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.

Concentrating Solar Power in Europe, the Middle East and North Africa： Achieving Its Potential

CSP （concentrating solar power） is a commercially available renewable energy technology capable of harnessing the immense solar resource in southern Europe, the MENA region （Middle East and North Africa）, and elsewhere. This paper summarises the findings of a study by the European Academies Science Advisory Council which has examined the current status and development challenges of CSP, and consequently has evaluated the potential contribution of CSP in Europe and the MENA region to 2050. It identifies the actions that will be required by scientists, engineers, policy makers, politicians, business and investors alike, to enable this vast solar resource to make a major contribution to establishing a sustainable energy system. The study concludes that cost reductions of 50%-60% in CSP electricity may reasonably be expected in the next 10-15 years, enabling the technology to be cost competitive with fossil-fired power generation at some point between 2020 and 2030. Incorporation of storage delivers added value in enabling CSP to deliver dispatchable power. Incentive schemes will be needed in Europe and MENA countries to enable this point to be achieved. Such schemes should reflect the true value of electricity to the grid, effectively drive research and development, and ensure transparency of performance and cost data.

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.

Solar fuel production through concentrating light irradiation

The climate crisis necessitates the development of non-fossil energy sources.Harnessing solar energy for fuel production shows promise and offers the potential to utilize existing energy infrastructure.However,solar fuel production is in its early stages of development,constrained by low conversion efficiency and challenges in scaling up production.Concentrated solar energy(CSE)technology has matured alongside the rapid growth of solar thermal power plants.This review provides an overview of current CSE methods and solar fuel production,analyzes their integration compatibility,and delves into the theoretical mechanisms by which CSE impacts solar energy conversion efficiency and product selectivity in the context of photo-electrochemistry,thermochemistry,and photo-thermal co-catalysis for solar fuel production.The review also summarizes approaches to studying the photoelectric and photothermal effects of CSE.Lastly,it explores emerging novel CSE technology methods in the field of solar fuel production.

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.

Coordinated Operation of Concentrating Solar Power Plant and Wind Farm for Frequency Regulation

As a dispatchable renewable energy technology, the fast ramping capability of concentrating solar power (CSP) can be exploited to provide regulation services. However, frequent adjustments in real-time power output of CSP, which stems out of strategies offered by ill-designed market, may affect the durability and the profitability of the CSP plant, especially when it provides fast regulation services in a real-time operation. We propose the coordinated operation of a CSP plant and wind farm by exploiting their complementarity in accuracy and durability for providing frequency regulation. The coordinated operation can respond to regulation signals effectively and achieve a better performance than conventional thermal generators. We further propose an optimal bidding strategy for both energy and frequency regulations for the coordinated operation of CSP plant and wind farm in day-ahead market (DAM). The validity of the coordinated operation model and the proposed bidding strategy is verified by a case study including a base case and sensitivity analyses on several impacting factors in electricity markets.

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.

Optical Design of a Solar Parabolic Concentrating Collector Based on Trapezoidal Reflective Petals

In this paper, detailed optical of the solar parabolic dish concentrator is presented. The system has diameter D = 2,800 mm and focal length f = 1,400 mm. The efficient conversion of solar radiation in heat at these temperature levels requires a use of concentrating solar collectors. In this paper, detailed optical design of the solar parabolic dish concentrator is presented. The parabolic dish of the solar system consists from 12 curvilinear trapezoidal reflective petals. This paper presents optical simulations of the parabolic solar concentrator unit using the ray-tracing software TracePro. The total flux on receiver and the distribution of irradiance for absorbed flux on center and periphery receiver are given. The total flux at the focal region is 4,031.3 W. The goal of this paper is to present optical design of a low-tech solar concentrator, that can be used as a potentially low-cost tool for laboratory-scale research on the medium-temperature thermal processes, cooling, industrial processes, solar cooking and polygeneration systems, etc.

Improving photoreduction of CO2 with water to CH4 in a novel concentrated solar reactor

COphotoreduction is an attractive process which allows the storage of solar energy and synthesis of solar fuels. Many different photocatalytic systems have been developed, while the alternative photo-reactors are still insufficiently investigated. In this work, photoreduction of COwith HO into CHwas investigated in a modified concentrating solar reactor, using TiOand Pt/TiOas the catalysts. The TiOand Pt/TiOsamples were extensively characterized by different techniques including powder X-ray diffraction（XRD）, Nadsorption/desorption and UV–vis absorption. The catalytic performance of the TiOand Pt/TiOsamples in the gas phase was evaluated under unconcentrated and concentrated Xe-lamp light and nature solar light with different concentrating ratios. Various parameters of the reaction system and the catalysts were investigated and optimized to maximize the catalytic performance of COreduction system. Compared with the normal light irradiation, the TiOand Pt/TiOsamples show higher photocatalytic activity（about 6–7 times） for reducing COinto CHunder concentrated Xe-lamp light and nature solar light. In the range of experimental light intensity, it is found that the concentration of the light makes it suitable for the catalytic reaction, and increases the utilization efficiency of the TiOand Pt/TiOsamples while does not decrease the quantum efficiency.

Economic analysis of solar energy development in North Africa

The economic analysis of solar energy development is the basis of promoting the solar energy planning in north Africa and realizing the clean energy power transmission among continents. In this paper, the cost development trend of photovoltaic(PV) power and concentrating solar power(CSP) generation is analyzed, and the levelized cost of energy(LCOE) of solar power generation is forecasted. Then, taking the development of Tunisian solar energy as an example in the context of transcontinental transmission, PV power with energy storage and PV-CSP power generation are given as two kinds of development plan respectively. The installed capacity configurations of the two schemes are given with production simulation method, and comprehensive LCOE are calculated. The studies show that based on the LCOE forecast value, the LCOE of PV-CSP combined power generation will decrease when the annual utilization hours of transmission channel is increased. It can be chosen as one of important mode of the North Africa solar energy development.

Application of Model Predictive Control Based on Kalman Filter in Solar Collector Field of Solar Thermal Power Generation

There are two prominent features in the process of temperature control in solar collector field.Firstly,the dynamic model of solar collector field is nonlinear and complex,which needs to be simplified.Secondly,there are a lot of random and uncontrollable,measurable and unmeasurable disturbances in solar collector field.This paper uses Taylor formula and difference approximation method to design a dynamic matrix predictive control(DMC)by linearizing and discretizing the dynamic model of the solar collector field.In addition,the purpose of controlling the stability of the outlet solar field salt temperature is achieved by adjusting the mass flow of molten salt.In order to further improve the ability of the system to suppress unmeasured disturbances,a steady-state Kalman filter is designed to estimate state variables,so that the system has better stability and robustness.The simulation verification results show that the DMC control system based on Kamlan filtering has better control effect than the traditional DMC control system.In the case of large fluctuations in solar radiation intensity and consideration of undetectable interference,the overshoot of the system is reduced by 4%and the rise time remains unchanged.

Capacity-operation collaborative optimization of the system integrated with wind power/photovoltaic/concentrating solar power with S-CO_(2) Brayton cycle

This paper proposes a new power generating system that combines wind power(WP),photovoltaic(PV),trough concentrating solar power(CSP)with a supercritical carbon dioxide(S-CO_(2))Brayton power cycle,a thermal energy storage(TES),and an electric heater(EH)subsystem.The wind power/photovoltaic/concentrating solar power(WP-PV-CSP)with the S-CO_(2) Brayton cycle system is powered by renewable energy.Then,it constructs a bi-level capacity-operation collaborative optimization model and proposes a non-dominated sorting genetic algorithm-Ⅱ(NSGA-Ⅱ)nested linear programming(LP)algorithm to solve this optimization problem,aiming to obtain a set of optimal capacity configurations that balance carbon emissions,economics,and operation scheduling.Afterwards,using Zhangbei area,a place in China which has significant wind and solar energy resources as a practical application case,it utilizes a bi-level optimization model to improve the capacity and annual load scheduling of the system.Finally,it establishes three reference systems to compare the annual operating characteristics of the WP-PV-CSP(S-CO_(2))system,highlighting the benefits of adopting the S-CO_(2) Brayton cycle and equipping the system with EH.After capacity-operation collaborative optimization,the levelized cost of energy(LCOE)and carbon emissions of the WP-PV-CSP(S-CO_(2))system are decreased by 3.43%and 92.13%,respectively,compared to the reference system without optimization.

Solar Radiation and Temperature Measurement of Solar Dish Concentrator System

Concentrating solar power （CSP） technologies could be one of the major contributor to worlds future energy needs and which would be cheap and clean sources of energy. This would improve energy utilization, higher conversion efficiency with reliable and affordable supply of electricity to the public. The proposed approach is using 18 inch diameter of solar dish concentrator to measure the solar radiation using the aluminium foil as a reflector. In this paper, solar radiation is collected to investigate the solar fraction on incoming solar energy in wet climate.

Natural gas pyrolysis in double-walled reactor tubes using thermal plasma or concentrated solar radiation as external heating source

The thermal pyrolysis of natural gas as a clean hydrogen production route is examined. The concept of a double-walled reactor tube is proposed and implemented. Preliminary experiments using an external plasma heating source are carried out to validate this concept. The results point out the efficient CH4 dissociation above 1850 K （CH4 conversion over 90%） and the key influence of the gas residence time. Simulations are performed to predict the conversion rate of CH4 at the reactor outlet, and are consistent with experimental tendencies. A solar reactor prototype featuring four independent double-walled tubes is then developed. The heat in high temperature process required for the endothermic reaction of natural gas pyrolysis is supplied by concentrated solar energy. The tubes are heated uniformly by radiation using the blackbody effect of a cavity-receiver absorbing the concentrated solar irradiation through a quartz window. The gas composition at the reactor outlet, the chemical conversion of CH4, and the yield to H2 are determined with respect to reaction temperature, inlet gas flow-rates, and feed gas composition. The longer the gas residence time, the higher the CH4 conversion and H2 yield, whereas the lower the amount of acetylene. A CH4 conversion of 99% and H2 yield of about 85% are measured at 1880 K with 30% CH4 in the feed gas （6 L/min injected and residence time of 18 ms）, A temperature increase from 1870 K to 1970 K does not improve the H2 yield.

High-temperature Thermal Properties and Wear Behavior of Basalt as Heat Storage Material for Concentrated Solar Power Plants

The microstructures,components,thermal stability,specific heat capacity and thermal conductivity of basalt sample were studied.Besides,as a comprehensive result of thermal expansion and contraction process,both the friction coefficient and wear rate of the basalt sample were also characterized.Our results indicate that basalt is an excellent candidate to be used as thermal energy storage material for concentrated solar power plants,and also provide a strategy for solar energy utilization in volcanic area with excellent geographical environment.

Thermal modeling and the optimized design of metal plate cooling systems for single concentrator solar cells

A metal plate cooling model for 400~ single concentrator solar cells was established. The effects of the thickness and the radius of the metal plate, and the air environment on the temperature of the solar cells were analyzed in detail. It is shown that the temperature of the solar cells decreased sharply at the beginning, with the increase in the thickness of the metal plate, and then changed more smoothly. When the radius of the metal plate was 4 cm and the thickness increased to 2 mm or thicker, the temperature of the solar cell basically stabilized at about 53℃. Increasing the radius of the metal plate and the convective transfer coefficient made the temperature of the solar cell decrease remarkably. The effects of A1 and Cu as the metal plate material on cooling were analyzed contrastively, and demonstrated the superiority of A1 material for the cooling system. Furthermore, considering cost reduction, space holding and the stress of the system, we optimized the structural design of the metal plate. The simulated results can be referred to the design of the structure for the metal plate. Finally, a method to devise the structure of the metal plate for single concentrator solar cells was given.

Production of metallic nanopowders(Mg,Al)by solar carbothermal reduction of their oxides at low pressure

The carbothermal reduction of MgO and Al_(2)O_(3) in argon flow at low pressure allows to lower the onset temperature of metal vapor formation.Thermodynamic calculations indicate that metal formation begins at 1400 and 1700 K for a primary vacuum(1000 Pa),respectively,for Mg and Al.In the experimental section,concentrated solar energy was used for the process heating in order to favor energy savings.The products of the reaction between MgO or Al_(2)O_(3) and 2 varieties of carbon(graphite,carbon black)in flowing argon atmosphere at a total pressure of around 1000 to 1600 Pa were studied using X-ray diffraction,and microstructure observations revealed the formation of metallic nanopowders with some by-products.Metallic conversions close to 45 wt%and 52 wt%,respectively,for Mg and Al,were obtained.The low conversion yield of the carbothermal reduction of MgO can be attributed to a backward reaction reforming MgO powder and to a sintering process between oxide particles at high temperature.Aluminum production challenge is to avoid formation of undesired by-products:Al_(2)O,Al_(4)C_(3) and Al-oxycarbides.Advantages and weaknesses of the used process are described and some improvements are proposed to increase metallic yields.