Peak Shaving Strategy of Concentrating Solar Power Generation Based on Multi-Time-Scale and Considering Demand Response

According to the multi-time-scale characteristics of power generation and demand-side response(DR)resources,as well as the improvement of prediction accuracy along with the approaching operating point,a rolling peak shaving optimization model consisting of three different time scales has been proposed.The proposed peak shaving optimization model considers not only the generation resources of two different response speeds but also the two different DR resources and determines each unit combination,generation power,and demand response strategy on different time scales so as to participate in the peaking of the power system by taking full advantage of the fast response characteristics of the concentrating solar power(CSP).At the same time,in order to improve the accuracy of the scheduling results,the combination of the day-ahead peak shaving phase with scenario-based stochastic programming can further reduce the influence of wind power prediction errors on scheduling results.The testing results have shown that by optimizing the allocation of scheduling resources in each phase,it can effectively reduce the number of starts and stops of thermal power units and improve the economic efficiency of system operation.The spinning reserve capacity is reduced,and the effectiveness of the peak shaving strategy is verified.

Research progress on protective coatings against molten nitrate salts for thermal energy storage in concentrating solar power plants

Concentrating solar power(CSP) has garnered considerable global attention as a reliable means of generating bulk electricity, effectively addressing the intermittent nature of solar resources.The integration of molten salt technology for thermal energy storage(TES) has further contributed to the growth of CSP plants;however, the corrosive nature of molten salts poses challenges to the durability of container materials, necessitating innovative corrosion mitigation strategies.This review summarizes scientific advancements in high-temperature anticorrosion coatings for molten nitrate salts, highlighting the key challenges and future trends.It also explores various coating types, including metallic, ceramic, and carbon-based coatings, and compares different coating deposition methods.This review emphasizes the need for durable coatings that meet long-term performance requirements and regulatory limitations, with an emphasis on carbon-based coatings and emerging nanomaterials.A combination of multiple coatings is required to achieve desirable anticorrosion properties while addressing material compatibility and cost considerations.The overall goal is to advance the manufacturing, assembly, and performance of CSP systems for increased efficiency, reliability, and durability in various applications.

Site Ranking and Potential Assessment for Concentrating Solar Power in West Africa

Access to electricity is poor in the Economic Community of West African States (ECOWAS). Concentrating Solar Power (CSP) presents better opportunities for increasing access to electricity and for diversifying sources of energy in the ECOWAS region;however, to date, except for Burkina Faso, no site evaluation pertaining to the region has ever been performed for CSP. This study provides potential assessment and site ranking for large-scale CSP projects in the ECOWAS region. It computes the nominal potential power and gives the corresponding energy yield with many scenarios. By considering only 1% of the suitable land area with daily DNI greater or equal to 5 kWh/m2, a land slope less or equal to 5% and distance to transmission line not more than 100 km, the study showed, for example, that West Africa has a potential nominal capacity of 21.3 GW for parabolic trough technology.

Energy and Exergy Analysis of a New Small Concentrating Solar Power Plant

A new small concentrating solar power plant which is suitable for urban area is presented, and a theoretical framework for the energy and exergy analysis in the overall power plant is also constructed. The framework can be used to evaluate the energy and exergy losses in each component. Furthermore, the energy and exergy efficiencies have also been computed and compared for the individual components as well as for the overall plant.

Development of Natural Gas in China--Concentrating Resources to Accomplish Major Undertakings, and Expediting Development through Diversified Ownerships

The development of China’s natural gas industry can be described as the story of an ancient but rising industry.In general,the route for China’s natural gas development is through concentrating resources to accomplish major undertakings,and expediting development through diversified ownerships.A brief review of the development of the natural gas industry in

Testing Bifacial PV Cells in Symmetric and Asymmetric Concentrating CPC Collectors

Bifacial PV cells have the capacity to produce solar electricity from both sides and, thus, amongst other advantages, allow a significantly increase both in peak and annual power output while utilizing the same amount of silicone. According to the manufacturer, the bifacial cells are around 1.3 times more expensive than the single-sided cells. This way, bifacial PV cells can effectively reduce the cost of solar power for certain applications. Today, the most common application for these cells is in stationary vertical collectors which are exposed to sunlight from both sides, as the relative position of the sun changes throughout the day. Another possible application is to utilize these cells in concentrating collectors. Three test prototypes utilizing bifacial PV cells were built. The initial two prototypes were built for indoor testing and differed only in geometry of the reflector, one being asymmetric and the other symmetric. Both prototypes were evaluated in an indoor solar simulator. Both reflector designs yielded positive electrical performance results and similar efficiencies from both sides of the cell were achieved. However, lower fill factor than expected was achieved for both designs when compared to the single cell tests. The results are discussed and suggestions for further testing are presented. A third prototype was built in order to perform outdoor evaluations. This prototype utilized a bifacial PV cells string laminated in silicone enclosed between 2 standard glass panes and a collector box with an asymmetric CPC concentrator. The prototype peak electrical efficiency and temperature dependence were evaluated. A comparison between the performance of the bottom and top sides of the asymmetric collector is also presented. Additionally, the incidence modifier angle (IAM) is also briefly discussed.

Central and western China Attracting More Investment──How the nation is now concentrating on development for all parts of the country

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Performance Improving of a Concentrating Photovoltaic System by Using a New Optical Adhesive

The objective of this present study is to manufacture a new silicone-based adhesive which is used for gluing and bonding the second optical elements (SOE) with Concentrating Photovoltaic solar cell (CPV) in order to guarantee a thickness that can provide a good silicone adherence to obtain long term stability and keeping a good solar transmittance performance, too. This new adhesive is made up of a mixture of silicone and transparent glass balls. The experimental part consists of the choice of the best size of glass balls with the suitable proportion of the glass balls weight in the mixture. For this purpose, ten samples were manufactured for every category of glass balls and weight ratio. Glass ball sizes between 100 and 1100 μm, and weight ratios between 1 and 10% were analyzed. For each category of glass balls, four proportions were mixed with the silicone. The thicknesses and transmittance of every sample were measured with appropriate instruments. The experimental results illustrate that the mixture containing balls with sizes inferior to 106 μm, is the best mixture which assures adhesive minimum thickness value necessary for an efficient mechanical bond and preserves also a good transmittance of solar irradiance.

Make Leapfrogging Development By Concentrating Resource On Selected Targets

The Chinese Academy of Sci-ences (CAS) has begun introducingthe trial implementation of theKnowledge Innovation Program(KIP)in an all-round manner just as,at the beginning of the new century,the state is about to implement itsTenth Five-Year Plan for thecountry’s ongoing economic andsocial development. This will

Realizing high photovoltaic efficiency with parallel multijunction solar cells based on spectrum-splitting and-concentrating diffractive optical element

Based on the facts that multijunction solar cells can increase the efficiency and concentration can reduce the cost dramatically, a special design of parallel multijunction solar cells was presented. The design employed a diffractive optical element （DOE） to split and concentrate the sunlight. A rainbow region and a zero-order diffraction region were generated on the output plane where solar cells with corresponding band gaps were placed. An analytical expression of the light intensity distribution on the output plane of the special DOE was deduced, and the limiting photovoltaic efficiency of such parallel multijunction solar ceils was obtained based on Shockley-Queisser＇s theory. An efficiency exceeding the Shockley--Queisser limit （33%） can be expected using multijunction solar cells consisting of separately fabricated subcells. The results provide an important alternative approach to realize high photovoltaic efficiency without the need for expensive epitaxial technology widely used in tandem solar cells, thus stimulating the research and application of high efficiency and low cost solar cells.

Design optimization of highly efficient spectrum-splitting and beam-concentrating diffractive optical element for lateral multijunction solar cells

Two improved algorithms are proposed to extend a diffractive optical element （DOE） to work under the broad spec- trum of sunlight. An optimum design has been found for the DOE, with a weighted average optical efficiency of about 6.8% better than that of the previous design. The optimization of designing high optical efficiency DOEs will pave the way for future designs of high-efficiency, low-cost lateral multijunction solar cells based on such a DOE.

Synthesis and Efficiency of a SphericalMacroporous Epoxy-dicyandiamide ChelateResin for Preconcentrating and SeparatingTrace Au, Hg, Pd and Ru from Samples

A novel spherical macroporous epoxy-dicyandiamide chelate resin was synthesized simply and rapidly from epoxy resin and used for the preconcentration and separation of trace amounts of Au (Ⅲ ), Hg (Ⅱ ), Pd (Ⅳ) and Ru (Ⅲ) ions from solution samples. The analyzed ions can be quantitatively concentrated by the resin at a flow rate of 2. 0 mL/min at pH 4, and can also be desorbed with 15 mL of 4 mol/L HCl + 0. 3 g thiourea from the resin column with recoveries of 96. 5%-99. 0%. After the chelate resin was reused for 7 times, the recoveries of these ions were still over 92%, and 400-1 000 times of excess of Fe(Ⅲ ), Al(Ⅲ ), Ni( II), Mn( Ⅱ ), Cr (Ⅲ ), Cu ( Ⅱ ), Cd (Ⅱ ) and Pb (Ⅱ ) caused little interference with the determination of these ions by an inductively coupled plasma optical emission spectrometer (ICP-OES ). The capacities of the resin for the analytes are in the range of 0. 35~0. 92 mmol/g. The RSDs of the proposed method are in the range of 1. 1 % ~4. 0% for each kind of the analyzed ions. The recoveries of a standard added in real solution samples are between 96. 5% and 98. 5%, and the results for the analyzed ions in a powder sample are in good agreement with their reported values.

Optimization of Conditions of Concentrating Protein in Rapeseed Meal by Ultrasonic-assisted Alcohol Washing

This study was performed to optimize the conditions for concentrating protein in commercial rapeseed meal by ultrasonic-assisted alcohol washing method. The effects of sonication time,particle size,ultrasonic power and liquid to solid ratio on protein content were investigated. The result showed that the optimal conditions for concentrating protein in rapeseed meal were: sonication time of 40 min,particle size of 40 mesh,ultrasonic power of 800 W and liquid to solid ratio of 9∶ 1. Under these conditions,the protein content in rapeseed meal was increased to 55. 47%,which was 10. 43% higher than that in rapeseed meal not treated by sonication.

Experimental evaluation of factors affecting performance of concentrating photovoltaic/thermal system integrated with phase‐change materials(PV/T‐CPCM)

The photovoltaic/thermal(PV/T)system is a promising option for countering energy shortages.To improve the performance of PV/T systems,compound parabolic concentrators(CPCs)and phase-change materials(PCMs)were jointly applied to construct a concentrating photovoltaic/thermal system integrated with phase-change materials(PV/T-CPCM).An open-air environment is used to analyze the effects of different parameters and the intermittent operation strategy on the system performance.The results indicate that the short-circuit current and open-circuit voltage are positively correlated with the solar irradiance,but the open-circuit voltage is negatively correlated with the temperature of the PV modules.When the solar irradiance is 500 W⋅m^(−2) and the temperature of the PV modules is 27.5℃,the short-circuit current and open-circuit voltage are 1.0 A and 44.5 V,respectively.Higher solar irradiance results in higher thermal power,whereas the thermal efficiency is under lower solar irradiance(136.2-167.1 W⋅m^(−2) is twice under higher solar irradiance(272.3-455.7 W⋅m^(−2))).In addition,a higher mass flow rate corresponds to a better cooling effect and greater pump energy consumption.When the mass flow rate increases from 0.01 to 0.02 kg⋅s^(-1),the temperature difference between the inlet and outlet decreases by 1.8℃,and the primary energy-saving efficiency decreases by 0.53%.The intermittent operation of a water pump can reduce the energy consumption of the system,and the combination of liquid cooling with PCMs provides better thermal regulation and energy-saving effects under various conditions.

Numerical Study of New-Type Receiver with Axially-Hollow Spiral Deflector for Parabolic Trough Direct-Steam-Generation Loop of Concentrating Solar Power System

The thermal stress-induced deformation issue of receiver is crucial to the performance and reliability of a parabolic-trough(PT) concentrating solar power(CSP) system with the promising direct steam generation(DSG) technology.The objective of the present study is to propose a new-type receiver with axially-hollow spiral deflector and optimize the geometric structure to solve the above issue.To this end,optical-flow-thermal multi-physics coupling models have been established for the preheating,boiling and superheating sections of a typical PT-DSG loop.The simulation results show that our proposed new-type receiver demonstrates outstanding comprehensive performance.It can minimize the circumferential temperature difference through the spiral deflector while lower the flow resistance cost through the axially hollow structure at the same time.As quantitatively evaluated by the temperature uniformity improvement(ε_(ΔT)) and the performance evaluation criteria(PEC),different designs are achieved based on different optimal schemes.When ε_(ΔT)is of primary importance,the optimal design with torsional ratio of 1 is achieved,with ε_(ΔT)=25.4%,25.7%,41.5% and PEC=0.486,0.878,0.596corresponding to preheating,boiling,superheating sections,respectively.When PEC is of primary importance,the optimal design with torsional ratio of 6-6.5 is achieved,with PEC=0.950,2.070,0.993 and ε_(ΔT)=18.2%,13.3 %,19.4% corresponding to preheating,boiling,superheating sections,respectively.

Liquid-based high-temperature receiver technologies for next-generation concentrating solar power:A review of challenges and potential solutions

To reduce the levelized cost of energy for concentrating solar power(CSP),the outlet temperature of the solar receiver needs to be higher than 700°C in the next-generation CSP.Because of extensive engineering application experience,the liquid-based receiver is an attractive receiver technology for the next-generation CSP.This review is focused on four of the most promising liquid-based receivers,including chloride salts,sodium,lead-bismuth,and tin receivers.The challenges of these receivers and corresponding solutions are comprehensively reviewed and classified.It is concluded that combining salt purification and anti-corrosion receiver materials is promising to tackle the corrosion problems of chloride salts at high temperatures.In addition,reducing energy losses of the receiver from sources and during propagation is the most effective way to improve the receiver efficiency.Moreover,resolving the sodium fire risk and material compatibility issues could promote the potential application of liquid-metal receivers.Furthermore,using multiple heat transfer fluids in one system is also a promising way for the next-generation CSP.For example,the liquid sodium is used as the heat transfer fluid while the molten chloride salt is used as the storage medium.In the end,suggestions for future studies are proposed to bridge the research gaps for>700℃liquid-based receivers.

Strength analysis of molten salt tanks for concentrating solar power plants

Promoting the development of concentrating solar power(CSP)is critical to achieve carbon peaking and carbon neutrality.Molten salt tanks are important thermal energy storage components in CSP systems.In this study,the cold and hot tanks of a 100 MW CSP plant in China were used as modeling prototypes.The materials and geometric models were determined based on related specifications and engineering experience.Mechanical characteristics of the tanks under steady condition,including the deformation,stress distribution,and stress concentration,were simulated and calculated.Furthermore,the strength of the tank walls was evaluated.The findings can be used as a reference for designing the molten salt storage tank and reducing the risk during the operation.

A switchable concentrating photovoltaic/concentrating solar power(CPV/CSP)hybrid system for flexible electricity/thermal generation

Due to the intermittency and indeterminacy of solar irradiance,balancing energy supply and load demand remains a challenge.This paper proposed a switchable hybrid system that combines concentrating photovoltaic/concentrating solar power(CPV/CSP)technology with thermal energy storage(TES)to achieve flexible electricity and thermal generation by adjusting the incident solar flux of photovoltaic(PV).The hybrid system can directly transfer surplus solar energy into high-quality heat for storage using a rotatable PV/heat receiver.The simulated results demonstrated that the hybrid system effectively improves power generation,optimally utilizes TES capacity,and reduces the levelized cost of electricity(LCOE).Over a selected seven-day period,the single-junction(1J)Ga As solar cells used in the hybrid system sustainably satisfied the load demand for more than five days without grid supplement,outperforming the CSP plant by an additional two days.The hybrid system utilizing the 1J Ga As with the base configuration of solar multiple(SM)of 1.26 and TES capacity of 5 h improved the annual power production and renewable penetration(RP)by 20.8%and 24.8%compared with the conventional CSP plant,respectively.The hybrid plant with monosilicon and a configuration of SM(1.8),PV ratio(1),and TES capacity(6 h)achieved an optimal LCOE of11.52$ct/k Wh and RP of 75.5%,which is 8.8%lower and 12.1%higher than the CSP plant,respectively.

Comprehensive Review of Line-Focus Concentrating Solar Thermal Technologies: Parabolic Trough Collector (PTC) vs Linear Fresnel Reflector (LFR)

In the present review,parabolic trough collector(PTC)and linear Fresnel reflector(LFR)are comprehensively and comparatively reviewed in terms of historical background,technological features,recent advancement,economic analysis and application areas.It is found that although PTC and LFR are both classified as mainstream line-focus concentrating solar thermal(CST)technologies,they are now standing at different stages of development and facing their individual opportunities and challenges.For PTC,the development is commercially mature with steady and reliable performance;therefore,extension of application is the main future demand.For LFR,the development is still in rapid progress to commercial maturity,yet indicating very promising potentials with high flexibility in novel designs and remarkable reduction in capital and operational costs.The question,which has to be answered in order to estimate the future perspectives of these two line-focus CST technologies,becomes which of these characteristics carries more weight or how to reach an optimal trade-off between them.

Numerical Assessment of the Thermal Efficiency of a Concentrated Photovoltaic/Thermal (CPV/T) Hybrid System Using Air as Heat Transfer Fluid

In this paper, we propose a thermal model of a hybrid photovoltaic/thermal concentration system. Starting from the thermal balance of the model, the equation is solved and simulated with a MATLAB code, considering air as the cooling fluid. This enabled us to evaluate some of the parameters influencing the electrical and thermal performance of this device. The results showed that the temperature, thermal efficiency and electrical efficiency delivered depend on the air mass flow rate. The electrical and thermal efficiencies for different values of air mass flow are encouraging, and demonstrate the benefits of cooling photovoltaic cells. The results show that thermal efficiency decreases air flow rate greater than 0.7 kg/s, whatever the value of the light concentration used. The thermal efficiency of the solar cell increases as the light concentration increases, whatever the air flow rate used. For a concentration equal to 30 sun, the thermal efficiency is 0.16 with an air flow rate equal to 0.005 kg/s;the thermal efficiency increases to 0.19 with an air flow rate equal to 0.1 kg/s at the same concentration. An interesting and useful finding was that the proposed numerical model allows the determination of the electrical as well as thermal efficiency of the hybrid CPV/T with air flow as cooling fluid.