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.

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.

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.

Demonstration of Pilot Scale Large Aperture Parabolic Trough Organic Rankine Cycle Solar Thermal Power Plant in Louisiana

During the calendar year of 2012 the University of Louisiana at Lafayette in conjunction with CLECO Power LLC (CLECO) has constructed and commissioned a pilot scale parabolic trough solar thermal power plant for the first time in Louisiana. The large aperture trough (LAT) solar collectors were provided by Gossamer Space Frames and are coupled with an organic Rankine cycle (ORC) power block provided by ElectraTherm, Inc. for study of the feasibility of cost-effective commercial scale solar thermal power production in Louisiana. Supported by CLECO and providing power to the existing CLECO grid, the implementation of state-of-the-industry collector frames, mirrors, trackers, and ORC power block is studied under various local weather conditions which present varied operating regimes from existing solar thermal installations. The solar collectors provide a design output of 650 kWth and preliminary actual performance data from the system level is presented. The optimal size, configuration and location for such a plant in the given solar resource region are being studied in conjunction with CLECO’s search for optimal renewable energy solutions for the region. The pilot scale size of the facility and implementation of the simpler ORC allow remote operation of the facility and flexibility in operating parameters for optimization studies. The construction of the facility was supported by the Louisiana Department of Natural Resources, the U.S. Department of Energy, and CLECO. The continued operation of the plant is supported by CLECO Power LLC and the University of Louisiana at Lafayette.

Progress in Research and Development of Molten Chloride Salt Technology for Next Generation Concentrated Solar Power Plants

Concentrated solar power(CSP)plants with thermal energy storage(TES)system are emerging as one kind of the most promising power plants in the future renewable energy system,since they can supply dispatchable and low-cost electricity with abundant but intermittent solar energy.In order to significantly reduce the levelized cost of electricity(LCOE)of the present commercial CSP plants,the next generation CSP technology with higher process temperature and energy efficiency is being developed.The TES system in the next generation CSP plants works with new TES materials at higher temperatures(>565℃)compared to that with the commercial nitrate salt mixtures.This paper reviews recent progressin research and development of the next generation CSP and TES technology.Emphasis is given on theadvanced'TES technology based on molten chloride salt mixtures such as MgCl_(2)/NaCl/KCl which hassimilar thermo-physical properties as the commercial nitrate salt mixtures,higher thermal stability(>800℃),and lower costs(<0.35USD·kg^(-1)).Recent progress in the selection/optimization of chloridesalts,determination of molten chloride salt properties,and corrosion control of construction materials(eg.,alloys)in molten chlorides is reviewed.

Increasing Coal-Fired Power Plant Operational Flexibility by Integrating Solar Thermal Energy and Compressed Air Energy Storage System

This paper proposed a novel integrated system with solar energy,thermal energy storage(TES),coal-fired power plant(CFPP),and compressed air energy storage(CAES)system to improve the operational flexibility of the CFPP.A portion of the solar energy is adopted for preheating the boiler’s feedwater,and another portion is stored in the TES for the CAES discharging process.Condensate water from the CFPP condenser is used for cooling compressed air during the CAES charging process.The thermodynamic performance of the integrated system under different load conditions is studied.The system operations in a typical day are simulated with EBSILON software.The system enables daily coal saving of 9.88 t and reduces CO_(2)emission by 27.95 t compared with the original CFPP at 100%load.Under partial load conditions,the system enables maximum coal saving of 10.29 t and maximum CO_(2)emission reduction of 29.11 t at 75%load.The system has maximum peak shaving depth of 9.42%under 40%load condition.The potential of the system participating ancillary service is also discussed.It is found that the integration of solar thermal system and CAES system can bring significant ancillary service revenue to a conventional CFPP.

Thermo-Economic Optimization of Solar Thermal Devices by Coherent Integration of Technologies

Radiation is a form of energy where the angular variable of the direction of its photons has a primary importance, particularly for radiation concentration processes, which are essential tools to reach high temperatures from radiation beams (as the solar ones) with moderate intensities. Solar radiation cannot be used directly to feed thermodynamic cycles, and optical concentration must be applied to that goal. In general, reflection from mirrors is preferred to refraction by lenses in this case, because they have less optical aberrations. Concentration conveys very high temperatures in the receiver. However, the higher the temperature, the lower the efficiency of the solar thermal apparatus. Besides that, economy also suffers quite a lot when going to very high concentration factors, which is one of the main burdens in the development of Solar Thermal Energy. A new configuration of solar radiation concentrator is presented. It includes a salient innovation in the way the mirrors are given the right curvature by mechanical forces. Those mirrors are originally flat and do not need any special thermal treatment for this purpose. The whole device concept has been guided by the principle of thermoeconomic coherence, which requires similar efforts in all degrees of freedom that have strong influence in the performance and cost of the system. The paper shows the decision tree that has oriented the project, following the principle of equilibrium in efforts, which leads to a design window of moderate values in the main variables. The prototype of this new configuration has already been built, and the first stage of research is considered to be finished, because the prototype has shown excellent conditions to include selected (fitting) technologies at a very low cost.

考虑碳交易的CSP电站-电极锅炉-热电联产联合供热系统优化策略

由于我国北方弃风光现象严重,为了提高新能源的利用效率,响应我国“碳达峰”和“碳中和”的双碳计划,提出了考虑碳交易的光热电站(CSP)-电极锅炉配合含储热热电机组联合供电、供热的优化策略。电极锅炉是一种高效电转热设备,在促进风电消纳方面具有重要意义,同时CSP电站在平抑风电波动、减少弃风等方面也具有重要作用。因此构建了风电-电极锅炉系统、CSP电站系统、储热系统(TES),通过TES将各子系统与热电机组联系起来构成一个整体,引入碳交易成本对系统进行优化调度建模,并利用YALMIP和CPLEX进行求解。以IEEE 30节点为例进行算例分析,通过仿真验证了该方法的有效性。与传统热电联产模型相比,该方法提高了可再生能源的容纳性,减少了碳排放量。

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.

计及风光不确定性的风-光-光热联合发电系统中光热电站储热容量优化配置

传统新能源电站之间联合形式单一且未考虑风光出力不确定性,弃风、弃光现象严重。为此,提出了一种考虑风光不确定性的风-光-光热联合系统的光热电站储热容量优化配置策略,利用电转热技术使风光电站和光热电站有效耦合,明确联合系统框架与原理;采用改进拉丁超立方抽样方法抑制风光出力的不确定性。最后,构建基于风光出力典型场景的光热电站储热容量双层优化配置模型,并进行算例求解,结果表明所提方法显著降低了系统总投资与运行成本,提高了清洁能源消纳能力。

考虑碳捕集与光热电站的综合能源系统优化调度

为高效处理综合能源系统IES(integrated energy system)中因热电供需矛盾导致的弃风及碳排放问题,构建了考虑碳捕集与封存CCS(carbon capture and storage)技术以及光热CSP(concentrating solar power)电站的优化调度模型。首先,利用CCS技术对热电联产CHP(combined heat and power)机组进行低碳化改造,建立碳捕集热电联产机组的数学模型;然后,在此基础上引入CSP电站,构成CSP-CHP-CCS协同框架,并建立含CSP-CHPCCS的IES低碳经济调度模型;接着,针对系统中的源、荷不确定性,采用信息间隙决策理论进行模拟分析,构建风险规避鲁棒模型;最后,通过算例仿真对比,验证了所提模型在促进新能源消纳和降低碳排放方面的有效性。

风电–CSP联合发电系统优化运行研究

为了抑制风电波动,减少弃风量,考虑到配备储热的太阳能热发电(concentrated solar power,CSP)系统具有可调度性,提出了一种风电—CSP联合发电系统。该系统由风电子系统、CSP子系统及电加热(electric heater,EH)子系统组成。其中,EH子系统的主要作用是将弃风电能转化为热能,并将热能送入CSP储热子系统(thermal energy storage,TES),既为弃风利用提供一条有效途径,又为CSP增加一个热源,使系统的可调度性和灵活性进一步提高。针对该联合系统,以最小化系统输出负荷与计划负荷间的偏差和最大化能源利用率为目标,建立了其混合整数规划调度模型。以未加EH子系统的风电–CSP联合发电系统为参照,通过案例对比研究了在晴天及部分阴云天气下系统的特性。结果显示该联合系统可更好地跟踪计划负荷,有效降低风电弃风量,为CSP储热子系统提供更多的热能,使系统具有更高的灵活性和可调度性。

基于三端柔性直流的光热储能站与新能源场站功率协同控制策略

新能源基地大多经传统交流方式接入高压交流或直流外送通道,为解决大规模新能源经交流接入方式下并网容量小、损耗大,以及功率波动对电网稳定性影响等问题,构建了一个基于柔性直流输电并网的风电和光伏、光热储能及电网三端柔性直流系统。基于直流电压-有功功率特性,提出一种适用于该系统的站间协调控制策略,根据柔性直流输电系统的直流电压波动情况,调整光热储能机组的出力,以平抑风、光功率波动,降低其对电网的影响。针对光热储能侧换流站,采用直流电压裕度下垂混合控制策略,通过控制器参数配置,抑制控制模式切换过程中的暂态过电压,提高系统响应速度。最后,在PSCAD/EMTDC中搭建三端柔性直流系统仿真模型,验证所提控制策略的有效性。

光热电站熔盐储罐热应力分析

基于光热电站熔盐储罐结构建立了储罐的三维计算模型,通过载荷施加及边界条件设置进行热应力耦合分析,得到不同斜温层位置储罐的热应力及位移分布情况。根据不同斜温层厚度、位置获得储罐罐壁热应力变化趋势。斜温层厚度越大,储罐罐壁热应力越小。斜温层位置由罐底上升到罐顶,罐壁热应力先增大后减小。这些结果不仅有助于深入了解储罐的工作性能和安全性,还为储罐的优化设计和改进提供了重要的理论依据和实践指导。

考虑置信容量和调峰能力的新能源基地光热电站配置方法

光热电站具有清洁低碳、长时间储能的友好并网特性,能有效平抑新能源出力波动。相比于传统火电机组,光热电站的调节能力依然存在不足,可能会降低新能源基地外送能力。为此,基于光热电站接入前后外送可靠性不变原则,建立针对光热电站置信容量及调峰能力的评估方法和模型。在此基础上,以新能源基地综合发电经济性为目标,考虑机组约束、外送约束、光热电站置信容量和调峰能力约束建立模型。通过算例仿真,采用时序模拟技术,对光热电站的储热时长和容量优化配置模型进行求解,给出典型场景下的光热电站配置方案,得到风光容量配比最优的容量配置方案,并分析不同风光容量配比下的经济性情况。所提的光热电站储热时长和容量配置方法能够有效提升新能源基地的低碳性,优化光热电站的投资收益。

含CSP电站的风光火储联合外送系统优化配置

为解决中国西北地区的新能源消纳问题,提出一种含CSP电站的风光火储联合外送系统优化配置方法。首先,根据风光火储的互补特性建立含CSP电站的风光火储联合外送系统的典型架构,并分析其工作机制;其次,结合拉丁超立方抽样以及基于时序自相关和互相关的时序重构、时序组合和场景择优,生成考虑时序自相关和互相关性的随机场景集;接着,以计及碳排放成本的系统收益和系统新能源消纳能力最优为多目标,构建含CSP电站的风光火储联合外送系统多目标优化配置模型,并通过增广ε-约束法结合商用软件CPLEX进行求解;最后,以西北某地区2025年电网规划数据构造的算例进行仿真,验证了该配置方法能有效提高系统收益,促进风光消纳,提高系统电力送出能力。

Development of Sensible Heat Storage Materials Using Sand, Clay and Coal Bottom Ash

In this paper, the mechanical and thermal properties of a sand-clay ceramic with additives coal bottom ash (CBA) waste from incinerator coal power plant are investigated to develop an alternative material for thermal energy storage (TES). Ceramic balls are developed at 1000&deg;C and 1060&deg;C using sintering or firing method. The obtained ceramics were compressed with a compression machine and thermally analyse using Decagon devise KD2 Pro thermal analyser. A muffle furnace was also used for thermal cycling at 610&deg;C. It was found that the CBA increased the porosity, which resulted in the increase of the axial tensile strength reaching 3.5 MPa for sand-clay and ash ceramic. The ceramic balls with the required tensile strength for TES were selected. Their volumetric heat capacity, and thermal conductivity range respectively from 2.4075 MJ&middot;m-3&middot;&deg;C-1 to 3.426 MJ&middot;m-3&middot;&deg;C-1 and their thermal conductivity from 0.331 Wm-1&middot;K-1, to 1.014 Wm-1&middot;K-1 depending on sand origin, size and firing temperature. The selected formulas have good thermal stability because the most fragile specimens after 60 thermal cycles did not present any cracks. These properties allow envisioning the use of the ceramic balls developed as filler material for thermocline thermal energy storage (structured beds) in Concentrating Solar Power plants. And for other applications like solar cooker and solar dryer.

含光热电站的热-电系统供暖期优化调度

为解决西北地区热电联产机组“以热定电”特性导致供暖期产生弃风的问题,提出一种含光热电站的热电联供系统优化调度策略。该模型将含储热的光热电站与电加热装置联合进行辅助供热,同时考虑能量损耗的影响,以系统综合成本最小、弃风率最低为目标,制订最优日前调度计划。模型对光热电站供热潜力进行深度开发,减弱了常规热电联产机组热电耦合程度,大大提高了风电消纳水平。最后利用西北某地区实际数据进行算例分析,验证模型有效性。结果表明,所提策略在促进风电消纳的同时降低系统综合成本。

含光热电站的热电联供型微网储热容量双层优化配置

含可再生能源的微网已成为能源领域重要的发展趋势,在此背景下,针对热电联产微网中储能优化配置的不足,构建了含有光热电站的热电联供型微网储热容量双层优化配置模型。上层模型以极小化光热电站日投资成本和热电联产微网日运行成本为优化目标,下层以极小化热电联产微网日运行成本为优化目标。利用Karush-Kuhn-Tucker最优性条件将双层模型转化为单层模型。算例证明了基于光热电站的储热系统提升了微网的经济性以及微网消纳可再生能源的能力,并分析了光热电站的储热容量和储热成本对热电联产微网投资成本和运行成本的影响,同时验证了所提双层规划模型的有效性。

离子热合成锰基氧化物及其可逆储热性能

光热电站需要配备大规模高温储热模块,金属氧化物可以通过可逆氧化还原反应实现热量的存储与释放。其中锰基氧化物无毒、廉价,极具潜力,但可逆性较差。为此,本研究采用深共溶溶剂离子热合成了锰基氧化物,探索了合成参数和铁掺杂对其储热性能的影响。离子热合成的MnCO_(3)前驱体在高温下分解释放CO_(2),使锰基氧化物具有丰富的孔隙结构,为氧气的传输与扩散提供通道,有利于氧化还原反应。离子热合成的Mn_(2)O_(3)比商业Mn_(2)O_(3)反应性能好,但其氧化反应速度较慢;合成温度150℃、掺杂20%Fe的锰铁氧化物的氧化速率快,储热密度高达300.66 J/g,反应可逆性最佳,可实现长期稳定循环。离子热合成策略可以增加锰氧化物中晶格氧占比,促进氧空位的迁移,从而提高可逆性和循环稳定性。