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The Solar Energy Technologies Office (SETO) Lab Call FY2019-21 funding program enables U.S. national laboratories to reduce costs and improve the lifetime and reliability of concentrating solar-thermal power (CSP) technologies, materials, components, and systems. These projects advance foundational research efforts toward cost targets of $0.05 per kilowatt-hour for CSP baseload plants with at least 12 hours of energy storage and $0.10 per kilowatt-hour for CSP peaker plants with six hours of energy storage or less. The funding program launched with larger FY2019 projects that last up to three years and the follow-on projects in FY2020 and FY2021 are smaller, one-year projects.

Researchers at the national labs will also conduct market analysis and explore photovoltaic and grid integration research as a part of this effort. Learn more about the SETO Lab Call FY19-21 projects.

APPROACH

These projects aim to improve the materials and components used within high-temperature CSP systems, enabling them to cost-effectively operate at temperatures greater than 700° Celsius. These projects will focus on improving CSP technologies, materials, and components in the following areas: the solar field, receiver, heat transfer medium, thermal storage, and operations and maintenance processes. One project will focus on using solar-thermal energy to produce fuel for industrial processes while three core support projects will repair and maintain current test facilities and provide software upgrades to standard CSP system performance technology.

OBJECTIVES­­­­­­

In order to reach SETO’s 2030 goals, CSP plants need to reach high operating temperatures to increase plant efficiency and lower overall system costs. Through analysis and testing, research teams will determine best practices for the engineering, construction, operations, and maintenance of CSP plants. Researchers will also develop and advance technologies that accurately assess and correct issues in the solar field, helping to improve system performance and reduce costs.

AWARDEES

FY2019 Projects

Project Name: Low-Cost, High-Temperature Ceramic Heat Exchangers  
Lab: Argonne National Laboratory           
Location: Lemont, IL      
Principal Investigator: Dileep Singh
Project Summary: As CSP systems move to power cycles with temperatures greater than 700° Celsius, high-temperature metallic alloys become prone to degradation from corrosion and/or oxidation, which can increase costs. This project will use high-temperature, low-cost ceramic materials with new designs and 3-D printing to develop ceramic heat exchangers. Ceramic system components can potentially reduce corrosion issues created by molten salt heat-transfer fluids and oxidation from gas phases. As a result, high-performance, high-reliability ceramic heat exchangers could provide a cost-effective pathway for operating CSP systems at elevated temperatures and enhance overall system efficiency.

Project Name: CSP Plant Construction, Start-Up, and Operations and Maintenance Best Practices Study               
Lab: National Renewable Energy Laboratory       
Location: Golden, CO    
Principal Investigator: Mark Mehos
Project Summary: This project will determine best practices for the engineering, construction, commissioning, operations, and maintenance of concentrating solar-thermal power plants in the United States and abroad. The team will obtain and analyze input from operators, owners, developers, financers, and engineering, procurement, and construction contractors of these systems. At the end of the project, a best-practices document will be published so that future plants will be able to minimize costs and maximize energy production.

Project Name: Integrated Heat Pump Thermal Storage and Power Cycle for CSP               
Lab: National Renewable Energy Laboratory       
Location: Golden, CO    
Principal Investigator: Joshua McTigue
Project Summary: This project will investigate the thermal performance and economic feasibility of a new integrated technology that couples solar power generation and grid-connected storage. By using thermal energy storage, which can be easily incorporated into CSP plants, this work will explore the effect of storing electricity from the grid by powering a heat pump that can charge a cold storage material. Cold storage could potentially enable very high net power cycle efficiencies. The team will develop techno-economic models to investigate several key variables in this new system design, including potential thermodynamic cycles, working fluids, and cold storage media. A study using California electricity market data will evaluate the economics of the new system and determine which performance metrics may make it economically feasible.         

Project Name: Development and Validation of a Xenon Arc Lamp Accelerated Aging Method for CSP Solar Mirrors               
Lab: National Renewable Energy Laboratory       
Location: Golden, CO    
Principal Investigator: Robert Tirawat
Project Summary: In order to better understand CSP mirror degradation and minimize operations and maintenance costs, this project will develop and validate an accelerated aging method for testing solar reflectors using a xenon arc lamp exposure chamber to simulate the effects of sunlight. This evaluation method will ensure that mirror performance testing is standardized and user-friendly. As part of this effort, several databases containing information on the degradation of mirror performance will be updated and consolidated into one platform to help develop the accelerated aging model and the experimental aging method for reflective surfaces.

Project Name: CSP Real-Time Operations Optimization Software             
Lab: National Renewable Energy Laboratory       
Location: Golden, CO    
Principal Investigator: Michael Wagner
Project Summary: This project will extend prior work on the National Renewable Energy Laboratory’s System Advisor Model (SAM) software for CSP, focusing on dispatch optimization and solar irradiance forecasting. This software can automate certain decision-making processes at CSP facilities to execute real-time, optimal operational strategies in these areas. Automating these processes can simultaneously account for operational factors beyond the knowledge of human operators, generate consistent and improved plant performance, and reduce long-term maintenance costs. Prior work in SAM has shown that optimized dispatch could increase a facility’s revenue by 5% to 25%, depending on the market.               

Project Name: Solar for Industrial Process Heat
Lab: National Renewable Energy Laboratory       
Location: Washington, D.C.        
Principal Investigator: Robert Margolis
Project Summary: This project will explore the potential role of solar energy technologies, including photovoltaic, solar-thermal, and hybrid approaches that produce electricity and/or heat, to meet a wide range of industrial process heat end uses in the U.S. manufacturing sector. The team will combine detailed information about the spatial-varying and time-varying patterns of industrial process heat demand with the availability of sunlight. They will estimate process parity—the point at which the levelized cost of energy (LCOE) from solar energy is equivalent to the LCOE from more traditional combustion sources when used for industrial process heat, based on specific times and geographical locations.

Project Name: Cast Components for High-Temperature CSP Thermal Systems   
Lab: Oak Ridge National Laboratory        
Location: Oak Ridge, TN               
Principal Investigator: Govindarajan Muralidharan
Project Summary: High-temperature CSP systems operate at temperatures greater than 700° Celsius, which can be a challenge for components made from conventional metal alloys. While these components are typically hammered into the appropriate shape and then welded, this project will explore the feasibility of casting, a simpler and lower-cost manufacturing process in which liquid metal is poured into a mold to create precisely shaped components. Casting is best suited for intricately designed CSP components like heat exchangers, tubes, and vessels and could significantly reduce fabrication costs, helping to reduce overall CSP capital costs.              

Project Name: Development of an Unmanned, Aerial, System-Driven, Universal Field Assessment, Correction, and Enhancement Tool Adopting Non-Intrusive Optics          
Lab: Sandia National Laboratories
Location: Albuquerque, NM
Principal Investigator: Julius Yellowhair
Project Summary: Sandia National Laboratories will collaborate with the National Renewable Energy Laboratory to develop a new optical characterization tool for solar collectors. An automated aerial drone carrying a high-resolution camera will survey a large-scale heliostat field to compare the heliostats to their original structural geometry. The images will reveal problematic mirror angles and so that maintenance crews can quickly repair and calibrate underperforming heliostats. This new technology has the potential to reduce operations and maintenance efforts and increase power production, helping to reduce the levelized cost of energy of a concentrating solar-thermal power plant.

Project Name: Solar-Thermal Energy Ammonia Production (STEAP)
Lab: Sandia National Laboratories
Location: Albuquerque, NM      
Principal Investigator: Andrea Ambrosini
Project Summary: This project will enable the use of solar-thermal energy to produce ammonia, a common industrial chemical that requires a lot of energy to produce. First, sunlight will activate solid particles in a concentrating solar-thermal power system to isolate nitrogen from air. Then the nitrogen will be activated to form a metal nitride, which can react with hydrogen to generate ammonia. The project team will develop materials that can be reliably and cost-effectively cycled for both the nitrogen separation and ammonia generation steps in the process.

CSP Core Capability Projects

Project Name: CSP Optical Facilities – Core Capability     
Lab: National Renewable Energy Laboratory       
Location: Golden, CO    
Principal Investigator: Judy Netter
Project Summary: This project will focus on the repair and maintenance of concentrating solar-thermal power (CSP) optical research facilities and equipment at the National Renewable Energy Laboratory (NREL). These resources will support ongoing and projected research needs of CSP researchers and enable NREL to repair and update its existing CSP research equipment that is essential to the optical characterization of CSP components. This funding will ensure the continual operation of this equipment and that CSP researchers will have the necessary tools to achieve the cost goals of the U.S. Department of Energy Solar Energy Technologies Office.           

Project Name: CSP Systems Analysis – Core Capability   
Lab: National Renewable Energy Laboratory       
Location: Golden, CO    
Principal Investigator: Craig Turchi
Project Summary: This project will provide vetted tools that estimate concentrating solar-thermal power (CSP) system performance, including emerging systems that may not yet be well defined. The work also includes upgrading the National Renewable Energy Laboratory System Advisor Model (SAM) related to CSP, as well as developing new modules within SAM to expand the types of CSP systems that can be simulated. Tracking CSP costs and performance using a consistent method is required to achieve the cost targets of the Solar Energy Technologies Office and provide strategic guidance to the U.S. Department of Energy.

Project Name: DOE’s National Solar-Thermal Test Facility Operations and Maintenance 
Lab: Sandia National Laboratories            
Location: Albuquerque, NM      
Principal Investigator: Joshua Christian
Project Summary: The National Solar-Thermal Test Facility operated by Sandia National Laboratories is the only large-scale CSP research and test facility in the United States. It provides established test platforms and researchers and technologists experienced in the CSP field on staff for assistance. This project will support the operations and maintenance needed to provide a safe, fully operational facility with testing capabilities that support DOE CSP awardees as they work to achieve the CSP cost goals of the Solar Energy Technologies Office.

FY2020 Projects

Project Name: Robust Solar Receivers Using MAX Phase Materials
Lab: Argonne National Laboratory
Location: Lemont, IL
Principal Investigator: Dileep Singh
Project Summary: As operating temperatures for concentrating solar-thermal power plants continue to increase, current metal-based receivers have structural stability issues that need to be addressed to accommodate higher temperatures. This project is developing receivers using ceramic materials that can operate at temperatures higher than 800 degrees Celsius. The team aims to demonstrate the viability of these new class of materials.

Project Name: Additive Manufacturing Of Corrosion Resistant UHTC Materials for Chloride-to-Supercritical Carbon Dioxide Brayton Cycle Heat Exchangers
Lab: Lawrence Livermore National Laboratory
Location: Livermore, CA
Principal Investigator: James Kelly
Project Summary: This project is developing an ultra-high-temperature ceramic heat exchanger based on Triply Periodic Minimal Surface geometries, which can only be fabricated by additive manufacturing methods. The goal is to develop a heat exchanger that provide up to ten times higher heat transfer coefficients per unit reactor volume, while retaining smooth features and moderate pressure drop, which enables compact design with high efficiency. It is being constructed from materials known to retain their strength at temperatures between 1200 and 2100 degrees Celsius and is expected to be compatible with molten chloride salts and supercritical carbon dioxide.

Project Name: Aerodynamic Analysis and Validation of Wind Loading on CSP Collectors Using High-Fidelity CFD Modeling
Lab: National Renewable Energy Laboratory
Location: Golden, CO
Principal Investigator: Shreyas Ananthan
Project Summary: This project is working to validate high-fidelity computations of wind loading on concentrating solar-thermal power structures using wind-tunnel test data provided by SolarDynamics LLC. The team is addressing the progressively complex issue by validating the loading on a single-parabolic-trough-collector assembly to understand the meshing requirements and simulation best practices, predicting and validating wind loading on waked collectors by simulating multiple rows in different configurations, and simulating wind-loading characteristics of large arrays that are not possible to test in wind tunnels.

Project Name: Electrochemical Control for Corrosion in Molten Chlorides During CSP Plant Operation
Lab: National Renewable Energy Laboratory
Location: Golden, CO
Principal Investigator: Judith Vidal
Project Summary: Due to their high thermal stability and low cost, molten chloride salts are a promising heat-transfer fluids for concentrating solar-thermal power plants. However, associated corrosion concerns must be addressed. This project focuses on designing electrochemical methods and reactors for controlling and mitigating identified corrosion mechanisms expected during plant operation. Through redox control mechanisms, the team uses electrochemical elimination of corrosive impurities formed by salt hydrolysis in the presence of oxygen or water. If galvanic coupling occurs, the team plans to use cathodic protection of dissimilar alloys. These approaches aim to keep corrosion to less than 20 microns per year.

Project Name: Solar Field Layout and Aimpoint Strategy Optimization
Lab: National Renewable Energy Laboratory
Location: Golden, CO
Principal Investigator: Alexander Zolan
Project Summary: Using existing software packages to obtain a layout of the solar collection field of a concentrating solar-thermal power plant without accounting for the aiming strategy may yield solutions with heliostats that cannot be used efficiently without compromising the receiver’s designed operating limits. This project develops a model that co-optimizes the layout and aiming strategies of a solar field to maximize the thermal energy generated by the field while operating within the design specifications of the receiver. The team utilizes state-of-the-art tools developed in its previous to characterize the thermal input to the receiver when provided a heliostat location and aiming strategy as input. This data is then used as input to an optimization model to obtain the best strategy within given limits. Advanced optimization techniques allow the model to obtain layouts and aiming strategies for commercial-scale plants.

Project Name: Development of Cast Valve Bodies for High Temperature Service
Lab: Oak Ridge National Laboratory
Location: Oak Ridge, TN
Principal Investigator: Govindarajan Muralidharan
Project Summary: This project aims to lower the costs of materials and components in concentrating solar-thermal power systems so capital costs can be minimized while still achieving high operating temperatures. To obtain the lowest cost in castings, there is a significant need to maximize yields in castings by decreasing rejects due to casting defects and to minimize waste in lost material in the gating systems. The scope of the work includes collection of data required for computational design of the casting, design of the rigging system for the casting using computational modeling, development of melting and casting process parameters, casting fabrication, casting integrity evaluation, comparison of experimental evaluation of casting quality with results from modeling, and evaluation of microstructure and tensile properties in a critical location.

Project Name: Interface Evolution with Molten Salts
Lab: Oak Ridge National Laboratory
Location: Oak Ridge, TN
Principal Investigator: Gabriel Veith
Project Summary: This project aims to understand the surface evolution of high nickel alloy surfaces under molten salt conditions. The team is using a variety of scattering and in situ approaches to follow the interface evolution, with nanometer resolution, as a function of time and temperature. Understanding these interfaces enables the team to identify and evaluate passivation layers and coatings that mitigate materials migration. Understanding changes in the salt chemistry allows for the prediction of additives to stabilize the salt chemistry. Additionally, the atomic scale in situ studies allows for the direct measurement of reaction mechanisms and kinetics aiding in the simulation of lifetime and hardware stability.

Project Name: Selective Thermal Emission with Radiation and Absorption in Annuli: An Advanced Heat Exchanger Concept for Supercritical Carbon Dioxide Power Cycles
Lab: Pacific Northwest National Laboratory
Location: Richland, WA
Principal Investigator: Peter McGrail
Project Summary: One of the key limitations affecting ability to achieve the efficiency and cost saving advantages of a solar thermal supercritical carbon dioxide power cycle resides with the primary heat exchanger, where costs can exceed 50 percent of the plant capital budget depending on design. This project lays the foundational groundwork for a new type of heat exchanger optimized to take advantage of radiative heat transfer to supercritical carbon dioxide. Using principles from the new field of optical metamaterials, selective thermal emission coatings are being designed to radiate light tuned to the strong infrared absorption band of carbon dioxide. Heat transfer simulations show that an advanced heat exchanger implementing this selective thermal emitter is 25-40 percent smaller than conventional heat exchanger designs.

Project Name: LIDAR for Autonomous Heliostat Optical Error Assessment
Lab: Sandia National Laboratories
Location: Albuquerque, NM
Principal Investigator: Dan Small
Project Summary: This project seeks to develop new uses for three-dimensional scanning Light Detecting and Ranging (LiDAR) sensors in the automatic/autonomous assessment of the optical errors in large-scale concentrating solar-thermal power heliostat fields. Experiments have demonstrated the ability of a 3D-LiDAR to acquire highly accurate point cloud measurements of facet mirrors across several heliostats at the National Solar-Thermal Test Facility and derive their facet canting angles and errors. The team is writing software for autonomous segmentation and error analysis and conducting in situ testing and evaluation at the National Solar-Thermal Test Facility.

FY2021 Projects

Project Name: Continuous Particle Monitoring and Removal for Molten Chloride CSP Systems
Lab: Argonne National Laboratory
Location: Lemont, IL
Principal Investigator: Nathaniel Hoyt
Project Summary: Maximizing the lifetimes of next-generation molten chloride CSP plants requires preventing and removing highly abrasive oxide particles that develop in the piping, valves, and pumps, because they cause contamination and other complications. This project is developing and testing a particle-monitoring technology that uses a novel electrical resistance tomography probe to capture images. The project is also developing a passive cyclonic separator that will efficiently remove particles from molten salts.

Project Name: Applying Deep Learning to Automate Optical Characterization Tools for Parabolic Trough Solar Fields
Lab: National Renewable Energy Laboratory
Location: Golden, CO
Principal Investigator: Guangdong Zhu
Project Summary: Underperforming parabolic troughs can decrease CSP plant efficiency. To improve performance, this project is developing a “distant observer” tool that collects aerial data to measure mirror and receiver misalignments. The collector characterization technology uses an unmanned aerial vehicle, computer vision, and novel deep learning machine methods to collect images of the troughs, enabling fast-responding control systems.

Project Name: Characterization of Turbulent Wind Conditions within a CSP Plant
Lab: National Renewable Energy Laboratory
Location: Golden, CO
Principal Investigator: Shreyas Ananthan
Project Summary: Predicting the performance and failure rate of parabolic trough collectors relies on data from wind tunnel testing. Limited understanding of interior wind loads, where some of the wind is shielded by the outer field, can lead to overengineering and higher cost. This project is field-testing at a CSP plant to obtain more accurate data on wind conditions. Researchers plan to install meteorological towers at the border and interior of the installation to monitor the wind patterns. Demonstrations will be held at Acciona’s Nevada Solar One facility. The data will be used to improve collector design and operation.

Project Name: Mechanical Failure Risk Management for In-Service CSP Nitrate Hot Tanks
Lab: National Renewable Energy Laboratory
Location: Golden, CO
Principal Investigator: Judith Vidal
Project Summary: The thermal energy storage tanks that store molten salt in CSP plants are susceptible to stress cracking without post-weld heat treatment. This project aims to reduce residual stresses with two heat-treatment methods: a ceramic pad heater and induction heating. The goal is to improve reliability of 347H stainless-steel tanks by optimizing cost-effective procedures while evaluating whether the post-weld heat treatments can be used for commercial applications. Researchers will use phased-array ultrasonic testing to determine the detection limits of defects and cracks and compare the detectable defects before and after the heat treatments.

Project Name: Development of an Open-Source Alloy Selection and Lifetime Assessment Tool for Structural Components in CSP
Lab: Oak Ridge National Laboratory
Location: Oak Ridge, TN
Principal Investigator: Rishi Pillai
Project Summary: This project is developing a cost-effective, open-source, alloy selection and lifetime prediction tool to account for stress, fatigue, and corrosion failures of structural and heat-exchange materials in CSP technologies. The tool will incorporate the temperature, alloy composition, alloy microstructure, operational requirements, and component thickness on the mechanical and corrosion behavior of iron and nickel alloy-based CSP materials. The lab will use extensive data sets to validate the tool and select the lowest-cost material for specified CSP components.

Project Name: Simplified High-Temperature Molten Salt CSP Plant Pre-Conceptual Design
Lab: Oak Ridge National Laboratory
Location: Oak Ridge, TN
Principal Investigator: Kevin Robb
Project Summary: CSP systems currently use nitrate salts as the heat-transfer fluid and thermal energy storage media. Molten chloride salts could enable higher operating temperatures for future CSP plants, leading to more-efficient power cycles. This project is developing a model for an innovative plant configuration using chloride salts, using a single storage tank that is potentially much lower cost than existing concepts.

Project Name: Estimating Value of CSP Autonomy Tasks
Lab: Sandia National Laboratories
Location: Albuquerque, NM
Principal Investigator: Randy Brost
Project Summary: This project is investigating current autonomous systems used in CSP plants to estimate their economic benefit and rank them by value. Examples of autonomous systems include closed-loop operation control of the collector field, robotic washing, and drone-based mirror calibration. This project will identify autonomy tasks, illustrate their technical requirements, and estimate their value to develop and inform high-value autonomy research and development.

Project Name: Horizontal High-Temperature Particle Conveyance
Lab: Sandia National Laboratories
Location: Albuquerque, NM
Principal Investigator:  Jeremy Sment
Project Summary: Replacing nitrate salts with a particle heat transfer and thermal storage medium is one viable route for next-generation CSP. Delivering hot, sand-like particles from the thermal storage vessel to the power cycle’s primary heater is an important consideration for commercial-scale CSP system design. The project team is developing a small, high-temperature prototype that would convey particles to gravity-driven heat exchangers aligned in a parallel network. Research will include insulation methods using transient heat-transfer models and designs to reduce particle and wall erosion.

Project Name: High-Temperature Particle/Supercritical Carbon Dioxide Test Loop for Accelerated Heat Exchanger Performance Testing
Lab: Sandia National Laboratories
Location: Albuquerque, NM
Principal Investigator: Kevin Albrecht
Project Summary: This project expands upon earlier SETO-funded research to improve particle-to-supercritical carbon dioxide (sCO2) heat exchangers. Researchers plan to conduct performance evaluation and control studies of particle heat exchanger technology at higher temperatures. They will use data from the previous project to test heat exchanger performance, including the design, construction, system integration, and manufacturing technique of a moving packed-bed particle/sCO2 heat exchanger. This project will address underlying performance issues through a controlled testing environment. A 20 kilowatt-thermal particle-to-sCO2 heat exchanger testing platform is available to test future novel concepts.

Project Name: Using Active Heliostat Control to Mitigate Wind Impacts and Improve Predictability for Particle Receivers
Lab: Sandia National Laboratories
Location: Albuquerque, NM
Principal Investigator: Brantley Mills
Project Summary: This project is working to minimize wind impacts on utility-scale CSP system particle receivers via heliostat control. A novel three-receiver concept that uses heliostats can maximize annual performance of the receivers and control the direction at which heliostats are aimed, creating more efficient particle receivers. The team will use computational fluid dynamics models to gain a three-dimensional understanding of performance, and add wind mitigation strategies to track different wind conditions to enhance system models.

Project Name: Eutectic Carbonates for Low-Cost, Efficient Thermochemical Heat Storage System
Lab: Savannah River National Laboratory
Location: Jackson, SC
Principal Investigator: Ragaiy Zidan
Project Summary: Thermochemical energy storage systems are low-cost, have high energy density, and can operate in high-temperature conditions. This project is developing a thermochemical energy storage system based on based on a molten carbonate mixture. This technology will be used in the thermochemical system to test wide-scale implementation. The system can enable seasonal energy storage by maintaining thermal energy at ambient temperature for long periods with no risk of thermal decay.

Learn more about SETO’s concentrating solar-thermal power research and other SETO Lab Call FY19-21 projects.