. However, compared to the state-of-the-art demonstrations, the proposed analysis is a significant step towards efficiency improvement, which can be exploited for future biomass demonstrations, attractive for electricity generation as well. • Performance of an externally-fired microturbine using biomass syngas is optimized. • Design point is determined through an optimization with preliminary cost insights. • Performance is compared with the validated data from a natural gas microturbine. • Electrical efficiency improved by 31.5% compared to average current demonstrations. • Syngas use results in an unavoidable efficiency decrease of 4.0 percentage points. [ABSTRACT FROM AUTHOR]

With the increasing penetration of wind power in power grid, accurate and reliable wind power forecasting is of great significance for the economic operation and safe dispatching of electrical power system. In practice, there exists complex spatial correlation between wind power variables, which brings great challenges to the accurate forecasting of wind power. However, traditional deep learning-based methods mostly focus on temporal feature while ignoring the spatial correlation between wind power variables, leading to low forecasting accuracy. To explore the spatial correlation among wind power variables and extract temporal features simultaneously, we propose a double attention-based spatial–temporal neural network (DA-STNet). First, graph attention network is employed to explore the spatial correlation between wind power variables based on a graph constructed by maximal information coefficient, which can consider the combined influences of multivariate on the wind power output. Then, by incorporating causal reasoning and data-driven element-wise attention measures, a novel temporal attention layer is proposed to extract the temporal feature of wind power sequences. Comprehensive experiments were conducted on one self-collected and one public dataset with three different multi-steps ahead forecasting tasks, and the experimental results demonstrated that the performance of proposed DA-STNet is superior to the existing methods on both real-world datasets. In the 24 h ahead experiment on the NWWPF dataset, the MSE of our model can reach as low as 0.136 and MAE can be decreased to 0.275. • A double attention-based spatial–temporal neural network (DA-STNet) is proposed for medium-term wind power forecasting. • Graph attention network is used to explore the dynamic correlation between different wind power variables. • A novel temporal attention layer is proposed to capture the temporal features. • Experiments were conducted on two datasets to verify the effectiveness of DA-STNet. [ABSTRACT FROM AUTHOR]

Replacing the baseload providers on the energy market with decarbonized renewable solutions increases frequency dynamics on the grid. In order to handle the concomitant risks and chances linked with this change of paradigm between energy producers and consumers, complex dynamic models are required to optimize energy management strategies. Industrial transcritical carbon dioxide (CO 2) heat pumps, such as the one developed by MAN Energy Solutions Schweiz AG (MAN ES), offer a proven solution for the decarbonization of the district heating sector. Furthermore, they are associated with pathways to increase the usage of this solution for sector coupling applications. This work presents a detailed Modelica model of the high-temperature CO 2 heat pump, focusing on the thermodynamic states of the refrigerant during load variations of the system. In a consecutive step, the model is validated against testbed data of a heat pump from MAN ES with over 35 MW heat supply and a lift from 40 to 100 K. The model results match the testbed data with an accuracy of over 95 % and demonstrate a full coverage of the performance map minimum to maximum speed, providing water-side supply temperatures of 50–109 °C. Realistic dynamics in fast load balancing operation are demonstrated where power consumption was varied by 80 % compared to maximum power within 30 s. Models of this kind are essential for an accurate prediction how decarbonized energy networks react by linking electricity and heat supply together. These predictions are ultimately useful to upgrade or optimize complex control strategies. • A large-scale, transcritical CO 2 heat pump is modeled in Modelica. • The model is successfully validated with measurements from a 35 MW testbed setup. • Motor speed and control valve dynamics variated separately as well as combinations are validated. • Fast dynamics of electrical power consumption (up to 7 MW in 30s) are demonstrated. • The model is qualified for implementation in real plant operation and control. [ABSTRACT FROM AUTHOR]

The development of novel technical solutions for the efficient recovery of waste heat is crucial for making accessible the large amount of thermal energy released by industrial processes, thus supporting the EU energy strategy. To this end, the EU-H2020 project CO2OLHEAT aims at developing and demonstrating a novel sCO 2 power unit of 2 MW capacity, recovering energy from flue gases at 400 °C. The CO2OLHEAT system features a relatively unconventional multi-shaft configuration where the sCO 2 compressor is driven by a dedicated radial expander, while the electrical power is generated via a separated axial turbine. The present study focuses on the design and fluid-dynamic analysis of the CO2OLHEAT compressor. The thermodynamic optimization of the cycle led to an overall pressure ratio slightly above 2.5, delivered with a two-stage centrifugal compressor. As typically found in sCO 2 power systems, the thermodynamic state of the fluid at the machine intake (P = 85 bar; T = 32 °C) is close to the critical point and to the saturation curve; therefore, the first stage of the machine demands a dedicated aero-thermodynamic design, which can account for the effects of non-ideal thermodynamics and of the potential onset of two-phase flows. The paper discusses the conceptual aero-mechanical design of the compressor and then focuses on its performance assessment over the full operating range via Computational Fluid Dynamics. Two alternative CFD models are applied, the first one based on the barotropic fluid representation and the second one featuring a complete thermodynamic model, both of them assuming homogeneous equilibrium in presence of multi-phase flows. The experimental validation and the application of the two models are presented and discussed. They are shown to provide similar outcomes, and indicate that the compressor fulfills the system requirement and guarantees wide rangeability. A thorough comparison between the CFD results highlights the implications of the underlying physical differences between the models, thus allowing to properly evaluate their use for the aerodynamic design and analysis of sCO2 compressors. • A two-stage sCO 2 radial compressor for waste heat recovery system is presented. • Two alternative CFD formulations are presented and experimentally validated. • The compressor performance and operation are assessed with the two CFD models. • The barotropic model is recommended for design, the full HEM for flow analysis. • The roughness highly influences the compressor performance but not the rangeability. [ABSTRACT FROM AUTHOR]

In this study, a fluidized-bed biofuel system was integrated with a Stirling engine (SE) to create a combined heat and power (CHP) system with high energy efficiency. Methods for ensuring the stability of the SE and fluidized-bed combustion were investigated and implemented. The proposed design was tested experimentally, and the system successfully produced electricity from the heat of the flue gas generated during biomass combustion. The Taguchi method was employed to maximize the temperature of the fluidized bed by modifying three parameters: the sand height, air flow rate, and biomass feed rate. The biomass used in this study was discarded mushroom sawdust waste. The biomass feed rate was varied from 9.5 to 17 g/min, and the air flow rate was varied from 50 to 60 L/min. The integrated CHP system was found to yield 90−100 W of electric power and 1077.3 W of heat energy for producing hot water. The oxygen, carbon dioxide, carbon monoxide, and nitric oxide concentrations of the flue gas produced under the optimized system parameters were analyzed, and minimal emissions of carbon monoxide and nitric oxides, which are harmful gases, were discovered. In most experiments on SEs in the literature, liquid or gaseous fuels have been used to power the engine. However, this study successfully used solid biomass fuel to power a practical SE, thus widening the knowledge on the utilization of this renewable energy source for electricity generation. The results of this study indicate that the proposed CHP system is stable, clean, and efficient. This system potentially provides a solution for two problems, namely the disposal of mushroom sawdust waste and the eco-friendly generation of heat and electricity. Therefore, the proposed system is promising for green and sustainable power generation in the future. • Optimizing the biomass feed rate and air flow rate can considerably enhance the combustion temperature. • Higher biomass feed rate leads to a lower CO concentration, which is attributable to the volatilization of biomass. • The CHP system produces 90 W of electric power and 1073 W of heat power. [ABSTRACT FROM AUTHOR]

Closed-Brayton-cycle (CBC) has considerable potential for power generation on hypersonic vehicles, but its power level is limited by the cold source onboard, commonly the hydrocarbon fuel. To achieve power enhancement of CBC with finite cold source, this study assessed and compared the power output and thermal efficiency of supercritical carbon dioxide (S–CO 2) and helium-xenon mixture (He–Xe) CBCs at ultra-high turbine inlet temperature (TIT), taking into account the thermal cracking of hydrocarbon fuel. Results indicate that raising TIT can significantly increase the electric power output for both CBC working fluids. The electric power under per unit mass flowrate of fuel is as high as 1600 kJ/kg at the TIT of 2000 K, making it easy to achieve megawatt-level power generation. The power enhancement of He–Xe CBC is more significant than S–CO 2 CBC when the TIT exceeds 2000 K. Moreover, the compressor inlet temperatures and cycle pressure of S–CO 2 CBCs are much higher than those of He–Xe CBC, causing additional challenges in the aerodynamic design and component manufacture. Therefore, He–Xe CBC operating at ultra-high TITs may be more suitable than S–CO 2 CBCs for high-power electricity generation mission on hypersonic vehicles. • Improving TIT is dramatically effective for power enhancement with finite cold source. • Electric power per unit mass flowrate of fuel is 1600 kJ/kg at TIT of 2000 K. • At ultra-high TITs, T 1 of S–CO 2 CBC is much higher than that of He–Xe CBC. • He–Xe closed-Brayton-cycle may be more suitable than S–CO 2 CBC. [ABSTRACT FROM AUTHOR]

While the US electric power sector transitioning towards a low-carbon system, the escalated adoption of renewable energy has paradoxically increased water consumption. Consequently, it is imperative to engineer a power generation matrix that mitigates CO 2 emissions and minimizes water utilization. The primary endeavor should be to meticulously identify the variables affecting water consumption changes, especially highlighting and addressing the inherent tension between water conservation and carbon reduction. Employing temporal and spatial Logarithmic Mean Divisia Index methodologies, this study meticulously investigated the factors driving water consumption changes across state-level electricity production sectors in the US from 2010 to 2018. The analysis revealed that the generation mix structure was a predominant factor in escalating water consumption, exerting a more substantial influence than total power generation. Moreover, while the water consumption coefficient initially mitigates the impact of other factors, its effectiveness diminishes over time. Utilizing spatial Logarithmic Mean Divisia Index techniques, this paper further delineated state-level disparities, illuminating the heterogeneous nature of water consumption across regions. Projections up to 2050 suggest that water consumption reductions could be realized even amidst a highly intense scenario. The study's robustness and reliability were further augmented by employing an adaptive Logarithmic Mean Divisia Index. • Temporal-spatial LMDI reveals significant shifts in the US power sector water consumption. • Water consumption coefficient, fuel structure, and generation identified as key drivers. • Scenario analysis forecasts significant water savings potential by 2050. • Findings highlight the necessity for integrated water-energy transition policies. • Study proposes targeted strategies for a sustainable energy-water nexus. [ABSTRACT FROM AUTHOR]

Multi-energy flow (MEF) calculation plays a key role in integrated energy system (IES) analysis. However, its practical implementation is challenged by the high computational burden and frequently changing topology. To mitigate these issues, the topological graph attention convolutional network with transfer learning (TGACN-TL) is proposed for MEF calculation in IES with electrical, natural gas, and heating networks. Specifically, the topological physics information is embedded in TGACN to improve the MEF calculation accuracy. Besides, the attention mechanism is leveraged by TGACN to capture and represent intricate graphical patterns inherent in the MEF data, thereby preserving essential graphical structure features. Furthermore, transfer learning is applied to utilize previously learned topological knowledge, facilitating adaptation to new electricity network topologies through updating partial model's parameters. The simulations demonstrate that the proposed TGACN with transfer learning achieves superior MEF calculation accuracy, maintaining robust performance across diverse conditions of uncertainty and topological variations. • A Topological Graph Attention Convolutional Network with the transfer learning model (TGACN-TL) for multi-energy flow calculation in integrated energy systems (IES). • TGACN for extracting intricate graphical features by integrating IES topology. • Automatically preservation of topological data information through a graph attention mechanism. • Adaptation to new electrical power network topology efficiently with transfer learning. [ABSTRACT FROM AUTHOR]

The micro-thermal power generation presents several challenges including reaction instability, large heat loss, and energy conversion. So, a micro-planar with multi-hole baffle for micro power generation is proposed with C 3 H 8 /CH 4 blended and reaction sensitivity analyzed. Effects of fuel sensitivities, baffle settings, operating conditions on combustion characteristics and performance of thermal are analyzed. Experimental results revealed the thermal performance of H 2 -fueled combustion with blended CH 4 and C 3 H 8 can be improved, while the H 2 /CH 4 /air burning obtains a higher improvement by promoting flame anchoring and reducing heat losses. Thermal reflux and high temperature zones can be generated at appropriate baffle positions and hole sizes to enhance the operating micro-combustor performance. Optimized baffles and CH 4 blending ratios significantly improved combustor output power and system efficiency. For instance, the maximum mean radiation temperature of 1347 K can be obtained in combustor C8-0.8 at m c = 25 % and m f = 4.08 × 10−5 kg/s. Meanwhile, micro-thermophotovoltaic (MTPV) system equipped with InGaAsSb cell can achieve a 3.4 W electrical power output and a system efficiency of 3.5 %. It provides solutions for recovering energy from exhaust gases and improving energy efficiency to develop efficient and sustainable micro-energy sources. [Display omitted] • Addition of CH 4 and C 3 H 8 to H 2 -fuel combustion is experimentally and numerically investigated. • H 2 -fueled characterization of combustion with CH 4 /C 3 H 8 blended and sensitivity analysis are presented. • The coupling of exhaust gas heat recovery, blended fuels, and baffle is employed to improve energy efficiency. • Energy efficiency and electrical output of micro-thermophotovoltaic are calculated and analyzed. [ABSTRACT FROM AUTHOR]

Accurately predicting electrical power demand is crucial to making related forecasts and to effective sustainable energy management. Most relevant state-of-the-art studies deploy models that do not use optimizing parameters and do not incorporate strategies for using forecast results. This study was designed to develop a novel electricity consumption forecasting model, the Symbiotic Bidirectional Gated Recurrent Unit, which integrates Gated Recurrent Unit, Bidirectional Technique, and Symbiotic Organisms Search algorithms. The results of tests on a series of evaluation criteria showed the proposed model performed significantly better than six comparison models when parameter optimization was used. For all three sector datasets, the proposed model generated the most-accurate predictions of all models. In practical terms, when supply is expected to exceed demand, the prediction results may be used to adjust power plant output to reduce wastage. Conversely, when demand is expected to exceed supply, Time-of-Use tariffs may be implemented based on time-of-day and seasonal fluctuations in demand to facilitate reductions in peak usage and level out overall demand. • A model called Symbiotic Bidirectional Gated Recurrent Unit was developed. • Symbiotic Organisms Search was applied to identify model hyperparameters. • The proposed model was tested on different area datasets. • The proposed model outperforms other models in predicting electricity across areas. • Power output may be adjusted and time-of-use tariffs applied based on forecasting demand. [ABSTRACT FROM AUTHOR]

Resonance tubes are often used to connect multi-stage looped thermoacoustic heat engine and linear alternators to form a multi-stage looped thermoacoustic electric generator. In this paper, we experimentally investigate the performance of a multi-stage looped thermoacoustic electric generator with two sets of resonance tubes of different lengths. With the increase of the length of resonance tubes from 1.5 m to 2 m, the system frequency decreases from 70 Hz to 62 Hz. The maximum output acoustic power increases from 6.97 kW to 8.16 kW, and the maximum output electric power increases from 5.09 kW to 6.24 kW. Meanwhile, the maximum thermoacoustic efficiency increases from 23.08 % to 23.94 %, the maximum acoustic-to-electric efficiency increases from 78.03 % to 82.06 % and the maximum thermal-to-electric efficiency increases from 17.79 % to 19.64 %. Numerical simulation is also conducted based on a 3-step coupling method and validates the experimental results. This study demonstrates that adjusting the length of resonance tubes in a multi-stage looped thermoacoustic electric generator is an effective way to tune the frequency as well as to improve the coupling between the multi-stage looped thermoacoustic heat engine and linear alternators. • A 4-stage looped thermoacoustic electric generator is built. • Resonance tubes with lengths of 1.5 m and 2 m are installed in the system. • Numerical simulation is based on a 3-step coupling method. • Frequency decreases with the length of resonance tubes increases. • Output power and efficiency increase with the length of resonance tubes increases. [ABSTRACT FROM AUTHOR]

The transmission line is one vital component of electrical power system. It determines some fundamental characteristics such as transmission efficiencies, voltage drops and line losses which are important matters to be considered in system planning, design and maintaining. The so-called PI-based modeling refers to using basic PI (proportional and integral) elements as well as other basic elements to implement one specific simulation. Grounded on the distributed-element model and addressing complex-element modeling, one PI-based simulation method is introduced in this study for teaching purposes and applied to modeling and simulation for performance testing of the power transmission line. The proposed method is demonstrated in the Simulink simulation environment and verified by performance testing of the power transmission line including complex-element-based equivalent distributed-element modeling for (short, medium and long) transmission lines, load flow analysis, short circuit test, open circuit test and the "Ferranti-effect" phenomenon, SIL (surge impedance loading) and series and shunt compensation simulation. Results indicate workability of the proposed method that it provides one convenient and vivid way for complex-element-based simulation modeling and solving numerical solutions as well. The proposed PI-based method for complex-element modeling and its Simulink-based simulation approach may be useful for related electrical engineering simulations and testing. • Only basic PI (proportional and integral) elements and other basic elements are employed for complex-element modeling. • Applied to modeling and simulation for performance testing of the power transmission line. • PI-based complex-element modeling method with simulation results may be useful for related electrical engineering simulation and testing. [ABSTRACT FROM AUTHOR]

Portable electric power generator with a power level of several hundred Watts plays an important role in outdoor activities, emergency relief and tactical power supply. As an external-combustion heat engine with outstanding heat source adaptability, free-piston Stirling generator (FPSG) owns attractive advantages of quietness, high thermal efficiency, and high reliability. This paper proposes a novel ultra-high frequency (UHF) FPSG-based portable power supply system driven by a diesel porous media evaporative combustor (PMEC). An experimental setup was designed and built based on the quasi-one-dimension thermoacoustic impedance matching of the FPSG and three-dimension thermal coupling of steady combustion and alternating flow between FPSG and combustor. The fundamental operating characteristics of the system were investigated in terms of combustion powers and electric loads. Preliminary experimental results show that a maximum output electric power of 350 We at a heating temperature of 875 K and a maximum fuel-to-electric efficiency of 11.98 % were obtained. Computational fluid dynamics (CFD) simulations were employed to delve into the intricate combustion and heat transfer processes, unveiling the formation of carbon deposits and confirming the efficacy of cyclone holes in reducing carbon deposition. This pioneering exploration of 130 Hz UHF and evaporative-combustion coupled heat transfer successfully showcases the feasibility of constructing a high-specific-power FPSG-based portable power system. • An innovative portable power generation system was proposed utilizing a free-piston Stirling generator. • Free-piston Stirling generator with an ultra-high operating frequency exceeding 130 Hz was built to demonstrate a high power density of 70 W/kg. • The integrated design of the high-temperature heat exchanger in the free-piston Stirling electric generator ensures reliability under elevated temperatures and pressures. • The novel design featuring inclined swirl air jet orifices and a gradually shrinking spout effectively eliminates severe carbon deposits, enhancing combustion and heat transfer efficiency. [ABSTRACT FROM AUTHOR]

Growing demand for electricity due to economic development contributes to increased greenhouse gas production, especially CO 2. However, emissions can be limited by enhancing the efficiency of primary energy conversion, such as integrating geothermal energy into coal-fired power plants. Therefore, this paper proposes replacing conventional feed-water heaters with geothermal preheaters to create a hybridized system. This study was based on a numerical model validated at a selected Polish power unit. The model was subsequently calibrated for off-design conditions to facilitate partial load analysis. The obtained characteristics outperformed those of the non-hybrid unit, generating over 18 MW of electric power output. Such an improvement could potentially boost the unit's net efficiency by more than 2.6 %. This enhancement is significant as power units typically operate under part load for approximately 90 % of the time, hence the need to evaluate the performance characteristics of hybridized units in those states. Furthermore, the research outlines the potential decrease in the plant's CO 2 emission factor, with reductions reaching up to 6.5 % under off-design conditions. Based on a gap analysis of the existing literature, this paper's comprehensive partial load evaluation serves as a new addition to research on hybridized systems. • An in-depth analysis of feed-water heaters operation is performed. • Turbine performance calculations for both design and off-design states is validated. • The comprehensive study of hybridized systems integrates three major factors. • Hybrid geothermal-fossil power cycle is vital for specific CO 2 emissions reduction. [ABSTRACT FROM AUTHOR]

Finding sustainable and infinite green energy options in a world that relies primarily on fossil fuels is crucial as traditional sources decline. Wave energy is an excellent example of an environmentally friendly power source. A multi-utility bio-inspired floating device consisting of two TSUSUCA (TSUnami Protection Solar Utilization and other Coastal Applications) Dolphin-shaped bodies integrated with a linear motion electricity generator (LMEG) connected to a rigid deck by a hinged connection is tested experimentally under irregular waves. This novel and innovative multi-utility floating offshore device can function as a tsunami barrier and a wave energy extraction device. Its performance and operating mechanism are investigated under 8 different sets of irregular waves. The examined sea states are represented by JONSWAP and PM wave spectra with a range of significant wave heights (0.05–0.20 m) and peak periods (1.5 and 2.0 s). The experimental results show that the overall electrical power efficiency of LMEG coupled to each Dolphin obtained for set 6 is 32.04 % and 30.81 % for both JONSWAP and PM spectrums, respectively. This bio-inspired device and its performance confirms the proof-of-concept while the presented study shall become a prime factor towards the development of more similar devices to harness wave energy. • A bio-inspired floating platform is proposed for tsunami protection and energy harnessing. • The concept is supported by detailed numerical investigations, as proof-of-concept. • Detailed experimental studies are useful to examine overall efficiency of device. [ABSTRACT FROM AUTHOR]

The concept of an energy hub within a microgrid has garnered significant attention from investors due to its potential for efficiently managing diverse energy sources and accurately forecasting energy prices. This study presents a model for an energy hub that facilitates the optimal operation of a microgrid with multiple energy carrier infrastructures under future-day scenarios. The primary objective of the optimization process is to minimize operating costs, environmental impacts, and technical limitations. The proposed energy hub model integrates both distributable generation, such as a Combined Cooling, Heating, and Power (CCHP) unit, and non-distributable generation sources, including wind turbines and photovoltaic systems. Additionally, it incorporates various energy storage components, namely Ice Storage Conditioner (ISC), Thermal Energy Storage (TES) systems, and Electric Vehicles (EVs). Furthermore, the study investigates the impact of a novel energy storage system called Solar Powered Compressed Air Energy Storage (SPCAES) on the operational and environmental performance of the energy hub. To address uncertainties stemming from predicted and actual variables, a two-level stochastic optimization problem is formulated based on the Information Gap Decision Theory (IGDT) with a Risk Aversion (RA) strategy. The overarching aim is to mitigate the risks associated with the information gap confronted by microgrid operators. Subsequently, the two-level stochastic optimization problem is transformed into a single-level problem using the Karush-Kuhn-Tucker method. The proposed framework employs the RA-IGDT method and utilizes the Elephant Herd Optimization (EHO) algorithm to effectively solve the optimization problem. By applying this proposed framework to a typical energy hub, this research demonstrates the effectiveness of energy storage systems in reducing operating costs and greenhouse gas emissions during daily energy management. The study highlights the potential of energy hubs and storage systems for cost-effective and eco-friendly microgrid energy management. Scenario 4, featuring the proposed energy hub with SPCAES and ISC storage, demonstrates a 15 % reduction in operating costs and a notable 20 % increase in peak-hour electrical power for sale, underscoring its economic and operational benefits. [Display omitted] • Literature gaps: Lack of holistic energy hub models and novel storage solutions like SPCAES. • Handling uncertainties: Need for advanced techniques like ML-based predictive analytics. • Risk-averse strategies: Insufficient examination within energy hub optimization. • Meta-Heuristic algorithms: Sparse application, offers an opportunity for exploration. • Practical insights: Bridging gaps to advance research and implement efficient energy management. [ABSTRACT FROM AUTHOR]

A novel auxiliary energy system for desalination plant based on proton exchange membrane fuel cell (PEMFC)-organic Rankine cycle (ORC) combined heat and power is proposed in this paper. A thermodynamic model of the system is established, and a dynamic net present value (NPV) calculation method under the context of time-of-day tariff is designed. The system output power, economic and environmental evaluation indicators under steady-state and dynamic operation are optimized using NSGA-III and TOPSIS. The parameters sensitivity analysis shows increasing the ORC system saturation pressure and the auxiliary equipment efficiency is beneficial to increase output power and reduce indirect CO 2 mass specific emission (MSE). However, excessive pressure and efficiency will lead to a significant decrease in NPV. Under steady-state optimization, the electrical power of the system is increased by 20.1 % compared to the conventional PEMFC system. And when the proposed system operates dynamically, the single-day power generation is 1620 kWh, which is 9.31 % higher than the PEMFC system. The single-day heated seawater production is 110.1 tons and the MSE is 0.105 kg/kWh. The NPV decreases significantly, but the system can pay for itself over its lifetime. Therefore, the proposed system has thermodynamic and economic performance advantages over the conventional PEMFC system. [Display omitted] • A novel PEMFC-ORC CHP auxiliary energy system for desalination plant. • A dynamic NPV calculation method based on time-of-day tariff. • Thermodynamic, economic and environmental performance indicators. • Steady-state and dynamic operating capacity configuration optimization. • Single-day power generation is 1620 kWh and NPV is $ 870 in dynamic operation. [ABSTRACT FROM AUTHOR]

Energy related CO 2 emissions from fossil fuels constitute nearly 80 % of the global greenhouse gas emissions and are largely responsible for effecting climate change. There is imminent need to reduce emissions and decarbonize the energy economy. Renewables and nuclear are the only carbon-free energy options. However, the pace of renewable deployment lags the rate needed to achieve net-zero by 2050. Also, fossil fuels are expected to continue to dominate the energy landscape into the foreseeable future. Built on these hypotheses, this article presents a global perspective on the multitude of giga-ton and tera-watt challenges in addressing energy security and climate change. It advocates a multi-prong strategy for a smooth transition into a sustainable future. This includes abandoning air-based combustion of fossil fuels in favor of advanced oxygen-based conversion technologies, expanding energy storage capacities to accelerate the penetration rate of renewables, universally pricing emissions, and rapidly deploying carbon capture technologies at massive scale. It also argues that decarbonization must prioritize zero-carbon output over zero-carbon input during this transition period. Accordingly, the article offers several oxygen-based technology options for cleaner utilization of fossil fuels including fuel cells for power generation and storage as well as downhill production of blue hydrogen. [Display omitted] • There is no singular or simple solution to address energy and climate change challenges. • Multi-faceted global strategies are needed to tackle energy and climate challenges in the context of technological options. • Fossil fuels will continue to dominate the energy supply, requiring arge-scale CCS and global pricing of CO 2 emissions. • High temperature fuel cells offer efficient conversion of fossil fuels to electric power with total carbon capture. • Decarbonization efforts must shift emphasis from carbon-free input to the output side of electric power with CO 2 capture. [ABSTRACT FROM AUTHOR]

Solar thermal power system and photovoltaic coupled system can supply electric energy based on renewable solar energy. To explore the optimal configuration of hybrid microgrid driven by solar energy and to achieve a stable and sufficient electric power supply for the distributed energy system, this paper configures a solar thermal-photovoltaic hybrid microgrid and compares the performance of several microgrids based on the power load analysis of the building. The working fluid and the microgrid configuration are determined based on the performance evaluation of single and hybrid microgrids. The effect of solar irradiation on economic and environmental performance is analyzed under the meteorological data of Xi'an and Lhasa in China. Furthermore, the configuration optimizations of a hybrid microgrid based on the actual load and basic load of the building are carried out to examine the performance of the system. Results indicate that economic and environmental performances are sensitive to solar irradiation. More than 50 % of the area of solar thermal collector can be saved for Lhasa compared with Xi'an. Solar thermal-photovoltaic hybrid microgrid with battery can decrease carbon emission and avoid dependence on the external power grid. • Cooling, heating, power load of a six-story building is evaluated and converted. • Multi-objective optimization of solar thermal power system microgrid is performed. • Configuration optimization of solar thermal-PV hybrid microgrid is carried out. • Optimal microgrid configuration under different power load types is compared. [ABSTRACT FROM AUTHOR]

A hybrid device consisting of a PCM-based photovoltaic/thermal system and a heat recovery wheel is introduced and its performance is examined analytically. This device is designed with the aim of supplying the heating load, cooling load and electrical load of a building and reducing the building's dependence on the air handling unit. The performance of the device at different hours on two days that represent the hot and cold days of a year, in different months and during a year for the weather conditions of Kermanshah, Iran, is investigated and then, the effect of the effective parameters on the annual yield of the device is checked. The investigation showed that by using the hybrid device, it is possible to provide 4.12–11.31 °C of pre-heating and 0.60–9.22 °C of pre-cooling of the outside air on January 15th and August 15th, respectively. Also, it was revealed that except in the three months of January, February and December, in the rest of the months the hybrid device is able to supply the entire thermal load required by the building. Finally, the total annual useful thermal power and electric power produced by the hybrid device was reported as 24776.49 kWh and 7747.66 kWh, respectively. • Hybrid PCM-based PTHC-HRW device is proposed. • In the hot/cold season, systems heat/cool the outside air and generate electricity. • Impact of various parameters on the energy yield of the system is examined. • Total annual useful thermal power produced by the hybrid device is 24776.49 kWh. • Total annual useful power yield of the hybrid device is 7747.66 kWh. [ABSTRACT FROM AUTHOR]

Superconducting systems can reduce the generation of Joule heat and improve energy utilization efficiency, which has a broad application prospect. Improving the energy conversion efficiency of the refrigerator in superconducting systems is crucial, which can further improve the energy utilization efficiency of superconducting systems and promote the large-scale application of superconducting systems. In this paper, an electrical analogy model is developed to calculate the energy conversion efficiency of the pulse tube refrigerator with active dual-piston. And a 40 K pulse tube refrigerator with a high cooling capacity using active dual-piston is designed and fabricated, the accuracy of the model is verified by comparisons of cooling capacity, compressor efficiency, and power of active dual-piston at 300W input electrical power of the compressor. A cooling capacity of 7.17 W can be obtained at 40 K with an electrical power of 506 W. The active dual-piston electrical power reduces from 20 W to 0 W as the diameter of active dual-piston decrease from 24 mm to 18 mm. This study contributes to designing and optimizing a high-energy conversion pulse tube refrigerator with an active dual-piston. • The energy conversion efficiencies of the compressor and cold finger are investigated experimentally. • The conversion efficiency is analyzed with the circuit analogy model. • The acoustic-electric conversion efficiency in the active phase shifter is considered. • The electrical power into the active phase shifter is investigated and optimized. [ABSTRACT FROM AUTHOR]

Nowadays, with the emergence of high-performance thermoelectric (TE) modules and the continuous optimization of generator structures, hydrocarbon combustion powered mini-/meso-/micro-scale thermoelectric generator (HCP- m -TEG) has shown an energy density not second to that of lithium batteries. This means that HCP- m -TEG now has potential value in some specific commercial fields. However, the single-digit electric power output and over-miniaturized structure of most existing HCP- m -TEGs result in narrow application scenarios. To obtain higher energy density and electric power output, this study constructs a novel compact high-performance HCP- m -TEG prototype based on swirl burner. The total volume and weight of the HCP- m -TEG prototype are only 863.65 cm3 and 2.470 kg. The experimental results show that under extreme, safe, and long-term operating conditions, the electrical power and overall efficiency of the prototype reach 76.93 W-3.81 %, 69.58 W-3.73 %, and 56.21 W-3.29 %, respectively. Compared to previous work, this prototype has achieved excellent energy density. Moreover, the emission, modularity and the practical plans of the prototype are fully discussed. The emission of this prototype is comparable to residential stoves, which ensure safety. By combining different numbers of generation units, several potential application modes can be developed. Overall, this prototype provides a high energy density HCP- m -TEG structure with broad commercial potential. • A novel compact HCP- m -TEG prototype based on swirl burner is constructed. • Featuring extreme compactness, high performance, lightweight and modular design. • The max electric power of 76.93 W with an overall efficiency of 3.81 % is generated. • Providing a foundation unit for HCP- m -TEG commercial applications. [ABSTRACT FROM AUTHOR]

This study presents a hybrid power generation system that combines a proton exchange membrane fuel cell (PEMFC) and an internal combustion engine (ICE), utilizing ammonia decomposition as the primary fuel source. The system comprises various components, including an ammonia decomposition subsystem, PEMFC, ICE, heat exchanger, solenoid valve, and power electronic converter. The research focuses on evaluating the system's performance by analyzing the impact of key thermodynamic parameters, such as decomposition temperature and separation ratio, as well as economic factors like ammonia and hydrogen prices, and service life. The findings reveal that the hybrid power generation system achieves a maximum output power of 16.23 kW and an efficiency of 50.28 %. Furthermore, it is observed that when the power ratio (α) between PEMFC and ICE is set to 1.2, the system achieves optimal electric power output. The levelized cost of energy (LCOE) for the system is calculated to be 0.0774 $ kWh−1 when the ammonia price is 0.35 $ kg−1. Additionally, the system exhibits a significant reduction in greenhouse gas (GHG) emissions, with an estimated decrease of 4.39 × 107 g. The hybrid power generation system has excellent thermodynamic, economic, and environmental performance, which lays a foundation for promoting the spread of high efficiency and zero pollution distributed hybrid power generation system. • A novel hybrid power system of PEMFC and ICE based on ammonia decomposition is presented. • The effects of thermodynamic and economic factors on the system performance are investigated. • The maximum power and efficiency of the system are 16.23 kW and 50.28 % respectively. [ABSTRACT FROM AUTHOR]

With the diversification of marine monitoring buoy functions, limited onboard batteries have been unable to meet the energy demand of multifarious carrying sensors. Finding a self-sustained power supply for marine monitoring buoys is an urgent problem, while wave energy is an ideal and promising option to address that problem. In this study, two wave-excited vibration energy harvesters (WVEHs) are proposed, which can be installed inside large buoys to provide a sustainable power supply. A full-coupled wave-to-wire model is developed to investigate the influence of blocks' mass, geometric size of buoys, mooring system and WVEH's quantity on the electric power performance of harvesters in realistic sea states. Parametric studies based on the Taguchi method imply that the sea state and the WVEH's quantity have a significant effect on the device's electric power performance. Numerical results indicate that the optimized two harvesters can produce a mean electric power of 777.50 W and 747.43 W , respectively, under a sea state with a peak wave period of 7 s and a significant wave height of 1.6 m. A high wave-to-wire efficiency of 2. 60 % is obtained for a specific system parameter combination. Furthermore, more electric power generation can be achieved by installing multiple harvesting units. • Two wave-excited vibration energy harvesters are proposed for large marine buoys. • A full-coupled wave-to-wire model is developed. • Harvesters are optimized based on the Taguchi method in realistic sea states. • A mean electric power of 777.50 W is achieved under a peak wave period of 7 s. [ABSTRACT FROM AUTHOR]

As is well known, traditional solar systems can only work under conditions of solar radiation, as solar energy is the sole energy source for photovoltaic generation and heat recovery. Few studies have focused on their continuous operation throughout the day and this research gap needs to be filled. Consequently, to pursue a round-the-clock electrical power generator, in this study, a two-stage system is constructed, consisting of the first-stage photovoltaic/thermal module and the second-stage solar thermal collector with thermoelectric generators in series. Thermoelectric generators ensure that the system runs normally by day, while also utilizing the heated fluid to achieve uninterrupted energy output at night. A numerical model of the system is developed to analyze the performance changes under continuous running. From the results, the second-stage module improves the daytime heat gain, effectively boosting the electrical contribution of thermoelectric generators, whether during the day or night. At the maximum input energy, photovoltaic cells generate the greatest power of 118.37 W with an average efficiency of 14.56%. The average efficiencies of thermoelectric generators in the daytime and nighttime are 0.97% and 0.53%, enhancing the total electrical output. Additionally, the comparative analysis is performed under different parameters, as well as an economic analysis. • A two-stage system consisting of the PV/T and ST+TE modules is constructed. • This system is a solar system that can achieve continuous operation and output. • During the day, PV and TE generate electricity and the heat is collected and stored. • During the night, the stored heat is used by TE for uninterrupted power generation. • The effects of the key factors and the economic analysis are investigated. [ABSTRACT FROM AUTHOR]

Maritime vessels have increased in size to facilitate the transportation of more goods and fuels between continents, but these huge ships rely on diesel engines and consume more fossil fuels that negatively affect the environment. A potential strategy is to replace traditional fuels with clean and green choices and upgrade engine performance. This research paper introduces a newly developed hybrid integrated marine engine involving a gas turbine, a solid oxide fuel cell, and two organic Rankine cycles. This potential engine is then analyzed using exergy, exergoeconomic, and exergoenvironmental analyses and assessments. It is found that the engine combination can produce 15.8 MW, which is increased by 50% compared to a traditional marine engine, and the engine performance reaches 38% energetic efficiency and 47% exergetic efficiency. Also, the exergetic efficiency based on the fuel and product principle is 54 %. This engine has a 243 $/h levelized cost rate and a 132 mPt/h environmental rate. Finally, the average overall specific product exergetic cost and specifc product-based environmental impact are obtained to be 60 $/GJ and 20 mPt/MJ, respectively. By comparing five potential fuel blends (namely MF1 with 25% hydrogen and 75% methane, MF2: 25% hydrogen and 75% methanol, MF3: 40% hydrogen and 60 % ethanol, MF4: 40% hydrogen and 60% DME, and MF5: 40% hydrogen, 15% methanol, 15% methane, 15% DME and 15% ethanol), the blend of methane and hydrogen with marine fuel (MF1) is found to be the most economical with the lowest environmental impact while the second option is the ethanol and hydrogen blend (e.g., MF3). • Five alternative fuels are chosen with different concentrations. • Hybrid marine engine produces 15.8 MW electric power with 54 % exergetic efficiency. • Hybrid marine engine has a total levelized cost rate of 243 $/h. • Total component-related environmental rate of hybrid locomotive is 132 mPt/h. • Specific product exegetic cost and environmental impact are 60 $/GJ and 20 mPt/MJ. [ABSTRACT FROM AUTHOR]

As a type of distributed power generation device, free-piston Stirling generator (FPSG) is characterised by compactness, high efficiency, and long life. This work devotes to exploring the dynamic response of a low-vibration dual-opposed FPSG by employing the newly-developed time-domain acoustic-electrical analogy (TDAEA) method. Transient evolutions of self-sustained oscillations are first exhibited, which contains the start-up and steady stages. An exploration on steady-state performance is then conducted, which shows the maximum thermal-to-electric efficiency of 46.6% with an electric power of 3.92 kW, implying its enormous potential in distributed power generation for low-vibration applications due to its dual-opposed configuration. Dynamic response with jump in external load and gradual variation in heating temperature are subsequently investigated in detail. The results indicate that an acute drop in electric resistance leads to an oscillation attenuation, particularly, a short circuit results in an emergency shutdown. With the heating temperature declining gradually, the oscillation attenuates and even stops. Based on these results, some general operating regulation principles for FPSGs are further concluded to avoid the cylinder striking as well as frequent start and stop. This study gives a deeper understanding on the dynamic characteristics of FPSGs, as well as broadens the usage of the TDAEA method. • A time-domain simulation method is established for dual-opposed free-piston Stirling generator. • Detailed exploration on dynamic response of the system is performed. • Some general operating regulation principles for free-piston Stirling generators are concluded. [ABSTRACT FROM AUTHOR]

This paper introduces a novel design of a speed amplified flux switching linear generator for the power take-off unit of an ocean wave energy converter. The design incorporates several innovative features, including semi-closed stator iron cores, four coil phases shifting, and a fixed pulley wheel mechanism. These enhancements aim to increase the generator's output power and reduce its cogging force. The fixed pulley wheel mechanism effectively doubles the relative speed of the translator with respect to the stators. The scientific originality of this work lies in the development of a comprehensive design methodology for wave energy converters, specifically focused on optimizing the power take-off design under different ocean environments. The proposed approach combines analytical techniques, hydrodynamic boundary element analysis, 3D electromagnetic finite element modeling, and machine learning methods. By synergistically employing these methods, the authors achieve an efficient and effective power take-off design. To facilitate the optimization process, a three-dimensional electromagnetic finite element model of the flux switching linear generator is developed. This model is refined and optimized to maximize the output power while minimizing the cogging force, using a regular sinusoidal wave motion as the excitation input. The experimental results confirm that the proposed flux switching linear generator outperforms conventional permanent magnet linear generators in terms of power output performance. Furthermore, the model is used to simulate and predict the generator's power output under various ocean environments, considering the hydrodynamics of the wave energy converter. In summary, this manuscript presents a significant contribution to the field of flux switching electromagnetic linear generator based wave energy harvesters. The novel generator design and the comprehensive design methodology offer valuable insights and advancements in the development of efficient wave energy converters. Illustration of a wave energy converter with a flux switching linear generator (FSLG) on the ocean surface and harvested electrical power for the wave energy converter of the proposed new optimal FSLG power take-off model (K em = 8 Tm and C p = 15 N m/s) in the irregular waves of the peak spectrum frequency of 1 rad/s and the significant wave height of 1.414 m. [Display omitted] • A novel speed amplified flux switching linear generator. • A semi-closed stator iron core foot configuration • Four phase coils are adopted for enhancing the performance • A synergy of analytical, finite element modelling, and machine learning methods • The wave energy converter design method under different ocean environments [ABSTRACT FROM AUTHOR]

If an approach based on the gradient steepest descent is utilized to adapt the parameters of a radial basis function network, then it requires dimensionality reduction of the input dataset for the complexity reduction and efficiency improvement, resulting in a more precise energy processes prediction. The convolution operation could provide one way to perform dimensionality reduction of the input dataset. In this research, the convolutional radial basis function network is utilized for the energy processes prediction. The advances are exposed as follows: (1) the convolutional radial basis function network containing a convolution part, a hidden part, and an output part is utilized for the energy processes prediction, (2) the convolution operation is utilized in the convolution part to perform dimensionality reduction of the input dataset, and to change the magnitude of the input dataset for the complexity reduction, (3) the gradient steepest descent is utilized to adapt the parameters in the hidden part and output part for the efficiency improvement. The convolutional radial basis function network is compared against the radial basis function network, the feedforward neural network, and the neuro fuzzy system for the hourly electrical power demand prediction and for the chiller prediction. • The convolutional radial basis function network is utilized for the energy processes prediction. • The convolution operation is utilized to perform dimensionality reduction for the complexity reduction. • The gradient steepest descent is utilized to adapt the parameters for the efficiency improvement. [ABSTRACT FROM AUTHOR]

Energy storage is a key factor in the development of renewables-based electrical power systems. In recent years, the thermochemical energy storage system based on calcium-looping has emerged as an alternative to molten salts for energy storage in high-temperature concentrated solar power plants. This technology still presents some challenges that could be solved by integrating the thermochemical energy storage system based on calcium hydroxide. This work studies a novel concentrated solar power system integrating calcium-looping and calcium hydroxide thermochemical energy storage systems. The results show that the combined use of hydration-dehydration cycles in the calcination-carbonation processes of the calcium looping for energy storage could partially solve the issue related to the multicyclic deactivation of calcium oxide. The improvement in the conversion of calcium oxide during carbonation is demonstrated experimentally when hydration-dehydration cycles are combined. Numerical simulations demonstrate the technical feasibility of the integrated process, with efficiencies ranging between 38-46%, improved with the increase in calcium oxide conversion in the carbonator, showing the potential of the proposed integration. • Novel integration of thermo-chemical energy storage systems based on CaO. • High temperature calcium looping as main high-efficiency energy storage system. • Medium temperature calcium hydroxide integrated as secondary energy storage system. • Dehydration-hydration processes enhance CaO multicyclic activity in carbonation. • Combined joint operation with roundtrip efficiencies exceed 45%. [ABSTRACT FROM AUTHOR]

Deep borehole heat exchanger (DBHE) extracts heat from mid-deep geothermal energy through heat transfer process. As DBHE commonly applies coaxial borehole heat exchangers with depth of 2–3 km, the volume reaches more than 30 m3, similar to the small heat tank underground. When the heat pump system turns off, the water in DBHE still extracts heat from the high-temperature ground and stores heat. This kind of heat storage characteristic of DBHE was studied in this paper with simulation analysis. Benefiting from the heat storage characteristic, the average heat extraction rate (Q r) of DBHE under intermittent operation is 8.6%–64.7% higher than Q r under continuous operation, with run-stop ratio decreasing from 24 to 0 to 8–16 per day. Then the influence of operation modes, parameters and thermo-physical properties of DBHE on the heat storage characteristic were studied quantitatively, proving the wide-range regulation ability of Q r. Therefore, the regulation ability of DBHE matches the variation of space heating load very well, and also matches the production rules of clean electric power like photovoltaic and wind power. Hence, the DBHE could further participate in the demand response of electrical power system, and absorb clean electric power. • The heat storage characteristic of deep borehole heat exchangers (DBHEs) was studied. • The heat storage characteristic improves the transient heat extraction rate obviously. • Operation modes and parameters influence the heat storage performance greatly. • The DBHEs have wide-range regulation ability of transient heat extraction rate. [ABSTRACT FROM AUTHOR]

Thermal management of triple-junction solar cell is crucial for enhancing electrical efficiency of a high concentrated photovoltaic (HCPV) system. In this paper, a HCPV system integrated with vapor chamber (VC) cooling and thermoelectric generator (TEG) is proposed to maximize the energy output. The VC as a passive cooling device can effectively extract the excessive heat from the triple-junction cell and the TEG module are used to convert the waste heat into electrical power thereby harvesting more energy. A detailed unsteady-state modeling of the VC based HCPV/TEG system is established in MATLAB. The effects of new VC structure, TEG type and concentration ratio on the dynamic performance of the system are discussed and a comparison with the CPV-TEG system without VC cooling is provided. Results reveal that effective cooling of the new VCs can maintain the sophisticated cell under 1000 suns at below 329 K and the average exergy efficiency of the system is 31.20%. It is observed that the appropriate selection of TEG module can improve the system performance. Using TEG5, the proportion of CPV power in total power for the proposed system reaches 99.02%, which increases by 2.81% compared with that of the reported CPV-TEG system without VC cooling. • A HCPV system integrated with VC cooling and TEG proposed to maximize energy output. • Unsteady-state modeling of VC-HCPV/TEG system is established in MATLAB. • VCs maintain cell below 329 K at 1000 suns and average exergy efficiency is 31.20%. • Appropriate selection of TEG module can improve the system performance. • The system provides a superior performance compared to CPV-TEG without VC cooling. [ABSTRACT FROM AUTHOR]

An innovative valorization process for biomass waste treatment has been developed in this study. The basic simulation process developed considering experimental studies, and it has been optimized by application of a pattern search algorithm to obtain the optimum output of energy efficiency, economic performance, and process safety index (PSI). Mainly, three different scenarios have been analyzed based on the sustainability index (SI). These SI has been determined through energy, economy, safety, and electric power potential. According to the results of the SI, the optimized processes are more sustainable (SI = 0.517 to 0.563) in all scenarios as compared to the basic process (SI = 0.503). Similarly, the economic analysis in terms of internal rate of return (%) of the basic process varies from 37 to 2% when the process efficiency dropped from 100 to 80%, and it varies from 44 to 6% for the optimized process without any subsidy. The optimized process has a potential of 2788–4044 kW of electric power generation from thermal energy of the process while it is only 2302 kW for basic scenario. Therefore, the optimized process has better energy, economic, electric power, and safety performances, thus it is more sustainable as compared with the basic process. [Display omitted] • Integration of pyrolysis and gasification for biomass valorization. • Pattern search algorithm application for valorization process optimization. • A novel sustainability index has been proposed. • Electricity potential from optimized process thermal energy is 2788–4044 kW. • Energy efficiency of the processes varies from 46% to 66%. [ABSTRACT FROM AUTHOR]

Solar thermal devices with large installation areas represent technical, economic, and environmental challenges to design, construct, and operate them. Heat pump assisted with a solar thermal installation (STI) guarantee heat load supply at target temperature of a process, minimizing STI occupied area, environment impacts and associated costs. This paper deals with the design of two heat pumps, each one assisted with a STI. For designing solar network (which together the storage tank makes up the STI), lower irradiance levels than winter period are considered, guaranteeing continuous process operation. For designing each heat pump, two refrigerants with Ozone Depletion Potential of zero and Global Warming Potential of 7 (in one of them) are evaluated. This designing methodology is applied to a second-generation production of bioethanol case study. When heat is generated through a heat pump assisted with STI, the solar network absorber area is reduced by 85%, comparing with required area if only a STI produces heating. The same thing happens to generate electric power. Solar fraction value is one, 81,360 tons/year of not burned bagasse avoids 63,142 tons/year of greenhouse gases emissions. Still always guaranteeing the supply of energy to process, the impacts on environment and soil are minimized. [Display omitted] • Significant reduction of large solar thermal installation and storage system areas. • The cost of solar thermal energy is below the cost of fossil fuels. • Operation of the solar collector network under adverse irradiance conditions. • Profitable heat and power production from solar thermal energy plus heat pumps. [ABSTRACT FROM AUTHOR]

Combined cycle gas turbine power plants (CCGTs) are a combined cycle consisting of a gas turbine and a steam turbine to generate electricity. Sometimes CCGTs incorporate cogeneration to produce both heat and power. After the gas fuel combustion in the gas turbine combustion chamber, the flue gases are passed through the Heat Recovery Steam Generator (HRSG) to extract heat and generate additional electrical power using the steam turbine. The CCGT technology is recognized for its highest efficiency of 58% in electricity production among the power production technology. A highly efficient CCGT power plant with 60% efficiency produces even 2.5 times less CO 2 than a modern coal power plant with an efficiency of 45% because of the use of gas fuel and electrical efficiency. The CO 2 emission can be reduced further when the post-combustion CO 2 capture methods are applied. To perform CO 2 capture and to reduce the CO 2 emission from power plants, the CO 2 mass fraction in flue gas is the crucial parameter for the operation of the Post-combustion Carbon Capture and Storage (PCCS) technology. The PCCS technology uses solvents, which is the aqueous solution of amine that reacts with flue gas and absorbs the CO 2 , which is treated and separated later. The paper presents the results of the energy analysis of a post-combustion carbon capture process when integrated with a combined cycle gas power plant. The study considered two different gas fuels such as methane and syngas. Syngas composition was determined from the sewage sludge gasification process and can be treated as zero-emission CO 2 gas fuel. When the flue gas produced from the syngas is used in PCCS at more than 50% of load conditions, the negative CO 2 emission level in large-scale CCGT power plants can be reached. The paper presents the results of mass and energy balance analysis of HRSG of a CCGT integrated with PCCS to perform CO 2 capture. The analysis of HRSG using flue gases from methane and syngas is performed by calculating the enthalpy of flue gas, rate of heat exchange, and temperature distribution of each component of HRSG. The comparison of the result shows slight differences due to the different composition and flow rates of flue gases. The flue gas at the outlet of two HRSG is used in the PCCS at different load conditions. An aqueous solution of 30 wt% Monoethanolamine (MEA) with rich loading of 0.5 mol-CO 2 /mol-MEA and a mixture of 16 wt% 2-amino-2-methyl-1-propanol (AMP) – 14 wt% Piperazine (PZ) with rich loading of 0.62 and 0.86 mol-CO 2 /mol-amine respectively are used in the PCCS. Due to the reboiler duty of amines, the steam consumed by the PCCS for AMP-PZ regeneration is less compared to MEA. Depending upon the flue gas and solvent used in the PCCS, the power consumed by the PCCS from CCGT power plant is measured from 9.6% to 11.6%. For the given operating condition of the CCGT and PCCS at more than 50% load condition, the negative CO 2 emission level can be achieved. • Analysis of the post-combustion carbon capture process with CCGT was performed. • Comparison of PCCS performances using MEA and AMP-PZ mixture solvent was performed. • Achieving negative CO 2 emission level in CCGT using PCCS are presented. • Flue gas from methane and syngas from sewage sludge were used in the PCCS analysis. • CO 2 emission in flue gases from methane and syngas fuel was calculated. [ABSTRACT FROM AUTHOR]

A prospective small power system that uses fuel from a small reactor to turn methanol into hydrogen is a proton exchange membrane (PEM) fuel cell (FC). This article examines the fuel conversion ability of the small methanol steam reformer (MSR) creating different vein channels with varying widths and angles on the reactor plate and PEMFC net electric power at various heated temperatures. For each channel, the catalyst quantity remains the same. The maximum hydrogen yield is 92.44%, methanol conversion 0.01187 kmole ⋅ m−3, and cell net electric power 133.86 W. The augmentation of hydrogen yield and methanol conversion from the innovative SR reactor by the vein channel of width 1.25 mm and angle 120° achieves 84.32% and 29.52% compared to the parallel-channel SR reactor under T wall of 250 °C. The novel SR reactor, having a vein channel with a width of 1.5 mm and an angle of 90°, acquires 29.09% compared to the parallel-channel SR reactor in PEM fuel cell net electric power under T wall of 250 °C, allowing low CO exhaust. The findings show that the novel SR reactor with a venous channel enhances the net electrical energy conversion of MSR and PEM fuel cells. • A vein channel carved on the reactor plate improves the reformer performance. • We examine how width and angle of vein affect the fuel cell net power. • Vein channels expand the contact area and prolong the inhabiting time past them. • The novel reformer has a hydrogen yield of 1.84 times the parallel-channel one. • The novel reformer has a fuel cell net power 1.29 times the parallel-channel one. [ABSTRACT FROM AUTHOR]

The aim of this paper is the investigation of cold energy recovery of liquefied natural gas (LNG) in regasification terminals achievable through direct expansion techniques. After an overview of the state of the art related to the LNG system and the technologies proposed for power recovery, multi-pressure direct expansion solutions with internal heat recovery (multi-pressure DE) are analysed. The purpose is to identify the highest level of recoverable energy and the optimal design parameters, considering technological constraints such as pressure and minimum end-expansion temperature. The multi-pressure DE solutions prove to be innovative power recovery methods because, with a relatively low use of seawater, it is possible to save regasified LNG and generate electrical power, valorising the energy invested in liquefaction. An estimate of recoverable power in operating terminals is carried out. Configurations with cryogenic or non-cryogenic turboexpanders are discussed. Using the proposed solution with non-cryogenic turboexpander and distribution pressure of 3.5 MPa, 56 kJ for each kg of LNG can be produced, which can become more than 150 kJ/kg with cryogenic turboexpanders. For long-distance distribution, cryogenic multi-pressure DE cycles can recover around 100–120 kJ per kg of LNG. The presented techniques can allow recovery of up to and over 30% of the maximum specific work available in LNG regasification. [Display omitted] • The expansion of LNG trade drives the interest in electricity recovery from cold gas. • Efficient power from LNG: Advancements in recovering cold energy for electricity. • Choosing the best path: Evaluating Direct Expansion and ORC for LNG cold recovery. • Examining the benefits of cryogenic Direct Expansion in LNG power recovery. • Investigating the benefits of multi-pressure direct expansion in LNG energy recovery. [ABSTRACT FROM AUTHOR]

Demand Response (DR) is acknowledged to play a relevant role in future electrical power systems. To achieve decarbonization, increasing shares of renewable electricity will induce changes in market design and system operation. New opportunities and challenges will emerge for all market participants. However, regulatory and technology bottlenecks combined with conflicts of interest among actors may deaccelerate DR implementation. This research performed a systematic literature review on five different databases to identify DR benefits and barriers attributable to different actors. Both benefits and barriers were found for all the stakeholders. Consumer bill savings and financial incentives were the most common benefits attributable to DR, on the contrary, consumer lack of interest and knowledge, privacy protection and cyber security were the most common referred barriers. In the second stage, both benefits and barriers were respectively divided into four main categories: Society-wide; Technology-wide; Financial and Market-wide and Environmental-wide benefits and Technology-wide, Economic and Market-wide context barriers. The classification of individual benefits and barriers demonstrated that some categories, such as technology-wide, are relevant both for benefits and barriers. DR implementation complexity and the number of stakeholders involved require DR policies to have certain specific characteristics to give them directionality towards DR successful implementation. • DR benefits emerge for all the stakeholders. • Consumer bill savings was the most common benefits attributable to DR. • Consumer lack of interest and knowledge was the most common barrier. • An environmental category was explicitly considered concerning benefits. • Technology-wide category was relevant both for benefits and barriers. [ABSTRACT FROM AUTHOR]

In order to harvest ambient renewable or recovery energy, a novel piezoelectric energy harvester which mainly includes vibrators, a rotor and a cylindrical outer casing is presented in this paper. The vibrator is made of a U-shaped bimorph piezoelectric beam with a magnet slab mounted on its free end, and the rotor is a disc with magnet slabs embedded in the grooves along its periphery. The theoretical analysis model of the harvester is established and the mechanical and electrical responses are obtained. The results indicate that the harvester can achieve a maximum response by adjusting the rotor speed to make it work near resonance. As the beam section width or the substrate thickness decreases, or the piezoelectric patch thickness increases, the effective power of the harvester generally increases. On the whole, the substrate thickness has the greatest influence on the responses of the harvester, the piezoelectric patch thickness follows, and the influence of the beam section width is the smallest. In particular, the electric power generated from the harvester can reach 8.19 KW by adjusting the values of the related design parameters, which is comparable to a traditional small windmill generator, and therefore the proposed harvester has an appealing application prospect. • A novel piezoelectric energy harvester made of U-shaped beams is developed. • A theoretical model is established to calculate the charge and voltage generated from the harvester. • The effects of a variety of design parameters on the response of the harvester are studied. • An electric power up to 8.19 KW can be generated by the novel piezoelectric harvester with a radius of 0.5 m. [ABSTRACT FROM AUTHOR]

A water-cooled, stove-powered thermoelectric generator was designed and tested to provide electricity in off-grid areas and under emergency conditions. An Ω-shaped heat collector, which facilitates the compact incorporation of 20 thermoelectric modules and works under the radiation heat transfer mode, was proposed. A power load test was performed and compared with previous studies, thereby indicating that a standardization is required for future studies. Different aspects for evaluating the performance of a stove-powered thermoelectric generator were discussed, and appropriate parameters to qualify a stove-powered thermoelectric generator were suggested. Thermoelectric efficiency was measured and compared with a theoretical prediction. A simplified theoretical model, which was verified with experimental data, was developed to explore the temperature distribution inside the thermoelectric module and the power generation performance of the entire stove-powered thermoelectric generator. Special efforts were exerted to reveal the influences of thermal grease, ceramic substrate, and thermal contact on the effective temperature difference. • A novel heat collector based on radiation heat transfer was proposed. • Over 50 W electric power can be outputted at a constant voltage of 12 V. • The thermoelectric efficiency of the present thermoelectric generator is 3.66%. • A model was developed to predict temperature distribution and power generation. [ABSTRACT FROM AUTHOR]

Natural Gas (NG) is constantly increasing its importance and widening its penetration in the world energy mix, so that the topic of its reliable and efficient transportation represents an enduring challenge of utmost importance. Within this framework, the design and operation of NG compression stations is a key aspect, significantly influencing the operation expenses of gas transport companies. Such plants are characterized by an increasing level of complexity both for the choice of the technology to adopt for gas compression and for the plant layout and integration, facing a combination of diverse energy demands including electric power, thermal and cooling demands. The present study is developed mining the data provided by the Italian natural gas infrastructure company, Snam Rete Gas, for a key compression station in the North-East of Italy. A feasibility study to increase the capacity of the compressor station has been carried out and an innovative trigenerative application has been proposed to fulfill the overall plant energy requirements, reducing primary energy needs by nearly 30%. Thanks to the outcome of the study, such trigenerative solution has been deployed by Snam Rete Gas. • A case study of a North Italian compression station owned by Snam Rete Gas. • A solution to increase efficiency and reliability of natural gas compression stations. • A comprehensive analysis of the diverse energy demands of the compression station. • Feasibility study of a trigenerative application to fulfill overall energy loads. • The trigenerative plant allows the reduction of primary energy needs by nearly 30%. [ABSTRACT FROM AUTHOR]

This paper presents the concept of compressed air energy storage (CAES) system with Partial Oxidation Gas Turbine (POGT) technology. In this type of turbine fuel is oxidized with an excess air coefficient λ of less than 1.0. Therefore, a given value of the turbine inlet temperature (TIT) can be reached at significantly lower air consumption. POGT products are electric power and combustible process gas that can be utilised in various ways. In this paper there is assumed a bottoming process, which consists of low pressure combustion and a secondary turboexpander. The system is considered to be functioning in power-to-power mode. However, POGT creates also other opportunities that can help improve flexibility of energy market. As the paper presents an initial study of possibilities the proposed system has been compared against the existing plant in Huntorf (Germany). In this way main differences as well as advantages and limitations of the proposed solution are compared against the existing conventional first generation CAES facility. The study is focused mainly on key thermodynamic parameters and potential performance improvement of the CAES process. The results revealed considerable round-trip efficiency gains. • CAES system with partial oxidation gas turbine (POGT) is proposed. • Performance of the system has been compared against the Huntorf CAES plant. • Round-trip energy efficiency gains are demonstrated. • Opportunities for system integration of CAES system with POGT are outlined. [ABSTRACT FROM AUTHOR]

In this paper, three ways of heat dissipation improvement from the electric motor windings have been investigated. The average winding temperatures that were measured during experiments in the reference state at the nominal rate and no heat removal enhancement reached the temperature values of 68 K above the room temperature. The first variant of heat dissipation improvement was based on covering the external surfaces of the machine by high emissivity material that allowed to decrease the temperature of the windings of approx. 4 K. The second variant was based on the application of two types of radiators on the external motor surfaces. The effect of this solution was the winding temperature reduction of 9 K in case of the first applied radiator and 16 K in case of the second radiator referring both to the rise above the ambient temperature and comparing to the case before modifications. In the next variant, an application of the thermal filler within the motor casing in the free space of the stator allowed to decrease the average windings temperature by 18 K. Then this motor configuration was equipped with the bigger radiator that allowed to reduce the temperature of approx. 30 K. • The detailed CFD model of the low power electric motor was introduced. • Heat dissipation intensifications were tested experimentally and numerically. • The most effective way of the hot-spot temperature reduction was combined method. • Combined method included thermal filler and external surface area development. [ABSTRACT FROM AUTHOR]

Closed-Brayton-cycle (CBC) is a potential onboard power generation technology for hypersonic vehicles, but finite cold source limits its power output. To achieve higher electric power, this study presents the power optimization and comparison between the simple recuperated and recompressing supercritical carbon dioxide (S-CO 2) CBC. Results indicate that the temperature distribution of precooler is essential to obtain its pinch point temperature difference. There is optimal fuel temperature difference in precooler for electric power of S-CO 2 CBCs. Although the recompressing layout has advantages on thermal efficiency, the simple recuperated layout exhibits better on electric power per unit mass flowrate of fuel (219.6 kW vs. 192.5 kW), because the latter utilizes more cooling capacity of fuel. Besides, the optimal inlet temperature of compressor for electric power with finite cold source is far higher than the design value for general S-CO 2 compressors (389 K vs. ∼305 K). In a word, it is more reasonable to develop the simple recuperated S-CO 2 closed-Brayton-cycle as onboard power generation system of hypersonic vehicles. • Pinch point occurs in precooler at high T f2. • There is optimal fuel temperature difference for power output. • Simple recuperated layout exhibits better on power than recompressing layout. • Optimal T 1 for power is far higher than general values. [ABSTRACT FROM AUTHOR]

This article aims to evaluate technical and economic feasibility of the direct contact type seawater freezing desalination (SFD) process proposed by Xie et al. (2018), where the cold energy is provided by regasification of liquefied natural gas (LNG). In the SFD process, the immiscible refrigerant that contains cold energy from LNG regasification is injected into a seawater tank to generate freshwater ice. The freshwater ice is separated and melted to obtain freshwater. Process analysis, integration and optimization are carried out with the aid of detailed material and energy balance models. The influences of some important operating variables of the ice generator, including the inlet temperatures of both refrigerant and seawater, the seawater flow rate and the ratio of seawater that is crystalized into freshwater ice are emphasized in this study. As the main operating cost and income of SFD process are strongly affected by both electricity and water prices, the comparison and effect of these prices in different regions are discussed. Sample calculations with the basis of 1 kg LNG/s show that the optimized SFD process is able to produce 1.64 kg/s of freshwater using 7.83 kg/s seawater when consuming 1.66 kW of electric power. [ABSTRACT FROM AUTHOR]

Electric hydraulic power steering (EHPS) system has been widely used in large and medium cars, which plays an important role in determining the energy loss, driving safety and driving comfort of vehicles. This work mainly discusses the parameter design of the EHPS system based on the multi-objective optimization method. Since there is no explicit standard for the performance indexes of EHPS system, this work takes the energy consumption, steering road feel, steering sensibility and steering stability as the main performance indexes of EHPS system. The quantization formula of each performance index is explored and deduced. Based on these, a multi-objective optimization model is established. Then, the non-dominated sorting genetic algorithm-III based on fitness function (NSGA-III-FF) is proposed, which has better convergence than the original non-dominated sorting genetic algorithm-III (NSGA-III). Besides, the technique for order preference by similarity to an ideal solution (TOPSIS) is applied to select the ideal optimization solution. Simulation results show that the NSGA-III-FF enhances the comprehensive performance of the EHPS system, which can successfully achieve the goal of multi-objective optimization for steering flexibility, steering road feel, and steering energy loss while ensuring the steering stability. [ABSTRACT FROM AUTHOR]

Intermittent renewable energy sources have been transformed from supplementary energy to dominant incremental alternative energy sources in the context of carbon neutrality target worldwide. For coastal countries, it is urgent to integrate abundant offshore energy into regional onshore renewable power sources economically and reliably considering the scarcity of land resources and negative environmental impacts. However, limited knowledge on the complex spatiotemporally synergy relationships between energy potential (onshore and offshore) is a barrier in making reasonable policies to promote collaborative development of onshore and offshore energies. This study presents a spatiotemporally explicit modelling framework for assessing the synergy potential characteristics of onshore and offshore renewable energy sources. The framework firstly estimates the technical potential of solar PV and wind energy across the country by using 40 years of hourly meteorological reanalysis data (1980–2020), and then investigates the long-term changes trend, stability, and complementarity of solar-wind energy potential spatiotemporally at both onshore and offshore sub-regions. We find that a considerable amount of solar PV and wind energy sources could be harnessed in China, and onshore potential across the country (178 PWh/yr) is approximate 20 times higher than offshore energy potential (8.9 PWh/yr). Overall, onshore solar-wind energy potentials exhibit statistically insignificant but slightly increasing trend over the past 40 years, while offshore wind potentials observe an opposite change trend for solar PV and wind energy production. Complementarity assessment showed the northeast and offshore parts of China present high complementarity effects for hourly and daily power production of solar-wind systems. Furthermore, inter-regional combination between offshore and onshore northwest regions also exhibits promising synergy effect for renewable energy power output. The results on resources dynamic and complementarity highlight the advantage of interregional resources cooperative configuration and electric power grid interconnections. The analysis performed in this paper could provide a global picture for the integration planning and collaborative development strategies formulation of on-/offshore renewable energy across the country. • Synergy potential of onshore and offshore renewable energy was evaluated. • Trend, stability, and complementarity of solar and wind potential were examined. • Onshore energy potential in China is 20 times higher than offshore potential. • Synergy development strategies of onshore and offshore energy were proposed. [ABSTRACT FROM AUTHOR]

At present, data centers serve as primary providers of information technology infrastructure, thereby consuming a significant quantity of electrical energy. Considering the growing trend of heightened electricity consumption and heat generation within data centers, leading to increased expenses, coupled with mounting attention to energy preservation and ecological preservation, the deployment of electricity generation systems and solar cooling technologies presents an alluring solution. The present study introduces an integrated system powered by a parabolic collector, an organic Rankine cycle, and a two-effect absorption chiller. A solar parabolic collector system was evaluated as a potential means of providing thermal energy to the power generation and cooling systems. The methodology employed in this study involved the utilization of an Organic Rankine Cycle (ORC) to produce electricity while the cooling generation process was carried out using an absorption cycle. The optimization of both the absorption system and the ORC was performed utilizing the temperature data derived from the parabolic collector. Ultimately, a contrastive analysis was conducted to explore the correlation between cooling storage and electrical power depending on the degree of the parabolic collector. The collective expenditure for electricity and cooling system maintenance within the data center amounts to 1202392 USD. Based on an analysis of the associated expenses for electricity and cooling, the Payback Period (PBP) is determined to be 3.407 years, whereas the Levelized Cost of Energy (LCOE) stands at 0.05815 $ per kilowatt hour. The proposed system underwent an annual assessment encompassing analysis of performance, as well as considerations of the pertinent factors of energy, economics, and the environment. The findings indicate that the utilization of this system can mitigate the release of 1421 metric tons of carbon dioxide annually. The suggested amalgamated framework that couples solar power generation and cooling system holds immense promise in the realm of sustainable development. This optimism stems from the notable advantages of energy conservation, prospective economic benefits, and eco-friendliness that the system embodies. • A novel multi-generation solar system present for data centers is proposed. • The system is comprised of the linear parabolic collector, absorption cycle, and organic Rankine cycle. • Energy, exergy and exergoeconomic, analyses is used for evaluating the proposed system. • Multi-objective optimization utilizing TOPSIS tool for different seasons. • The best payback period and the LCOE parameter are obtained 3.407 years, is 0.05815 $/kWh, respectively. [ABSTRACT FROM AUTHOR]