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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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Thermophysical Properties Experimentally Tested for NaCl-KCl-MgCl 2 Eutectic Molten Salt as a Next-Generation High-Temperature Heat Transfer Fluids in Concentrated Solar Power Systems

A new eutectic chloride molten salt, MgCl 2 -KCl-NaCl (wt% 45.98–38.91–15.11), has been recognized as one of the most promising high-temperature heat transfer fluids (HTF) for both heat transfer and thermal storage for the third-generation concentrated solar power (CSP) systems. For the first time, some essential thermophysical properties of this eutectic chloride molten salt needed for basic heat transfer and energy storage analysis in the application of concentrating solar power systems have been experimentally tested and provided as functions of temperature in the range from 450 °C to 700 °C. The studied properties include heat capacity, melting point, heat of fusion, viscosity, vapor pressure, density, and thermal conductivity. The property equations provide essential database for engineers to use to calculate convective heat transfer in concentrated solar receivers, heat exchangers, and thermal storage for concentrated solar power plants.

14 SOLAR ENERGY↗
DOE OSTI2020

System Design of a 2.0 MWth Sodium/Molten Salt Pilot System

Nitrate molten salt concentrating solar power (CSP) systems are currently deployed globally and are considered state-of the art heat transfer fluids (HTFs) for present day high-temperature operation. Although slightly higher limits may be possible with molten salt, to fully realize SunShot efficiency goals of $15/kWhth HTFs and an LCOE of 6¢/kWh, HTF technologies working at higher temperatures (e.g., 650 °C to 750 °C) will require an alternative to molten salts, such as with alkali metal systems. This investigation explores the development of a 2.0 MWth sodium receiver system that employs a sodium receiver as the HTF, as well as with a ternary chloride (20%NaCl/40%MgCl/40%KCl by mol wt.%) salt as a thermal energy storage (TES) medium to facilitate a 6-hr. storage duration. A sodium-to-salt heat exchanger model as well as a salt-to-sCO2 primary heat exchanger model are employed and evaluated in this investigation. A thermodynamic system design model was developed using Engineering Equation Solver (EES) where state properties were calculated at inlets and outlets along both hot and cold legs of the pilot-scale plant. This investigation assesses receiver performance as well as system efficiency studies for the pump and system operational ranges. Results found that high efficiency sodium receivers were found to have higher heat transfer coefficients and required far less spreading of incident flux. The system performance model results suggest that for a pump speed of 2400 RPM, respective hot and cold pump TDH values were determined to be 260.1–307 ft. and 260.1–307 ft for pump flow rates of 90–120 GPM.

41 EE - Solar Energy Technologies Office (EE-4S)↗
DOE OSTI2011

Second-surface silvered glass solar mirrors of very high reflectance

This paper reports methods developed to maximize the overall reflectance second-surface silvered glass. The reflectance at shorter wavelengths is increased with the aid of a dielectric enhancing layer between the silver and the glass, while at longer wavelengths it is enhanced by use of glass with negligible iron content. The calculated enhancement of reflectance, compared to unenhanced silver on standard low-iron float glass, corresponds to a 4.4% increase in reflectance averaged across the full solar spectrum, appropriate for CSP, and 2.7% for CPV systems using triple junction cells. An experimental reflector incorporating these improvements, of drawn crown glass and a silvered second-surface with dielectric boost, was measured at NREL to have 95.4% solar weighted reflectance. For comparison, non-enhanced, wetsilvered reflectors of the same 4 mm thickness show reflectance ranging from 91.6 - 94.6%, depending on iron content. A potential drawback of using iron-free drawn glass is reduced concentration in high concentration systems because of the inherent surface errors. This effect is largely mitigated for glass shaped by slumping into a concave mold, rather than by bending.

14 SOLAR ENERGY↗
DOE OSTI2016

Solar Process Heat Potential in California, USA

The cost for solar industrial process heat (SIPH) is quantified by defining the levelized cost of heat (LCOH). The state of California, in the United States offers a favorable environment for SIPH given its excellent insolation, industrial gas prices typically higher than the national average, and policies promoting solarthermal deployment. Given historically low gas prices, competing with natural gas remains the primary challenge to deployment. However, this study finds that the solar LCOH from Concentrating Solar Power (CSP) collectors for many regions in California is expected to be lower than the LCOH from natural gas, using a representative installed solar hardware price and the average price for industrial natural gas in California. Lastly, modifications are in progress to the parabolic trough and Direct Steam Generation (DSG) trough and Linear Fresnel models within NREL's System Advisor Model (SAM) to allow users to more easily predict performance for these industrial heat and steam-generation applications.

14 SOLAR ENERGY↗
DOE OSTI2019

Case Study of a Californian Brewery to Potentially Use Concentrating Solar Power for Renewable Heat Generation

With the increasing relevance and acceptance of solar thermal for industrial process heat (IPH), a case study for a proposed concentrating solar power (CSP) integration into an existing Californian brewery is highlighted. The thermal generation from a 1 MWth solar field was modelled in the System Advisor Model (SAM), and the economics considered the viability of the project where different variables such as the installed solar field cost were investigated on metrics such as Net Present Value (NPV) and payback period. For the Base Case, without the 30% Investment Tax Credit (ITC), and using a 2017 Federal income tax rate of 35%, the project’s NPV reached $0 (i.e., the project becomes viable), when the installed solar field cost reached $158/m2. With the 30% ITC and 35% tax, the solar field installed cost is estimated at $324/m2 to obtain an NPV = $0. The biggest influences on project viability measured by NPV were the project life, Federal tax rate, and the solar field cost.

case study↗
DOE OSTI2011

High-Temperature Phase Change Materials (PCM) Candidates for Thermal Energy Storage (TES) Applications

It is clearly understood that lower overall costs are a key factor to make renewable energy technologies competitive with traditional energy sources. Energy storage technology is one path to increase the value and reduce the cost of all renewable energy supplies. Concentrating solar power (CSP) technologies have the ability to dispatch electrical output to match peak demand periods by employingthermal energy storage (TES). Energy storage technologies require efficient materials with high energy density. Latent heat TES systems using phase change material (PCM) are useful because of their ability to charge and discharge a large amount of heat from a small mass at constant temperature during a phase transformation like melting-solidification. PCM technology relies on the energyabsorption/liberation of the latent heat during a physical transformation. The main objective of this report is to provide an assessment of molten salts and metallic alloys proposed as candidate PCMs for TES applications, particularly in solar parabolic trough electrical power plants at a temperature range from 300..deg..C to 500..deg.. C. The physical properties most relevant for PCMs servicewere reviewed from the candidate selection list. Some of the PCM candidates were characterized for: chemical stability with some container materials; phase change transformation temperatures; and latent heats.

14 SOLAR ENERGY↗
DOE OSTI2011

Concentrating Solar Power (Fact Sheet)

Concentrating Solar Power (CSP) offers a utility-scale, firm, dispatchable renewable energy option that can help meet the nation's goal of making solar energy cost competitive with other energy sources by the end of the decade.

14 SOLAR ENERGY↗
DOE OSTI2011

2010 Solar Technologies Market Report (Book)

The U.S. Department of Energy (DOE) 2010 Solar Technologies Market Report details the market conditions and trends for photovoltaic (PV) and concentrating solar power (CSP) technologies. Produced by the National Renewable Energy Laboratory (NREL), the report provides a comprehensive overview of the solar electricity market and identifies successes and trends within the market from both global andnational perspectives.

14 SOLAR ENERGY↗
DOE OSTI2012

Transmission Benefits of Co-Locating Concentrating Solar Power and Wind

In some areas of the U.S. transmission constraints are a limiting factor in deploying new wind and concentrating solar power (CSP) plants. Texas is an example of one such location, where the best wind and solar resources are in the western part of the state, while major demand centers are in the east. The low capacity factor of wind is a compounding factor, increasing the relative cost of newtransmission per unit of energy actually delivered. A possible method of increasing the utilization of new transmission is to co-locate both wind and concentrating solar power with thermal energy storage. In this work we examine the benefits and limits of using the dispatachability of thermal storage to increase the capacity factor of new transmission developed to access high quality solar andwind resources in remote locations.

14 SOLAR ENERGY↗
DOE OSTI2012

Development and Demonstration of an Innovative Thermal Energy Storage System for Baseload Power Generation

The objective of this project is to research and develop a thermal energy storage system (operating range 300°C - 450°C) based on encapsulated phase change materials (PCM) that can meet the utility-scale base-load concentrated solar power plant requirements at much lower system costs compared to the existing thermal energy storage (TES) concepts. The major focus of this program is to develop suitable encapsulation methods for existing low-cost phase change materials that would provide a cost effective and reliable solution for thermal energy storage to be integrated in solar thermal power plants. This project proposes a TES system concept that will allow for an increase of the capacity factor of the present CSP technologies to 75% or greater and reduce the cost to less than $20/kWht.

14 SOLAR ENERGY↗
DOE OSTI2012

Concentrated Solar Thermoelectric Power (Fact Sheet)

Massachusetts Institute of Technology (MIT) is one of the 2012 SunShot CSP R&D awardees for their advanced power cycles. This fact sheet explains the motivation, description, and impact of the project.

14 SOLAR ENERGY↗
DOE OSTI2012

10-MW Supercritical-CO2 Turbine (Fact Sheet)

National Renewable Energy Laboratory is one of the 2012 SunShot CSP R&D awardees for their advanced power cycles. This fact sheet explains the motivation, description, and impact of the project.

14 SOLAR ENERGY↗