Concentrated Solar Power Tower Research Articles

A Nonintrusive Optical Approach to Characterize Heliostats in Utility-Scale Power Tower Plants: Camera Position Sensitivity Analysis

Abstract Optics plays a major role in the effectiveness of concentrating solar power (CSP) technologies. The nonintrusive optical (NIO) approach developed by the National Renewable Energy Laboratory uses uncrewed aircraft system (UAS)-based imaging to survey heliostats in a commercial-scale power tower CSP plant and characterize their optical errors. The image processing algorithm uses photogrammetry to calculate the camera position for each image frame, and the accuracy of the estimated optical errors is highly sensitive to the calculated camera position accuracy. In this study, we simulate a series of case studies in python to examine the impact of different parameters of the sensitivity of the camera calculation, including the number of facet corners used as control points for the photogrammetric calculation, precision error in the detected pixel locations of the facet corners in the image, and precision error of the canting and mounting positions of the facets of the heliostat. The case studies consider heliostat geometry based on three commercial designs to serve as representative examples of different possible sizes of heliostats that the NIO method could be applied to. The results show that increasing the number of control points can improve accuracy for heliostats with many facets, pixel precision has a significantly larger impact on camera calculation accuracy than facet canting and mounting errors, and the camera distance and focal length must be chosen to ensure adequate pixel accuracy on the heliostat surface depending on the size of heliostat. Based on the results, recommendations for the allowable values of each parameter are provided to achieve the required NIO optical error estimation accuracy depending on the size of heliostat.

Life cycle assessment of typical tower solar thermal power station in China

In light of the growing environmental awareness and the sustainable development consideration in energy policies, the environmental impacts of concentrating solar power (CSP) have attracted significant attention. Considering that the site selection of CSP stations and databases used for evaluation has an important impact on the environment, the objective of this study is to assess the impact of concentrating solar power tower (CSP-T) station with thermal storage devices in the geographical context of China from environmental perspective by the life cycle assessment (LCA) method. To achieve this goal and ensure the reliability of the research results, a 2 × 50 MW capacity, double tank solar nitrate energy storage, and 12-h energy storage time CSP-T station in Dunhuang, Gansu, was selected. In addition, its model was constructed using the eFootprint online platform, assessing the environmental impacts of the CSP-T station according to the cradle-to-grave system boundary. Moreover, the impact assessment was performed in terms of key metrics, such as energy payback time (EPT), carbon cost of electricity (CCOE), carbon flow analysis, and environmental benefits of energy conservation and emission reduction. The results showed that the production stage is the most significant source of environmental impact in the life cycle of the CSP-T station, with the condensing system and heat storage system contributing 50.17 % and 47.64 % respectively. It can be found that the EPT of the CSP-T station is estimated at 4.88 years, accounting for 16.25 % of the operation cycle of the thermal power station, and varies depending on the station's location. It can be reduced to 3.19 years in places such as North Africa with abundant light intensity. Furthermore, the CCOE of the CSP-T station is 0.04 kg CO2/kWh. Overall, CSP-T station has over 95 % environmental benefits for energy conservation and emission reduction for most indices compared to thermal power station. Although the Chemical Oxygen Demand (COD) index is slightly lower, it still reaches 82.67 %. To promote the ecological development of the CSP-T station in China, this study usually includes a brief comment or relevant improvement recommendations after each comparative analysis.

Exploring the 3E, hydrogen, and ammonia creation potentials of a concentrated solar power (CSP) plant using an air-cooled condenser.

The need to move to more sustainable energy generation has become a major concern among world leaders due to the debilitating effect of greenhouse gases on the environment. Africa has the greatest potential to transition to more sustainable energy sources due to its enormous renewable energy resource potential, particularly solar. This study thus assessed the potential of generating power using a concentrated solar tower power plant (CSTP) at three different locations in Algeria. The study evaluated the system's technical, environmental, economic, and employment creation potential and analyzed the hydrogen and ammonia creation potential using the electricity produced by the CSTP system. Naama, Laghouat, and Ghardaia recorded annual energies of 507 GWh, 502 GWh, and 547 GWh, with capacity factors of 57.6%, 57.6%, and 62%, respectively. A real levelized cost of energy ranging between 7.72 and 8.47 cent$/kWh was obtained. A total of 8530 tons of nitrogen and 1844 tons of hydrogen will be theoretically needed to produce ammonia (fertilizer) for 500,000 hectares of arable land for agricultural activities. In addition, using hydrogen from the CSTP system to produce the estimated ammonia will save 6124.56 tons of CO2 emissions from polluting the environment annually. The creation of thousands of direct and indirect jobs will significantly benefit Algerians. The study concluded with some policy recommendations based on its findings.

Reticulated porous structures of La0.8Al0.2NiO3-δ perovskite for enhanced green hydrogen production by thermochemical water splitting

The preparation and optimisation of La0.8Al0.2NiO3-δ (LANi82) perovskite shaped as reticulated porous ceramic (RPC) structures for H2 production by thermochemical water splitting is presented for the first time. The perovskite was first synthesised in powder form following a modified Pechini method. The redox properties of the LANi82 were first tested under N2/air flow in a thermogravimetric analyser. After that, the sponge replica method for preparing RPCs was optimised in terms of slurry composition and final thermal treatment to obtain a LANi82-RPC structure with porosity and strength appropriate to enhance heat and mass transfer in further solar reactors. The optimised LANi82-RPC material showed an outstanding hydrogen production of 8.3 cm3 STP/gmaterial·cycle at isothermal conditions (800 °C). This production was increased up to 11.5 cm3 STP/gmaterial·cycle if the thermal reduction was performed at 1000 °C. Additionally, a stable activity with almost constant H2 production in consecutive cycles was obtained for the optimised LANi82-RPC in both cases. The structure of the reticulated porous materials, with open macroporosity and wide interconnected channels, enhances heat and mass transfer, leading to higher hydrogen productions of the LANi82-RPC as compared to the materials as powder form in the same experimental set-up. These facts reinforce the favourable prospects of LANi82-RPC for large-scale hydrogen production, improving the coupling to current solar thermal concentration technologies developed, such as concentrated solar power tower.

Experimental isochoric apparatus for bubble points determination: Application to CO2 binary mixtures as advanced working fluids

Carbon dioxide binary mixtures are increasingly considered as working fluids in transcritical power cycles, due to the capability to perform liquid-phase compression even at high environmental temperatures. However, a robust thermodynamic model is essential for optimal and reliable design conditions. It is widely recognised that fine-tuning the equation of state with experimental vapour-liquid equilibrium data of the mixture significantly enhances its reliability.In this work, a new apparatus dedicated to vapour-liquid equilibrium measurements of mixtures is presented. The proposed method consists of a constant-volume system, where bubble points are identified from the divergence of slope of the isochoric lines between the two-phase and liquid regions, in the temperature-pressure plane. The temperature and pressure limits of the apparatus are 503 K and 25 MPa.Bubble points of CO2 binary mixtures with hexafluorobenzene (C6F6) and n-pentane (C5H12) have been measured and compared with previous literature data for validation purposes. Then, the CO2 mixture with octafluorocyclobutane (c-C4F8) is experimentally studied, addressing a literature gap in bubble point data. The data are used to calibrate the thermodynamic model, leading to affordable design conditions of the power cycle compared to the non-optimised thermodynamics scenario, in a concentrated solar power tower plant.

Equivalent Breakeven Installed Cost

Technoeconomic analysis (TEA) is commonly used to determine economic viability of power-generating technologies, including concentrating solar power (CSP) and thermal (CST) production plants. Levelized cost of electricity (LCOE) and analogous measures provide an estimate of long-term costs for operating power plants over their designed lifetimes by accounting for revenues and costs in a time-discounted manner. While these measures are effective when assessing a technology’s total lifecycle costs and productivity under various designs, TEA of candidate incremental technology improvements from the lens of LCOE can be limited when required investment and LCOE impacts are small. In this work, we propose a novel metric for TEA of a plant component technology that recasts relative changes in levelized system costs into component-specific capital cost budgets. This measure, which we refer to as the equivalent breakeven installed cost, is the maximum budget for the technology component that leads to improved levelized costs. We illustrate the usefulness of this metric using the example of candidate heliostat improvements for a CSP tower plant. Here, the results suggest that a reduction in mirror washing costs yield a total plant O&M cost of $37/kWe-yr, which is a breakeven proposition if the average reflectance is reduced from 0.90 to 0.85 as a result of the cost savings.

Evaluation of the Levelized Cost of Energy With New Costs for Concentrating Solar Power Tower Plants in Northern Chile and Impact of Green Taxes

The world is undergoing an energy transformation, from a system based on fossil fuels to a system based on renewable energy, in order to reach the Paris Agreement target. Chile is no exception, and through the Asociación de Concentración Solar de Potencia (ACSP) has generated a new cost structure for tower-based Concentrated Solar Power (CSP) technology in the framework of the Long-Term Energy Plan, which updates the costs reported in previous studies. The changes experienced in this cost structure make it necessary to study the impact of this cost structure on the levelized cost of energy (LCOE). This work develops simulations of CSP tower plants analyzing their generation and the LCOE based on the new cost structure mentioned, for the north of Chile between the Arica and Parinacota region and the Coquimbo region. The most relevant results show a significant reduction in the LCOE, compared to studies from 2020, reaching a minimum LCOE value of 52,6 USD/MWh. On the other hand, the impact on the net social benefit of including the green tax to the merit order of each of the generating plants that make up the electric park until 2021 is studied, which yields a negative impact under current legislation.

Assessment of Climate Change Impacts and Water Restrictions on Solar Tower Plants

Climate projections under the high-emission representative concentration pathway “RCP-8.5” scenario are used to show the effects of global warming on the energy production of two similar concentrated solar tower power plants in Spain and Chile from 2025 to 2060. Results show a reduction of the annual energy production of almost 1.8% for Chile and an increase of almost 6% in the Spanish plant, but an increase of 10% water consumption due to both the increase in dry- and wet-bulb temperatures and changes in the direct normal irradiation caused by climate change. When the effect of water restrictions is included in the model caused by the foreseen reduction in water availability in Spain, the increase of the annual energy production is only 2%. Finally, the levelized cost of energy (LCOE) calculated during the whole power plant lifetime (35 years) with respect to the LCOE obtained at the beginning of the project is increased by 1.1% in the Chilean plant, whereas in the Spanish plant, it can be reduced more than 2.5% if there are no water restrictions, while a reduction of 0.4% is expected in a scenario with water restrictions. Results show that careful consideration of climate projections should be considered to properly estimate the economic viability of solar tower plants.

A solar based system for integrated production of power, heat, hot water and cooling

Renewable energy sources have gained great importance in meeting the increasing energy demands in today's world and reducing the environmental impacts, such as greenhouse gas emissions, particularly caused by traditional fossil fuel sources. In this study, a unique integrated energy system driven by solar power is proposed. In order to achieve poly-generation, a concentrated solar power tower system is integrated with a Rankine cycle, an organic Rankine cycle, an absorption cooling system, greenhouses, and a water heating system. The proposed system is designed to generate power, hot water, cooling, and heating for residential buildings and greenhouses. The system analysis is performed in terms of thermodynamics using energy and exergy principles, and then both energy and exergy efficiencies are used to assess the system's overall performance. Through parametric studies, the effects of changing various operating parameters and conditions on performance are examined. The energy and the exergy efficiencies for the overall system are found to be 22.64% and 21.8%, respectively.

Co-optimisation of the heliostat field and receiver for concentrated solar power plants

In a concentrated solar power (CSP) tower plant, it is essential to understand the performance of the subsystem formed by the heliostat field and the receiver, operated with an optimal aiming strategy that guarantees the safety and lifetime of the receiver while maximising performance. State-of-the-art studies optimise the heliostat field, aiming strategy and the receiver independently. However, the field and the receiver are interdependent and co-optimisation of the field-receiver subsystem is necessary to obtain the optimal configuration. Fast and accurate annual performance assessments of the subsystem are needed to calculate the annual energy output and the Levelised Cost of Energy (LCOE) of the full CSP system. In this study, a co-optimisation method is proposed based on coupled instantaneous optical, thermal and mechanical models integrated into a system-level model for annual simulation of full system and economics. The resulting system-model is then used for design optimisation based on a genetic algorithm. Several techniques are implemented to make this complex and computationally expensive problem tractable. The proposed method is used to optimise the design of two systems composed of a surround field and a liquid sodium-cooled cylindrical external receiver for first the annual performance and then the LCOE. The good behaviour of the method is confirmed by a sensitivity study. The LCOE-based optimisation leads to a less efficient system than the efficiency-based optimisation but a higher capacity factor. The methods presented are applicable to other CSP plant configurations, including state-of-art molten salt power tower plants.

Studies on thermal-hydraulic characteristics of supercritical CO2 flows with non-uniform heat flux in a tubular solar receiver

Supercritical CO2 (SCO2) Brayton cycle is one of the best approaches for concentrated solar power tower, with tubular solar receiver being one of the most attractive options to directly heat SCO2. The superposition of drastically variable properties of SCO2 and uneven distribution of solar irradiance flux poses a great challenge to the design and optimisation of solar receiver, thus the studies on thermal-hydraulic characteristics of SCO2 in solar receiver become crucial to deal with the challenge. In this study, the thermal-hydraulic characteristics of SCO2 in a vertical receiver tube under axially and circumferentially non-uniform heat-flux conditions are numerically studied with average heat flux ranging from 150 kW m−2 to 210 kW m−2 and mass flux ranging from 400 kg m−2 s−1 to 700 kg m−2 s−1, and the influences of buoyancy on the flow and heat transfer characteristics are evaluated. The non-uniform distribution of the axial heat flux leads to 1.2%–20.5% increase in the overall heat transfer coefficient, while more severe local heat transfer deterioration is observed. The buoyancy effect changes the flow structure, resulting in suppression of turbulence intensity and formation of thick momentum and thermal boundary layers, which is closely related to the severe heat transfer deterioration of SCO2 under non-uniform heat-flux conditions. Bo* could well predict the buoyancy effect in a vertical tube under non-uniform heat-flux conditions. Compared with upward flow, downward flow could effectively alleviate heat transfer deterioration and reduce wall temperature gradient especially for axially non-uniform heat-flux condition. The present work could provide guideline for the design and optimisation of tubular solar receiver and solar power system with SCO2 as heat transfer fluid.

Thermo-economic analysis of integrated gasification combined cycle co-generation system hybridized with concentrated solar power tower

Integrated gasification combined cycle (IGCC) systems have the ability to utilize low-quality coal with reduced emissions and multiple co-generation capabilities (i.e., power, chemicals and fuels). Integration of solar power tower (SPT) with IGCC co-generation can provide an opportunity to use lignite coal with lowest greenhouse gas emissions. In this work, thermodynamic and economic evaluations of solar-IGCC 100% power (power only) hybrids and co-generation (electricity, methane and ammonia) hybrids have been performed using Aspen Plus® V.11 and system advisor model (SAM). Two designs (i.e., large and medium solar) of the SPT have been simulated and optimized for Pakistani weather conditions. Thermodynamic evaluations include, net electrical efficiency, effective energy efficiency and solar-to-electric efficiency of hybrid plants. Economic estimations include, levelized cost of energy, total plant costs, operating and maintenance costs for hybrid plants. Specific CO2 emissions after hybridization are also evaluated. Total annualized revenue at flexible market scenarios and production scenarios have also been evaluated. The net boosted electrical efficiency of 100% power (Hyb-1A) is 38.77%, and the improved efficiency after flue gas integration with SPT for the pre-heating of boiler feed water is 39.10%. The minimum specific CO2 emission achieved from one hybrid combination (Hyb-4A) is 42.1 kg/MWhnet.

Demonstratingsolarpilot’s Python Application Programmable Interface Through Heliostat Optimal Aimpoint Strategy Use Case

Abstractsolarpilot is a software package that generates solar field layouts and characterizes the optical performance of concentrating solar power (CSP) tower systems. solarpilot was developed by the National Renewable Energy Laboratory (NREL) as a stand-alone desktop application but has also been incorporated into NREL’s System Advisor Model (SAM) in a simplified format. Prior means for user interaction with solarpilot have included the application’s graphical interface, the SAM routines with limited configurability, and through a built-in scripting language called “LK.” This article presents a new, full-featured, python-based application programmable interface (API) for solarpilot, which we hereafter refer to as CoPylot. CoPylot enables python users to perform detailed CSP tower analysis utilizing either the Hermite expansion technique (analytical) or the SolTrace ray-tracing engine. CoPylot’s enables CSP researchers to perform analysis that was previously not possible through solarpilot’s existing interfaces. This article discusses the capabilities of CoPylot and presents a use case wherein we populate a model that obtains optimal solar field aiming strategies.

Combined direct oxy‐combustion and concentrated solar supercritical carbon dioxide power system—Thermo, exergoeconomic, and quadruple optimization analyses

For the global future energy systems, concentrated solar power (CSP) and direct CO2 capture systems are of the most important key technologies, however, each of these systems has shortcomings. This study addresses the solar intermittency and power control complexity of the CSP systems and the substantial energy penalty of the direct oxy-combustion (DOC) supercritical carbon dioxide (sCO2) power systems by integrating both systems. Herein, innovative power cycle configurations that integrate the CSP tower system with DOC sCO2 power cycle are introduced. The configurations include two basic cycles for comparison and validation purposes and three integrated cycles. The basic configurations are: an intercooled sCO2 power cycle driven by DOC system (S1), and a stand-alone basic CSP tower system (S2). The integrated configurations are: CSP/DOC system where the CSP works as a preheater (S3); CSP/DOC system where the CSP works as a reheater (S4); and CSP/DOC system where each system heats part of the working fluid to drive its high-pressure turbine (S5). The hybrid configurations reduce the fuel and the parasitic power consumptions of the basic DOC systems (S1) and reduce the capital cost associated with the conventional CSP systems (S2) by eliminating the need for thermal storage. Over practical ranges of operational parameters, comprehensive thermoeconomic, exergoeconomic, and optimization analyses for the proposed configurations are performed. Compared to the conventional CSP system, the LCOE of the hybrid system is lower by 50%. Among the hybrid configurations, the energetic and exergetic performances of S4 are the best with the lowest LCOE. According to the optimization analysis, S4 has a thermal efficiency of 55.29% at LCOEs of 7.705¢/kWh. S3, S5, S2, and S1 have thermal efficiencies of 52.90%, 48.72%, 45.56%, and 40.54% at LCOE of 7.970, 8.138, 7.864, and 6.351¢/kWh, respectively.

Systematic decision-making framework for evaluation of process alternatives for sustainable ammonia (NH3) production

Ammonia (NH3) is the second highest produced chemical commodity worldwide, which commonly used in manufacturing of fertilisers, refrigerants, dyes and other chemicals. Haber Bosch process is the most established process to produce NH3 from hydrogen (H2) and nitrogen (N2). However, this process releases large amount of greenhouse gases (GHG) annually as this process consumes H2 which produces from steam methane reforming process that utilises methane (CH4) from natural gas. In addition, such process also consumes large quantity of energy to support the production of NH3. In order to enhance the sustainability of NH3 production, renewable energy (RE) such as solar can be used to replace the traditional energy system that consumes fossil fuels. Besides, production of H2 and N2 via water electrolysis and air separation technology which powered by RE can further enhance the sustainability of NH3 production. Such process is known as green NH3 production. One of the challenges of utilising RE is to have a stable supply of power. Therefore, concentrated solar power (CSP) is a good option to overcome this challenge, because it has capability of providing stable power supply. Based on literature review and market survey, a superstructure which consists of all possible and available technologies for production of green NH3 using CSP as an energy supply is presented. Next, the advantages and disadvantages of each alternative are evaluated and summarised in a comparison table. Ranking matrices are developed to evaluate and rank the alternatives quantitatively to determine the optimum pathway for green NH3 production. Based on the analysis, a conceptual integrated green NH3 production which involves a CSP tower plant with a two-tank molten salt thermal energy storage (TES) system is determined as the optimum pathway. Such process fulfils the electricity demand of a pressure swing adsorption (PSA) air separator, polymer electrolyte membrane (PEM) and NH3 synthesis plant. The results of this work are useful for feasibility studies on the commercialisation of green NH3 production.

Sensivity analysis of a multi-generation system based on a gas/hydrogen-fueled gas turbine for producing hydrogen, electricity and freshwater

To investigate a multi-generation system for hydrogen, freshwater, and electricity production, the system consists of a concentrated solar power tower cycle, a steam-methane reforming cycle, a Hydrogen-gas turbine, and a reverse osmosis desalination cycle. To enhance the system performance and minimize negative environmental impacts, each cycle of a multigeneration system is considered separately and is then subjected to 4E analyses using EES software. Appropriate values of each item were selected, and the system was subjected to the main calculations. The multi-generation system generates 12.9 MW of power, 96.18 kg/s of freshwater, and 5.2 kg/s of hydrogen. According to the 4E analysis results, the energy and exergy efficiency of the entire system are 50.18%, 51.91%, respectively. The exergy destruction in the entire system is 324351 kJ/s, and the highest exergy destruction in the entire system has occurred in the combustion chamber of the methane reforming cycle and in the reformer, respectively.

Impact of asymmetrical heating on the uncertainty propagation of flow parameters on wall heat transfers in solar receivers

Uncertainties may skew the understanding of experiments or numerical simulations results. The impact of the flow parameters uncertainties of measurement on wall heat flux is investigated in a non-isothermal turbulent channel flow. A heat transfer correlation dedicated to gas-pressurized solar receivers of concentrated solar tower power is used. Both symmetric and asymmetric heating conditions are tested. A sensitivity study is performed. The effects of the wall and bulk temperatures are analyzed in a large bulk-to-wall temperature ratio range. The Guide to the expression of Uncertainty in Measurement (GUM) is applied and provides an analytical expression of the uncertainty propagation. Assuming the quasi-normality and quasi-linearity of the studied function, this method provides approximate results. The results obtained following the methodology described in the GUM are then compared to the direct computation of the wall heat flux with altered temperatures. The study shows a dependence of the high heat flux estimation to some temperature variations, highlighting the necessity of accurate measurements. This is particularly salient in the end region of the solar receiver, i.e. when the bulk and the wall temperature are close. The GUM produces very satisfying estimations in the symmetric conditions and quite satisfying estimations in the asymmetric conditions. This study shows that the accuracy of measurement devices should be adapted according to their location in the solar receiver. • A heat transfer correlation is used to determine wall heat flux sensitivity. • Uncertainty propagation in symmetric and asymmetric heating are compared. • The general uncertainty management procedure provides reliable results. • The bulk temperature and the cold wall temperature require accurate measurements. • The uncertainty propagation is very dependent on the location in the solar receiver.

Dynamic corrosion testing of metals in solar salt for concentrated solar power

Potassium nitrate and sodium nitrate in mixing proportion of KNO3–NaNO3 40-60 wt% (also called solar salt) has been successfully used for over a decade as heat storage medium for concentrated solar power parabolic-trough collector plants at temperatures up to 400 °C. At temperatures of 560 °C, reached in state-of-the-art solar tower systems, corrosion of metallic components in contact with solar salt can become an issue and has caused leaks and plant shut-downs in recently built tower projects. While the corrosion rates of several materials have been determined for different temperatures in static molten salt immersion experiments, there is a lack of corrosion data for dynamic in-service conditions. In this work, a dynamic corrosion test has been conducted on 19 different material types including protective coatings, mimicking flow-rate, temperature gradient and draining of in-service operation of a receiver in a concentrated solar power tower. The measured corrosion rates are presented and compared to static corrosion tests reported in literature.

Techno-economic analysis of a solar tower CSP Plant with thermal energy storage in southern Honduras

For many years, solar thermal energy has been relegated to second place to photovoltaic solar energy in terms of electricity generation. At the end of the 1980s, an alternative to solar photovoltaic plants emerged, Concentrated Solar Power (CSP) technology. This type of technology presents a commercial option for grid-connected solar plants for the utility market due to its high performance and efficiency in energy conversion, as well as its clean generation of electricity without greenhouse gas emissions. Currently, in Honduras the use of solar thermal energy is reduced to heating processes and product sanitation in the industrial sector, wasting the country’s great solar thermal potential. This document focuses on the evaluation of a Solar Tower CSP plant with 10 hours thermal storage in the southern area of Honduras, analyzing the departments of Valle and Choluteca. The methodology used for this research is a quantitative approach based on collecting meteorological data of the solar resource in the area and costs associated with the plant, this to test a hypothesis. This evaluation was carried out from a technical, economic and environmental point of view. The research managed to determine values of Levelized Cost of Electricity (LCOE), Net Present Value (NPV), Internal Rate of Return (IRR) and project recovery period for the different scenarios presented in the two departments analyzed. Putting all the results together, it was found that the department of Valle has the lowest LCOE compared to the department of Choluteca. Likewise, the values of NPV, IRR and recovery period determine that the project is more profitable in the department of Valle.

Effect of Two Different Heat Transfer Fluids on the Performance of Solar Tower CSP by Comparing Recompression Supercritical CO2 and Rankine Power Cycles, China

China intends to develop its renewable energy sector in order to cut down on its pollution levels. Concentrated solar power (CSP) technologies are expected to play a key role in this agenda. This study evaluated the technical and economic performance of a 100 MW solar tower CSP in Tibet, China, under different heat transfer fluids (HTF), i.e., Salt (60% NaNO3 40% KNO3) or HTF A, and Salt (46.5% LiF 11.5% NaF 42% KF) or HTF B under two different power cycles, namely supercritical CO2 and Rankine. Results from the study suggest that the Rankine power cycle with HTF A and B recorded capacity factors (CF) of 39% and 40.3%, respectively. The sCO2 power cycle also recorded CFs of 41% and 39.4% for HTF A and HTF B, respectively. A total of 359 GWh of energy was generated by the sCO2 system with HTF B, whereas the sCO2 system with HTF A generated a total of 345 GWh in the first year. The Rankine system with HTF A generated a total of 341 GWh, while the system with B as its HTF produced a total of 353 GWh of electricity in year one. Electricity to grid mainly occurred between 10:00 a.m. to 8:00 p.m. throughout the year. According to the results, the highest levelized cost of energy (LCOE) (real) of 0.1668 USD/kWh was recorded under the Rankine cycle with HTF A. The lowest LCOE (real) of 0.1586 USD/kWh was obtained under the sCO2 cycle with HTF B. In general, all scenarios were economically viable at the study area; however, the sCO2 proved to be more economically feasible according to the simulated results.