Solar Thermal Plants Research Articles

Effect of in situ synthesized and additives on the thermal performance of mullite thermal storage ceramics

High-performance thermal storage ceramics can enable utilization of solar thermal power generation plants. In this work, in situ synthesis was used to prepare mullite thermal storage ceramics. Calcined bauxite, talc, and kaolin were used as raw materials. The effects of additives (e.g., SiC, Si3N4, TiC, and ZrB2) on the density, mechanical durability, phase components, microstructure, and thermal performance of the mullite ceramics were studied. The results showed that the thermal expansion coefficient, thermal conductivity, and heat storage density of the mullite ceramics were affected by their phase components. SiC and Si3N4 did not decompose during the in situ syntheses, but TiC and ZrB2 decomposed. With the addition of 10 wt% SiC, the thermal conductivity improved to 2.72 W (m K)−1 (298 K). The heat storage density of this material was 688 kJ kg−1 (273–1073 K). Consequently, the in situ synthesized mullite thermal storage ceramic with added SiC could be a promising candidate material for a compound latent-sensible heat storage system.

Life cycle assessment (LCA) of a concentrating solar power (CSP) plant in tower configuration with different storage capacity in molten salts

Although studies on the levelized cost of energy (LCoE) of concentrating solar power (CSP) plants were published in recent years, these studies were not related to the environmental impact generated. To fill this literature gap, this study compares the environmental impacts generated by four tower solar thermal plants with different storage capacities, 3, 6, 9, and 17.5 equivalent hours in nominal conditions were considered, being the plant of 17.5 h, a plant in operation. Results show that the environmental impacts generated throughout its useful life decrease when storage capacity increases. But when the storage capacity goes from 9 h to 17.5 h, the impacts generated are practically the same. Of the four plants analyzed, the most environmentally efficient plant is the one with a storage capacity of 9 h.

Influence of sunshape and optical error on spillover of concentrated flux in solar thermal power tower plant

It is important to calculate and evaluate the spillover of flux reflected by heliostats on the heat shields for the construction, operation and optimization of solar thermal power tower plant. By establishing a concentrated flux distribution model of power tower plant based on the real sunshape and taking haze, optical error, shadowing and blocking effect into consideration, the authors calculated the flux density distribution on the receiver and heat shields under various conditions. The results show that the radiation energy on heat shields can reach about 15–45 MW under typical conditions, accounting for 1%–8% of the total received energy of the system. The flux density on heat shields is between 30 and 70 kW/m2, which is equivalent to the flux level of trough solar concentrator system. The calculations and fitting results show that the energy proportion on heat shields is positively correlated with circumsolar ratio(CSR) and optical error. The effect of CSR on the energy proportion of heat shields is linearly increasing, while the effect of optical error is nonlinear. This indicates that the spillover flux on heat shields can compensate for the loss of the receiver caused by haze, optical errors of heliostats.

Feasibility analysis of solar photovoltaics for the feeding of cooling pump of a natural gas power plant

In the present work, the energy and exergy analysis of combined cycle power plant were carried out using the actual operating parameters to investigate the exergetic efficiency, exergy destruction/losses for the components. The energy and exergy efficiencies of the combined cycle power plant were found to be 48.4% and 47.2%, respectively. The results of the energy analysis show that the condenser is associated with the highest energy losses occurred in the system but according to the exergy analysis, the combustion chamber has the highest exergy destruction rate among the system components. The attention is focused on a solar photovoltaic (PV) system satisfying partly the energy demands of an cooling water pumps. An integrated solar Photovoltaic Combined Cycle System is proposed as a means of integrating a photo voltaic solar thermal plant with the modern combined cycle power plants. The 1 MW direct solar PV system which supply the electricity of the cooling water pump that uses electricity most in the system is proposed as a way to increase the efficiency of this plant. The electricity consumption of this pump is thus reduced by about 0.25% with the usage of the electricity directly supplied by the solar PV generator. Electricity from the solar PV system is partly used to operate a cooling pump to mitigate the electricity demands. The 29.2% of the electricity demanded by the cooling pump is provided by the photovoltaic production.

Techno-economic assessment of application of particle-based concentrated solar thermal systems in Australian industry

Australia has significant areas with high quality solar resources, but the requirement for large scale solar thermal plants to be financially competitive in the electricity market appears to have hindered uptake. Industrial use of heat provides an alternative route to market where the technology is not impacted by poor efficiencies in converting heat to electricity and an appropriate scale can be applied to the demands of a specific site. A re-examination of prior industrial energy use studies in Australia was used in combination with solar data and published data on industrial sites to identify three specific industrial sites for case studies. These sites were selected to cover applications in three industries with varying scale and temperature requirements. The primary solar technology selected utilizes a particle receiver on a tower with associated storage and heat exchanger for hot water/steam production or heating a gas reactor. The wide range of temperatures possible with this technology appears to be desirable for development of a general-purpose industrial heat system. Comparison with parabolic trough systems that are commercially available was conducted for cases where the required temperatures were appropriate. In all assessments, the optimized solar plant designs approach cost competitiveness with the estimated cost of natural gas purchase for the relevant locations and industrial scales. In smaller and lower temperature applications, parabolic trough systems are likely to be appropriate conventional choices, but the particle system exhibited a high degree of flexibility across multiple sites and applications, which is encouraging to future commercial application.

Optimal Participation of Heterogeneous, RES-Based Virtual Power Plants in Energy Markets

In this work, the optimal participation of heterogeneous, Renewable Energy Source (RES)-based Virtual Power Plant (VPP) in Day-Ahead Market (DAM) and Intra-Day Market (IDM) is studied. For this purpose, a detailed model of the RES-based VPP and of the market operation is needed. The VPP includes both dispatchable and non-dispatchable RESs and flexible demand assets. This paper presents an improved, linear solar thermal plant model to consider its non-linear efficiency curve. A novel demand model with two flexibility levels that are associated with the different market sessions is also proposed. The market operation allows for updates of energy offers and this is used by the VPP to submit DAM auctions and to participate subsequently in IDM to correct for deviations. Finally, the optimal participation of the VPP in energy markets is assessed under different weather conditions.

Hybridization of a parabolic trough-based thermal plant for industrial heat and power generation

In this study, the hybridization of a solar thermal (ST) plant based on parabolic trough solar collectors for a dairy plant in Mexico is technically and economically evaluated. The study is based on dynamic TRNSYS simulations, as well as a thermal steady-state model developed in the engineering equation solver (EES). The performance of the hybrid plant (LCPVT) is investigated and compared to that of an ST plant with the same installation area in low, medium, and high solar resource locations. For the aforementioned locations, cost savings and environmental impacts are assessed considering different fuels. The results demonstrate that the LCPVT plant reached a peak thermal output of 70.4 kW and a peak electrical power output of 16.2 kW over the summer. Although the ST plant generates up to 11% more heat than the LCPVT system, the LCPVT system can generate an additional 22,211 kWh of electricity every year. The initial investment of the hybrid plant was 16.5% higher than that of the ST plant. Accordingly, the hybrid plant can achieve payback periods less than 5.0 years when the hybrid receptor fractional cost is less than 0.3 and the displaced fuel is diesel or liquified petroleum gas.

Feasibility and Zoning of Establishing Solar Power Stations to Produce Sustainable Energy From the Environment in Northwestern Iran

Attention to climatic and environmental potentials for exploitation and meeting human needs has been considered for many years. But the optimal and correct use of this potential requires accurate knowledge and subsequent careful planning. Today, the use of climate and productive energy from the environment is more of a concern for researchers. This investigation aims to appraise the feasibility of establishing solar thermal power plants (solar panels) by examining eight climatic and atmospheric parameters in the environment based on fuzzy logic in northwestern Iran. In this study, the weather datum of 22 Urban Climate Synoptic stations were prepared to evaluate the climatic conditions for the feasibility of establishing a thermal solar power plant for sustainable development using fuzzy logic in the north-west of Iran for each synoptic station during a statistical period of 31 years (1990–2020). This research used eight climatic parameters: average max temperature, average temperature, average min relative moisture, mean relative moisture, total monthly precipitation, and a daily average of Sunny hours, altitude, and wind speed in this systemic model. MATLAB software was used to combine the input data from fuzzy logic and ANFIS Adaptive Neural Network. The climate zoning map for establishing a thermal solar power plant with the scores obtained for each of the parameters and finally the final map was drawn using the ArcGIS. The results show that the fuzzy logic method showed a great variety of options for the establishment of solar thermal power plants using climatic parameters. In total, after obtaining the final rating for each of the 22 stations, Bonab station, with a coefficient score of (0.544–0.589), and Miyaneh station with a score (0.543–0.577), located in East Azarbaijan Province, in the north-west of Iran are appropriate for the establishment of a solar power plant. The Northwest of Iran is suitable to meet the needs of various energies, including domestic electricity, due to the potential stemming from its favorable climatic conditions climate; therefore, it is necessary to take steady steps to develop this important industry. Also, the accuracy of MATLAB and ArcGIS software with a high level of 0.96% confidence in finding a suitable place for the establishment of solar power stations was confirmed. According to the final results obtained from the integration and fuzzification of 8 climatic parameters and zoning of suitable and unsuitable areas for prioritization, Ardabil station with a score of 0.345% in the priority of inconvenient location, and Bonab station with a score of 0.589% in the priority of where the best places were for the establishment of solar power stations. Considering the findings of the present study, the central region and distant locales in mountainous areas were suitable places for the establishment of solar panels. The valuable results of the present study can be given more attention by the sectors that use a lot of sustainable energy. The results of this research in the field of sustainable energy production from the environment are more in the spotlight.

Optical and thermal integration analysis of supercritical CO2 Brayton cycles with a particle-based solar thermal plant based on annual performance

Central receiver concentrating solar power (CSP) plants based on particles as heat transfer fluid in solar circuits and supercritical CO2 (S–CO2) Brayton cycles can fulfil the requirements for next generation CSP to improve solar-to-electric efficiency and reduce energy storage costs. However, effective incorporation of these two concepts requires an in-depth understanding of their characteristics and an appropriate approach to match them. This paper addresses the importance of the design features and annualized performances of the optical subsystem (heliostat-receiver) and the thermal-to-electricity subsystem (solar receiver-energy storage-power block) on the global optimization of any integrated CSP plant. The analysis lies in a complete model of a particle-based CSP plant, which includes detailed modeling for the solar field, a cavity solar receiver with an up bubbling fluidized bed (UBFB) tubular panel, particles storage tanks and a recompression S–CO2 Brayton cycle. The design incident irradiance on the receiver aperture (IR) and the particles temperature at the receiver outlet (Tp) are identified as key parameters determining the solar-to-electric integration procedure and affecting the overall plant design and annual performance. Regarding subsystems located upstream and downstream of the receiver, the effects of heliostat and power block characteristics on the optimal IR and Tp are also evaluated, represented by the heliostat beam quality and main compressor inlet temperature. Results show that IR around 1,200–1,500 W/m2 provides the maximum system design efficiency and annual efficiency. Improvements on heliostat beam quality and power block efficiency help to increase the optimal IR and overall system efficiency. In the optimal range of IR, increasing Tp leads to higher system design efficiency, but lower system annual efficiency and annual electricity output. The optimal combination of IR and Tp contributes to a minimum heliostat design area, representing the integration trade-off between the system optical and thermal characteristics.

Technical assessment of 10 MW solar thermal plant using nano-fluids and molten salts: a case study of Saudi Arabia

Technical assessment of 10 MW solar thermal plant using nano-fluids and molten salts: a case study of Saudi Arabia

Numerical Optimization and Energetic Advantages of an Innovative Solar Power System Based on Scheffler Receiver Coupled with Volumetric Expanders

In the current context of increasing public awareness of the externalities of fossil fuel-based energy consumption, improvement in new technologies for energy-saving systems has become a crucial target to reduce both global warming and air pollution. Being motivated by such a critical matter, this study presents an innovative solar thermal plant based on volumetric expanders as work-producing devices coupled with Scheffler solar receivers as a thermal source. Nowadays, Scheffler receivers are well performing owing to high efficiency of the focal receiver which reduce heat losses. Simultaneously, screw expanders are volumetric machines which are able to convert thermal to mechanical power with acceptable efficiency also by expanding vapor-liquid blends at low operating pressures. The numerical model presented in this study evaluates the energetic benefits of the proposed solar power system for various operating situations. Parametric optimization of this solar power plant is then performed in a broad range of operating conditions: the optimum evaporation temperatures, together with the corresponding maximum global efficiencies, were so defined under various solar radiation intensities. The numerical results attained in this research prove that solar electricity generation systems based on screw expanders coupled with the Scheffler receivers are a promising technology.

Compatibility of alumina forming alloys with LiNO3-containing molten salts for solar thermal plants

The next generation of solar thermal plants will increase the operating temperatures; thus, new structural materials with better performance than the currently used should be required. Alumina forming alloys (AFA) are an alternative since they have been reported as highly resistant to corrosive environments, including molten salts. In this study, two AFA (OC4 and HR224) were exposed to a ternary lithium-containing nitrate molten salt mixture (57 wt.% KNO3–30 wt.% LiNO3–13 wt.% NaNO3) at 550 °C for 1000 h to determine their corrosion compatibility through gravimetric and complementary techniques. The mass gain results revealed a good performance of both alloys, allowing them to be recommended for use in solar thermal plants. However, HR224 showed lower weight change attributed to a thin layer of non-porous and continuous corrosion products composed of nickel oxide and aluminum-nickel spinel, which act as protective compounds. On the contrary, OC4 showed a thick multi-layer structure of highly porous, rough, and irregular corrosion products composed mainly of iron oxides and spinels.

Simulation of the impact of the atmospheric weather state on the efficiency of functioning of solar thermal and power plants

THE PURPOSE. Determine the impact of the meteorological state of the atmosphere on the efficiency of the functioning of solar thermal and power plants. Modeling the molecular absorption of solar radiation by the atmosphere. Modeling the optical characteristics of the gaseous components of the atmosphere, atmospheric aerosol and clouds.METHODS. A method for numerical modeling of incoming solar radiation fluxes their functioning to determine the efficiency of solar thermal and power plants. The solar fluxes are calculated by stacking layers in a multi-stream approximation, taking into account the multi-tiered cloud cover and the probability of overlapping the sky with clouds. The absorption of radiation by the gaseous phase of the atmosphere is taken into account by the method of equivalent mass in an inhomogeneous atmosphere. The optical characteristics of the dispersed phase of the atmosphere are calculated using the Mie theory.RESULTS. An electronic database has been created on the optical characteristics of the gaseous components of the atmosphere, the optical characteristics of atmospheric aerosol and clouds. The effect of anthropogenic impact on the flux of solar radiation falling on the underlying surface is taken into account. The developed modeling takes into account the effect of humidity on the optical characteristics of atmospheric aerosol and its multicomponent composition, depending on the location of the power plant.CONCLUSION. The information necessary for numerical modeling of meteorological effects on the functioning of solar thermal and power plants is generalized. When calculating solar radiation fluxes, direct illumination of the light-receiving surface by solar radiation, scattered radiation by atmospheric aerosol and clouds are taken into account.

Fault Detection and Isolation Based on Deep Learning for a Fresnel Collector Field

With the advancement of new technologies, power systems are increasingly equipped with more sensors and actuators, heightening the risk of failure. This fact, together with the vulnerability of solar plants -not only to internal faults but also to the action of the sun, rain, wind, and animals, among others- gives rise to the need for detecting and identifying faults to deal with them. Methods that detect and diagnose faults play a crucial role in solar plants, allowing the systems to cope with them as soon as they occur and before they lead to large-scale problems. This work proposes using neural networks to detect and distinguish mirror and flow rate faults in a Fresnel plant. In addition, a defocusing stage is added to access hard-to-isolate faults, increasing the accuracy of 89.61% to 97.43%. These results contribute to the problem of isolability in thermal solar plants. The simulations for obtaining the neural networks and the results were conducted on a model of the Fresnel plant located at the Engineering School of Seville, Spain (ETSI).

Optical evaluation of 3D printed CPC by coupling photogrammetry and ray tracing analysis

Manufacturing methods of CPC collectors, regardless the application, have not undergone significant modifications in recent years; the main manufacturing methods are hydraulic press stamping and some other machining methods, which generate errors in geometric curvature and damage to the high-reflectivity film coating, reducing the overall optical efficiency of the CPC. In this work, we propose a method for the fabrication of cylindrical CPCs (widely used in water-heating, disinfection, and wastewater treatment applications), which comprises the use of a 3D printed mold complemented with a structural styrofoam molding. The proposed method presents the advantage of improving the quality of the CPC profile with less damage on the surface of the high reflectivity coating and with a reduction in the quantity of deformations because of its machining processes. To evaluate the effectiveness of the presented method, an experimental-simulation test was carried out based on a photogrammetric technique combined with a Ray tracing Monte Carlo method. The test procedure compared the CPC manufactured with the proposed method (called 3DMCPC) versus one manufactured by a conventional machining technique (referred as CM-CPC). The results obtained show a geometrical mean error value of 1.2 mm for the 3DM-CPC compared to 3.19 mm for the CM-CPC. Optical assessment by ray tracing showed a relative efficiency of 95% for the 3DM-CPC versus 82% of the CM-CPC, both of them compared to the theoretical ideal geometry of a 2D-1 Sun CPC. The benefit could be estimated in a simulation to be 9.4% in the annual performance of a 1000 L CPC thermal energy solar plant.

Proposal of a Solar Thermal Power Plant at Low Temperature Using Solar Thermal Collectors

To this day, only two types of solar power plants have been proposed and built: high temperature thermal solar one and photovoltaic one. It is here proposed a new type of solar thermal plant using glass-top flat surface solar collectors, so working at low temperature (i.e., below 100°C). This power plant is aimed at warm countries, i.e., the ones mainly located between -40° and 40° latitude, having available space along their coast. This land based plant, to install on the seashore, is technologically similar to the one used for OTEC (Ocean Thermal Energy Conversion). This plant, apart from supplying electricity with a much better thermodynamic efficiency than OTEC plants, has the main advantage of providing desalinated water for drinking and irrigation. This plant is designed to generate electricity (and desalinated water) night and day and all year round, by means of hot water storage, with just a variation of the power delivered depending on the season.

Evaluation methodologies of damage related issues for heat exchangers in the thermal storage energy system

Thermal oil is used as a heat transfer fluid in many thermal solar power systems, while molten salts are used to store thermal energy. The oil absorbs solar energy and transports it to a water-steam cycle via heat exchangers, where it is transformed into electric energy via a turbo-generator or stored in a thermal energy storage device for subsequent transmission to the water-steam cycle. The complexity of these thermal solar plants is rather significant, as they mix conventional engineering used in power stations (water-steam cycle) or petrochemical (oil pipeline) with modern solar (parabolic trough collector) and heat storage (molten salts) technology. This paper focuses on modelling in heat exchanger tubes in molten salt energy storage systems, and it offers a comprehensive model of the process. By developing such a model, the groundwork for future study into heat exchangers model failure analysis is established.

Results of Long-Term Operation of Solar Thermal Plants in Russia

Results of Long-Term Operation of Solar Thermal Plants in Russia

Alkali-activated and hybrid materials: Alternative to Portland cement as a storage media for solar thermal energy

This study is part of the research line that sees it necessary to develop materials that are alternatives for Portland cement (PC), using industrial by-products such as blast furnace slag and fly ash. This line arises because of the serious environmental consequences suffered by our planet throughout many decades, which have led the cement industry to reduce the amount of CO2 emitted in the production of PC, since it is a highly polluting process. The chemical and physical properties of the materials were studied. In this way, the study of the thermal properties is interesting to test the feasibility of the mortars to use them as solid media to storage thermal energy, since most of the research focus on the thermal properties of concrete is oriented toward fire resistance. Storing solar thermal energy improves the operation of solar power thermal plants. It is being studied that the use of concrete (composed of PC) contributes efficiently to concentrated solar power (CSP) technology. To avoid the use of PC due to environmental concerns, alkaline-activated mortars are manufactured with blast furnace slag using alkaline solutions such as sodium hydroxide (NaOH) and commercial sodium silicate (SiO2/Na2O=0.8), as well as hybrid mortars using 80% fly ash or blast furnace slag and 20% PC. After experimental analysis and a simulation to measure the conduction within the mortars through a commercial Computational Fluid Dynamic software (CFD, ANSYS Fluent), it can be concluded that the mechanical and thermal properties of most of the alternative mortars manufactured in this study are better than the ones obtained in the PC. Most notably, the slag alkaline-activated mortar increases those properties significantly.

Dust impact on concentrated solar power: A review

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.