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The effects of global warming are severely recognizable and, according to the OECD, 47% of the world's population will soon live in regions with insufficient drinking water. Already, many countries depend on desalination for fresh water supply, but such facilities are often powered by fossil fuels. This paper presents an energy self-sufficient desalination system that runs entirely on solar power. Sunlight is harvested using parabolic trough collectors with an effective aperture area of 1.5 m × 0.98 m and a theoretical concentration ratio of 150 suns, in which a concentrator photovoltaic thermal (CPV-T) hybrid-absorber converts the radiation to electricity and heat. This co-generated energy runs a multi-effect distillation (MED) plant, whereby the waste heat of multi-junction concentrator solar cells is used in the desalination process. This concept also takes advantage of synergy effects of optical elements (i.e., mirrors), resulting in a cost reduction of solar co-generation compared to the state of the art, while at the same time increasing the overall efficiency to ~75% (consisting of an electrical efficiency of 26.8% with a concurrent thermal efficiency of 48.8%). Key components such as the parabolic trough hybrid absorber were built and characterized by real-world tests. Finally, results of system simulations, including fresh water output depending on different weather conditions, degree of autonomy, required energy storage for off-grid operation etc. are presented. Simulation results revealed that it is possible to desalinate around 2,000,000 L of seawater per year with a 260 m2 plant and 75 m3 of thermal storage. [ABSTRACT FROM AUTHOR]

Ternary carbonate salts (Li2CO3-Na2CO3-K2CO3) are promising heat transfer fluids to increase the efficiency of the electric power in concentrated solar power (CSP) technology. However, the corrosion produced at high operating temperatures is a key challenge to tackle for employing cost-effective steels as construction materials in CSP. In this work, the use of stainless steels with amorphous carbon was investigated, for the first time, as a surface modification method to mitigate the corrosion of structural CSP materials by molten salts. In doing so, an amorphous carbon (a-C) film of 100 nm in thickness was deposited on the 301LN stainless steel's surface by the carbon thread evaporation technique. The corrosion behavior of the 301LN was assessed in carbonate salt at 600 °C for 1000 h. This film decomposed forming carbide layers, contributing to corrosion mitigation due to the generation of denser oxide layers, decreasing the Li+ diffusion through the stainless steel. [ABSTRACT FROM AUTHOR]

In this study, corundum-magnesium aluminate spinel (C-MAS) composite heat storage ceramics were synthesized by co-adding MgO and TiO 2 to Al 2 O 3. The effects of TiO 2 and the Al 2 O 3 /MgO ratio on the heat storage performance were evaluated. The findings reveal that Ti4+ integrates into the corundum and MAS lattice, leading to lattice distortion and facilitating solid-phase reaction and MAS generation. Optimal performance is observed at an Al 2 O 3 /MgO ratio of 95:5, with dense structure, minimal pores, and uniform grain size, exhibiting exceptional thermal shock resistance. They withstand 30 thermal shocks (RT-1100 °C) with a 7.12 % increase in bending strength. Moreover, the addition of MgO and TiO 2 significantly enhances the specific heat capacity, characterized by an average specific heat capacity of 1.06 J·g−1·°C−1 and a heat storage density of 1443.83 kJ·kg−1 (RT-1100 °C). TiO₂ introduces additional point defects or alters existing ones in the Al₂O₃ matrix, increasing heat capacity through defect thermal motion. The formation of MAS leads to higher specific heat capacity, due to the greater degrees of freedom and complex lattice vibrations of the spinel structure. These properties position C-MAS composite ceramics as promising candidates for the heat storage materials of the new generation of solar thermal power generation. [ABSTRACT FROM AUTHOR]

This study develops the heliostat curve tracing parametric model (HCTPM) to predict solar energy distribution in concentrated solar power (CSP) systems with sun-tracking capabilities. HCTPM uses curve tracing techniques to visualize flux distribution on mirrors and receivers, producing results that align closely with established models like HFLCAL, which use Gaussian and Tonatiuh ray-tracing methods. Simulations revealed that deviations in energy distribution increase as Sun shape error decreases, with greater impact on flux density and sensitivity. Variations in Sun disk radius caused notable deviations, especially in elliptical projections. The model's flexibility in adjusting mirror shapes and sizes allows for the evaluation of spill losses, optimizing mirror designs for different positions. Spill loss analysis showed that larger mirrors reduce spill loss on mirrors but increase it on receivers, particularly when mirrors deviate from the north. Although total spill loss decreases with larger mirrors, this effect weakens as receiver spill loss grows. These findings emphasize the importance of optimizing mirror and receiver design to maximize energy efficiency and minimize resource waste, contributing to more sustainable solar energy systems. The HCTPM model plays a crucial role in improving the sustainability of CSP systems by optimizing configurations based on Sun disk characteristics, reducing energy losses, and promoting efficient resource use. [ABSTRACT FROM AUTHOR]

As concentrated solar power (CSP) systems evolve, the new generation of CSP systems will utilize chloride molten salts, which are cost-effective and have high operating temperatures, but are highly corrosive. In order to reduce the corrosiveness of chloride salts, we investigated the addition of different levels of Mg to chloride salts to study the effect on corrosion. In this paper, the corrosion behavior of 310S stainless steel with aluminum in high-temperature molten salt NaCl-KCl-MgCl2 was studied. By adding different contents of magnesium corrosion inhibitor, the corrosion mechanism and the effect of the corrosion inhibitor were explored. The results show that the lowest corrosion rate of 6.623 mm/y was obtained for the aluminum-formed 310S with 0.05 wt.% Mg. However, the corrosion rate rises when the Mg content exceeds 0.05 wt.% compared to the corrosion rate of corroded specimens without Mg. Changing the added Mg content does not affect the corrosion products. For 310S stainless steel with aluminum, its corrosion inhibition was best achieved by adding 0.05 wt.% Mg to the chloride molten salt. [ABSTRACT FROM AUTHOR]

In the last two decades, Peru has experienced a process of transformation in the sources of its energy matrix, increasing the participation of clean energy such as solar photovoltaic (PV), on-shore wind, biomass, and small hydro. However, hydropower and natural gas remain the main sources of electricity, whereas off-shore wind, biogas, waves, tidal, and geothermal sources are currently underdeveloped. This article presents the enormous potential of Peru for the generation of electrical energy from a solar source equivalent to 25 GW, as it has in one of the areas of the world with the highest solar radiation throughout the year. In addition, this article presents the main advantages, benefits, and considerations of the implementation of solar photovoltaic technology, with emphasis on (i) the potential of solar energy, showing the available potential and an installed capacity by the year 2024 equivalent to 398 MW, (ii) current solar energy sources, characterizing existing industrial solar photovoltaic (PV) energy plants, and (iii) future solar energy facilities projections, stating the portfolio of solar renewable energy plant projects to be implemented in the future considering an installed capacity of 7.2 GW by 2028. Additionally, lessons learned, challenges, and directions for the future development of solar energy in the country are presented. Finally, the article concludes that if Peru takes advantage of solar potential by considering a sustainable future perspective and implementing strategic land-use planning, the southern region will be transformed into a world-class territory for renewable energy development considering the hybridization of concentrated solar power (CSP) systems with solar photovoltaic (PV) systems and solar energy storage systems. [ABSTRACT FROM AUTHOR]

Artificial intelligence offers the opportunity to use the large amounts of data from commercial CSP power plants to supplement the experience of operations personnel through accurate predictions to optimize predictive maintenance and operations management. As a constant high outlet temperature of the solar field even under fluctuating environmental conditions is a relevant factor for the efficiency of commercial CSP power plants, the focus of this work is on the prediction of solar field outlet temperature. The analysis of this work is based on operating data of the commercial CSP power plant Andasol III in Spain with a temporal resolution of 5 minutes over a period of 5 consecutive years. To optimize the prediction, the three models random forest, feed forward artificial neural network – also known as multiple layer perceptron (MLP) – and long short-term memory (LSTM) network were compared in their performance and optimized separately by means of hyperparameter variation. The best results were achieved with the LSTM model with a mean absolute error of 6.78 K averaged over the prediction period of one year. By using AI models, future deviating outlet temperatures can be predicted at an early stage. These predictions offer the possibility to keep the outlet temperature more constant by predictive adjustment of the mass flow and thus increase the efficiency of the solar field and the whole CSP plant.

Concentrated Solar Power (CSP) plants integrated with Latent Heat Thermal Energy Storage (LHTES) systems offer a promising solution for dispatchability, reliability, and economic concerns generally associated with renewable energy technologies. These systems, however, require an operational life of up to 30 years to compete with power plant systems operating on fossil fuels. This is a significant challenge due to the high temperatures and corrosive eutectic salts utilised in LHTES systems. Additionally, these systems and its subcomponents are expected to be under varying degrees of stress due to the diurnal cyclic temperature variations inherent in the plant’s operational cycle. Hence, it is crucial to understand the various factors that can affect the operational life of materials used in such applications and conduct thorough material compatibility studies to assess the combined impact of these operating conditions on corrosion mechanisms. This study presents a novel static immersion test approach using modified Compact Tension (CT) specimens manufactured from 316L to investigate the effects of Na2CO3:NaCl (59.45:40.55 wt.%) salt, elevated temperatures (700 ℃ for up to 1000 hours), and stress on corrosion induced in the alloy. The post-exposure results are characterised with Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) shows that corrosion mechanisms are significantly affected by factors such as high operating temperatures leading to changes in both corrosion morphology and rate, high stresses causing localised preferential corrosion, as well as corrosive salt and oxygen availability affecting the type of corrosion induced.

This work proposes a pumped thermal energy storage (PTES) integrated into the power block of a concentrated solar power plant. The power block operates under a Hybrid Rankine–Brayton (HRB) cycle using propane as the working fluid. During PTES charging, some thermal energy is obtained from a dedicated compressor (additional to that of the HRB cycle), which is stored. During discharge, both compressors (HRB and PTES) are off, restoring the consumed energy and resulting in about a 13% increase in nominal power output. The system is also able to store thermal energy that would otherwise be rejected through the condenser if the PTES were turned off, leading to efficiency improvements in some cases. Considering the 2022 Spanish electricity market prices, the proposed PTES integration with 4 h of storage is feasible. The levelized cost of storage is calculated and compared to those of other PTES systems, achieving around a 40% reduction compared with an equivalent PTES Rankine. These results encourage future studies where the proposed PTES could be integrated into other power cycles that include a recompression process. [ABSTRACT FROM AUTHOR]

The development of a new generation of solid particle solar receivers (SPSRs) with high solar absorptivity (0.28–2.5 μm) and high infrared emissivity (1–22 μm) is crucial and has attracted much attention for the attainment of the goals of "peak carbon" and "carbon neutrality". To achieve the modulation of infrared emission and solar absorptivity, two types of medium- and high-entropy rare-earth hexaboride (ME/HEREB6) ceramics, (La0.25Sm0.25Ce0.25Eu0.25)B6 (MEREB6) and (La0.2Sm0.2Ce0.2Eu0.2Ba0.2)B6 (HEREB6), with severe lattice distortions were synthesized using a high-temperature solid-phase method. Compared to single-phase lanthanum hexaboride (LaB6), HEREB6 ceramics show an increase in solar absorptivity from 54.06% to 87.75% in the range of 0.28–2.5 μm and an increase in infrared emissivity from 76.19% to 89.96% in the 1–22 μm wavelength range. On the one hand, decreasing the free electron concentration and the plasma frequency reduces the reflection and ultimately increases the solar absorptivity. On the other hand, the lattice distortion induces changes in the B–B bond length, leading to significant changes in the Raman scattering spectrum, which affects the damping constant and ultimately increases the infrared emissivity. In conclusion, the multicomponent design can effectively improve the solar energy absorption and heat transfer capacity of ME/HEREB6, thus providing a new avenue for the development of solid particles. [ABSTRACT FROM AUTHOR]

The study evaluated the use of mining seawater pipelines in a CSP+MED plant at commercial scale based on solar tower molten salts technology, with 111.2 MWe and 13 hours of thermal energy storage in northern Chile. The plant is coupled to the biggest seawater pipeline in the country, from Centinela mining facility. Results shown that the CSP+MED plant required all the seawater pumping capacity of the pipeline in order to cool the thermal cycle of the CSP plant using the MED plant. In terms of electricity production, the MED plant integration affects significantly the annual electricity production of the plant, when compared with an optimized CSP plant and to a CSP plant with the same design but without the MED plant and considering a once through cooling system, lowering the electricity production an 46.05% and 25.82% respectively. On the other hand, the CSP+MED plant integration produces 14.06 hm3 of freshwater annually, which translated in an additional income equivalent to 28.14 MM USD each year, which is substracted from the OPEX costs of the plant for the LCoE calculations. For this reason, the results showed that the lowest LCoE is reached by the CSP+MED plant configuration, but is highlighted that the economic analysis assumed an ideal situation, and further business models must be studied in order to share the benefits of the seawater pipeline integration between the CSP+MED plant owner and the mining facility that owns the seawater pipeline.

Molten salts are the most widely used thermal energy storage system in Concentrated Solar Power (CSP) plants, accounting for 50% of the installed capacity. Many studies have conducted life cycle assessments of the Greenhouse Gas (GHG) emissions produced within the CSP ecosystem; however, it has not yet been standardized for molten salt storage. This study compares GHG emissions of molten salt storage in CSP with conventional coal and natural gas power plants, to measure the environmental impact they can have in the CSP ecosystem. This was achieved with the use of simulations for 48 operational CSP plants worldwide using the system advisor model with their respective operation conditions. Results show that for the three configurations studied, CSP plants would result in annual 3,99 MMtCO2eq of emissions displaced when compared to a coal power plant and 1,61 MMtCO2eq compared to a natural gas power plant.

The efficient operation of a solar field is an essential factor for the commercial operation of a concentrating solar power (CSP) plant. In addition to predictive control for the highest possible constant outlet temperature at high mass flow, efficient operation also includes early detection of defective components and heat losses. This work presents a method for non-invasive heat loss detection as a strong indication for vacuum losses, based on measured operational data of Andasol III, an operating 50 MW parabolic trough collector (PTC) plant located in southern Spain. To detect vacuum losses via this method, mass flow rate and temperature reduction are determined separately for each individual loop via the analysis of a short-term temperature rise of the heat transfer fluid (HTF) during preheating. While the temperature reduction was measured directly, the mass flow was determined via the thermal time-of-flight (ToF) method using the same installed temperature sensors. By measuring thermal step responses during the preheating of the solar field at nighttime operation, the influence of fluctuating direct normal irradiance (DNI), misalignment of the absorber tubes and an offset in collector focus was circumvented. In the scope of the presented work, single loops were detected, which show a higher heat loss at lower mass flow rate and therefore have an increased probability of a higher vacuum loss. Better localization and early detection of these vacuum losses would allow the corresponding absorber tubes to be renewed at the economically and environmentally best time, improving the efficiency of the solar field and thus the entire CSP plant.

As concentrated solar power (CSP) systems evolve, the new generation of CSP systems will utilize chloride molten salts, which are cost-effective and have high operating temperatures, but are highly corrosive. In order to reduce the corrosiveness of chloride salts, we investigated the addition of different levels of Mg to chloride salts to study the effect on corrosion. In this paper, the corrosion behavior of 310S stainless steel with aluminum in high-temperature molten salt NaCl-KCl-MgCl2 was studied. By adding different contents of magnesium corrosion inhibitor, the corrosion mechanism and the effect of the corrosion inhibitor were explored. The results show that the lowest corrosion rate of 6.623 mm/y was obtained for the aluminum-formed 310S with 0.05 wt.% Mg. However, the corrosion rate rises when the Mg content exceeds 0.05 wt.% compared to the corrosion rate of corroded specimens without Mg. Changing the added Mg content does not affect the corrosion products. For 310S stainless steel with aluminum, its corrosion inhibition was best achieved by adding 0.05 wt.% Mg to the chloride molten salt.

The global energy sector is now transitioning its structure towards carbon neutrality aided by renewable resource use. Despite its immense potential, solar energy contributes minimally to the global energy mix due to its intermittent nature and challenges with power demand fluctuations. Increased use of distributed solar sources alters market dynamics, necessitating conventional power plants to ramp up output during lower renewable energy production times and manage oversupply risks. Concentrated solar power (CSP) can contribute to grid decarbonization, but its high levelized cost of electricity (LCOE) impedes widespread adoption. This study proposes hybridizing CSP and photovoltaic (PV) technologies, aiming to leverage their synergy to maximize economic benefits. We develop a comprehensive process design framework that utilizes a robust multi-objective optimization (MOO) approach, which factors in techno-economic and environmental objectives while accounting for model uncertainty from resource prices and life cycle assessment indicators. Optimization results reveal that in Ivanpah, California, hybrid CSP + PV can reduce 41 % of LCOE and limit environmental impacts compared to standalone CSP plants. This robust framework also identifies design trends, such as a constant dependence on the PV field, and a trade-off between the installed area of the solar concentrators and the backup boiler operation. The optimal unit sizes, less susceptible to future market fluctuations and potential changes in the global warming potential (GWP) of technologies, contribute significantly to robust and sustainable energy planning decisions.

The utilization of the Solar Salt (60 wt%NaNO3/40 wt%KNO3) mixture as a Thermal Energy Storage (TES) medium is gaining importance due to its scalability and cost-effectiveness. However, the corrosion of metallic components presents a significant challenge. This study explores the intricate interplay between salt chemistry and its corrosivity, particularly at elevated temperatures exceeding the state-of-the-art bulk temperature 565 °C. The study manipulates salt decomposition by adjusting the oxygen partial pressure in the purge gas over Solar Salt and investigates the evolution of salt chemistry with and without the presence of steel. It analyzes the corrosion behavior of two types of stainless steel, AISI 316L and AISI 310, under different gas purging atmospheres. Furthermore, it employs a gold particle tracing technique to identify and monitor the formation and growth of the corrosion layer on the steel surface. The results reveal that nitrogen gas purging significantly enhances salt decomposition and its corrosivity over time. The presence of steel also influences salt decomposition depending on the purged gas atmosphere. In a nitrogen atmosphere, the presence of steel can increase the nitrite levels, while an air atmosphere results in an elevated concentration of oxide ions. In air, the AISI 310 alloy shows slightly better performance than AISI 316L. Both alloys experience substantial mass loss in the nitrogen-purged atmosphere. Interestingly, the presence of gold particles within the middle of the corrosion layer in the air purged atmosphere visually illustrates a counter diffusion involving various cations and anions across the corrosion layer.

The radiative properties of sintered bauxite (ACCUCAST ID80) and AMS4003 particles were measured and compared to assess their performances as direct absorption and heat transfer media for particle-based concentrated solar power (CSP) plants. Reflectance measurements were performed over the spectral range 0.2–20 µm and used to calculate solar and thermal emission properties of the particles. In addition, reflectance was measured as a function of temperature up to 1000 °C for the spectral range 1–20 µm. The solar absorptance of AMS4003 was greater than that of ACCUCAST both before and after thermal cycling of the materials at 1000 °C, although thermal cycling was found to substantially decrease the solar absorptance of both materials. The thermal emittance of AMS4003 was also greater than that of ACCUCAST at all temperatures tested. Finally, the radiaitve properties measured in this study were used to estimate absorber efficiencies as a way to compare the particles in terms of their performance in a solar receiver. AMS4003 yielded greater efficiencies than ACCUCAST, suggesting its potential as a material for CSP.

Green hydrogen has been considered as one of the energy carriers of the future, and Chile can become a production leader due to its great renewable energy potential. Cheap electricity is one of the key drivers for making green hydrogen a cost-effective energy carrier for many sectors. However, without energy storage, only a small operational electrolysis capacity can be achieved, and therefore, the share of the CAPEX in the levelized cost of hydrogen (LCOH2) increases [1]. This work set out to conduct a techno-economic analysis for the integration of large-scale green hydrogen production and a hybrid CSP+PV plant of 100 MWe in northern Chile, one of the world's solar hotspots. For a better understanding on the benefits of such integration, the performance of the hybrid solar plant was compared to the performance offered by each independent solar technology and with a grid-connection via a PPA mechanism. In addition, this study takes into account the costs of storage and transport to potential local and international consumers.

MgCl2-NaCl-KCl salts mixture shows great potential as a high-temperature (> 700 °C) thermal energy storage material in next-generation concentrated solar power plants. Adding Mg into molten MgCl2-NaCl-KCl salt as a corrosion inhibitor is one of the most effective and cost-effective methods to mitigate the molten salt corrosion of commercial Fe-Cr-Ni alloys. However, it is found in this work that both stainless steel 310 and Incoloy 800H samples were severely corroded after 500 h immersion test at 700 °C when the alloy samples directly contacted with the over-added Mg in the liquid form. The corrosion attack is different from the classical impurity-driven corrosion in molten chloride salts found in previous work. Microscopic analysis indicates that Ni preferentially leaches out of alloy matrix due to the tendency to form MgNi2/Mg2Ni compounds. The Ni-depletion leads to the formation of a porous corrosion layer on both alloys, with the thickness around 204 μm (stainless steel 310) and 1300 μm (Incoloy 800H), respectively. These results suggest that direct contact of liquid Mg with Ni-containing alloys should be avoided during using Mg as a corrosion inhibitor for MgCl2-NaCl-KCl or other chlorides for high temperature heat storage and transfer. [ABSTRACT FROM AUTHOR]

This study sought to determine an optimal scenario concerning multiple climatic parameters to maximize the performance of a solar system. A molten salt energy storage unit was used to enable round-the-clock power generation and maximize the system's reliability. A solar concentrator with heliostats and a solar receiver was employed to absorb solar energy, and a modified steam Rankine cycle was utilized to generate power. A total of 12 scenarios were evaluated based on three climatic parameters (ambient temperature, sunshine duration, and wind speed) and one techno-economic parameter (number of heliostats). Sankey analysis, which is a novel technique used to determine the optimal scenarios in the literature, revealed that Scenario 8 was optimal. This scenario showed the maximum exergy rate, minimum exergy destruction, and lowest cost rate. This scenario considered the sunshine duration of 11 h, ambient temperature of 16 °C, wind speed of 3 m/s, and 300 heliostats, resulting in output energy of 1582 kWh and exergy destruction of 34250 kWh. The parametric analysis showed that the turbine and superheater temperatures had the greatest effects on the system performance. The exergy analysis of the system demonstrated that the heliostats and solar receivers accounted for the largest portions of exergy destruction. Multi-objective optimization via response surface method yielded the optimal exergy round-trip efficiency of 11.5% and optimal cost rate of 229.2 $/h. The economic analysis of the system revealed that the solar subsystem had the highest cost rate. In terms of efficiency and production power, this system will perform differently in different parts of the world and under different weather conditions. To this end, it is important to find out where this particular system will be more efficient and powerful. Six different scenarios have been defined for the parametric analysis of the proposed system in order to achieve reliable results. For the case study, Los Angeles and San Diego were selected as the regions with the highest similarity to the optimal scenario in terms of sunshine duration, ambient temperature, and wind speed, whereas Paris and Toronto were randomly selected. The performance of the system showed that the system can produce 2612.3 megawatts of electricity in the city of San Diego and 2472.4 megawatts of electricity in the city of Los Angeles. Also, by setting up this system, it is possible to provide electricity for 51 to 54 residential units. The proposed system performed better in regions with climatic parameters similar to those in the optimal scenario. [ABSTRACT FROM AUTHOR]

• Innovative thermocline TES prototype with internal heat exchangers tested by ENEA. • A vertical internal channel assists the movement of the molten salt in the tank. • A dynamic 2D axis-symmetric CFD model of the prototype has been developed. • The model is validated against the experimental data under justified assumptions. • The model is exploited to assess how the channel diameter affects the performance. Thermocline thermal energy storage is a (potentially) cost-effective alternative to the more widespread two-tank solution, as both the hot and the cold medium are stored in a single tank. An innovative single-medium indirect thermocline technology was recently developed by ENEA and a prototype was experimentally tested at the Casaccia laboratories. The storage tank is equipped with two flat-coil heat exchangers (HXs) located at the bottom and at the top of the tank, for the charge and discharge phases, respectively. The storage medium is a mixture of molten salt (Hitec XL) and the heat transfer fluid is a mineral oil (Delcoterm Solar E15). An internal vertical channel, which assists the motion of the storage medium during the charge and discharge transients, connects the two HXs. In this paper, a detailed, transient 2D axisymmetric Computational Fluid Dynamics (CFD) model of the prototype has been developed. The model simulates the charge and discharge transients, determining the heat losses and the temperature distribution of the molten salt in the tank. The computational domain includes the storage medium, the tank insulated walls and the main components immersed in the molten salt, i.e., the heat exchangers and the vertical channel. The model has been first calibrated by best-fitting the data measured during a test conducted without any thermal load, then validated against another independent set of experimental data. A first comparison against a charge transient showed some discrepancies between the computed and the measured temperatures of the salt, which could be explained by assuming the presence of a bypass at the location of the HXs. This assumption is discussed and justified in the paper. The CFD domain has then been modified to include the bypass, and this allowed to successfully validate the model against experimental data in both charge and discharge phases. The validated model is finally exploited to assess how a variation in the diameter of the internal vertical channel could affect the thermal performance of the storage system in a charge transient. The results indicate that decreasing the channel diameter leads to an increase of the salt temperature at the very top of the tank at the cost of a longer time to fully charge the storage. [ABSTRACT FROM AUTHOR]

Thermal energy storage (TES) based on molten salts has been identified as a key player in the transition from fossil fuels to renewable energy sources. Solar Salt, a mixture of NaNO3 (60 wt%) and KNO3 (40 wt%), is currently the most advanced heat transfer and storage material used in concentrating solar power (CSP) plants. Here, it is utilized to produce electricity via a Rankine cycle, with steam temperatures reaching 550 °C. The goal of this study is to increase the operating temperature of solar salt to over 600 °C, allowing it to be adapted for use in high-temperature Rankine cycles with steam temperatures greater than 600 °C. Yet, this goal is impaired by the lack of available thermodynamic data given the salt's complex high-temperature decomposition and corrosion chemistry. The study explores the thermodynamics of the decomposition reactions in solar salt, with a focus on suppressing decomposition into corrosive oxide ions up to a temperature of 620 °C. The results provide a new understanding of the stabilization of solar salt at previously unexplored temperatures with effective utilization of gas management techniques. [ABSTRACT FROM AUTHOR]

Concentrated solar power (CSP) with heat storage system, as a clean power, owns the capability of generating power continuously and stably, peak shaving and providing system inertia, which is one of the technologies to effectively solve the volatility of renewable energy. This paper proposed a steady state power approximate mathematical model for CSP with heat storage. This model takes the solar radiance as the input, and utilizes the simplified proportional integral to simulate the photo-thermal-electric conversion and the heat storing process, wherein the output power control strategy is considered as well. The simulation results show that the model is in good agreement with the measured curves under sunny and cloudy conditions, and can be used to analyze the sensitivity of the power characteristics of CSP power stations to key parameters.

Concentrator PhotoVoltaics (CPV) may generate considerable heat as a byproduct in addition to power. Using that heat as concentrated solar power (CSP) to thermally desalinate salt water would allow for value addition in arid regions by supplementing produced electricity with fresh water. This paper discusses the primary trade-off between the net electricity amount and the net distilled water amount, both of which are desirable products in a hybrid concentrated photovoltaic and thermal system (CPV-T). While higher temperatures promote freshwater generation, they also cause a quick fall in cell efficiency, reducing the quantity of power generated and causing cell deterioration. The CPV-T receiver, which is partially covered with cells and then supplementary heated in a cell-free portion, is modeled and established. Furthermore, simple-stage and multistage desalination unit models are presented, linked to the receiver, and examined to cope with the reduced temperature limits of this receiver. The results demonstrate a CPV-T receiver's ability to generate both electrical power and freshwater, while also demonstrating that the cell temperature constraint can become quite important beyond 50% of the receiver surface coverage. These first order results establish the system's validity and potential and will aid the system designer in the initial system design.

Solar energy is considered as an eco-friendly, cost effective, viable as well as de facto everlasting resource meant for the society. The sustainable development objective of decelerating the climate change has attracted widespread research in the transformation of solar into other useful forms of energy. Although several technologies are prevailing to transform the solar energy, photothermal transformation of solar light into thermal energy exhibits vantage when applied for desalination and water purification in order to mitigate the water crisis and the photothermoelectric effect can cause power generation. The review encompasses the origin of photothermal conversion, the plausible mechanisms involved in the photothermal process, the pre-requisite condition of the material for the efficient conversion, thermal management by integrating the photothermal process and the thermo-electric effect for utilizing broad solar spectra using hybrid modules. This review article also provide a fundamental perception and enhanced understanding of various schemes based on photo-thermo-electric and photo-thermoelectric effect and their recent progress towards its application as power generators and catalytic progress. This aims to propose a model for the realistic outline and development of a module for effectual translation of solar into electrical energy in energy as well as environmental sectors. [Display omitted] • Envisaging the conversion of abundant solar into electrical energy, exploiting the concept of photothermoelectric effect. • Embraces integration of photo-thermal and thermo-electric concept via photo-thermo-electric (P-T-E) effect. • Phonetically similar P-TE effect works with distinct mechanistic approach and generate optoelectronic response. [ABSTRACT FROM AUTHOR]

It is imperative to address the critical problem of water scarcity in sub-Saharan Africa, especially in light of the aggravating effects of climate change brought on by the extraction of fossil fuels. In order to ensure the availability of drinkable water in these places, this research proposes integrating concentrated solar power (CSP) with desalination systems (DS). Present research is focused on identifying and evaluating potential locations for DS/CSP implementation within Mauritania by employing a comprehensive, multi-criteria decision-making framework. This framework synthesizes mathematical approaches from multi-criteria analysis with geospatial analysis techniques, considering a range of factors including environmental impact, economic viability, demographic demands, and climatic conditions. Research findings reveal that 10% of the Mauritanian, approximately 103070 km ^2 , presents optimal conditions for the deployment of DS/CSP facilities. The study delineates the coastal regions as prime candidates for seawater desalination plants, while the densely populated southeastern areas are identified as suitable for brackish water desalination systems. Conversely, the less inhabited northern territories hold the potential for decentralized brackish water desalination plants. Hence this study provides a holistic approach for DS/CSP systems installation to manage water scarcity as well as energy security issues in Mauritania. And also provides basis for formulating future policies in the region.

The aim of the research is a techno-economic analysis of the use of concentrated solar energy technologies in the Iraqi city, considering the concentrated solar energy technology is a renewable energy technology that derives its resources from the sun and is replenished at a rate that exceeds its use. It is also inexhaustible and environmentally friendly energy from its environmental footprint, unlike traditional fossil energy which produces greenhouse gases and a major cause of global warming. This research measures the costs of concentrated solar energy technology to Reduce the effects caused by other energies and work to fill part of the shortfall in the total electricity production, even at a specific percentage, in preparation for spreading a culture of these clean technologies, and proposing investment in concentrated solar power (CSP) technology and choosing the best sites according to radiation rates. Direct solar radiation on which these technologies depend for their work. By comparing the cost between these clean technologies and traditional fossil techniques. In this research, the province of (Al-Anbar) was selected and the economic criteria for the construction of a concentrated solar power plant were studied. The study showed that the technology of concentrated solar energy has a direct impact on the cost of producing electrical energy and reduces the cost of producing kilowatt-hours by (9-11) cents the range to discount rate (5-7) and capacity factor ranged (40 %,45%), regardless of the environmental problems produced by plants that operate on fossil fuels. [ABSTRACT FROM AUTHOR]

Many sites with high solar radiation face high dust loads that reduce energy generation by concentrated solar power plants. This review presents the attenuative impacts of atmospheric aerosols, as well as reflectivity losses due to soiling of solar reflectors, by covering both experimental investigations and numerical studies; along with presenting the theoretical background. The chemical nature of aerosols, and the physics of soiling and atmospheric extinction phenomena (scattering and absorption) are also reviewed. Suspended particles like aerosols result in atmospheric extinction of the solar radiation that reaches the concentrators, and the deposition of these particles on the solar reflectors provokes decreases up to 80% in their reflectivity, and thus enhances the cumulus of optical losses and the reduction of energy production. Even though dust affects both CSP and photovoltaics, CSP technologies suffer more losses. The impact of dust should be particularly considered during the planning phase of solar thermal plants, since its consequent reduction in energy output can be severe. While there have been multiple papers to review dust-related problems for PV, the present paper is the first literature review dedicated to the impact of soiling on concentrated solar power. [ABSTRACT FROM AUTHOR]

Next-generation concentrated solar power (CSP) plants are required to operate at temperatures as high as possible to reach a better energy efficiency. This means significant challenges for the construction materials in terms of corrosion resistance, among others. In the present work, the corrosion behavior in a molten eutectic ternary Li2CO3-Na2CO3-K2CO3 mixture at 600 °C was studied for three stainless steels: an austenitic grade AISI 301LN (SS301) and two duplex grades, namely 2205 (DS2205) and 2507 (DS2507). Corrosion tests combined with complementary microscopy, microanalysis and mechanical characterization techniques were employed to determine the corrosion kinetics of the steels and the oxide scales formed on the surface. The results showed that all three materials exhibited a corrosion kinetics close to a parabolic law, and their corrosion rates increased in the following order: DS2507 < SS301 < DS2205. The analyses of the oxide scales evidenced an arranged multilayer system with LiFeO2, LiCrO2, FeCr2O4 and NiO as the main compounds. While the Ni-rich inner layer of the scales presented a good adhesion to the metallic substrate, the outer layer formed by LiFeO2 exhibited a higher concentration of porosity and voids. Both the Cr and Ni contents at the inner layer and the defects at the outer layer were crucial for the corrosion resistance for each steel. Among the studied materials, super duplex stainless steel 2507 is found to be the most promising alternative for thermal energy storage of those structural components for CSP plants. [ABSTRACT FROM AUTHOR]

Next generation concentrated solar power (CSP) plants promise a higher operating temperature and better efficiency. However, new issues related to the corrosion against protection of the construction alloys need to be solved. In this work, two different duplex stainless steels grades, namely 2205 (DS2205) and 2507 (DS2507), were evaluated for their compatibility with the eutectic molten salt mixture of Li2CO3-K2CO3-Na2CO3 at 500 °C in air for thermal energy storage applications. Corrosion tests combined with complementary microscopy, microanalysis and mechanical techniques were employed to study the oxide scales formed on the surface of the duplex steels. The corrosion tests evidenced that the attack morphology in both duplex steels was a uniform oxidative process without localized corrosion. DS2507 presented a better corrosion resistance than DS2205, due to the formation of thinner, compact and continuous oxide layers with higher compositional content in Cr, Ni and Mo than DS2205. The oxide scales of DS2507 showed more remarkable mechanical integrity and adhesion to the metallic substrate. [ABSTRACT FROM AUTHOR]

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Endpoint impacts related to the transformation of land—including that related to energy infrastructure—have yet to be fully quantified and understood in life cycle assessment (LCA). Concentrated solar power (CSP) which generates electricity by using mirrors to concentrate incoming shortwave radiation onto a receiver, may serve as an alternate source of reliable baseload power in the coming years. As of 2019 (baseline year of the study), the United States (U.S.) had 1.7 GW of installed capacity across a total of eight CSP sites. In this study, we (1) develop an empirical, spatially explicit methodology to categorize physical elements embodied in energy infrastructure using a LCA approach and manual image annotation, (2) use this categorization scheme to quantify land- and ecosystem service-related endpoint impacts, notably potential losses in soil carbon, owing to energy infrastructure development and as a function of electricity generated (i.e., megawatt-hour, MWh); and (3) validate and apply this method to CSP power plants within the U.S. In the Western U.S., CSP projects are sited in Arizona, California, and Nevada. Project infrastructure can be disaggregated into the following physical elements: mirrors (“heliostats”), generators, internal roads, external roads, substations, and water bodies. Of these elements, results reveal that mirrors are the most land intensive element of CSP infrastructure (>90%). Median land transformation and capacity-based land-use efficiency are 0.4 (range of 0.3–6.8) m2/MWh and 40 (range of 11–48) W/m2, respectively. Soil grading and other site preparation disturbances may result in the release of both organic and inorganic carbon—the latter representing the majority stocks in deeper caliche layers—thus leading to potentially significant losses of stored carbon. We estimate three scenarios of soil carbon loss into the atmosphere across 30 years, based on land transformation in m2 per megawatt-hour (m2/MWh) and carbon stock in kilograms of carbon per megawatt-hour (kg C/MWh). Results reveal that potential belowground CO2 released may range from 7 to 137% of total life cycle CO2 emissions. While this study takes a simplistic approach to estimating loss of carbon, the broad methodology provides a valuable baseline for improving comparative analyses of land-related endpoint impacts across energy technologies and other product systems.

An innovative approach for the characterization of the mirror geometry of Concentrating Solar Thermal (CST) plants is presented in this article. The approach takes advantage of the current advances in the commercial unmanned aerial vehicle (UAV) technology to perform airborne, close-range photogrammetry for accurate characterization of the mirror's geometry. To improve spatial resolution and, thus, reconstruction performance, the approach involves a projector for projecting a feature-rich image on the surface of the mirror to be characterized. A UAV flying on a predetermined flight path is used to capture overlapping snapshots of the projected image using its on-board high definition digital camera. By the use of photogrammetry tools, the snapshots are stitched together and processed accordingly to reconstruct the surface of the reflector. Although the approach was tested and validated experimentally by characterizing the mirror surface of a single-facet heliostat, the developed method can also be applied for the characterization of any type of solar concentrating mirror geometry. • Heliostat mirror characterization. • Unmanned Aerial Vehicles (UAV), drone-based photogrammetry. • Concentrated Solar Thermal (CST) plant mirror geometry reconstruction. • CST reflector field characterization. • CST plant operation and maintenance. [ABSTRACT FROM AUTHOR]

This study utilizes decision tree algorithms to estimate the financial feasibility of concentrated solar power (CSP). The main focus of CSP is on solar tower (ST) technology combined with two backup systems, such as biomass boilers and thermal energy storage (TES). The main goal is to develop three decision tree algorithms to predict the power plant's profitability factor (P F) for each of the following three operational scenarios: solar tower-base case-no biomass (ST-BC-NB), solar tower-operation strategy 1-medium biomass (ST-OS1-MB), and solar tower-operation strategy 2-full biomass (ST-OS2-FB). P F was predicted according to main input parameters, including direct capital costs, biomass cost, annual escalation rate, hourly electricity price, annual escalation rate, and peaks and troughs for daily electricity prices. Thermal energy storage was in five different capacities: no-thermal energy storage (No-TES), 5 h, 10 h, 15 h, and 20 h. The decision tree models demonstrated accurate predictions with low errors, high confidence levels, and most data falling within the 95% confidence interval for the "No-TES" case. Solar power plants with biomass backup had a 30% reduction in generation costs compared to conventional plants. The configurations without thermal energy storage had the highest profitability, with a maximum P F of −0.014 USD/kWh and a 25% chance of achieving profitability. • Decision tree analysis evaluates economic feasibility of Concentrated Solar Power. • Solar tower modes (ST-BC-NB, ST-OS1-MB, ST-OS2-FB) predict P F. • Thermal energy storage capacities analyzed: No-TES, 5–20 h. • Accurate predictions, low errors, high confidence for "No-TES" case. • Solar thermal plants with biomass backup reduce generation costs by up to 30 %. [ABSTRACT FROM AUTHOR]

Solar energy is pollution‐free with less impact on the ecosystem, but it has limitations due to its intermittent nature attributed to sun availability for specific hours, resulting in less energy conservation efficiency. Similar to the purpose of carvings on the leaves to collect water, we are presenting a nanometer‐thick layer of silicon or chalcogenide with fused silica for photons enhancement in red and the blue portion of the spectrum within the solar energy reaching the earth's surface. The design is based on nanorod imprints on micrometer‐sized conventional fused silica, ensuring better absorption and transportation toward hybrid photovoltaic cells. Hybrid solar cells (comprising silicon and perovskites) are typically termed the future of solar power, but will not be discussed here. Effective area, optical power concentration, and second‐ and higher‐order dispersions can further help design and develop the photon concentrators. [ABSTRACT FROM AUTHOR]

Heliostat tracking is a critical component of the solar field of concentrating solar power tower (SPT) systems and can be the source of significant losses in power and profit when it lacks the necessary accuracy. This paper presents an advanced heliostat drive system for the SPT generation plant. An integrated model for the heliostat drive system based on dual axes tracking is proposed using an inexpensive angle sensor. The mathematical model of the integrated drive system is developed, including the solar, tower, and heliostat models. The matlab simulation model for the proposed integrated drive system is developed and evaluated. An experimental prototype for a dual-axis heliostat is built using Class-E direct current choppers and an inexpensive Gyro angle sensor. The prototype is tested and considered in the Dhahran region in Saudi Arabia under different operating conditions. A comparative study between simulation and experimental results is conducted to assess the efficacy and accuracy of the proposed controller drive system and validate the developed integrated model. Both simulation and experimental results demonstrate the effectiveness of the proposed dual-axis trackers to follow the sunbeams throughout the year. [ABSTRACT FROM AUTHOR]

Concentrator PhotoVoltaics (CPV) may generate considerable heat as a byproduct in addition to power. Using that heat as concentrated solar power (CSP) to thermally desalinate salt water would allow for value addition in arid regions by supplementing produced electricity with fresh water. This paper discusses the primary trade-off between the net electricity amount and the net distilled water amount, both of which are desirable products in a hybrid concentrated photovoltaic and thermal system (CPV-T). While higher temperatures promote freshwater generation, they also cause a quick fall in cell efficiency, reducing the quantity of power generated and causing cell deterioration. The CPV-T receiver, which is partially covered with cells and then supplementary heated in a cell-free portion, is modeled and established. Furthermore, simple-stage and multistage desalination unit models are presented, linked to the receiver, and examined to cope with the reduced temperature limits of this receiver. The results demonstrate a CPV-T receiver's ability to generate both electrical power and freshwater, while also demonstrating that the cell temperature constraint can become quite important beyond 50% of the receiver surface coverage. These first order results establish the system's validity and potential and will aid the system designer in the initial system design. [ABSTRACT FROM AUTHOR]

Parabolic trough collectors are widely used to generate thermal and/or electrical energy from direct solar irradiation. These collectors use parabolic mirrors to precisely focus sunlight onto so-called absorber tubes. The optimal design and geometric alignment of all necessary components is essential in order to achieve a high degree of efficiency and a high energy yield. However, this optical fine-tuning process can be quite challenging and is in many cases avoided by using absorber tubes with larger diameters, which in turn cause greater thermal losses and a higher material effort. This paper describes a simple, yet reliable and quantifiable way to measure the optical performance of a parabolic trough collector using a commercial multi-junction solar cell (CPV). The presented measurement system allows for convenient adjustment of the parabolic mirror and the effective optimization of the overall collector design. The theoretical background is discussed and the test setup is described in detail. Measurement results are presented, ranging from the determination of the actual optical concentration ratio, the optimal centering and height adjustment of the absorber tube to the measurement of the contribution of the individual mirror segments, revealing that the investigated industrial parabolic trough collector can be improved in terms of optical accuracy. Finally, an optical surveillance of the mirror using a line laser was performed to validate the results. • New way to measure the optical performance of a parabolic trough collector. • Multi-junction solar cell (CPV) are used as a light sensor. • Theoretical background and various measurement setups and results are presented. • Optical concentration ratio of 128 x was measured with a parabolic trough collector. [ABSTRACT FROM AUTHOR]

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 °C) compared to that with the commercial nitrate salt mixtures. This paper reviews recent progress in research and development of the next generation CSP and TES technology. Emphasis is given on the advanced TES technology based on molten chloride salt mixtures such as MgCl2/NaCl/KCl which has similar thermo-physical properties as the commercial nitrate salt mixtures, higher thermal stability (> 800 °C), and lower costs (

Sustainable Development Goals (SDGs) of the United Nations (UN) underline the importance of harnessing renewable energy sources for enhancing access to clean energy without compromising the global emission goals. This study explores the impact of climate change on global solar energy potential in the near- (2015–2040) and far-future (2041–2100). Simulated energy variables from five General Circulation Models (GCMs) participating in the Coupled Model Intercomparison Project phase 6 (CMIP6) for three different Shared Socioeconomic Pathways (SSPs) – SSP1-2.6, SSP2-4.5 and SSP5-8.5 are used for the assessment. It is found that there is a 6–10% decrease (with respect to 1981–2014 climatology) in Photovoltaic (PV) potential in the Indian subcontinent and China in the boreal autumn that is possibly linked to increased post-monsoon cloud cover. A consistent decrease is noticed in North America and Australia, whereas in Europe, the projected decrease in PV potential, even for the worst emission scenario (SSP5-8.5), is restricted only to the boreal winter season, thereby posing no real threat to future PV power planning. However, a mild decrease in PV potential in Africa during austral summer and a consistent decrease in Concentrated Solar Power (CSP) all over the world contradict earlier studies. Change in PV potential during the far-future using CMIP6 model projections. The typical diagram shows the percentage change during the period of 2041–2100 (far-future) with respect to the period of 1981–2014 (historical) under worst climate change scenario (SSP5-8.5) during boreal winter (Dec-Jan-Feb). A significant decrease (>10%) over the whole of North America and western Europe and up to 4–10% decrease in Asia, Africa and Australia. Entire analysis is helpful for local scale energy planning. [Display omitted] [ABSTRACT FROM AUTHOR]

Solar energy offers an affordable solution to cooking and other household problems of day-to-day life. However, its intermittent nature limits its applications and hence storage is required for the same. In this paper, the numerical simulation of a thermal energy storage system (TES) has been presented. In this analysis, a model is built to estimate the charging and discharging time of packed bed thermal energy storage (PBTES) system. The model consists of a cylindrical container filled with a concrete pebble. The heat transfer fluid used is air passed through the packed-bed. Several parameters are modified to study the impact of pebble diameter and void fraction over the charging and discharging time of PBTES system. The system is built to store energy for18 h with a temperature range between 300 and 120°C, so that it delivers 2.5 kW after charging. [ABSTRACT FROM AUTHOR]

• Looking for improving concentrate solar power plant energy storage capacity. • Physico-chemical characterization of a mixture of NaNO3-KNO3-NaCl-KCl molten salt. • Experimental measurements of melting point, temperature degradation, and heat capacity. • Relationship between chloride addition into nitrates salts and changes in properties. • The addition of low amounts of chlorides enhances energy density and thermal stability. Th e thermo-physical properties of a working fluid (WF) strongly affect the energy efficiency and economic performance of a concentrating solar power plant (CSP) with thermal energy storage (TES). Consequently, the use of molten chloride salts instead of the current solar salt (NaNO3-KNO3 64–36% mol) has been extensively proposed. Nevertheless, the strong corrosiveness of magnesium chloride, needed to reduce the chloride-based WF melting point to CSP operational level, has inhibited this shift's industrial-economic applicability. In this work, sodium and potassium nitrate and chloride transition paths are proposed by gradually incorporating NaCl and KCl into the current solar salt. This path is expected to allow CSP working temperature to increase gradually, obtaining benefits at a controlled industrial risk. Five levels of chlorides –from 0 to 50% mol Cl- – were studied on a solar salt, evaluating their main thermo-physical properties. The results show that the addition of chlorides in all evaluated ranges increased the solar salt's thermal stability, ranging from 592 °C to 642 °C (50% mol Cl-). The melting temperature remained within the ranges of interest for CSP applications, varying between 211 °C (14% mol Cl-) and 243 °C (50% mol Cl-). The viscosity and heat capacity showed a significant dependence on the chloride content and temperature. Finally, the wider operative temperature range and the enhanced energy density through chloride addition are positive outcomes that would improve CSP efficiency and reduce the volume of and capital expenditures for the TES system. Conversely , the viscosity and phase miscibility can be of concern at operative low-temperature levels. [ABSTRACT FROM AUTHOR]

Next generation concentrated solar power (CSP) plants promise a higher operating temperature and better efficiency. However, new issues related to the corrosion against protection of the construction alloys need to be solved. In this work, two different duplex stainless steels grades, namely 2205 (DS2205) and 2507 (DS2507), were evaluated for their compatibility with the eutectic molten salt mixture of Li2CO3-K2CO3-Na2CO3 at 500 °C in air for thermal energy storage applications. Corrosion tests combined with complementary microscopy, microanalysis and mechanical techniques were employed to study the oxide scales formed on the surface of the duplex steels. The corrosion tests evidenced that the attack morphology in both duplex steels was a uniform oxidative process without localized corrosion. DS2507 presented a better corrosion resistance than DS2205, due to the formation of thinner, compact and continuous oxide layers with higher compositional content in Cr, Ni and Mo than DS2205. The oxide scales of DS2507 showed more remarkable mechanical integrity and adhesion to the metallic substrate.