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The utilization of supercritical carbon dioxide (sCO 2) in the Brayton cycle presents several advantages, such as compact equipment, high efficiency, and rapid response time. The sCO 2 power cycle can be applied in coal-fired power, solar thermal power, and nuclear power systems. Over the past 10 years, many scholars have researched sCO 2 power systems. The compression (pressurization) process is a core thermodynamic process in sCO 2 power cycles, achieved through the use of compressors. Therefore, compressors are important components in sCO 2 power systems. This paper provides a summary of recent studies on compression processes and compressors for sCO 2 power systems. The impact of near-critical-point characteristics of the compression process on equipment and sCO 2 power cycle systems is discussed. The investigations of the performance parameters, design considerations, design methods, and performance prediction methods of sCO 2 compressors are reviewed. The typical research results on CO 2 condensation at the compressor inlet, the effects of operating conditions on compressor performance, as well as optimization of design parameters, are also summarized. Additionally, it provides a summary of sCO 2 compressor prototypes developed by research institutes worldwide and experimental studies. Finally, the current issues with sCO 2 compressors are addressed, and the main future research directions are proposed. This paper will contribute to the development of compressors and promote the acceleration of the commercialization of sCO 2 power systems. • Summary of recent studies on compression processes for sCO 2 power systems. • Near-critical-point characteristics of compression process is discussed. • Summary of compressor prototypes by research institutes and experimental studies. • Current issues and future research directions on sCO 2 compressors are presented. [ABSTRACT FROM AUTHOR]

Accurate photovoltaic (PV) power forecast is crucial to power systems. Solar irradiance forecast is the fundamentals of PV power forecast. Current researches merely focus on improving the forecast accuracy. There hasn't been comprehensive study on the spatial-temporal characteristics of solar irradiance forecast errors. Thus, this paper analyzed the error characteristics of solar irradiance forecast provided by European Centre for Medium-Range Weather Forecasts (ECMWF), one of the most accurate numerical weather prediction (NWP) products. ECMWF's forecasts were compared with ERA5 solar irradiance reanalysis data to reveal the error distribution characteristics. Four-year (2017–2020) data from the geographical region bounded by 63°N, −126°W, 21°S, and 36°E (covering most parts of Europe and North America) were studied. Experiments show that solar irradiance forecast errors peak at noon of the local time. Furthermore, correlations between solar irradiance forecast errors and other weather variables were also revealed. Experiments show that solar irradiance forecast errors have negative correlation with low cloud cover forecast errors and positive correlation with air temperature forecast errors. The possible reasons for the correlation relationship were also analyzed in detail. This paper systematically reveals the spatial-temporal characteristics of solar irradiance forecast errors and provides a useful guideline for solar PV system operation. • Error distribution of ECMWF's solar irradiance forecast in Europe and North America is revealed. • Solar irradiance forecast errors in Europe are smaller than those in North America. • Solar irradiance forecast errors peak at noon of local time. • Solar irradiance forecast errors have slight seasonal and monthly differences. • Correlation between solar irradiance forecast errors and other weather variables is revealed. [ABSTRACT FROM AUTHOR]

Traditional flat PV heat pumps has low irradiation density, large PV area, and the PV evaporators are always fixed, causing large area occupation and lots of irradiation missing, which limit the application and system efficiency. To solve the problems, a novel concentrated PV-air dual-source heat pump system (CPV-DSHP) was proposed in the previous paper, but the annual performance and economic comparison with flat PV-DSHP (FPV-DSHP) are still blank, which are extremely concerning to researchers. Besides, the paper also fills related content about the impact of irradiation composition on the system performance and economics, as well as the irradiation comparison on tracking CPV and fixed FPV surface. From the calculation of the validated model, it's found that the CPV-DSHP system could capture 6098 MJ and 2213 MJ more solar energy, and produce 282.21 kWh and 100.16 kWh more electricity in Garze and Hefei in a year. The annual concentration efficiency is 82.73 % in Garze where direct irradiation accounts for 68.89 %, which is only 73.15 % in Hefei with 39.84 %.The COP PVT is annually lifted by 0.40 in Garze. Although the two systems could both get payback in 5∼6 years, the CPV-DSHP only shows economic advantages in places with good direct irradiation conditions like Garze. • A novel concentrated PV-air dual-source heat pump system (CPV-DSHP) is presented. • The annual performance and economic comparison in different cities are supplemented. • The CPV-DSHP could produce 282.21 kWh more electricity in Garze in a year. • The annual concentration efficiency is 82.73 % in Garze with better direct irradiation. • Payback time is 5∼6 years but CPV-DSHP only shows economic advantage in Garze. [ABSTRACT FROM AUTHOR]

New materials and designs have been developed and proposed to enhance the thermal and electrical performance of photovoltaic-thermal (PV/T) systems in recent years. Despite the significant attention received by PV/T technology, the available PV/T modules are scarce due to complex system designs, environmentally unfriendly working fluids, and low thermal efficiency. In this paper, a highly efficient water-based PV/T system is proposed by combining an innovatively designed cooling system with a PV module. An experimental evaluation of the designed PV/T system was carried out in laboratory conditions. The test results of the PV/T system showed that when the inlet mass flow rate and temperature were 0.0458 kg/s and 11.90 °C, the PV/T system reached the maximum thermal efficiency of 96.47 ± 1.40 %. The increase in mass flow rate from 0.0042 kg/s to 0.0375 kg/s and the decrease in inlet temperature from 17.70 °C to 11.40 °C led to a 12 % improvement in thermal efficiency of the PV/T system showing that the inlet mass flow rate and temperature have a significant influence on thermal efficiency. The developed 3-D numerical model accurately estimated the outlet temperature of the PV/T system. A maximum of 3.43 % error occurred between the experimental results and model output. • The paper proposes a novel, highly efficient, state-of-the-art PV/T system. • The designed PV/T system achieves a maximum thermal efficiency of 96.47 ± 1.40 %. • The designed cooling system reduces the PV module temperature by 40.72 °C. • The electrical conversion efficiency of the PV module is enhanced by 18.32 %. [ABSTRACT FROM AUTHOR]

The solar-assisted heat pump (SAHP) systems are increasingly gaining attention for their potential feasibility in various fields due to their energy saving benefits. However, the available research shows that SAHP still has potential for improvement in drying filed, especially in terms of combining vapor compression heat pumps with solar energy. Consequently, this paper aims to summarize the development of SAHP technology and provide guidance for the application of SAHP technology in the drying field. The development of the SAHP systems is reviewed in this paper, including four ways to enhance the performance of SAHP systems are discussed: photovoltaic/thermal systems, collector optimization, energy storage and ejector enhancement. The technology of energy storage and ejector enhancement will inspire the development of SAHP technology. Additionally, research on optimizing the performance of hybrid heat source heat pump systems is also discussed, and a review of alternative refrigerants that could be used in SAHP systems. It could be found that R134a is the most widely used in SAHP systems currently, but it needs to be replaced soon for its high GWP. HFOs refrigerants are a good alternative. Furthermore, the application prospect of SAHP systems in drying field is also analyzed. Finally, based on the current research status of SAHP technology, the future development trend and research directions of solar-assisted heat pump drying (SAHPD) are proposed: developing suitable refrigerants for heat pump systems; researching high-efficiency heat storage technology; developing multi-heat source assisted heat pump systems; and optimizing the operation strategy of SAHPD using artificial intelligence. • Four ways to enhance SAHP systems are reviewed. • Study on optimization of hybrid heat source heat pump systems is summarized. • The alternative refrigerants in SAHP systems is investigated. • The application prospects of SAHP systems for drying field are analyzed. • The future development trend of SAHPD systems is proposed. [ABSTRACT FROM AUTHOR]

Photovoltaic double skin façade (PV-DSF) offers a versatile solution to address the escalating energy demands of buildings by combining power generation and indoor air temperature adjustment functionalities. Most prior research concentrated on its summer performance, while the winter season receives less attention. This paper concentrates on its operation performance in winter, to provide an experimental framework for its efficient operation. In this regard, the performance of internal circle and thermal buffer mode (both are possible operation modes in winter) were compared via control variable experiments, and the feasibility of mechanical ventilation is also examined regarding the trade-off between the energy consumption of fans and additional energy benefit. These experiments were performed in the full-size experiment rig at Harbin, China, a city with severe cold climate. The experiment results conclusively demonstrate that the internal circle mode can outperform the thermal buffer mode on a cold, sunny day by 10.9%, and the total energy-saving potential can be further increased by 12.6% if fans are activated to enhance cavity airflow. While the experimental data during partly cloudy emphasizes the significance of a suitable operation schedule and shows that PV-DSF can only be switched to internal circle mode when cavity air is fully heated. • The performance of photovoltaic double skin façade (PV-DSF) in winter is studied. • A fully-size experiment rig is constructed to perform comparison experiment. • The internal circle mode can outperform thermal buffer mode by 10.9% in clear day. • The fans can speed up cavity airflow and improve total energy efficiency by 12.6%. • The results of this paper emphasize the importance of a real-time control strategy. [ABSTRACT FROM AUTHOR]

A new absorber surface is designed for solar air heaters to make them compact and enhance heat transfer parameters. The current paper presents the novel absorber design using a tubular surface having three-pass in counter-flow. The absorber tubes are constructed from thin sheets of aluminium; 15 tubes are closely spaced in line with each other to establish three-pass, i.e. five tubes per pass. The research paper investigates numerically and experimentally the thermo-hydraulic performance of a Tubular Three-pass Solar Air Heater (TTPSAH). The numerical model was developed using MATLAB to predict the performance and outlet air temperature. The error in numerical and experimental evaluation is approximately 5%, showing promising results. It was found that the TTPSAH accelerates heat transfer in a compact surface area. The maximum thermal efficiency was evaluated as 60.04%, 41% and 33.3% for an airflow rate of 0.006 kg/s, 0.004 kg/s, and 0.002 kg/s respectively. Thermal enhancement with a maximum outlet air temperature of 110.6 °C, 91.4 °C and 80.2 °C was recorded at a mass flow rate of 0.002 kg/s, 0.004 kg/s and 0.006 kg/s in glazed conditions. Furthermore, the research includes an estimation of the energy cost per kilowatt-hour (kWh), which amounts to $0.017, $0.025, and $0.0311 for mass flow rates of 0.006 kg/s, 0.004 kg/s, and 0.002 kg/s, respectively. • To increase the applicability of solar energy a novel tubular three-pass solar air heaters was designed. • The mathematical model and experimental results are in good agreement. • The maximum outlet air temperature of 110.6 °C attained for a flow rate of 0.002 kg/s. • The thermohydraulic performance parameters of TTPSAH was also studied. [ABSTRACT FROM AUTHOR]

Water scarcity is a major global challenge, with 2.3 billion people living in water-stressed countries and the potential for 700 million people to be displaced by 2030 due to widespread water scarcity. The increasing effects of climate change and overpopulation are exacerbating the problem, particularly in arid and remote regions. One potential solution is the harvesting of atmospheric water, which is estimated to be a vast source of freshwater at 12,900 km3. This study aims to provide a comprehensive and up-to-date review of the latest research in the field of atmospheric water harvesting systems. The purpose of this review is to present the various types of harvested water, the use of solar energy, the methods of gathering it, and the mathematical models used in the literature. The paper has covered numerous types of atmospheric water harvesting techniques, including harvesting dew and fog. In addition, the paper has also discussed water harvesting technologies that rely on sorbent materials. The primary focus of the paper is to present recent advances in water harvesting systems, such as dehumidifying, condensing, vapor compression refrigeration cycles (VCRCs), thermoelectric coolers (TECs), air conditioning units, fuel cells, and integrated systems. The paper aims to provide a comprehensive understanding of the latest developments in atmospheric water harvesting systems. The paper also presents an assessment of the efficiency and effectiveness of these water harvesting systems. The paper concludes by comparing various approaches to provide accurate descriptive information regarding the amount of water harvested. Additionally, the article proposes suggestions to enhance current water harvesting systems and outlines potential future initiatives. • Water harvesting from fog and dew is a promising source of water. • Sorbent materials have the capacity to absorb moisture and generate water from the atmosphere. • TECs are suitable for collecting atmospheric water across many global regions. • Top water-collecting materials absorb moisture, convert it to water in few in minimal time. • VCRC-based devices offer substantial atmospheric water harvesting potential, analysis shows. [ABSTRACT FROM AUTHOR]

Many attempts were made in solar energy to find advanced solar energy technology for solar cell which is with high power conversion efficiency; calculation output current by output voltage using a model of solar cells is very useful for this major aim. Although there are many models can be used to estimate current via voltage from solar cells, no one parameter in the models is a correlation to power conversion efficiency. One simplification of single diode model is proposed in this paper. Not only this model is in form of explicit function, but also one parameter as parallel conductance is correlation to power conversion efficiency. The accuracy of the proposed model is evaluated using thirty experimental data. It was found that in all experimental cases, very good match between measured and calculated is reached. The first important result indicates that power conversion efficiency independent on solar cell connection in series due to parallel conductance independent on solar cell connection in series. The major contribution is that the mathematical relationship between power conversion efficiency and parallel conductance is found in this paper. It is envisaged that the proposed methodology can be a very good route for researchers to discover advanced solar cell. • One simplification of single-diode model is proposed in this paper. • The accuracy of the proposed model is evaluated using twenty-nine experimental data. • Conductance that is responsible for the power conversion efficiency of solar cell. • Power conversion efficiency is quantitatively link to conductance is found. • Good application results are obtained. [ABSTRACT FROM AUTHOR]

Adding propane to CO 2 can improve the thermal efficiency of the supercritical Brayton cycle under high condensation temperatures. Integrating the thermal energy system in a direct-heated solar power tower plant can maximize the thermal utilization of solar energy. In this paper, the thermodynamic model of the plant is constructed, and an operation strategy is proposed to realize round-the-clock operation by flexible scheduling of solar, molten salt, and fossil fuel energy supply. Notably, the potential of adding propane to CO 2 in the plant was analyzed by comparing the off-design performance and the operation behavior under typical days. The results show that the thermal efficiency of the plant using CO 2 -propane is not only 1.63% higher than the original, but also the adequate utilization time of solar energy will be prolonged by 0.3 h. In addition, the hot molten salt filling rate of the CO 2 -propane system is more sensitive to changes with direct normal irradiance. However, the performance of the system will deviate from the optimal design value when the heating mode is switched. The achievements from this paper have testified the CO 2 -propane cycle is better than the initial cycle in the direct-heated solar power tower plant under off-design conditions. The system scheme and operation strategy can be regarded as valuable references for CO 2 -based mixtures application. • The CO 2 -propane is used as working fluid in a direct-heated solar power tower plant. • An operation strategy is proposed to realize all-weather stable operation. • The performance of the plant will deviate from the optimal design value at sunset. • The solar energy adequate utilization time will be prolonged after adding propane. [ABSTRACT FROM AUTHOR]

Photovoltaic energy is one of the clean and efficient energies which has been developing quickly in the last years. As the penetration of solar plants is increasing in the electricity network, new problems have arisen in network operation. This paper models a high penetration factor of solar energy in the electricity network and investigates the impact of solar energy growth on both the generation schedule of different power plants and in the natural gas transmission network. Fuel management of gas power plants is modeled through simulation of the natural gas transmission network. To this end, an increase in the penetration of solar energy in the electricity network inevitably leads to a sudden increase in the output of gas fired units and a linear and integrated model with the electricity and the natural gas transmission networks has been presented to analyze both of them at the same time to better depict the impact of a high penetration of the solar energy in natural gas transmission grids. In this method, natural gas transmission network and Security Constrained Unit Commitment (SCUC) are presented in a single level program. Gas network constraints are linearized and added to the SCUC problem. The stress imposed on the gas network due to a sudden increase in the load of the electricity network is investigated. Conclusions are duly drawn. • This paper models a high penetration factor of solar energy in electricity networks. • Fuel management of gas power plants is modeled by simulation of natural gas network. • Integrated model of electricity and natural gas transmission networks is presented. • Presenting a single level program for natural gas and security constrained unit commitment. • Studying the stress imposed on the gas network due to high penetration of the solar energy. [ABSTRACT FROM AUTHOR]

Due to the higher practicability and annual utilization, the dual-use heat pump systems are more popular in practical demonstrations. Although there are various kinds of designs for such system, most of them focus on the performance enhancement in heating mode and pay little attention to the cooling capacity. The proposed three-dimensional composite heat exchanger structure based on a concentrator plus fins could not only improve the total output in heating mode but also lower the condensing temperature by shading the solar energy with the concentrator to improve the cooling COP. Different from previous study, this paper focus on the improvement potential in cooling mode of the novel system. Experiments are carried out and used for the validation of mathematical model. By analyzing the physical state of the refrigerant during the cycle, the mechanism is revealed in detail and depth. Results show that the dryness decrease at evaporator inlet caused by the condensing temperature drop is the main reason for capacity improvement, while the mass flow rate also has crucial impact. With high mass flow rate, the mean cooling COP of proposed system could be as high as 3.1, 0.16 higher than the system without concentrator shading. • The paper presents the improvement impact in the cooling cycle. • Experiments are carried out for the validation of distributed parametric model. • The decreased dryness at the evaporator inlet explains for the increased cooling. • Lower condensing temperature may cause lower cooling energy with fixed throttling. • Proposed system could get a mean cooling COP of 3.1, 0.16 higher than irradiated system. [ABSTRACT FROM AUTHOR]

The existing Chinese solar greenhouse (CSG) had different spatial structure types, which spatial structure can make the greenhouse fully utilize solar energy and obtain the best thermal performance effect is worthy of further research. This paper took the CSG in the Shenyang area as the research object. A mathematical model was established to simulate the three-dimensional dynamic thermal environment of CSG at the crop level by combining experimental and computational fluid dynamics (CFD) numerical simulation. The model can well describe the heat transfer process in the greenhouse. Based on this model, the effects of variation of multiple structural parameters on the temperature distribution, solar energy interception, heat storage and release performance of CSG were quantitatively specified. The simulation results demonstrated that for the CSG with a span of 10 m in the Shenyang area, the optimal ridge height was 6.2 m, the optimal north wall height was 4.4 m and the optimal horizontal projection length of the north roof was 2.0 m. Furthermore, the spatial structure parameters of CSG with an 8 m–12 m span were obtained for the Shenyang area. This paper can provide theoretical guidance for the design and optimization of spatial structure parameters of CSG in the Shenyang area. • A CFD model was established to simulate the thermal environment of crop level in CSG. • The CFD model can accurately depict the dynamic heat and mass exchange process in CSG. • The effect of structural parameters on the thermal environment of CSG was expounded. • The structural parameters of CSG with 8 m–12 m span were obtained for the Shenyang area. [ABSTRACT FROM AUTHOR]

The photovoltaic double skin façade (PV-DSF) is a cutting-edge building envelope renowned for its dynamic nature and power generation capabilities, which attracts substantial scientific attention. However, the current lack of experimental support makes it challenging to draw definitive conclusions about the influence of façade material. This study aims to address this gap by investigating the energy performance of PV-DSF with different façade materials, thereby establishing an empirical foundation for its optimization. In this regard, the full-size comparison experiments on PV-DSF with 20/40% photovoltaic (PV) glass as external façade and laminated/double glass as internal glass were conducted in Harbin, China. The EnergyPlus software is adopted for the simulation of lighting energy consumption. The results indicate that PV-DSF with 40% PV outperforms that with 20% PV, leading to significant reductions in total energy consumption in both summer (22.73%) and winter (16.84%). The double glass can prevent 0.49 MJ of total heat gain in summer, which is accompanied by a marginal 0.03 MJ increase in winter energy consumption. In total, for optimal annual performance, 40% PV and double glass are recommended as the façades of PV-DSF. The results of this investigation can provide an experimental foundation for PV-DSF optimization in sustainable building design. • This paper presents the semi-experimental study on photovoltaic double skin façade. • The impact of façade material on the net energy-saving performance is studied. • The 40% photovoltaic (PV) glass outperforms 20% PV glass in both summer and winter. • The double glass possesses great advantage in summer, with a tiny short in winter. • From the view of year-round operation, 40% PV and double glass are recommended. [ABSTRACT FROM AUTHOR]

Given the cascade utilization of photon energy, concentrating spectral beam splitting hybrid conversion technology is one of the state-of-the-art solar energy harvesting schemes. In this paper, a novel photovoltaic-thermochemical hybrid system based on a Cassegrain concentrator is proposed for ameliorating optical efficiency and thermochemical conversion under spectral splitting. On this basis, solar energy penetration is improved by concentrating optimization and reactant flow regulation. A specially developed splitter is used to allocate different radiation bands, allowing for the thermochemical storage of photovoltaic loss at mid/low temperatures. The mathematical method covering ray tracing, parameter optimization, solar multi-effect conversion process, and evaluation is constructed and verified, by which the optical characteristics, thermodynamic regulation, and economic feasibility are quantitatively investigated. The results show that the optical efficiency of 79.2% can be obtained by multi-objective optimization considering the uniformity of energy flux and the deviation of ray incidence angle for the first time. With the assistance of the reactant flow strategy, the hybrid system has a solar-product conversion efficiency of more than 36.4% and a stable exergy conversion capacity under different irradiance conditions. Moreover, the system demonstrates a potential investment return and a controllable levelised cost of electricity. In summary, the research results will contribute to the feasibility of full-spectrum solar absorption and the applicability of dish concentrators in distributed scenarios. • Cassegrain concentrator exhibits impressive adaptability in the SBS hybrid system. • Optical optimization and reactant regulation boost solar energy penetration. • Photon cascade allocation enables energy level enhancement and storage. • Potential for high-grade energy conversion and financial viability is demonstrated. [ABSTRACT FROM AUTHOR]

Abstract Solar aided (coal-fired) power generation (SAPG) system has been proved to be an efficient way to utilize the solar energy for power generation. Due to the instability of the solar radiation, a SAPG system generally operates under transient working conditions. In this paper, performance simulation sub-models of main components in a SAPG plant are established based on the lumped parameter assumption. A 330 MW SAPG power plant as a case study is simulated. The variations of the performances, main parameters of the plant with the solar field heat output and the dynamic responses under a typical day are analyzed. The results show that when the heat output of the solar field changes from 0 kJ/h to 2.13 × 108 kJ/h, the coal saving rate will increase to 6.4%, and the solar power generation share (the proportion of the power from the solar energy to the total power from the SAPG plant) will increase to 7.74%. During the analysis process, in order to optimize the solar field, the concept of the solar field equivalent efficiency (SFEE) is proposed and the optimal velocity of heat transfer fluid (HTF) in absorber tube is obtained. Highlights • The transient model of a solar aided power generation (SAPG) system is developed. • The concept of solar field equivalent efficiency (SFEE) is proposed in this paper. • The optimal velocity of heat transfer fluid in the absorb tube is obtained. • Performances of SAPG system with different solar field heat output are revealed. • The dynamic responses of the SAPG system under a typical day are analyzed. [ABSTRACT FROM AUTHOR]

The heliostat field of solar power tower (SPT) system occupies a large proportion of both the total investment and total energy losses of a plant. However, the optimization design of a heliostat field is a challenging work, because there are too many parameters to be optimized. In this paper, a new high-dimensional genetic algorithm toolbox (HDGA) is developed in Visual Studio Community 2015 for the heliostat field design, in which a new crossover strategy is employed for the high-dimensional optimization. The algorithm is verified by both mathematical models and engineering cases, the results show that HDGA is more effective for the high-dimensional problem, and its convergence speed is much faster than that of the genetic algorithm toolbox developed by the University of Sheffield (Sheffield GA). The new algorithm is explained in detail and the optimal field layout is presented. With the new algorithm, a heliostat field referencing to the Gemasolar plant is optimized in this paper. The results show that the optical performance of the heliostat field is improved significantly than that of the un-optimized case, and the optical efficiency of 63.7% is reachable at the design point. At the same time, the annual insolation weighted efficiency is 56.9%. [ABSTRACT FROM AUTHOR]

Integrating solar heat and calcium looping (CaL) process into the existing lignite-fired power generation system is a promising technology to control CO 2 emission. However, the heat released from carbonation process led to the temperature increase of exhaust flue gas together with heat losses in boiler. To recover the waste heat from the exhaust flue gas, this paper proposed a solar-aided lignite-fired power generation system with CaL process CO 2 capture, lignite pre-drying and feedwater preheating (i.e., design III). Besides, design I without waste heat recovery and design II with only lignite pre-drying were simulated for comparison. Through the case study based on a solar-aided 330 MW lignite-fired power generation system, thermal and techno-economic performance of design III was the best on the design condition. Its standard coal consumption rate was 374.44 g/kWh, which was 61.12 g/kWh and 8.24 g/kWh lower than design I and design II, respectively. With the new design, the annual net profit of design III is $18.2924 M, with $0.5652 M higher than design II. The sensitivity analysis indicated that the thermal performance of design III was also the best under various conditions of CO 2 capture efficiency and integrated solar heat. • Solar tower, lignite Pre-drying and Feedwater preheating were integrated with CaL process CO 2 capture. • The new design recovered the waste heat from exhaust CO 2 -lean flue gas caused by carbonation process. • The new design decreased the standard coal consumption rate and increased the thermal efficiency. • The new design was proved economically feasible based on annual net profit. • Sensitivity analysis was conducted to study the influences of CO 2 capture efficiency and integrated solar heat. [ABSTRACT FROM AUTHOR]

The interactions and energy transfer between liquid metal and water are of great research value in developing and utilizing clean energy (solar and nuclear). Understanding how much energy transfer exists in interactions and the consequences of these interactions is crucial for ensuring the stability of energy development and response measures in case of accidents, especially in third-generation ultra-high temperature concentrated solar power and fourth-generation nuclear energy systems. In this paper, a jet visualization test was performed to investigate the interaction characteristics of liquid metal with water. We found that the energy transfer between liquid metals and water is constrained, distinguishing three distinct pressurization modes due to mass transfer, while also developing an energy transfer model for liquid metals. First, the visualization data show that liquid metal-water interaction consists of four stages: coarse mixing, large steam bubble expansion and fragmentation, direct contact and bubble migration. This process is accompanied by the splashing of metal droplets and shaking of the free liquid surface. Furthermore, the water escapes from the melt pool under some conditions, and modal boiling occurs at the surface of the melt pool, hindering heat exchange. Subsequently, three cover gas pressurization modes were distinguished according to the different interactions of liquid metal with water. Finally, based on the perspective of restricted energy transfer, the liquid metal temperature drop model was established, and there is an appropriate matching between the model and test data with ±20 % uncertainty. • We discovered the restricted energy transfer between liquid metal and water. • Based on the perspective of restricted energy transfer, the liquid metal temperature drop model was developed, which matches the test data better. • The phase behavior and sudden increase characteristics in pressure in the interaction between liquid metals and water were clarified. [ABSTRACT FROM AUTHOR]

Considering the huge consumption of traditional energy and the rising demand for electricity, the development of renewable energy is very necessary. In this paper, an energy system integrating biomass energy, solar and two-stage organic Rankine cycle (ORC) is proposed, which uses the stable energy output of biomass energy to compensate for the volatility of solar modules. The proposed system comprises a biomass boiler, photovoltaic thermal panels (PV/T), evaporators, condensers, working medium pumps, turbines, a preheater and an air preheater. In addition, conventional and advanced exergy, exergoeconomic and exergoenvironmental (3E) analyses are carried out. Conventional 3E analyses reveal two components that require priority improvement. They are respectively evaporator 1 with the largest exergy destruction (708.2 kW) and exergy destruction environmental impact rate (775.3 mPt/h) and evaporator 2 with the largest exergy destruction cost rate (19.15$/h). The results of advanced 3E analyses show that the largest avoidable endogenous exergy destruction is condenser 1 (136.6 kW), the largest avoidable endogenous exergy destruction cost rate is condenser 2 (3.377$/h), and the largest avoidable endogenous exergy destruction environmental impact rate is condenser 1 (196.1mPt/h). These mean that these components have great potential for improvement in reducing exergy destruction, saving cost and protecting the environment. In addition, the avoidable endogenous exergy destruction/cost/environmental impact rate of evaporator 2 are negative, so evaporator 2 is not suitable as a priority component for improvement, which is contrary to the conclusions of conventional 3E analyses. It is found that conventional 3E analyses can only point out the biggest exergy destruction point, but cannot indicate whether the components with the greatest exergy destruction have the greatest potential for improvement. However, advanced 3E analyses can show the improvement potential of each component by improving its own performance and the external conditions. Therefore, it is necessary to conduct advanced 3E analyses. [ABSTRACT FROM AUTHOR]

The paper aims to study the impact of Thermal Energy Storage (TES) technology on the dynamic characteristics of Concentrated Solar Power (CSP). An integrated dynamic model of a CSP plant is firstly established, which combines the concentrating system, the TES system, and S–CO 2 Brayton power cycle system. Three TES alternatives are considered: two-tank molten salt TES (TT-TES), packed-bed TES with solid fillers (PBS-TES), packed-bed TES with phase change materials (PBP-TES). Using this integrated dynamic model, the thermal performance and economic feasibility of different TES technologies applied to CSP are compared and analyzed. The results indicate that utilization of packed-bed TES primarily impacts the optical efficiency of the heliostat field and the thermal efficiency of the power cycle, while having minimal effect on the receiver's thermal efficiency. Furthermore, during the vernal equinox, the daily average system efficiencies of CSP configurations integrating TT-TES, PBS-TES, PBP-TES technologies are 26.0 %, 25.5 %, and 24.5 %, respectively. Meanwhile, the use of packed-bed TES systems significantly reduces the material cost of the TES. In comparison to the TT-TES, the PBP-TES and the PBS-TES can reduce cost by 21.2 % and 42.3 %, respectively, and decrease TES volume by 83.0 % and 63.8 %, respectively. • An integrated dynamic model of a concentrated solar power is established. • The influence of three TES technologies on the dynamic characteristics of CSP is studied. • The TES technologies include two-tank molten salt TES, packed-bed TES with solid fillers, and packed-bed TES with PCMs. • Packed-bed TES affects charging and discharging processes, causing energy loss. • Packed-bed TES reduces cost and volume compared to two-tank molten salt TES. [ABSTRACT FROM AUTHOR]

Partial shading conditions (PSCs) caused by clouds, trees, buildings, and other factors can lead to uneven irradiance on the photovoltaic (PV) panel, resulting in reduced power output and decreased service life of PV systems. To deal with this problem, a reconfiguration method for hybrid photovoltaic-thermoelectric generation (PV-TEG) systems based on an improved firefly algorithm (IFA) is proposed in this paper. Firstly, the method uses PV-TEG hybrid system to make full use of the waste heat of traditional PV systems to improve the utilization rate of solar energy. Secondly, IFA is employed to adjust the electrical connection between the modules to reduce the adverse effects of PSC and increase the total output power of the system. To validate the effectiveness of this method, three different scale PV-TEG hybrid systems of 4 × 4, 9 × 9, and 15 × 9 are reconfigured under practical and standard shading conditions, and the results are compared with those obtained using PSO, GA, BWOA, AO, and ACO. The results demonstrate that the IFA-based reconfiguration enhances the output power by 31.19 %, 21.49 %, and 21.84 % for 4 × 4, 9 × 9, and 15 × 9 arrays compared with that without reconfiguration, respectively. Finally, hardware-in-the-loop (HIL) experiments further verify the hardware feasibility of the proposed method. • A reconfiguration method is proposed to mitigate the influence of PSCs. • IFA is proposed to search the best reconfiguration strategy. • Multiple cases verified the efficiency of IFA in reconfiguration of hybrid systems. • HIL test verified the feasibility of proposed method in engineering implementation. [ABSTRACT FROM AUTHOR]

Maintaining the security of supply is one of the challenges that system operators face. Variability and uncertainty increase due to the penetration of variable renewable energy sources such as solar and wind, while flexible technologies such as traditional thermal units are phased out to reduce emissions. The current methods for assessing power system adequacy are based on historical operations and are generally intended to be applied to thermal-dominated electricity systems. Therefore, it is necessary to improve current adequacy assessment methods since they usually neglect the flexibility of power systems. This paper presents a methodological approach for jointly assessing the adequacy and flexibility of power systems. The methodology's usefulness is demonstrated through its application to the Spanish power system. For the case study, results show that new closed-looped pumped storage hydro technology provides 25% flexibility while contributing to adequacy due to higher installed capacity and round-trip efficiency. Due to shorter storage duration, batteries only contribute to flexibility, supplying 16% of the total operating reserves. Therefore, this study shows that metrics of flexibility and individual contribution to the power system adequacy complement each other and simultaneously enable the scarcities of power systems to be observed. • The approach identifies technologies contributing to adequacy, flexibility, or both. • Storage technologies behave differently depending on the service to be provided. • New pumped hydro storage provides 25% flexibility regarding power variations. • Batteries provide 15% of flexibility requirements in terms of operating reserves. • 12% of the battery capacity serves to maintain adequacy during critical periods. [ABSTRACT FROM AUTHOR]

China has set a goal of carbon neutrality by 2060 and is determined to increase wind and solar power to 1200 GW by 2030, even though it already has the world's largest installed capacity of renewables. However, the lack of flexibility in the power system will limit the development of a higher proportion of renewable energy. This paper evaluates the applicability of different types of flexible power sources in China for the first time. Above all, it describes the current situation of China's power industry and the necessity of increasing flexible power sources, establishes an evaluation system from the perspectives of benefit, opportunity, cost & risk, then determines 19 evaluation criteria. The BOCR-ANP-TOPSIS method was used to evaluate the system, where the ANP method determines the weights and the TOPSIS method ranks the alternatives. The result shows that pumped storage hydropower has the highest overall ranking, followed by the flexibility transformation of coal-fired power. Coupled with sensitivity and comparative analysis, valuable findings that will help future energy policymakers are reported. • Evaluating the applicability of different flexible power sources in China for the first time. • The identification of criteria for the selection of flexible power sources was given. • Making recommendations for China's flexible power source development policy. • The BOCR-ANP-TOPSIS method adopted can be extended to select flexible power sources in different regions meticulously. [ABSTRACT FROM AUTHOR]

As the proportion of solar power generation increases, accurate solar irradiance forecast used to connect solar power to the grid has become crucial. Multi-parameter prediction is one of the most commonly-used methods for solar irradiance forecast. Effective additional variables can improve the accuracy of the model, while invalid additional variables can lead to over fitting or under fitting of the model. To address this issue, this paper proposes the information gain factor as the basis for proactively selecting input variables. Firstly, the experiment combines 10 kinds of additional variables with GHI and inputs them into five models: auto regressive model (AR), gradient boosting decision tree (GBDT), convolutional neural network (CNN), long short-term memory (LSTM) and convolutional long short-term memory (ConvLSTM). Then, the impact of additional variables on prediction accuracy is analyzed and used as a basis for verifying the feasibility of the proposed method. Finally, the Pearson correlations and information gain factors between these variables and GHI are calculated separately. The results indicate that the information gain factor is more suitable as a basis for selecting input variables than the Pearson coefficient. [Display omitted] • Information gain factor is proposed to help select inputs for multi-parameter prediction models. • The additional variables beneficial for solar irradiance forecast are found. • Variable influence rate is proposed to evaluate the influence of additional variables on the models. • The effectiveness of information gain rate has been proven through experiments. [ABSTRACT FROM AUTHOR]

Thermal grids will play a key role in the development of local energy communities and the achievement of 100% renewable societies. Such systems allow excess heat produced by distributed producers through renewable energy sources (also referred to as "thermal prosumers") to be shared among other consumers characterized by high heat demand or who still depend on fossil fuels. However, to achieve more reliable results when performing energy analyses, it is of utmost importance to develop models of prosumers' substations, where technical details (e.g., type of connections, heat exchangers, valves, etc.) and controllers are accounted for. Starting from the layout of a bidirectional substation for a thermal energy network proposed in the literature, this paper proposes a dynamic model that replicates the experimental setup in the TRNSYS environment. Validation results show a good matching between simulation and experiments in terms of dynamic behavior and energy balance. To show the capabilities of the proposed model, a prosumer with heat available from 205 m2 solar thermal collectors is considered as a case study. The analysis is performed by assuming two locations characterized by different irradiation values, i.e., Palermo (Italy) and Berlin (Germany). The results show that exchanging the excess heat produced on-site with a heating network allows the solar collectors to reach peak heat production, which is 130 kW and 110 kW for Palermo and Berlin, respectively. The surplus heat sold to the network is equal to 66% and 29% of the total energy exchange within the substation for Palermo and Berlin, respectively. Conversely, the self-consumption of the produced heat accounts for 21.2% and 30.6%, respectively. The model prospectively represents a valuable tool to develop feasibility studies in Thermal Energy Communities and assess the potential of innovative energy- and cost-effective operation strategies. • A model of a thermal prosumer substation exchanging with a District Heating Network (DHN) was created in TRNSYS • The virtual model was validated through experimental data by showing a good matching between simulation and experiments • To show the capabilities of the model, a prosumer equipped with 205 m2 solar thermal collectors is considered as a case study • Results showed that the prosumer substation allowed for optimal exploitation of the heat produced by the solar collectors • The proposed model represents a viable tool to perform analyses applied to renewable energy systems in prosumers networks [ABSTRACT FROM AUTHOR]

Wind and solar power depress market prices at times when they produce the most. This has been termed the 'cannibalization effect', and its magnitude has been established within the economic literature on current and future markets. Although it has a substantial impact on the revenue of VRE technologies, the cannibalization effect is neglected in the capital budgeting literature, including portfolio- and real options theory. In this paper, we present an analytical framework that explicitly models the correlation between VRE production and electricity price, based on the production costs of surrounding generation capacity. We derive closed-form expressions for the expected short-term and long-term revenue, the variance of the revenue and the timing of investments. The effect of including these system characteristics is illustrated with numerical examples, where we find the cannibalization effect to decrease projected profit relative to investment cost from 33% to between 13% and − 40 %, depending on the assumption for the future VRE capacity expansion rate. Using a real options framework, the investment threshold increases by between 13% and 67%, due to the inclusion of cannibalization. • An analytical framework to consider cannibalization in investment decisions for VRE • We present closed-form expressions for the expected value and variance of revenues • An investment timing problem illustrates one potential use of the analytical framework • Expected VRE growth rates have a large impact on the revenues and optimal timing [ABSTRACT FROM AUTHOR]

This paper compares different strategies to transform the heating sector into a future 100% renewable energy solution. It focuses on the consequences for infrastructures in terms of grids and storage across the electricity, gas and heating sectors. The hypothesis is that these consequences are rarely taken into proper consideration, even though the costs are significant and differ substantially between the alternative pathways. While the smart grid scenarios are based on electricity as an energy carrier, the “smart energy systems” approach is based on a cross-sectoral use of all grids. Using Denmark as a case, this paper shows how the current gas and district heating grids each have twice the capacity of the electricity distribution grid. Moreover, the existing gas and thermal storage capacities are substantially higher and the additional future capacities are more affordable than within the electricity sector. The conclusion is that the “smart grid” pathway requires a 2–4 times expansion of the electricity grid and significant investments in electricity storage capacities, while the “smart energy systems” pathway can be implemented with relatively few investments in affordable minor expansions of existing grids and storage capacities. [ABSTRACT FROM AUTHOR]

The fossil energy crisis is a great test for human society and the prospect of methanol reforming hydrogen fuel cell technology is of great concern. Higher production cost is also an important factor in limiting the combined cycle power plant. The integrated system enables the overall energy utilization efficiency to improve. Methanol can be made from coal gasification and liquefaction and coal chemical industry has received the attention and support from the state and it is an extremely promising technology. Based on the large scale commercial process simulation software Aspen Plus, this paper constructs a distributed energy system based on solar methanol reforming SOFC which combines GT-ST power generation system with AHP-AR. The results show that the efficiency of SOFC, total electrical efficiency and total system thermal efficiency of the method are 35%, 66% and 90% respectively. In this paper, the performance analysis of SOFC integrated system is carried out which reveals the affinity of solar energy and chemical energy. The results show that the new system increases the power generation and reduces the coal consumption rate. [ABSTRACT FROM AUTHOR]

This paper presented a numerical investigation into a solar/waste energy driven sorption/desorption cycle employing a novel LiCl-Sillicon-Gels adsorbent bed. Several adsorbent materials available for air drying, e.g., silica gel, zeolites, silica gel haloid compound, consolidated composite desiccant, etc., were compared each other, leading to the selection of a most suitable desiccant material (i.e., LiCl-Sillicon-Gels), which has an adequate regeneration temperature of 80 °C and relatively higher moisture absorption capacity of 0.5 g/g. A dedicated adsorbent bed structure was devised to allow both solar radiation and warm air (generated from the waste heat) to pass through to vaporize the water reserved in the voids of the bed. The mass and energy conservation principles were applied to both air and adsorbent within the bed, leading to the development of a specialist mathematical model able to characterize and evaluate the performance of the sorption/desorption cycle. On this basis, the desorption process driven by both solar radiation and waste heat and associated sorption process were simulated side by side. The performance of the sorption/desorption cycle, represented by moisture extraction volume (D me ), moisture extraction/removal efficiencies (ƞ me /η mr ), and dehumidification coefficient of performance (DCOP), and their correlations with the major operational factors, e.g. swapping time of working mode, parametrical data of the process/regeneration air and solar radiation, were investigated and characterized. The results of the research indicated that the system can achieve a good performance (i.e., moisture extraction volume of 7–7.2 g/kg, moisture extraction/removal efficiencies of 0.4–0.5 and 0.5 to 0.57, and DCOP of 0.35–0.37) under a typical wet climatic condition (i.e., 30–35 °C and 70–80% RH). Increasing solar radiation intensity to 1,800 W/m 2 could lead to a significant rise in DCOP (from 1 to 5). Furthermore, the geometrical set-up of the adsorbent chambers/beds and cycle was optimized, giving the recommended air flow channel length of 0.7–0.9 m and air flow turning number of 5–7. The swapping time of the beds in terms of the function is suggested to 2.5–3 h. Compared to the conventional adsorption system, the new system can achieve around 90% saving in fossil fuel energy use. In summary, the paper made first of its kind effort in designing, characterizing and optimizing a novel solar/waste energy driven sorption/desorption cycle with LiCl-Sillicon-Gels as the bed filling material, which would help realization of the sustainable air treatment process in both building and industrial sectors, thus contributing to the energy saving, carbon emission reduction, as well as sustainable development on the global scale. [ABSTRACT FROM AUTHOR]

Organic Rankine Cycle (ORC) is promising in utilizing low-medium thermal energy, and solar energy is widely considered as the most attractive renewable energy for the future. Consequently, electricity production by coupling ORC and solar energy can reduce the fossil fuel consumption and lower the CO 2 emissions over the world. However, the intensity of solar radiation keeps changing throughout the daytime, so it is important to study the daytime performance of solar-ORC system to guarantee a proper operation. Based on the discretized parameter model built in Dymola, dynamic performances of a small-scale power plant driven by parabolic trough collector (PTC) under clear sky and cloudy sky conditions are analyzed in this paper, respectively. The results show that degree of super heat, evaporation pressure and output power are relevant to direct normal irradiance (DNI) and follow the variation of DNI from morning to afternoon. Particularly, this paper pays attention to analyze the system's responses to the cloud blockage using the dynamic model. It shows that short period (5 min) of cloud blockage of the sun poses no severe influence, while the cloud occurring at morning can cause the system to break down easily. In addition, a conventional PID control strategy is considered for the PTC-ORC system under the weather condition of cloudy sky. The optimized system can generate 105.54 kWh and the system without control can generate 84.95 kWh. The generation can improve 24% compared to the system without control. [ABSTRACT FROM AUTHOR]

Lack of reliable data often prevents new private investments in renewable energy and government programs in this sphere. The paper offers a novel renewable energy resources system of potentials: energy, resource saving and environmental; better designed and more accurate methods for calculating the future exploitable technical potentials of wind and solar PV energy for a wide range of generating equipment in centralized and distributed power systems, taking into account existing social and environmental limitations. The paper also presents the latest assessments of these potentials for Russia and its 85 regions (in terms of fossil fuel saving and substitution, power and heat production and environmental effects), offering solutions to overcome methodological limitations of previous country-level assessments, such as incomplete or unreliable sources, absence of hourly, daily and monthly assessments, etc. Given the limitations of existing network of national meteorological stations and satellite monitoring systems it was decided to use NASA SSE database as a source of meteorological information. The methodology was validated through a comparative analysis of the data obtained in the course of this study and the data of wind monitoring campaign carried out by a German engineering company in one Russia's region for 18 months using 70 m masts. [ABSTRACT FROM AUTHOR]

Lower prices for photovoltaic systems lead to the spread of building-integrated photovoltaics (BIPV). In this paper, a simple method is proposed to evaluate the electrical power produced by Solar Photovoltaic Blinds (SPB). The equations allow to assess slat mutual shading and view factors and are applicable to any slat inclination, any orientation and any geometry. The possibility that the PV layer does not entirely cover the lamella is also considered. A parametric study is performed to evaluate the impact of geometric factors on the annual yield. The paper shows that 1) The south-east (or -west) orientation provides maximum electrical production. 2) Automating closing PV blinds in summer, when room is unoccupied, allows to increase electricity production by approximately 9% for the south, east and west exposures and 16% for the north exposure. 3) There is a slat distance/width ratio that maximizes the annual electricity produced. It depends on the handling strategy and is about 0.6 for energy optimizing methods and 0.7 for standard uses. 4) Solar tracking that maximizes the radiation entering the room in winter significantly reduces electricity production. 5) The reflectivity of the back of the slats has a little influence on the annual production (up to 5%). • A new mathematical approach is presented to estimate electrical output of PV blinds. • The method is applicable to any location and window orientation. • Annual electricity production can reach up to 78 kWh/m2. • A parametric analysis is conducted to obtain the optimum geometry for the PV blind. • Performance depends significantly on handling strategy. [ABSTRACT FROM AUTHOR]

To solve the problems of the current optimization methods for solar segmented thermoelectric generator performance based on numerical methods, this paper applied deep neural networks to optimize the device geometry for improved thermo-mechanical performance. The motivation for using the deep neural network is to overcome the lengthy computational time and very high computational energy required by the traditional numerical method in optimizing the segmented thermoelectric generator performance. The numerical model is built using ANSYS software and the effects of temperature dependency in the 4 thermoelectric materials are considered to ensure result accuracy. Furthermore, 16 possible geometry parameters which were previously not considered, encompassing the individual and combined segment's heights and cross-sectional areas are optimized to find which set of parameters are the best in maximizing the device performance. The deep neural network is a regressive multilayer perceptron with network hyperparameters comprising 2 hidden layers with 5 neurons per layer. The training process is governed by the Levenberg-Marquardt standard backpropagation algorithm to minimize the mean squared error and maximize the regression correlation between the neural network forecasted outputs and the numerical-generated dataset. The most significant contribution of the proposed deep neural network is that it was able to quickly and accurately forecast the device performance in just 10 s, which was 2880 times faster than the conventional numerical-based optimization approach. Additionally, the optimized device had a maximum efficiency of 18%, which was 78% higher than that of the unoptimized device. Also, the thermal stress of the optimized device was 73% less than that of the unoptimized device design, indicating an extension in the device mechanical reliability and service lifetime. The results reported in this paper will accelerate the ease at which efficient, long-lasting segmented thermoelectric generators are manufactured by harnessing the power of artificial intelligence. [Display omitted] • AI driven geometry optimization of STEG thermo-mechanical performance using DNN. • 3D FEM considers 16 STEG geometry parameters that were previously neglected. • AI fixes shortcomings of conventional FEM method in optimizing STEG performance. • DNN forecasted device performance in just 10s, 2880 times faster than FEM. • Optimized STEG is 78% more efficient than conventional STEG, reduces failure by 73%. [ABSTRACT FROM AUTHOR]

Innovative hybrid source for electricity, cooling and desalinated water production based on a mixed fossil fuel/solar energy supply, equipped with triple-component chiller configuration, has been presented in the paper. The system was erected and recently commissioned in King Abdulaziz City for Science and Technology (KACST) in Kingdom of Saudi Arabia to operate as a working laboratory supplying media to adjacent buildings of the Solar Village complex. In the Arabian Gulf region, increased demand, especially for cooling and desalinated water, as well as fluctuating availability of electricity from the grid in summer period is visible, what makes such a stand-alone installation operation justified especially in remote areas. Abundant availability of intermittent solar energy correlated with cooling demand led to development of novel triple-component chiller configuration consisting of absorption, adsorption and compressor chiller. Two Diesel internal combustion engines had been selected to supply electricity and heating when solar energy is not available. Paper presents results of installation commissioning, during which the performance of the system for three different operating scenarios was assessed. Maximum efficiency was achieved for maximum renewable energy production option reaching 324.91% with renewable share at a level of 89.99%. For the maximum cooling capacity production, the efficiency of the system was 124.89% with 18.6% share of renewable energy. The lowest efficiency, of 93.09%, system obtained for the night scenario. • Novel, patented triple-component configuration of chillers has been presented. • Hybrid source for energy and desalinated water production has been commissioned. • Solar panels integration enabled maintaining cooling and distillate production. • Efficiency in max. Renewable energy scenario has reached 325% during commissioning. • Renewable energy share has reached 90% during commissioning. [ABSTRACT FROM AUTHOR]

This paper proposes an innovative thermal collector for photovoltaic-thermal (PV/T) systems. The thermal behavior of the photovoltaic module and the designed cooling box flow are coupled to achieve the thermal and electrical conversion efficiencies of the water-based PV/T system. Different inlet mass flow rates and temperatures are simulated under normal operating cell temperature conditions (NOCT). The temperature distribution and average temperature of the photovoltaic module layers are investigated. The results show that when the mass flow rate is 0.014 kg/s, and the inlet flow temperature is 15 °C, the PV module reaches an electrical conversion efficiency of 17.79% with 76.13% of thermal efficiency. The designed cooling system exhibits better performance with a significant increase in thermal and electrical conversion efficiency compared to current solutions in the literature. The findings in this paper highlight the utility of PV/T systems and their massive potential to popularize the solar energy field and harvest thermal and electrical energy simultaneously. • The paper investigates a newly designed state-of-art cooling system for PV modules. • The PV module reaches an electrical conversion efficiency of 17.79% with 76.13% of thermal efficiency. • The designed system is compared to current solutions in the literature and exhibits better performance. [ABSTRACT FROM AUTHOR]

This paper quantifies that current net-zero building definitions will remain as necessary but not sufficient conditions in sustainable decarbonization efforts until they recognize exergy destructions as one of the root causes of emission responsibilities. A direct relationship between exergy destructions and nearly-avoidable carbon dioxide emissions has been set as a sufficient condition to upgrade the decarbonization mindset. This relationship is demonstrated in a case study where a solar prosumer building with photovoltaic panels and a ground-source heat pump, known as a net-zero energy building, is responsible for emissions. Based on the second law, emission responsibilities, primarily at the PV panels and the heat pump, were identified. By replacing them with advanced photo-voltaic-heat panels with temperature peaking and heat pump with adsorption cooling machines, carbon dioxide emission responsibility due to avoidable exergy destructions was reduced by 96%. The main attribute is using solar power only for electric power instead of downgrading it downstream to heat or cold by the heat pump, minimizing exergy mismatches between electrical and thermal power. The paper also shows that a net-zero energy building may neither be a net-zero exergy building nor a zero-carbon building due to these exergy destructions. • Second Law redefines Net-zero buildings, showing unrecognized root emissions causes. • Exergy destructions are responsible for these root causes. • Unrecognized root emission causes are at least 60% of known sources. • A case study shows that solar prosumers may be upgraded for nearly nearly-zero carbon building. • Net-zero carbon building is not possible for inevitable and irreversible exergy destructions. [ABSTRACT FROM AUTHOR]

This paper reports an experimental investigation on a design of solar water heater system (SWH) employing evacuated tube heat pipe solar collectors (HPSCs) and a latent heat storage (LHS) tank. In this design, solar energy incident on the HPSC is collected and stored in the LHS tank via a heat pipe with fins attached to the condenser ends inside the LHS tank. The stored heat is then transferred to the supply water via a set of finned pipes located inside the LHS tank. In this paper, the design, the working principles and the experimental thermal operations of the charging only and discharging only modes are presented. The effects of weather conditions in a tropical region and supply water flowrates and hot water draw off time are also reported. The thermal efficiency of the system in sunny days is in the range of the 38%–42%, while in cloudy-rainy days this efficiency drop to the range of 34%–36%, which indicates a range of about 8% fluctuation in different conditions. It was illustrated that the flowrate has direct proportion on the overall efficiency of the system in the tested range. Advantages of the heat pipe and phase change material together cover their disadvantages like overheating of the heat pipe and low thermal conductivity of the phase change material. By this design for energy storage tank, the thermal stratification effect is completely removed. This system could be a stand-alone system for night hot-water demands or part of a SWH configuration. [ABSTRACT FROM AUTHOR]

In the present context, energy access to remote rural households through local energy generating systems has been recognized as a cost effective and extent efficient option. With increased emphasis on eco-friendly technologies and high fuel cost associated with conventional energy generation, the use of renewable energy resources (small hydro, biomass, solar, wind energy etc.) are being explored. The present paper is focused on the optimal sizing of a stand-alone Integrated Renewable Energy System (IRES) which comprises the resources of micro hydro power (MHP), biogas, biomass, solar and wind energy. Initially, a demand response (DR) strategy based on energy consumption scheduling of appliances has been suggested and modelled in the paper. This strategy aims to minimize the peak hourly energy consumption of the study area. Further, different combinations of system components without and with DR strategy were considered and optimized for power reliability criteria of 0% and 5% unmet load. It has been found that significant amount of savings in system sizes and costs are obtained with DR strategy compared to system without DR. [ABSTRACT FROM AUTHOR]

In recent years, solar energy has been considered as one of the principle renewable energy source for electric power generation. In this paper, single diode photovoltaic (PV) system and double/bypass diode based PV system are designed in MATLAB/Simulink environment based on their mathematical modeling and are validated with a commercially available solar panel. The novelty of the paper is to include the effect of climatic conditions i.e. variable irradiation level, wind speed, temperature, humidity level and dust accumulation in the modeling of both the PV systems to represent a realistic PV system. The comprehensive investigations are made on both the modeled PV systems. The obtained results show the satisfactory performance for realistic models of the PV system. Furthermore, an in depth comparative analysis is carried out for both PV systems. [ABSTRACT FROM AUTHOR]

This paper construct a CCHP and renewable energy based hybrid energy system driven by distributed energy resources (DERs CCHP). Then, the paper constructs performance indexes from energy, economic and environment. Thirdly, the paper proposes a multi-objective optimization model for DERs CCHP system under four optimization of energy rate (ER), total operation cost (TOC), carbon dioxide emission reductions (CER) and joint optimization. Finally, Guangzhou Higher Education Mega Center (GHEMC) in China is taken as the object for comparatively analyzing the operation performance of DERs CCHP system and CCHP system driven by natural gas (NG CCHP system). Results show: Joint optimization mode could balance the results of different optimization modes. DERs CCHP system shows better operation performance. ER of ER optimization, CER optimization and joint optimization are higher than that of NG CCHP system. NPV of all optimization modes is positive, IRR are bigger than the expected yield rate. DERs CCHP system could reduce CO 2 emission by utilizing wind energy and solar energy to replace NG. The sensitivity analysis indicates the performance of the DERs CCHP system will become better with the increase of chiller COP, decrease of NG price and wind-photovoltaic equipment cost. [ABSTRACT FROM AUTHOR]

In this paper, a novel multigenerational integrated system that is able to produce five useful commodities, such as freshwater, space heating, hot water, power and hydrogen for a community, is proposed and investigated. The system uniquely covers heat storage by molten salt heat storage along with hydrogen production by magnesium-chlorine (Mg–Cl) based thermochemical cycle. Additionally, the present system has a multi-effect desalination plant to provide freshwater community needs. A solar power tower is offered due to its capability of harvesting high energy levels. The heat recovered by the solar power receiver is passed through an organic Rankine cycle (ORC) to meet the need for the high-temperature level that is required for the thermochemical cycle. The molten salt storage tanks are used to offset the mismatch between demand and supply for the necessary energy to run the system in case of the absence of solar irradiation. The suggested system is intended to leverage solar and geothermal energy sources to generate practical necessities like power, heat, and hot water for residential applications of a projected community. The system is then analyzed in detail thermodynamically in the context of exergy and energy approaches. In addition, the subsystems are analyzed parametrically to study the performance of the overall system to observe how the ambient and working conditions change the system efficiencies. The city of Vancouver in Canada is selected as the potential location where the system performance assessment is carried out accordingly. As a result of the present thermodynamic analysis, the energetic and exergetic efficiencies for the system are obtained as 45.45% and 52.32%. The total exergy destruction rate is another exergy metric to compare both versions, where the rate of 163967.39 kW exergy destruction is obtained for the overall system. • A novel multigenerational integrated system developed with the Mg–Cl thermochemical cycle • Energy and exergy approaches and thermodynamics used to analyze the system efficiencies • Parametric study is carried out to observe the various effects on system performance. • The energy and exergy efficiencies found 45.45% and 49.65% to produce hydrogen, power, fresh water, and heat. [ABSTRACT FROM AUTHOR]

A novel hydrogen production system based on a sulfur-iodine (S–I) thermochemical water-splitting cycle driven by 100% solar energy is proposed in this paper. A solar power tower (SPT) with thermal energy storage (TES) is used to supply heat stably. Considering the large heat recovery potential in the S–I cycle, a supercritical carbon dioxide (S–CO 2) Brayton cycle is used to improve the system performance. A complete thermodynamic model and detailed description of the energy and exergy flow from the sun to SPT, TES, S–I cycle, S–CO 2 Brayton cycle and hydrogen is obtained. The system performance in the base case and actual weather conditions are obtained. The influence of major parameters on the system performance is investigated. The results show that the hydrogen production rate is 3.52 mol s−1 in the base case. Using the S–CO 2 Brayton cycle, the overall energy and exergy efficiency can be increased from 10.6%, 11.1% to 30.5%, 32.4%, respectively. The solar part accounts for 48.2% of the total energy loss and 76.1% of the exergy destruction. In addition, increasing DNI , the maximum reaction temperature, the regeneration ratio of the S–CO 2 Brayton cycle (RR) can improve the system performance, and the system efficiency is more sensitive to RR. • A novel cascade solar hydrogen production system using the S–I cycle is proposed. • The hydrogen production system is driven by 100% solar energy. • The energy/exergy transfer of the solar-to-hydrogen process is fully quantified. • The S–CO 2 Brayton cycle is used to realize energy cascade utilization. • The effect of the DNI , the T max and the regeneration ratio is assessed. [ABSTRACT FROM AUTHOR]

The EU Renewable Energy Directive 2018/2001 (RED II) has unlocked the participation of local citizens and authorities in collective renewable energy projects through the concept of Renewable Energy Communities (REC). In this context, the present study proposes an optimization model to support REC's investment decisions on the renewable generation portfolio and operational electricity sharing management. The model presented follows an annualized investment optimization approach considering that one REC member can invest in additional renewable generation. A case study of a REC with three members is presented in a framework of four scenarios and results are discussed using the levelized cost of electricity (LCOE) and the marginal realized price concepts. A sensitivity analysis is also performed to address the interannual variability of the solar and wind resources. In the base case scenario, which corresponds to the site-specific conditions of the investing REC member, an overall net revenue of 87 k€/year was computed. The sensitivity analysis for this scenario showed that the investment is more sensitive to the solar resource, with revenues changing between −3.3% and 0.1% in comparison with the average resource availability. This paper contributes to the existing literature by identifying the main drivers behind the optimal investment decision of a REC, which result from the relationship between the marginal realized price and the levelized cost of the electricity generated by each renewable technology. The results supported by the present model reinforce the benefits of RECs as enablers for the deployment of renewable generation, thus contributing to the decarbonization of the energy systems. • Optimization model to support investment decisions in PV/Wind capacity in a REC. • Incremental investments are justified if marginal realized price exceeds the LCOE. • Within a REC the optimal investment is higher than in individual self-consumption. • Results are more sensitive to the solar resource for the base case scenario. • REC is an enabler for the deployment of renewable generation. [ABSTRACT FROM AUTHOR]

The energy of solar airships comes from solar array, and the amount of solar radiation received by solar array determines airship endurance. Many studies optimize the solar array layout to receive more solar radiation. However, most of them are for flexible thin-film array. The influence of the size of the currently commonly used crystalline silicon panels on received energy is not considered. This paper establishes a solar irradiation model and a receiving energy model suitable for crystalline silicon arrays. The effects of array shape, array location, and module size on the energy received by crystalline silicon solar arrays are analyzed at different flight latitudes. Then, an improved genetic algorithm is designed to optimize the array geometric parameters. The results show that altering the size and layout of solar modules significantly influences energy capture, with opposing trends between regions of mid-low latitudes and high latitudes. Airships flying at mid-low latitudes should adopt larger solar modules, while airships flying at high latitudes should adopt smaller ones. After the optimization using the proposed algorithm, the received energy of solar array is further enhanced. The optimization resulted in a 2% improvement at mid-low latitudes and an 18% improvement at high latitudes over conventional optimization. • Develop energy receiving model for crystalline silicon solar cell array. • Optimize geometric parameters of solar array using improved genetic algorithms to increase received energy. • Evaluate the improved effectiveness of adding solar module size in optimization. [ABSTRACT FROM AUTHOR]

This paper aims to employ multi-agent-based energy management and optimization to design a set of interconnected micro-grids with the ability to exchange electricity with the main grid. Initially, the micro-grid components, their governing mathematical model, and the pricing mechanism are introduced. In the next step, the energy management framework is constructed based on three objective functions: minimizing electricity costs, maximizing renewable energy penetration, and providing maximum possible satisfaction. A multi-agent system composed of several operational agents is presented. To evaluate the applicability of the proposed approach case study was conducted. The proposed multi-agent-based optimization is employed to define the most promising solution for the energy system. The solution contains PV power installation, battery storage capacity, home appliances operational schedule, and the energy flow between micro-grids and the main grid. Simulation results indicated that the average annual earnings of the households from interacting with the main grid could be enhanced by 32.9% after performing the optimization procedure. Finally, variations in the distribution classes and investment costs were conducted to observe the effect of changing presumed parameters. Varying the investment costs revealed that for PV-specific investment costs greater than 1500 $/kW, employing solar power generation is not favorable from an economic point of view. However, it should be noted that the required PV installation capacity and hence the required investment strongly depends on the available solar energy. As a result, for regions with smaller annual irradiation, the configuration of the energy system may be quite different. To sum up, the study's overall results show that the proposed multi-agent optimization framework provides a powerful tool to design and operate energy systems composed of several energy sources and versatile users. • The configuration and operation of interconnected micro-grids is optimized. • Multi-agent framework surpasses the rule-based optimization. • Energy import from the main grid increases when more users prioritize the comfort. • When the initial cost of PV exceeds 1500 $/kW, using solar power is not efficient. • The minimum grid dependency must be satisfied subsequent to the other objectives. [ABSTRACT FROM AUTHOR]

The energy sector of Morocco relies mainly on imported fossil fuels. The expensive import bills associated with fossils, as well as the global drive for greenhouse gas (GHG) emission reduction, have compelled the country to consider the utilization of renewable energy resources such as hydro, wind, and solar for energy generation. Power generation from wind and solar is highly intermittent hence require storage systems to guarantee supply security. Considering the abundant nature of sheep rearing in Morocco, power generation from sheep dung through anaerobic digestion (AD) can serve as an alternative power generation source to alleviate the intermittent situations of wind and solar since biomass supply for AD is not affected by the weather. Therefore, this paper evaluates the capability of hybrid power generation, using AD of sheep dung, wind, and solar in two selected areas of the Fez-Meknes region in Morocco. A mixed-integer linear programming model was implemented in A Mathematical Programming Language (AMPL) using a linear solver of CPLEX. The results of the analysis indicated that only standalone wind generation and hybrid wind/PV/biogas generation are able to meet the total load demand of the two study locations. The hybrid generation resulted in a total carbon emission of 349.30 and 3871.60 g/year at a cost of 13,088.38 and 145,394.13 $/year for Tazouta and Fez respectively in supplying the whole load of the study locations, whiles the standalone wind generator resulted in a total carbon emission of 274 and 2603 g/year at a total cost of 23,352 and 239,500 $/year for satisfying the electric load of these two regions respectively. The results shows that, hybrid solar/wind/PV is the most ideal for supplying power to the two study locations in terms of cost and load satisfaction, while the wind is the most ideal in terms of load satisfaction and carbon emissions. • Sheep dung potential for generating electric power in rural areas of Fez-Meknes. • Wind, solar and biogas electricity generation in water-stressed areas of Morocco. • Hybrid renewable energy generation. [ABSTRACT FROM AUTHOR]

The integrated solar combined cycle system (ISCC) primarily consists of solar thermal power generation equipment and gas turbines. This system effectively mitigates the inherent randomness associated with power generation due to weather conditions while simultaneously providing electric and heat loads. However, due to the difference in response speed of various power generation equipment, it is difficult to respond quickly as the strength of illumination and electricity-heat load demand change, seriously affecting the system's stability operation. This paper proposes an active disturbance rejection control (ADRC) method for the ISCC system considering the different response speeds of generation equipment. Firstly, the mathematical model of the ISCC system is established, in which the system's response speed is improved through the inertial power compensation method. Then, the ADRC method is used to reduce the disturbance caused by uncertain factors, such as solar radiation intensity and load demand change, to ensure the balance between electric and thermal power supply and demand. Finally, based on the measured weather data from National Renewable Energy Laboratory (NREL), the proposed method's performance is evaluated, compared with the hybrid H 2 /H ∞ control method and the auto-coupling proportional integral differential (ACPID) control method. Comparison results show that the ADRC method has better control effectiveness and dynamic response performance, powerfully shortens the system stability time, and reduces overshoot. • A mathematical model of an integrated solar combined cycle system is constructed. • An active disturbance rejection control method for the integrated solar combined cycle system is proposed. • The system's response speed is improved through the inertial power compensation method. • The large-scale changes in solar radiation intensity and load demand are considered. • The results show that the method has better control effectiveness and dynamic response performance. [ABSTRACT FROM AUTHOR]

To efficiently utilize renewable energy sources primarily consisting of wind and solar power, large-scale compressed air energy storage (CAES) can be implemented using underground salt caverns. In this paper, the abundant wind and solar energy resources and the geological conditions of the three major salt mines in Jiangsu Province are introduced. A geomechanical model is established based on the Huai'an rock salt formation. The simulation results show that as the internal air pressure (IAP) increases, the safety factor increases, and the displacement, plastic zone, volume shrinkage, and equivalent strain decrease. Based on the above results, the minimum IAPs of caverns AN 13 and AN 21 are recommended to be 10–12 MPa. According to estimates, to store 15% of wind and solar power in Jiangsu Province through CAES by 2050, a 9894.0 × 104 m3 salt cavern volume is needed, of which at least 77.8 million m3 can be provided by salt mining enterprises. The cost of reconstructing an underground salt cavern is 12.1 billion yuan, while the investment in surface equipment is 746.7 billion yuan. We provide an economical and feasible solution for achieving carbon neutrality in Jiangsu Province in this study. • A CAES salt cavern is utilized to achieve a 100% renewable energy power system in Jiangsu Province. • The non-salt interlayers significantly reinforce the stability of CAES salt caverns. • The minimum internal air pressure of the CAES salt cavern is recommended to be 10–12 MPa in Huai'an. • A preliminary evaluation of the investment cost of CAES salt caverns is analyzed. [ABSTRACT FROM AUTHOR]

The rapid development in technology and changing food habits have drastically altered the cooking method in recent years. Electric ovens are dominating the cooking sector in bakeries, restaurants, and domestic cooking. India holds the second position in terms of revenue generated by the sales of cookers and ovens. The electrical energy requirements are also adding up with electricity-based cooking. In addition, solar energy-dependent solar cooking appliances are available in the market, but they come with their own set of merits and demerits. This paper discusses the new concept and development of an Electric-Solar hybrid cooking appliance. The implemented control mechanism in the fully-featured hybrid OTG (Oven, Toaster, & Griller) oven shows the simplicity and ease of using solar energy in conjunction with electrical energy. The experimental and numerical results show that the temperature distribution inside an electric-solar hybrid oven saves energy up to 51% and takes much less cooking time than electric ovens and solar cooking appliances when operating in hybrid mode. The STEPCO (Solar Thermal-Electric Powered Cooking Oven) oven has demonstrated potential for a relatively quick return on investment, with a payback period of around 2.3 years in hybrid mode and 3.7 years in solar mode. Experimental testing has shown that the hybrid mode of the STEPCO oven achieves an impressive efficiency of 63%, which is significantly higher than that of the electric and solar modes, which are only 35% and 4.0%, respectively. Additionally, the STEPCO oven has the environmental benefit of emitting very little CO 2 during the cooking process when used in hybrid mode and zero CO 2 emissions when used in solar mode. • A novel cooking oven is designed and developed to operate in three modes. • CFD analysis is used to validate the temperature inside the oven in hybrid mode. • The hybrid oven saves up to 51% of energy and reduces annual CO 2 emissions. • The oven has shorter payback times of 2.3 and 3.7 years in hybrid and solar modes. • STEPCO oven has an efficiency of 63% in hybrid, more than solar and electric modes. [ABSTRACT FROM AUTHOR]