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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 559 records · Page 31

Anomalous abundances of solar energetic particles and coronal gas: Coulomb effects and First Ionization Potential (FIP) ordering

The first ionization potential (FIP) ordering of elemental abundances in solar energetic particles and in the corona which can both be explained Coulomb effects is discussed. Solar energetic particles (SEP) and coronal gas have anomalous abundances relative to the photosphere. The anomalies are similar in both cases: which led to the conclusion that SEP acceleration is not selective, but merely preserves the source abundances. It is argued that SEP acceleration can be selective, because identical selectivity operates to determine the coronal abundances. The abundance anomalies are ordered by first ionization potential (FIP).

Mullan, D. J.↗

Viability Assessment of Wind and Solar Renewable Energy Generation in Support of Nationwide Vehicle Electrification

In 2022, the U.S. transportation sector was the largest source of greenhouse gas emissions in the country, with the combination of passenger and commercial vehicles contributing 80% of these emissions. As adoption of passenger electric vehicles continues to climb, sights are being set on the electrification of heavy-duty commercial vehicle (HDCV) fleets. The sustainability of these shifts relies in part on the addition of significant renewable energy generation resources to both bolster the grid in the face of increased demand, and to prevent a shift in the source of greenhouse gas (GHG) emissions to the grid, as opposed to a true net reduction. Additionally, it is necessary to quantify the variations in economic viability across the country for these technologies as it pertains to their productive capabilities. Doing so will encourage investment and ensure that the transition to electrified HDCV fleets is commercially viable, as well as sustainable. In an effort to meet these goals, multiple computational frameworks are used to locate suitable land for renewable infrastructure development, and to quantify spatiotemporal variations in the potential energy generation and financial viability of development sites across the Unites States. First, the Oak Ridge Siting Analysis for power Generation Expansion tool (OR-SAGE) is used to assess the suitability of land for potential wind and solar energy development across the contiguous U.S. From there, resource data from the National Solar Radiation Database (NSRDB) and the Wind Integration National Dataset (WIND) are used in concert with the National Renewable Energy Laboratory (NREL) Renewable Energy Potential (ReV) model to calculate the variation in potential generation capacity for each resource. Additionally, the capital and operational expenditures are calculated for an example configuration of each renewable technology. These measures are then used to calculate the levelized cost of energy (LCOE) of potential sites. All of these results are then processed and analyzed to determine where in the U.S. solar and wind energy are most viable. This viability is based on available generation potential, consistency and stability of energy generation over time, and economic viability with respect to LCOE.

Miller, Brandon [ORNL] (ORCID:0009000300169201)↗

Addressing Regulatory Challenges to Tribal Solar Deployment: Preprint

Although Tribal land represents more than 5% of the solar photovoltaic technical potential in the United States, this resource is largely untapped due to a range of barriers, including complex project economics, Tribal technical and human resource capacity, project funding and financing obstacles, and regulatory challenges. To identify and better understand the regulatory barriers, the National Renewable Energy Laboratory (NREL) and the Midwest Tribal Energy Resources Association (MTERA) engaged Tribes, utilities, and regulators. Funded by the U.S. Department of Energy, the 3-year effort seeks to address regulatory challenges or barriers that affect Tribal solar projects differently - specifically or disproportionately because they are located on Tribal lands. This paper, largely excerpted from a comprehensive (draft) guidebook released by NREL and MTERA, provides an overview of 13 key regulatory barriers identified through this research, as well as potential short- and long-term solutions. In addition, the paper points to potential pathways for addressing key barriers through case studies highlighting successful Tribal solar projects along with considerations for stakeholders working with Tribes. These resources can support stakeholders in creating meaningful relationships and pursuing workable solar projects.

ENERGY PLANNING, POLICY, AND ECONOMY,SOLAR ENERGY↗

Experimental study of Ar 38 + α reaction cross sections relevant to the Ca 41 abundance in the solar system [Experimental study of Ar 38 + α induced cross sections relevant to the Ca 41 abundance in the solar system]

In massive stars, the 41 Ca(n,α) 38 Ar and 41 K(p,α) 38 Ar reactions have been identified as the key reactions governing the abundance of 41 Ca, which is considered as a potential chronometer for solar system formation. So far, due to experimental limitations, the 41 Ca(n,α) 38 Ar reaction rate is solely based on statistical model calculations. In the present study, we have measured the time-inverse 38 Ar(α,n) 41 Ca and 38 Ar(α,p) 41 K reactions using an active target detector. The reactions were studied in inverse kinematics using a 133-MeV 38 Ar beam and 4 He as the active-gas target. Both excitation functions were measured simultaneously in the energy range of 6.8 ≤ E c.m. ≤ 9.3 MeV. Furthermore by using detailed balance the 41 Ca(n,α) 38 Ar and 41 K(p,α) 38 Ar reaction rates were determined, which suggested a 20% increase in the 41 Ca yield from massive stars.

79 ASTRONOMY AND ASTROPHYSICS↗

The Contribution of Solar Brightening to the US Maize Yield Trend

Predictions of crop yield under future climate change are predicated on historical yield trends1,2,3, hence it is important to identify the contributors to historical yield gains and their potential for continued increase. The large gains in maize yield in the US Corn Belt have been attributed to agricultural technologies4, ignoring the potential contribution of solar brightening (decadal-scale increases in incident solar radiation) reported for much of the globe since the mid-1980s. In this study, using a novel biophysical/empirical approach, we show that solar brightening contributed approximately 27% of the US Corn Belt yield trend from 1984 to 2013. Accumulated solar brightening during the post-flowering phase of development of maize increased during the past three decades, causing the yield increase that previously had been attributed to agricultural technology. Several factors are believed to cause solar brightening, but their relative importance and future outlook are unknown, making prediction of continued solar brightening and its future contribution to yield gain uncertain. Consequently, results of this study call into question the implicit use of historical yield trends in predicting yields under future climate change scenarios.

Matthijs Tollenaar↗

Collaboration to Enable Higher Penetrations of Solar Power Generation Using the Natural Gas Pipeline System for Energy Storage (CRADA CRD-14-00567)

This unique project explored one possible solution for photovoltaic (PV) generation to become a reliable and dispatchable energy resource similar to conventional baseload fossil fuel electricity generation. Solar power generation is a renewable resource that varies naturally from day-to-day as well as seasonally. To use solar power as a baseload generation asset requires a flexible storage system that can recover power on both a daily and seasonal basis. Converting solar power to natural gas (i.e., first to hydrogen and then to methane) and having access to utility-scale storage in the natural gas network has the potential to make solar power generation a baseload asset. This will: 1) Increase the net energy yield from solar resources by increasing the effective capacity factor and maximize the energy produced during the assets’ lifetimes. 2) Improve the economics of energy storage for solar project developers, thereby accelerating the deployment of new solar generation. 3) Reduce the impact of increasing solar penetration on congestion of the electrical transmission system by shifting power delivery in time using the gas pipeline network for long-duration storage. 4) Reduce the impact of increasing solar generation on electrical distribution system control. 5) Offer alternative revenue sources for solar power generation beyond electricity including: hydrogen (H 2 ) production for stationary fuel cells and fuel cell electric vehicles, conversion of carbon dioxide (CO 2 ) to methane (CH 4 ) as a direct drop-in replacement for fossil natural gas use, and transmission as high volumetrically-dense CH 4 for use in transportation, heating, power generation, chemical production or conversion back to H2 at the point of use. Additional work was added to this CRADA in modification 4 having a primary objective to characterize the performance of the electrolyzer, Southern California Gas (SoCalGas) bioreactor and balance of plant to demonstrate production of renewable natural gas (RNG) from renewable H 2 and CO 2 using single-cell, self-replicating organisms. The additional scope of work allowed researchers to ramp up gas flowrates and pressure of the system over the designed range to grow the cells and begin to show the load-following capabilities of this anaerobic gas fermentation process. These activities enabled the research team to predict system performance at much greater scales; namely 10’s of mega-watts (MWs) of electrolyzer nameplate capacity.

14 SOLAR ENERGY↗

Investigation of test methods, material properties, and processes for solar cell encapsulants

Progress in solar energy technology is reported in the following areas: aging and life prediction methodology and devices for solar cell encapsulation; the function of adhesion chemistry, primers, and a new diagnostic technique for estimations of bond durability; a study of fire retardant formulations for decreasing the potential flammability of solar modules; initial studies of the electrical insulating properties of encapsulation materials and measurement of the intrinsic dielectric strength; antisoiling compounds for the prevention of soil build-up on the outer surface of the module; and low temperature processing encapsulants that permit module fabrication at temperatures less than 100 C. Another area of study has been added to determine the degree to which formulation and processes affect the module quality and manufacturing yield.

Willis, P. B.↗

Applicability of solid state microwave technology to solar power satellites

A potential SPS design using antenna mounted GaAs FET's as the basic dc-RF converter is described, together with the rationale of why such a design may represent a viable cost effective complement to current SPS designs using tube type dc-RF converters such as klystrons or crossed field amplifiers. An initial description of a microwave antenna array module is given, together with a concept of how such a module is to be integrated into the SPS overall design. A comparison is made of several such designs using either antenna mounted or solar cell mounted dc-RF converters.

Nalos, E. J.↗

The Potential for Energy Storage to Provide Peaking Capacity in California Under Increased Penetration of Solar Photovoltaics

In this report, we examine the potential for replacing conventional peaking capacity in California with energy storage, including analysis of the changing technical potential with increased storage deployment and the effect of PV deployment. We examine nine years of historic load data, a range of storage durations (2-8 hours), and a range of PV penetration levels (0%-30%). We demonstrate how PV increases the ability of storage to reduce peak net demand. In the scenarios analyzed, the expected penetration of PV in California in 2020 could more than double the potential for 4-hour energy storage to provide capacity services.

14 SOLAR ENERGY↗

Synthesis of Bi{sub 2}S{sub 3} quantum dots for sensitized solar cells by reverse SILAR

Quantum Dot Sensitized Solar cells (QDSSC) have great potential to replace silicon-based solar cells. Quantum dots of various materials and sizes could be used to convert most of the visible light into the electrical current. This paper put emphasis on the synthesis of Bismuth Sulphide quantum dots and selectivity of the anionic precursor by Successive Ionic Layer Adsorption Reaction (SILAR). Bismuth Sulfide (Bi{sub 2}S{sub 3}) (group V – Vi semiconductor) is strong contestant for cadmium free solar cells due to its optimum band gap for light harvesting. Optical, structural and electrical measurements are reported and discussed. Problem regarding the choice of precursor for anion extraction is discussed. Band gap of the synthesized quantum dots is 1.2 eV which does not match with the required energy band gap of bismuth sulfide that is 1.7 eV.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Midmarket Solar Policies in the United States: A Guide for Midsized Solar Customers

The midscale market for solar photovoltaics (PV) has not experienced the same high growth rate as residential- or utility-scale market segments in the past five years when solar PV deployment increased rapidly. Midscale solar can be defined as behind-the-meter solar PV between 50 kilowatts and 2 megawatts adopted by multi-housing residential, commercial, industrial, non-profit, and other entities. A number of challenges face the midscale segment, including difficulties in contracting, mismatch between tenant lease and PV financing terms, high transaction costs relative to project sizes, and inefficiencies in matching prospective projects with capital. The changing policy landscape across U.S. states provides both opportunities and challenges to midmarket solar. Some states, such as California, are expanding system capacity limits for policies such as net metering, thus enabling a wider range of customers to benefit from excess generation. A number of states and utilities are making changes to rate design to introduce new or higher user fees for solar customers or reduced tariffs for net metering, which decrease the value of solar generation. An understanding of these policies relative to project feasibility and economics is important for prospective customers to make informed decisions to adopt solar PV. This guide complements existing solar policy resources to help potential customers navigate through the policy landscape in order to make informed decisions for their solar investment. The first part of this guide introduces the key solar policies necessary for policy-based decision-making, which involves using knowledge of a solar policy to improve project economics and efficiency. Policies that could result in policy-based decisions include interconnection standards, net metering, user fees, incentives, and third-party ownership policies. The goal of this section is to equip prospective customers and project developers with the tools necessary to understand and use solar policies in a dynamic policy environment. The second part of this guide provides a complete, state-by-state inventory of midmarket solar policies for potential customers and developers to use as reference when making policy-based decisions. Although solar policies are dynamic, the profiles provide a framework for assessing policies to build the parameters that could be used to determine feasibility and structure of a solar PV system for midmarket customers and developers.

14 SOLAR ENERGY↗

U.S. Department of Energy Solar District Cup Collegiate Design Competition

The Solar District Cup is a multidisciplinary collegiate competition that challenges student teams to design and model standalone solar and solar-plus-storage systems for multiple buildings on a local electrical distribution network, such as a college campus, across a development, or in a district. Students learn cross-cutting skills that prepare them to become part of the next generation of the distributed energy workforce. Student teams act as renewable energy developers proposing to solar and solar-plus-storage system requests. Students, faculty, and prospective employers can benefit from knowing about this program and what students learn--either immediately as participants, mentors, or judges, or as potential employers of Solar District Cup alumni. RE+ is also one of our competition partners.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Multiscale astrobiology with the Vera C. Rubin Observatory Legacy Survey of Space and Time

The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) presents an unprecedented opportunity to advance the search for astrobiologically relevant data across diverse astronomical environments. Through its extensive imaging capabilities, LSST will enhance our inventory of Solar System objects and assess their potential astrobiological conditions. Beyond the Solar System, LSST will survey billions of stars, contributing to the detection of exoplanets, characterizing planetary atmospheres at a zeroth-order level, identifying transient phenomena, and exploring conditions within habitable zones. In this paper, we highlight LSST’s unique contribution to astrobiology, complementing other missions and expanding the search for life beyond Earth in the coming decades.

79 ASTRONOMY AND ASTROPHYSICS↗

Proposed electromagnetic wave energy converter

Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

Bailey, R. L.↗

The ultraheavy cosmic rays - Propagation and selective acceleration

Results of calculations of ultraheavy cosmic ray propagation are examined in the light of recent observations and theoretical advances with the objective of distinguishing the effects of propagation from nucleosynthesis and preferential acceleration. The results presented here have been calculated by the method described in Margolis (1983), with elements from iron (Z = 26) to uranium (Z = 92) combined in a single calculation. The source abundances of Anders and Ebihara (1982) have been used as a reference composition. It is shown, in particular, that the relative abundances of Sr and Ba are substantially increased by using the modified ionization potential dependence (MIPD) compared with solar abundances and the first ionization potential dependence (FIPD) model. In contrast, Pb shows similar enhancements in both FIPD and MIPD models.

Margolis, S. H.↗

The relationship of the large-scale solar field to the interplanetary magnetic field - What will Ulysses find?

Using photospheric magnetic field observations obtained at the Stanford Wilcox Solar Observatory, results from a potential field model for the present solar cycle are given, and qualitative predictions of the IMF that Ulysses may encounter are presented. Results indicate that the IMF consists of large regions of opposite polarity separated by a neutral sheet (NS) (extended to at least 50 deg) and a four-sector structure near solar minimum (produced by small quadripolar NS warps). The latitudinal extent of the NS increases following minimum and the structure near maximum includes multiple NSs, while a simplified IMF is found during the declining phase.

Hoeksema, J. T.↗

30-kW SEP Spacecraft as Secondary Payloads for Low-Cost Deep Space Science Missions

The Solar Array System contracts awarded by NASA's Space Technology Mission Directorate are developing solar arrays in the 30 kW to 50 kW power range (beginning of life at 1 AU) that have significantly higher specific powers (W/kg) and much smaller stowed volumes than conventional rigid-panel arrays. The successful development of these solar array technologies has the potential to enable new types of solar electric propulsion (SEP) vehicles and missions. This paper describes a 30-kW electric propulsion vehicle built into an EELV Secondary Payload Adapter (ESPA) ring. The system uses an ESPA ring as the primary structure and packages two 15-kW Megaflex solar array wings, two 14-kW Hall thrusters, a hydrazine Reaction Control Subsystem (RCS), 220 kg of xenon, 26 kg of hydrazine, and an avionics module that contains all of the rest of the spacecraft bus functions and the instrument suite. Direct-drive is used to maximize the propulsion subsystem efficiency and minimize the resulting waste heat and required radiator area. This is critical for packaging a high-power spacecraft into a very small volume. The fully-margined system dry mass would be approximately 1120 kg. This is not a small dry mass for a Discovery-class spacecraft, for example, the Dawn spacecraft dry mass was only about 750 kg. But the Dawn electric propulsion subsystem could process a maximum input power of 2.5 kW, and this spacecraft would process 28 kW, an increase of more than a factor of ten. With direct-drive the specific impulse would be limited to about 2,000 s assuming a nominal solar array output voltage of 300 V. The resulting spacecraft would have a beginning of life acceleration that is more than an order of magnitude greater than the Dawn spacecraft. Since the spacecraft would be built into an ESPA ring it could be launched as a secondary payload to a geosynchronous transfer orbit significantly reducing the launch costs for a planetary spacecraft. The SEP system would perform the escape from Earth and then the heliocentric transfer to the science target.

Dawn spacecraft↗

Preliminary calculation of solar cosmic ray dose to the female breast in space mission

No regulatory dose limits are specifically assigned for the radiation exposure of female breasts during manned space flight. However, the relatively high radiosensitivity of the glandular tissue of the breasts and its potential exposure to solar flare protons on short- and long-term missions mandate a priori estimation of the associated risks. A model for estimating exposure within the breast is developed for use in future NASA missions. The female breast and torso geometry is represented by a simple interim model. A recently developed proton dose-buildup procedure is used for estimating doses. The model considers geomagnetic shielding, magnetic-storm conditions, spacecraft shielding, and body self-shielding. Inputs to the model include proton energy spectra, spacecraft orbital parameters, STS orbiter-shielding distribution at a given position, and a single parameter allowing for variation in breast size.

Shavers, Mark↗