Solar Thermal Power Plants Research Articles

Thermodynamics performance optimization of a hybrid solar gas turbine power plant in Colombia

A thermodynamic model is presented for evaluation of a solar hybrid gas-turbine power plant. The model uses variable ambient temperature and estimates direct solar radiation at different day times. The plant is evaluated in Barranquilla, Colombia, with a solar concentration system and a combustion chamber that burns natural gas. The hybrid system enables to maintain almost constant the power output throughout day. The model allows optimizing the different plant parameters and evaluating maximum performance point. This work presents pressure ratio ranges where the maximum values of overall efficiency, power output, thermal engine efficiency and fuel conversion rate are found. The study is based on the environmental conditions of Barranquilla, Colombia. The results obtained shows that optimum pressure ratio range for power output and overall efficiency is between 6.4 and 8.3, when direct solar radiation its maximum at noon. This thermodynamic analysis is necessary to design new generations of solar thermal power plants.

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.

Analyses and assessments of a direct steam generation PTC-based solar power plant with two approaches of exergy and emergy

The present study focuses on the energy, exergy, exergoeconomic, exergoenvironmental, emergoeconomic and emergoenvironmental analyses, besides enhanced exergy analysis, for a solar thermal power plant with direct steam generation. Results show that the overall emergoeconomic factor of the DSG solar power plant is 85.34%, and its total emergoenvironmental factor is 85.56%. Enhanced exergy analysis reveals that the avoidable percentage of the emergoenvironmental rate allocated to exergy destruction of the solar field, low-pressure turbine, and high-pressure turbine is 10%, 42%, and 34%, respectively. These values are equal to 11%, 45%, and 38%, respectively.

Design of automation control thermal system integrated with parabolic trough collector based solar plant

This paper presents enhanced design for automation control of processes involved in a solar system which utilizes programmable logic controller to auto-mate tracking system for obtaining maximum solar radiation. Three areas are involved in this proposed multi area system where 1st and 2nd area considers solar power plant with thermal system based parabolic trough collector with fixed so-lar isolation and random isolation of solar energy whereas third area comprises of solar thermal system with dish Stirling realistic unit. Energy efficiency can be increased by using solar concentrator along with Stirling engine. Optimization of gain of the controller is by utilizing crow search novel algorithm. Crow search algorithm is an optimization technique, which provides better performance at complex time varying noisy condition and time in-varying noisy condition. The proposed controller is evaluated by obtaining the optimized parameters of the system whose comparison is done by operating proposed controller with and without renewable sources of energy thereby revealing better performance for both conditions. Testing is done in different areas with fixed solar isolation and random stisolation of solar energy involved in solar thermal power plant based on parabolic trough collector. Gain and parameters of the controller of the solar power plant are optimized by utilizing automation for operation of solar concentrator with parabolic trough collector. Data acquisition and monitoring is done by human machine interface in order to report safe operation. The simulation results of integrated solar thermal system involving dish Stirling with parabolic trough collector, shows that dynamic response of the proposed controller operating with renewable solar energy is better than that of non-renewable energy source.

Analysis of Reflectors in Concentrated Solar Power Plants

Throughout comparing to limited in time fossil fuels such as coal, petroleum, and natural gas, solar energy is observed to be extremely appealing as a renewable energy source in the twenty-first century due to its unending supply and nonpolluting nature. Concentrating Solar Power is a type of renewable energy that uses the sun's energy to generate electricity and heat. CSP plants can be used for desalination and solar fuel production. Work more productively make up the majority of the applications. Solar Thermal Power Plants (STPPs) are large-scale renewable energy infrastructures that use heat generated by contracted solar beams. The main goal of this paper is to provide a comprehensive literature review on central solar receivers, as well as to investigate terms like solar thermal energy and concentrated solar plants.

Simulation and optimization of a Concentrating Solar Power Plant with Thermal Energy Storage in Sebha city by using system advisor model (SAM)

Concentrated solar power (CSP) is viewed as one of the most promising alternatives in the field of solar energy utilization; parabolic trough collector (PTC) solar power plants are the most commercially established among the power plants operating with CSP technology. In this paper, a parabolic trough solar thermal power plant with thermal energy storage was evaluated in terms of design and thermal performance, using the SAM program of NREL (System Advisor Model). This program is used to evaluate the active and economic performance of a plant such as monthly energy production, annual energy production, and level cost of energy (LCOE).one representative site in south Libya, Sebha city, which offers an annual average direct normal radiation (DNI) of more than 6.0 kWh/m2/day, has been chosen for the analysis and optimization of the proposed 100 MWe PTC Solar power plant. The optimization is carried out with solar multiple (SM) and full load hours of thermal energy storage TES as the parameters, to minimize the Levelized cost of electricity and maximize the annual energy yield. Based on the findings of the study, the proposed 100 MW PTC solar power plant with thermal energy storage can contribute to the sustainable energy future of Libya with reduced dependency on fossil fuels. This design and performance analysis of the plant encourages further development and innovation of solar thermal power plants in all regions of Libya.

Facilitating developments of solar thermal power and nuclear power generations for carbon neutral: A study based on evolutionary game theoretic method

Solar thermal power and nuclear power generations are two most promising clean energy power approaches, which are effective for reducing carbon emissions. In order to promote the coordinated development of solar thermal power and nuclear power in China under the background of carbon neutral, the current paper develops a partnership comprised by the energy investment company (EIC), solar thermal power plant (STPP) and nuclear power plant (NPP). By utilizing the evolutionary game theory method and current policies of China, the evolutionary process simulations of the three participants under different conditions are conducted, which demonstrate that steady states could be achieved under different partnerships. Impact investigation results of typical influential factors indicate that longer annual operation time of power plant, larger subsidy and higher electricity price sold to the power grid are favorable to promote the partnership smoothly. Suitable investment ratio of the STPP and NPP should be considered as a larger investment ratio of the STPP and NPP has incentive influence on EICs and STPPs but inhibiting impact on NPPs. The results of the current study have certain reference value for the policy and strategy formulations for facilitating the developments of solar thermal power and nuclear power generations.

Outdoor exposure approach in a harsh environment toward the study of corrosion aspects of primary solar reflectors

Corrosion is among the most observed phenomena that threaten the profitability of concentrated solar thermal power plants and constitutes a real risk factor for metallic materials. Solar reflectors are between the impacted materials by corrosion because they are composed of metallic reflective layers that can easily be oxidized in air. To avoid this, paint systems could be applied in the back of the reflective layers as a barrier, that prevents the diffusion of corrosive elements to the metal layer. Metallic structures that support those reflectors can also be easily corroded and are replaced with composite structures that are not affected by corrosion. However, the durability of the paint protection systems and the composite structures must be inspected to ensure their effectiveness in protecting solar mirrors against corrosion, since they are found in sites that are often characterized by arid conditions, which affects corrosion protection solutions. This work is devoted to study the corrosion aspects and the parameters that affect the resistance of the protection systems of glass solar mirrors and solar mirrors fixed on composite structures by the use of a real outdoor exposure facility on a coastal site. The results show the important role of the paint coating layers number on the protection against corrosion. Also, the role of edge protection and shape were highlighted. Solar mirrors fixed on composite structures show a weak resistance because of the degradation of the fixing glue which creates areas of retention of salts and moisture that cause an aggressive corrosion of the metal layers.

Soiling forecasting of solar plants: A combined heuristic approach and autoregressive model

The soiling process of photovoltaic devices and heliostats is considered an important phenomenon to take into account in the design and operation of commercial Photovoltaic (PV) and Concentrating Solar-Thermal Power (CSP) plants, since in both cases the efficiency of these surfaces for solar use presents unexpected fluctuations. Many magnitudes and parameters influence in a complex manner the soiling process of an outdoor surface. In this work, it is assumed that a random disturbing source acts continuously on the surface causing its degree of soiling. Based on this assumption, a heuristic approach based on an analogous electrical model is proposed to simplify the complexity of the phenomenon. This model justifies the time series analysis of electrical losses due to soiling of a PV module by fitting an autoregressive-moving-average (ARMA) model to recorded time series at CIEMAT. This ARMA(1, 1) model allows predicting the average efficiency of this PV module in a period of 38 days with a Normalized Mean Bias Deviation (NMBD) of 1.35% and a mean relative error of 3.12%. This result can be improved by applying ordinary least squares to the model to minimize the NMBD obtaining a value of 0.17% and a mean relative error of 0.07%.

Load frequency control of a m ulti‐source multi‐area thermal system including biogas–solar thermal along with pumped hydro energy storage system using MBA ‐optimized 3DOF‐TIDN controller

In this article, load frequency control has been studied in an unequal three-area system under a deregulated environment. The area 1 comprises thermal and biodiesel units, area 2 has thermal and solar thermal power plant (STPP), and area 3 has thermal with biogas, wind turbine system (WTS) along with pumped hydro energy storage (PHES) units. A new secondary controller called three degree-of-freedom tilt-integral-derivative with filter (3DOF-TIDN) controller has been proposed, and its performance is compared with integral, tilt-integral-derivative with filter, and two degree-of-freedom-TIDN controllers. The investigation reveals 3DOF-TIDN controller provides better dynamic performance in terms of settling time, peak deviation, and magnitude of oscillations in both generating and motoring mode of PHES. The stability analysis has been performed for the proposed system using different secondary controller. The controller parameters are optimized using novel optimization technique called Mine Blasting Algorithm. In this study, real-time OPAL-RT digital simulator has been used to effectually execute the considered power system under various scenarios, and the obtained results are compared with MATLAB/Simulink results. Further, a comparative study of dynamic responses of the system has been carried out considering different mechanical energy storage devices like PHES, flywheel energy storage device, and compressed air energy storage, and the analysis shows that PHES gives superior performances than others. Robustness analysis of proposed controller gains is also conducted, considering different uncertainties.

Characteristic analysis of thermal energy storage system using synthetic oil as a heat transfer fluid: techno-economic modeling and LAB scale demonstration

ABSTRACT A dual-media thermal energy storage system consisting of ceramic pebbles as a storage material and high-temperature heat transfer fluid (HTF) is analyzed for 1 MWe National Solar Thermal Power Plant. A numerical model has been formulated to study the thermocline behavior of tanks at different operating conditions. Based on the numerical model, a Lab-scale test facility is developed to validate the numerical model. The main objective of this study is to analyze the formation of the thermocline thickness for various operating parameters such as mass flow rate, void fraction, pebbles diameter, and thermal diffusivity of HTF and storage materials, along with a parametric optimization. The numerical result shows that, as the mass flow rate increases, the discharge time can cause the varying temperature at the outlet that is unenviable. The percentage movement of the thermocline layer was observed to be 70.37% with an increase in the mass flow rate of 18.75%. Similarly, it was found that the percentage increase in the volumetric heat transfer coefficient increased by 9.56%, with an increase in mass flow of 18.75%. The lower pebble diameter gives the superlative results for thermocline thickness, but it causes a great deal of pressure drop, which causes exergy loss. However, the percentage improvement in volumetric heat transfer coefficient was found to be 80%, with a 33.33% reduction in pebble diameter. It is concluded that a smaller size pebble diameter reduces the thermocline thickness, but it needs to be optimized to counter the problem of pressure drop. Parametric optimization has been done by considering various parameters such as D/L ratio, void fraction, mass flow rate, pebble diameter, thermal diffusivity of solid and HTF. Signal to noise ratio (SNR) has been taken into account to get the optimized value of the parameters. An empirical correlation has been developed to calculate thermocline thickness which is valid for a D/L 1. Further, a Techno-economic cost analysis of the TES (DMT) system for a 1 MWe CSP plant is done to study the economic facet of the system.

Life cycle assessment of the solar thermal power plant integrated with air-cooled supercritical CO2 Brayton cycle

Supercritical carbon dioxide (sCO2) Brayton cycle offers the potential of higher thermal efficiency and lower costs of electricity generation for concentrated solar power (CSP) applications. Besides its economic potential, the environmental sustainability needs to be examined. For this purpose, detailed life cycle assessment (LCA) of the solar driven sCO2 power generation system is carried out. The pollutant emissions and primary energy consumptions of the CSP plant with two typical sCO2 Brayton cycles including simple recuperative cycle and recompression cycle are analyzed and compared. Global warming potential (GWP), acidification potential (AP), respiratory effects potential (REP) are obtained. The life cycle greenhouse gas (GHG) emissions of parabolic trough (PT) plant with sCO2 cycle and steam Rankine cycle are compared. Finally, uncertainty analysis is carried out to study the effect of environmental factors (solar irradiation and ambient temperature) and parameter design of the PT system (turbine inlet temperature, life span and thermal energy storage (TES) capacity) on the LCA results and ensure the reliable comparison. It is found that for the PT plant with sCO2 power cycle, the auxiliary electricity consumption from the grid, TES and solar field manufacture account for 92% of the total environmental impact and 98% of the total energy consumption, while sCO2 power cycle only accounts for a small part. The environmental performance of the recompression layout is better than that of the simple recuperative layout. For the CSP application, the GHG emissions of the sCO2 cycle are 21%∼41% less than that of the steam Rankine cycle.

Redox cycle of calcium manganite for high temperature solar thermochemical storage systems

Thermochemical energy storage via metal oxide redox cycling is a potential cost-effective approach to store solar energy both chemically and thermally at high temperatures, enabling efficient solar thermal power production round-the-clock and on-demand. Perovskite manganites are a low-cost redox material that undergoes reversible reaction without side reactions up to 1000 °C and offers high storage capacities, which makes them promising energy storage materials in next-generation solar thermal power plants. In this study, the thermal properties of a typical perovskite manganite, CaMnO3, has been studied. CaMnO3 shows 893.2 kJ/kg energy storage capacity from 200 °C to 1000 °C, and 0.133 non-stoichiometry in N2. The material exhibits excellent stability with 150 redox cycles between 500 °C and 1000 °C. The thermodynamic efficiencies of two solar-driven combined cycle power systems with CaMnO3 based thermochemical energy storage system are also investigated. The steady-state mass and energy conservation equations are solved for all system components to calculate the thermodynamic properties and mass flow rates at all state points in the system. Preliminary results for a system with 120 MW nominal solar power input at a solar concentration ratio of 1000 are presented, designed for constant round-the-clock operation with 9 h of on-sun and 15 h of off-sun operation. The CaMnO3 particles store and release energy via the sensible heat and reaction heat, yield a net power block efficiency of approximately 60% and an overall energy conversion efficiency of up to 48.7%. Required storage tank sizes for the solids are estimated to be up to 2–3 smaller than those of state-of-the-art molten salt systems.

Digital design and 3D printing of innovative SiC architectures for high temperature volumetric solar receivers

In order to demonstrate that digital material engineering methodology is able to address the design and optimisation of architectured ceramic materials, solar volumetric receivers employed in Solar Thermal Power Plants (STPP) have been studied. A digital design approach for obtaining new receivers, at the macroscopic structural scale, is proposed. This approach couples virtual structure generation, ray tracing and thermal simulations at the scale of the base structural components (microscopic scale). Then, a recently developed process for manufacturing silicon carbide (SiC) parts by binder jetting is used to elaborate three optimised structures which are tested on-sun at high temperature in a solar concentrator reproducing the STPP operation conditions. The results obtained with these structures, having original shapes, are promising: the average experimental outlet air temperature reaches a maximum of 1133 K, energy yields can reach 0.49 despite high experimental heat losses, and all the SiC structures, made with a new material based on 3D printing, withstood the high temperatures reached, up to 1500 K. Comparison between digital and experimental results shows that the approach presented in this paper paves the way to a new digital material engineering approach.

Thermoeconomic analysis and optimization of a hybrid solar-thermal power plant using a genetic algorithm

The hybridization of solar-thermal and combustion technologies for power generation is an emerging concept that brings the possibility to mitigate carbon dioxide emissions while maintaining a firm supply. This work presents a thermoeconomic model for a distributed-scale (<100 kWe) hybrid solar-thermal power plant, developed to study its performance under different operating conditions in a region with a yearly direct normal irradiance of around 1600 kWh/m2 yr. The proposed system consists of a combined Rankine-Brayton cycle with a solar receiver and natural gas combustor working in series as heat sources to the topping cycle. A genetic algorithm was employed to perform a multi-objective optimization of such system, and the result was a set of Pareto-optimal designs, which were compared to a pre-defined reference design. Resulting optimized solutions yield levelized electricity costs as low as 0.179 USD/kWh, as opposed to the 0.237 USD/kWh associated with the reference design. Average 1st and 2nd law efficiencies of up to 27.97 % and 33.53 % were achieved, respectively, which represent increases of up to 7.71 % and 7.31 %. Finally, average solar shares of up to 65 % are possible for optimized designs versus the 58.4 % yielded by the base design.

High-temperature molten-salt thermal energy storage and advanced-Ultra-supercritical power cycles

The work explores the opportunities offered by higher temperature heat transfer/heat storage fluids, and higher temperature power cycles, in higher concentration solar thermal power plants. The goal is to design a renewable energy plant able to supply fully dispatchable electricity to the grid at a cost, inclusive of dispatchability, better than using wind and solar photovoltaic with external energy storage by batteries. By increasing the receiver/hot tank temperature from 565-575 to 730°C, the efficiency of the thermal cycle increases by 30% vs. current plants working with conventional steam Rankine cycles (thermal efficiency η∼52% vs. present η∼40%). The proposed design permits 24/7 electricity production at the rated power of the turbine practically all year-round. In the hypothesis of no cost penalty for the use of a novel heat transfer and heat storage fluid, and of the higher pressure and temperature of the power cycle, that is a reasonable long term goal of an industrialized and mass-produced solution, the Levelized Cost of electricity may be improved from the 7.29-7.97 ¢/kWh of a current technology 100 MW design of annual average capacity factor 93-95.5%, to the 6.18-6.68 ¢/kWh of a 126 MW design of annual average capacity factor 94.9-97.7% of the novel technology. The work demonstrates the benefits of internal thermal energy storage by molten salt in supplying energy to renewable energy only grid, and the opportunity to further evolve the basic design now employed towards higher temperatures.

Fractal textured surfaces for high temperature corrosion mitigation in molten salts

Mitigation of corrosion of structural materials in contact with molten salts is imperative in high temperature applications such as nuclear and solar thermal power plants. This paper introduces, for the first time, a novel approach to corrosion mitigation through fractal surface texturing and details a systematic corrosion study of a variety of structural materials. Multiscale fractal textured surfaces on SS316, In800H, In718, In625, and Ha230 were fabricated via chemical etching, whose parameters were optimized to obtain surface fractal dimensions above 1.90. The influence of grown oxides was examined by annealing the optimized etched surfaces with high fractal dimensions at a high temperature. The corrosion mitigation characteristics of plain, etched and etched-annealed surfaces were systematically studied in molten 60% NaNO 3 + 40% KNO 3 at 600 °C. The fractal textured surfaces are shown to reduce corrosion rate by 30% for ferrous alloys and by over 80% and up to 87% for high nickel content alloys. Elemental composition analysis reveals that the corrosion oxides are correspondingly diminished on fractal textured surfaces compared to plain surfaces. The study is significant in that any existing material may be made more corrosion resistant through this simple surface modification and treatment.

Simulation of Performance for 140 MW Thermal Power Station at Alkuraymat Using Solar Parabolic Trough Concentrators with Thermal Storage

Solar power is a primary source of renewable energy and one of the most effective strategies for reducing emissions by reducing the consumption of fossil fuels. Alkuraymat power station produces about 140 MWe divided into 120 MWe produced from a combined cycle and 20 MWe from a solar field with Therminol VP-1 as a heat transfer fluid. For environmental considerations, the present work aims to evaluate the design parameters and thermal performance of the Alkuraymat power plant operated with parabolic trough solar field with thermal energy storage simulated by using System Advisor Model (SAM) software. Alkuraymat location is suitable for using a concentrated solar thermal power plant due to receiving an annual direct normal irradiance of about 2,522.15 kWh/m²/year. The results indicated that the concentrated solar thermal power plant consists of 514 solar collector loops, with each loop comprising of 4 parabolic trough collectors. As well, the proposed plant can produce annual electricity of efficiency of the power plant the 893.82 GWh andost Cevelized LRelated to the optimization of the system configuration, the is 19.4%. thermal energy storage and the full load hours of ,of energy equal to 4.79 Cents/kWhparabolic Additionally, the suggested design of thereduces from 16 to 12.5 hrs. motivates further trough concentrated power plant and the study of its performance . solar t thermal power plants in the Egyp of improvement innovation and

Thermo-economic analysis of an integrated solar thermal cycle (ISTC) using thermal storage

Solar integrated power plants are a combination of the concentrated solar power plant and thermal power plant. The thermal energy storage systems, when integrated with concentrated solar power based solar cycle, can address issues related to energy availability during non-solar hours.This study presents an integration of concentrated solar power technology based solar energy capture and storage with the 210 MW conventional Rankine cycle based thermal power plant in Dadri (India). The mathematical model of Integrated Solar Thermal Cycle (ISTC) has been developed which includes the modelling of the Linear Fresenel reflector solar system, steam power cycle, and two tank thermal storage method. Here, water and molten salt are chosen as heat transfer fiuid in the collector loops as a medium to transfer and store the solar thermal energy. A MATLAB code is used as a simulation tool to analyse the ISTC performance for different parametric variations such as temperature difference in the solar receiver, solar output, the mass flow rate of heat transfer fluids, fuel-saving ratio by varying direct normal irradiation. Based on the simulation, it is discussed that the integration of solar field with power cycle offers enhanced efficiency along with the reduction of emission of carbon dioxide. Integration of solar field with Thermal Energy Storage (TES) using two tank method with molten salt further improves the efficiency of the power cycle up to 40%. Based on results of simulations, it is discussed that ISTC using two tank method with molten salt results into the saving of large amount of fuel by replacement of one and two feed water heater(s) which ensures the recovery of the capital expenditure within approximately 10 years. Further, this improvisation contributes to environment and society by curtailing the emission of carbon dioxide drastically.

Electric vehicle integrated MPC scheme for concurrent control of voltage and frequency in power system network

The growing integration of renewable sources with grid poses challenges in the field of voltage and frequency control. This study features combined automatic voltage regulator and load frequency control model of a three-area power system network with each area containing thermal and diesel power plants along with the introduction of solar thermal power plant, wind, and geothermal power plants. The Harris Hawks Optimization (HHO) based centralized Model Predictive Controller (MPC) has been discussed and implemented for the effective and simultaneous control of voltage and frequency in all three areas of the wind integrated power plant. To further deal with increased oscillations in frequency profile of the system caused due to renewable integration, the electric vehicle (EV) participation has been considered in each area to provide an auxiliary control against frequency deviations. Effectiveness of the proposed EV based MPC-HHO algorithm has been successfully verified after adding different nonlinearities, parameter uncertainties, disturbances, and time-delays in the wind integrated power system.