Operation Of Concentrated Solar Power Plants Research Articles

Towards CSP technology modeling in power system expansion planning

Power systems with a high level of renewable energy penetration face challenges due to the inherent properties of some renewable energy sources, such as their variability and uncertainty. These systems require reliable technologies capable of handling large ramps and flexibility needs. Concentrating Solar Power (CSP) has been identified as one solution, which has been researched and implemented in several countries. This paper presents a novel analysis and evaluation of the impacts of choosing an inadequate representation of CSP technology in power system planning tools. The current state of CSP in power system expansion planning in the literature is examined, providing a classification for the modeling of investment and operation of CSP plants. Based on a proposed analysis framework, different models and configurations for CSP plants are evaluated and applied to a 5-bus test system. One of the key findings is that the selected model highly impacts the computational effort (150% more processing time), the quality of the planning decision (14% more overall costs), and the total emissions (up to 52% more emissions). A storage-based model proves to be the most suitable option, considering the operation and investment costs, as well as computational burden. The selected model achieves a 1% error compared to the results obtained with a reference model, while also requiring 40% less computation effort. The proposed framework can be applied to other power system structures by choosing the best suited CSP modeling.

Design of a Continuous Electrochemical Purification Reactor for Corrosion Mitigation in Molten Chloride Salt Systems

The utility of molten chloride salts in concentrating solar power (CSP) is dependent on the ability to maintain low corrosive impurities. Without proper purification, the corrosion rates of containment alloys exceed the industry standard of corrosion—under 20 μm/year. An extensive body of literature focuses on the initial purification stage of molten chloride salts. However, occurrences such as maintenance, leaks, and so forth expose the salt to the atmosphere and reintroduce impurities. Therefore, it is critical to develop a purification strategy that can control impurity levels during CSP plant operation. Here we present the design and fabrication of a purification vessel to continuously remove impurities out of flowing molten salt.

Long-Term MERRA-2 Reanalysis Data Indicate Atmospheric Environmental Changes for Three Major Concentrating-Solar-Power-Plant Project Areas in Xinjiang, China

The characteristics, distributions, and trends of the aerosol optical depth (AOD) and dust aerosol optical depth (DAOD) of three major concentrating solar power (CSP)-plant project areas (Hami, Turpan, and Ruoqiang) in Xinjiang, China were investigated and analyzed during 1980–2022 using the Modern-Era Retrospective analysis for Research and Applications Version 2 (MERRA-2) reanalysis products. The monthly variation, seasonal variation, inter-annual variation, distributions of AOD and DAOD, and proportions of dust in the aerosols in these three CSP-plant project areas were computed and analyzed. Overall, the annual mean AOD at 550 nm in the Turpan project area was the highest (0.20–0.36), while Ruoqiang had the lowest annual mean AOD at 550 nm (0.13–0.30), and the annual mean AOD at 550 nm in Hami was distributed between 0.17 and 0.33. After 2010, the change in the rate of the annual mean AOD showed an overall downward trend in Hami and Ruoqiang, indicating that the atmospheric environmental changes in both areas were more favorable for the operation of CSP plants. In the project areas of Hami, Turpan, and Ruoqiang, more than 90% of the AOD values were mainly in ranges 0.10–0.30, 0.10–0.35, and 0.05–0.30, respectively. As expected, the AOD values in spring and summer were significantly higher than those in autumn and winter in the three study areas. In spring, the dust contents (i.e., ratios of DAOD to AOD) were the highest, accounting for 64% (Hami), 67% (Turpan), and 69% (Ruoqiang) of the total aerosol contents. In all three areas, the proportions of dust in aerosols in spring have shown an increasing trend since 2000, suggesting that the negative impact of the dust on the power generation efficiency in these areas has gradually been increasing. Therefore, it is recommended that the CSP plants in Hami, Turpan, and Ruoqiang develop a strategy for cleaning heliostats, especially in spring, to reduce the impact of dust adhesion on the efficiency of the CSP plants.

Mixed Multi-Pattern Regression for DNI Prediction in Arid Desert Areas

As a crucial issue in renewable energy, accurate prediction of direct normal solar irradiance (DNI) is essential for the stable operation of concentrated solar power (CSP) stations, especially for those in arid desert areas. In this study, in order to fully explore the laws of climate change and assess the solar resources in arid desert areas, we have proposed a mixed multi-pattern regression model (MMP) for short-term DNI prediction using prior knowledge provided by the clear-sky solar irradiance (CSI) model and time series patterns of key meteorological factors mined using PR-DTW on different time scales. The contrastive experimental results demonstrated that MMP can outperform existing DNI prediction models in terms of three recognized statistical metrics. To address the challenge of limited data in arid desert areas, we presented the T-MMP model involving combined transfer learning and MMP. The experimental results demonstrated that T-MMP outperformed MMP in DNI prediction by exploiting the significant correlation between meteorological time series patterns in similar areas for data augmentation. Our study provided a valuable prediction model for accurate DNI prediction in arid desert areas, facilitating the economical and stable operation of CSP plants.

Assessment and Perspectives of Heat Transfer Fluids for CSP Applications

Different fluid compositions have been considered as heat transfer fluids (HTF) for concentrating solar power (CSP) applications. In linear focusing CSP systems synthetic oils are prevalently employed; more recently, the use of molten salt mixtures in linear focusing CSP systems has been proposed too. This paper presents a comparative assessment of thermal oils and five four nitrate/nitrite mixtures, among the ones mostly employed or proposed so far for CSP applications. The typical medium-size CSP plant (50 MWe) operating with synthetic oil as HTF and the “solar salt” as TES was considered as a benchmark. In the first part of the paper, physical properties and operation ranges of different HTFs are reviewed; corrosion and environmental issues are highlighted too. Besides an extensive review of HTFs based on data available from the open literature, the authors report their own obtained experimental data needed to thoroughly compare different solutions. In the second part of the paper, the impact of the different HTF options on the design and operation of CSP plants are analyzed from techno-economic perspectives.

Water and CSP—Linking CSP Water Demand Models and National Hydrology Data to Sustainably Manage CSP Development and Water Resources in Arid Regions

A systematic approach to evaluate Concentrating Solar Power (CSP) plant fleet deployment and sustainable water resource use in arid regions is presented. An overview is given of previous work carried out. Once CSP development scenarios, suitable areas for development, and the water demand from CSP operations were evaluated, appropriate spatiotemporal CSP performance models were developed. The resulting consumptive patterns and the impact of variable resource availability on CSP plant operation are analysed. This evaluation considered the whole of South Africa, with focus on the areas identified as suitable for CSP, in order to study the impact on local water resources. It was found that the hydrological limitations imposed by variable water resources on CSP development are severe. The national annual theoretical net generation potential of wet-cooled Parabolic Trough decreased from 11,277 to 120 TWh, and that of wet-cooled Central Receiver decreased from 12,003 to 170 TWh. Dry cooled versions also experience severe limitations, but to a lesser extent—the national annual theoretical net generation potential of Parabolic Trough decreased from 11,038 to 512 TWh, and that of Central Receiver decreased from 11,824 to 566 TWh. Accordingly, policy guidelines are suggested for sustainable CSP development and water resource management within the context of current South African water use regulation.

Design and analysis of concentrating solar power plants with fixed-bed reactors for thermochemical energy storage

Concentrating solar power (CSP) integrated with thermochemical energy storage (TCES) has the potential to deliver cost-effective and dispatchable renewable power. In this work, a system-level analysis of CSP with fixed-bed reactors for TCES is provided. First, we simulate fixed-bed reactors at various operating conditions and build effective surrogate models. Second, we develop an optimization model for the design and operation of CSP plants under seasonal solar variability. Using the proposed model, we compare the performance of three types (redox, hydroxide, and carbonate) of solid-gas TCES systems. Results show that, with careful design, TCES can potentially improve the plant performance over two-tank molten salt storage. Finally, the impacts of key process parameters and reaction properties are analyzed to provide guidance for future TCES development.

Solar resource assessment in Seville, Spain. Statistical characterisation of solar radiation at different time resolutions

The characterisation of the solar resource of a site is essential for different phases of solar energy projects. While only rough estimates of yearly levels of solar irradiation (global or direct, depending on the technology) are needed in their very early stages, the required depth of the assessment increases as the project advances, including long-term estimates that can only be obtained through a statistical analysis of a continuous and long-term database of solar radiation measurements. This paper provides the results of a statistical analysis of thirteen years of Global Horizontal Insolation (GHI) measurements and Direct Normal Insolation (DNI) measurements from Seville, Spain (37.4°N, 6.05°W) at different time resolutions, i.e. from annual to nearly instantaneous (5-s). In addition, a new methodology for gap-filling is proposed which keeps the frequency distribution of the original dataset and reduces the uncertainty of the aggregated values (hourly, daily, monthly, yearly) due to the gaps. Some relevant results of this analysis are: (a) the instantaneous values of GHI and DNI have bimodal distributions, although of different characteristics, in agreement with the results of some works developed in similar climate locations; (b) the frequency distributions of the instantaneous and 10-min clearness index (kt) and beam fraction index (kb) are almost identical, suggesting 10min as a good time resolution for the simulation of Concentrated Solar Power (CSP) systems oriented to feasibility analyses; (c) the distributions of hourly kt and kb values, show significant differences with respect to the instantaneous ones; (d) the difference between the percentile 99 (P99) of the instantaneous GHI and its maximum value is very high, because of the enhancement effect due to the cloud reflection, while for the DNI the corresponding values are much closer. The comparison with the results of other locations of similar climates suggest that these results can be extrapolated, at least, to other locations of similar climates. Other, more site-specific, results are: (a) the number of typical overcast days in summer is extremely low, while it takes its maximum value in December, suggesting this month as the best for maintenance operations that require halting the operation of CSP plants; (b) the annual mean daily values are 4.98kWhm−2 for GHI and 5.68kWhm−2 for DNI, with a low inter-annual variability and a greater monthly variability which depends on the season. The monthly and yearly average values from Seville have been compared with three long-term databases derived from satellite images. The best concordance in GHI values is found with NASA’s Surface Meteorology and Solar Energy (NASA SSE), but NASA SSE provides significantly higher DNI values compared to the Seville database. A comparison of one year of DNI and GHI measurements recorded at two locations, Durban (South Africa) and Abu Dhabi (United Arab Emirates), with high solar potential is also addressed.

Optimization of an encapsulated phase change material thermal energy storage system

Thermal energy storage enables uninterrupted operation of a concentrating solar power (CSP) plant during periods of cloudy or intermittent solar availability. This paper presents a transient computational analysis of an encapsulated phase change material (EPCM) thermal energy storage (TES) system for repeated charging and discharging cycles to investigate its dynamic response. The influence of the design and operating parameters on the dynamic charge and discharge performance of the system is analyzed to identify operating windows that satisfy technoeconomic targets of storage cost less than $15/kWht, round-trip exergetic efficiency greater than 95%, charge time less than 6h and a minimum discharge period of 6h. Overall, this study illustrates a methodology for design and optimization of encapsulated PCM thermal energy storage system (EPCM-TES) for a CSP plant operation.

Design of a latent thermal energy storage system with embedded heat pipes

Thermal energy storage plays an important role in extending the operation of a concentrating solar power (CSP) plant to times when sufficient solar energy is unavailable for generation of electricity. Extending the CSP plant operation increases its capacity factor and can lead to reduction in the levelized cost of electricity equivalent to that of fossil-fueled power plants. In view of this, latent thermal energy storage (LTES) system embedded with gravity-assisted heat pipes is considered in the present study. Transient numerical simulations are presented and the influence of the design and operating parameters on the dynamic charge and discharge performance of the system is analyzed to identify operating windows that satisfy the U.S. Department of Energy SunShot Initiative targets, which include, storage cost less than $15/kWht, round-trip exergetic efficiency greater than 95% and charge time less than 6h for a minimum discharge period of 6h. Overall, this study illustrates a methodology for design and optimization of LTES with embedded gravity assisted heat pipes (HP-TES) for a CSP plant operation.

Concentrating solar power plant investment and operation decisions under different price and support mechanisms

Abstract The dispatch opportunities provided by storage-enhanced Concentrating Solar Power (CSP) plants have direct implications on the investment decisions as not only nameplate capacity but also the storage capacity and the solar multiple play a crucial role for the viability of the plant investment. By integrating additional technical aspects and operation strategies, this paper extends the optimization model proposed by Madaeni et al. , How Thermal Energy Storage Enhances the Economic Viability of Concentrating Solar Power . Using a mixed integer maximization approach the paper yields both the optimal layout decision and the operation of CSP plants. Subsequently, the economic value of CSP storage is analyzed via energy modeling of a Spanish plant location under the respective wholesale market prices as well as the local feed-in tariff. The analysis shows that investment incentives for CSP plants with storage need to appropriately account for the interdependency between the price incentives and the plant operating strategy. As the resulting revenue characteristics influence the optimal size of solar field and storage differing operating strategies also give rise to differing optimal plant layouts. Most noteworthy, the current Spanish support scheme offers only limited incentives for larger thermal storage capacity.

Value generation of future CSP projects in North Africa

This paper discusses the value generation potential for local and international industry in different development scenarios of the concentrating solar power (CSP) market in North Africa until 2030. It analyzes the economic impact resulting from the participation of North African and European companies during construction and operation of CSP plants. The assessment is based on a self-developed solar technologies market development model (STMD) that includes economic and technical requirements and constraints for the creation of a local CSP market. In-depth interviews with industry stakeholders provide specific input, validate the calculations and complement the quantitative model results and conclusions. Long-term potential for locally generated revenues from CSP plant construction are modeled and lead to a share of local revenues of up to 60%. Potential market size of solar power plants in North Africa could reach total revenues of 120 Billion euros and thus demand for components and services contribute to national gross domestic products significantly. Recommendations are given for regional industry cooperation and policy actions for the support of local and international CSP industry in North Africa in order to improve the investment environment and growth of renewable energies in the region.