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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Vascular Carbon/Carbon composites for concentrated solar power

Due to their exceptional mechanical and thermal properties under high temperature conditions, for the first time, a novel vascular (embedded channels) Carbon/Carbon (C/C) composite was developed for use as a modular concentrated solar power (CSP) gas receiver. The fabrication process involves the combination of the vaporization of sacrificial component (VaSC) technique with conventional methods to produce C/C composites with well preserved channels. Different heat treatments were evaluated together with X-ray diffraction (XRD) analysis to determine optimal fabrication conditions that maintains the material and channel’s integrity. Mechanical testing confirms that structural integrity is maintained, with statistical analyses indicating no compromise in flexural strength or modulus. Furthermore, this research introduces an innovative pathway for efficient CSP gas receivers, which can bridge the gap towards improved energy generation efficiency in next-gen CSP plants through higher operating temperatures with the use of C/C composites.

14 SOLAR ENERGY↗
NASA NTRS1982

Cassegrainian concentrator solar array exploratory development module

A miniaturized Cassegrainian concentrator solar array concept is under development to reduce the cost of multi-kW spacecraft solar arrays. A primary parabolic reflector directs incoming solar energy to a secondary, centrally mounted inverted hyperbolic reflector and down onto a solar cell mounted on an Mo heat spreader on a 0.25 mm thick Al heat fin. Each unit is 12.7 mm thick, which makes the concentrator assembly roughly as thick as a conventional panel. The output is 100 W/sq and 20 W/kg, considering 20% efficient Si cells at 100 suns. A tertiary light catcher is mounted around the cell to ameliorate optic errors. The primary reflector is electroformed Ni with protective and reflective coatings. The cells have back surface reflectors and a SiO antireflective coating. An optical efficiency of 80% is projected, and GaAs cells are being considered in an attempt to raise cell efficiencies to over 30%.

Patterson, R. E.↗
DOE OSTI2026

Technoeconomic Analysis Round Robin of a Retrofit of the Ivanpah Concentrating Solar Plant with a Molten-Salt System with Thermal Energy Storage

While the fidelity of technoeconomic analysis (TEA) models for concentrating solar thermal systems has improved in recent years, there is a lack of consensus on the specific inputs used to forecast performance of a newly built tower system due to a lack of validations and post-mortems available to the public. This effort is a joint initiative between multiple international organizations to validate and compare their TEA models. The specific case study is a proposed retrofit of one unit of the Ivanpah Solar Energy Generating System to include molten-salt storage, replacing the steam generation system with a molten-salt receiver, salt-to-steam heat exchanger train, and new balance of plant while keeping the existing steam turbine, solar field, and interconnection in place, using plant data for calibration. This manuscript discusses several of the agreed-upon assumptions for this study as well as a preliminary analysis from prior work that motivates the study.

14 SOLAR ENERGY↗
DOE OSTI2023

The material challenges of the next generation of concentrated solar power

This is an introductory seminar about the cleantech-to-market pathway with a focus on material innovation in Concentrated Solar Power. This seminar will first lay out the business model of cleantech companies to identify the players in technical innovation. With a summary of the desires of the major player, this seminar will dive into the possibility, potential, and challenges of next-generation Concentrated Solar Power to answer these desires, followed by a detailed discussion on the material challenges. The scope of our project “Scalable, Infiltration-Free Ceramic Matrix Composite for the molten salt receiver” will be presented as one potential way to solve these challenges. In the end, this seminar will present some job opportunities to inspire the audience to participate in cleantech innovation.

42 ENGINEERING↗
NASA NTRS1977

Solar concentration by curved-base Fresnel lenses

The solar concentration performance of idealized curved base line focusing Fresnel lenses is analyzed. A simple optical model was introduced to study the effects of base curvature and lens f-number. Thin lens ray tracing and the laws of reflection and refraction are used to develop expression for lens transmittance and image plane intensity profiles. The intensity distribution over the solar spectrum, lens dispersion effects, and absorption by the lens material are included in the analysis. Model capabilities include assessment of lens performance in the presence of small transverse tracking errors and the sensitivity of solar image characteristics to focusing.

Cosby, R. M.↗
NASA NTRS1981

Offset paraboloidal solar concentrator

Section of conventional paraboloid, offset from its major axis, is used as reflector in solar concentrator. Design increases solar gathering efficiency by 3 to 4 percent by eliminating shadowing and blocking of solar rays. In addition, reflector can be folded toward receiver, reducing wind-loading and making maintenance easier.

Chow, E. Y.↗
DOE OSTI2023

Coupled Experimental and High-Temperature Discrete-Element Method Modeling Studies of Aluminosilicate Particle Handling in Concentrated Solar Power Environments

Chemically inert, aluminosilicate based particles have been investigated as both a thermal transport and sensible energy storage medium for concentrated solar power facilities. These particles will experience a wide range of operating temperatures (300-1000 K) and handling conditions (dense to dilute falling particle curtains, dense granular flows, or dense structures), requiring specially-designed and optimized infrastructures. The relative influence of collisional and frictional interactions between particles varies based on temperature-dependent particulate properties and greatly impacts the bulk, granular flow behavior. These underlying physics are captured using discrete element method modeling tools. However, this modeling method is computationally expensive as each particle position and interaction is tracked during the simulation. These modeling methods are further complicated by introducing temperature-dependent particle properties, high-temperature radiative exchange, and directional irradiation sources experienced by granular flows in concentrated solar power environments. Coupled experimental and numerical studies of aluminosilicate particles in rotary kilns and dense particle curtains were performed for bulk temperatures up to 1073 K. The three particle types investigated included Carbobead HSP 30 /60, Carbobead CP 30/60, and Granusil 4030. Temperature, spatial, and velocity profile data were extracted from experimental runs using embedded K-type thermocouple probes and particle image velocimetry techniques. Experimental and numerical studies were compared using spatial temperature profiles, velocity fields, and shape profiles of the bulk, granular flows. Numerical models were developed using commercially available discrete element method modeling software, Aspherix®. Existing Aspherix® functionality was expanded by introducing coupled radiative exchange modeling tools. The laboratory-scale rotary kiln was developed to investigate the steady-state heat and mass transfer performance of aluminosilicate particles based on particle type, bulk handling temperature, and wall roughness. The rotational speed of the rotary kiln was varied to control the relative impact of collisional and frictional effects upon the granular flow behavior. Heat and mass transfer performance was categorized based on the Froude number and the observed flow regimes of slipping, rolling, cascading, and centrifuging. Coupled discrete element method modeling studies were used to evaluate the effects of temperature-dependent, particulate mechanical properties upon bulk flow behavior and upon the relative effects of radiative, advective, and/or conductive heat transfer. A high-temperature (< 1073 K) falling particle curtain was similarly fabricated to investigate the heat and mass transfer performance of aluminosilicate particles in particle handling situations dominated by inter-particle collisions. The impact of particle type, flow preheat temperatures (< 1073K), and bulk mass flow rates were investigated upon the particle curtain shape, temperature, and velocity profiles. Coupled discrete element method modeling studies were performed to evaluate the varying impact of temperature-dependent, particulate mechanical properties on the bulk flow behavior and the temperature profile of the particle curtain.

14 SOLAR ENERGY↗
DOE OSTI2026

Concentrating solar thermal power in the U.S.: lessons from setbacks at Ivanpah, light for the future

Concentrating solar thermal power (CSP) exhibits promise as a source of firm electricity. The proposed termination of Ivanpah’s power purchase agreement hinders confidence in the country’s CSP future. This work highlights how the lack of thermal energy storage (TES) undermined the first-of-a-kind plant’s economics as California’s grid transformed. Then, possible futures of the Ivanpah facility are analyzed; results show retrofitting with state-of-the-art TES systems could provide better returns.

14 SOLAR ENERGY↗
NASA NTRS1981

Advanced solar concentrator mass production, operation, and maintenance cost assessment

The object of this assessment was to estimate the costs of the preliminary design at: production rates of 100 to 1,000,000 concentrators per year; concentrators per aperture diameters of 5, 10, 11, and 15 meters; and various receiver/power conversion package weights. The design of the cellular glass substrate Advanced Solar Concentrator is presented. The concentrator is an 11 meter diameter, two axis tracking, parabolic dish solar concentrator. The reflective surface of this design consists of inner and outer groups of mirror glass/cellular glass gores.

Niemeyer, W. A.↗
NASA NTRS1985

Design, performance investigation and delivery of a miniaturized Cassegrainian concentrator solar array

A miniaturized Cassegrainian concentrator (MCC) solar array concept is being developed with the objective of significantly reducing the recurring cost of multikilowatt solar arrays. The desired cost reduction is obtained as a result of using very small high efficiency solar cells in conjunction with low-cost optics. In the MCC single element concept and panel concept, incident solar radiation is reflected from a primary parabolic reflector to a secondary hyperbolic reflector and finally to a 4-millimetr diameter solar cell. A light catcher cone is used to improve off-axis performance. An element is approximately 13-millimeters thick which permits efficient launch stowage of the concentrator system panels without complex optical component deployments or retractions. The MCC elements are packed in bays within graphite epoxy frames and are electrically connected into appropriate series-parallel circuits. A MCC single element with a 21 sq cm entrance aperture and a 20 percent efficient, 0.25 sq cm gallium arsenide solar cell has the same power output as 30-sq cm of 11-percent efficiency (at 68 C) silicon solar cells. The MCC concept provides the potential for a significant reduction in array cost due to a 99 percent reduction in required cell area and a 30 percent reduction in array area relative to planar array of equivalent power.

Patterson, R. E.↗
DOE OSTI2020

Integration of a Concentrating Solar Steam Topping Turbine to an Existing Geothermal Binary Power Plant (CRADA CRD-17-700 Final Report)

U.S. Geothermal Inc. is a publicly traded leading renewable energy company focused on the development, production, and sale of electricity from geothermal energy with operating generation facilities at Raft River, Idaho; San Emidio, Nevada; and Neal Hot Springs, Oregon. (U.S. Geothermal was acquired by Ormat Technologies, Inc. since the execution of this project). This project will evaluate the integration of a concentrating solar steam topping cycle with a geothermal bottoming binary cycle. This hybrid plant configuration will enable high efficiency conversion of the solar heat to electrical power, while simultaneously increasing the power output of the bottoming cycle. Such a design has the potential to reduce the cost of electrical power from concentrating solar power (CSP) and geothermal plants, and a viable design could be deployed at existing geothermal plants that have experienced resource productivity decline as well as in greenfield projects. This analysis will examine US Geothermal’s Raft River power plant for implementation of this concept. INL and NREL have previously collaborated in the analysis of geo-solar hybrid power plants. These two labs will again work together to model the solar field, steam-topping, and geothermal bottoming cycles in order to investigate the performance of the proposed cycle. This analysis will provide US Geothermal with technical information including equipment specifications and estimated power generation necessary to advance the concept toward implementation. A successful project outcome has two parts: One would be for US Geothermal to have a process flow diagram (heat and mass balance), and performance parameters for the major pieces of equipment. US Geothermal could then use this information evaluate the techno-economic feasibility of the hybrid power cycle, and serve as the basis for subsequent detailed equipment design, purchase, and installation of the cycle. The second would be for the developed solution to be published by DOE for use by other geothermal developers both to retrofit underperforming plants and to lower the LCOE of new developments.

15 GEOTHERMAL ENERGY↗
NASA NTRS2020

Implementation Concept of Operation for a Multi-Purpose Cassegrain Solar Concentrator, Micro-Spectrometers, and Electrostatic Neutralizers to Enable In Situ Construction Activities plus Lunar, Planetary, and Deep Space Science Exploration on the Moon

The ability to utilize regolith would support human missions to the Moon and Mars by both stabilizing the surface as well as the use of indigenous resources. Precision landing requirements include surface stabilization to prevent damage or contamination due to regolith projectiles as a result of plume interaction with regolith. The use of indigenous resources rather than hauling materials from Earth appears to be economically a palatable option by converting indigenous resources to usable products. However, such activities have new technical challenges to overcome the issues related to lunar environmental conditions, a wide range of temperature fluctuation, extremely high vacuum, and electrostatically charged fine regolith dusts. For both the regolith sintering and extraction of resources onsite, a Cassegrain solar concentrator was studied for not only sintering lunar regolith into a hardened stabilized surface, but also other multiple applications. This report illustrates a Cassegrain solar concentrator that has multi-functional capabilities for space missions. Proper design and implementation of high-performance lightweight composite materials for the primary mirror of the Cassegrain concentrator can offer multiple capabilities to be performed on the Moon. The multiple applications studied with Cassegrain concentrators are (1) Solar sintering for landing pad and habitats, (2) Harvest of volatiles: H2O, O2, H2, and He-3, (3) Space antenna for telemetry and telecommunication, and (4) Space telescope with 20-meter aperture that exceeds the space telescopes to date in terms of the State-of-Art (SOA) in resolution and aperture diameter. In this study, a key emphasis was placed on the NASA Langley-developed boron nitride nanotube (BNNT) nanocomposite technology which is ideal for the segmented primary mirror structure of the Cassegrain system because it promises a very low coefficient of thermal expansion (CTE) and negligible Poisson ratio. Also, BNNT nanocomposites offer several noticeable benefits, such as light weight, radiation shielding capability, and mechanical strength for structural applications. Additionally, the NASA Langley-developed bullet-like micro-spectrometer and electrostatic power generator were reviewed for mineral mapping applications and electrostatic power generation and dust mitigation from electrostatically charged regolith.

landing pad↗
DOE OSTI2026

Heliostat sizing methodology for concentrating solar thermal industrial process heat projects

This study presents a method to obtain a heliostat size that minimizes the levelized cost of heat (LCOH) of a heliostat-based concentrating solar thermal system for applications of solar heating for industrial processes at operating temperatures from 565 to 1550°C. The method extends prior work by embedding a routine for system design that obtains near-optimal subsystem sizes, increasing the fidelity of drive cost functions, and adding an optical performance model to supplement the previously developed cost models, which we update to reflect current pricing trends. An illustrative business case is developed for Daggett, California, targeting specified annual thermal energy outputs of 50 to 400 GWh th . Optical performance is modeled using verified estimates from the literature. A surrogate heliostat cost model, derived from commercial heliostat designs and scaled for production volume, installation, and operations and maintenance costs, is used to develop cost functions. Results show that heliostat size strongly affects the LCOH, producing a characteristic U-shaped trend with a robust near-optimal window of 7-20 m 2 ; the heliostat size producing the lowest project cost in our study grows slightly as the project size increases, and is reduced as the operating temperature increases. The findings in this study are consistent with the general trend of smaller heliostats being deployed at existing projects for high-temperature industrial process heat and reflect the significant reduction in power electronics and other per-heliostat costs. The methodology we propose is general and can be tailored to revised cost curves as the technology continues to evolve.

14 SOLAR ENERGY↗
DOE OSTI2022

Numerical and Experimental Investigation of Nanostructure-Based Asymmetric Light Transmission Interfaces for Solar Concentrator Applications

Research in asymmetric light transmission interfaces has been recently gaining traction. While traditionally considered for optical circuitry applications, there is a new interest to use these interfaces in luminescent solar concentrators. Previous studies have shown that applying them to the top surface of a concentrator could mitigate surface losses. This paper presents experimental results for proof-of-concept asymmetric light transmission interfaces that may have potential applications in luminescent solar concentrators. The interfaces and the underneath substrate were created in a single step from polydimethylsiloxane using silicon molds fabricated on <100> wafers via anisotropic wet etching. The resulting structures were pyramidal in shape. Large surface areas of nanostructures repeating at 800 nm, 900 nm, and 1000 nm were tested for backward and forward transmission using a spectrometer. Results showed a 21%, 10%, and 0% average transmissivity difference between the forward and backward directions for each periodicity, respectively. The trends seen experimentally were confirmed numerically via COMSOL simulations.

Oliveto, Vincent↗
DOE OSTI2023

High Temperature Ceramic Heat Exchangers for the Gen3 Concentrated Solar Power Systems

As part of the Department of Energy’s Solar Energy Technology Office (SETO), the Concentrated Solar Power (CSP) Gen3 Demonstration Roadmap outlined the various technology pathways, goals, and technology needs/gaps to integrate CSP to a supercritical CO 2 (sCO 2 ) power cycle that operates at temperatures >700 °C. It is envisioned that the higher temperature power cycle will enhance the overall system efficiencies and reduce the levelized cost of electricity (LCOE) to meet a 2030 cost target of $0.05/kWhe for baseload CSP plants with ≥12 hours of storage. In this regard, there is a need for heat exchangers (HXs) that can operate at high sCO 2 pressures and temperatures >700 °C. Since current high-temperature alloys degrade at high temperatures, as part of this project, advanced ceramic materials, HX designs, and low-cost additive manufacturing approaches were developed to fabricate and evaluate the performance of the lab-scale ceramic HX prototypes.

14 SOLAR ENERGY↗
DOE OSTI2020

Leveraging concentrating solar power plant dispatchability: A review of the impacts of global market structures and policy

Concentrating solar power (CSP) integrated with thermal energy storage delivers flexible and dispatchable power, which is an increasingly valuable quality as electricity systems integrate growing penetrations of variable renewable energy. Valuing and compensating CSP's dispatchability and flexibility requires electricity market structures and policies that appropriately remunerate generation during high-value portions of the day. In this paper, we review previous analyses of CSP economics and deployment, and we find that continued CSP growth will require valuation mechanisms that appropriately compensate for CSP's flexibility during both plant design and plant operation. We then review market structures that drive CSP operations and dispatch in jurisdictions where CSP is being developed, with perspectives from Spain, Chile, Australia, Morocco, South Africa, the United States, China, and the United Arab Emirates (Dubai). Despite broad agreement that CSP's dispatchability provides value to electricity grids, countries' policies for remunerating and leveraging such dispatchability varies widely. As deployment of CSP and variable renewable energy grows, it will be increasingly important to redesign current integration policies to signal the delivery of CSP's grid services more appropriately.

14 SOLAR ENERGY↗
DOE OSTI2023

Multi-Objective Optimization of a Bi-Metal High-Temperature Recuperator for Application in Concentrating Solar Power

Supercritical CO 2 closed Brayton cycles are a major candidate for future power cycle designs in concentrating solar power applications, with high-temperature recuperators playing an essential role in realizing their high thermal efficiency. Here, printed circuit heat exchangers (PCHEs) are often chosen for this role due to their thermal-hydraulic and mechanical performance at high temperatures and pressures, all while remaining compact. However, PCHEs can be costly because of the high-performance materials demanded in these applications, and the heat exchanger internal geometry is restricted by their manufacturing process. Additively manufactured heat exchangers can address both of these shortcomings. This work proposes a modular bi-metal high-temperature recuperator with integrated headers to be produced with additive manufacturing. Beginning with existing PCHE channel geometries, a 1D heat exchanger model is developed. Then, multi-objective optimization is used to maximize the heat transfer effectiveness of a lab-scale device while limiting its size. Two distinct channel geometries emerge from the optimization. Optimal designs achieve up to 88% effectiveness with negligible pressure drop. Deterioration of effectiveness due to axial conduction of heat in the heat exchanger walls is found to be a notable problem for lab-scale PCHEs, and the optimal designs obtained here minimize its detrimental effects. A sensitivity analysis reveals that the effectiveness of the recuperator is much less sensitive to variation in mass flowrate in off-design operation when axial conduction is significant, while increasing the length of the device easily increases effectiveness.

14 SOLAR ENERGY↗