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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Monolithically Integrated $\varepsilon$-Ge/In x Ga 1-x As Quantum Well Laser Design: Experimental and Theoretical Investigation

Here, we have analyzed the electrical and optical phenomenon occurring in a $\varepsilon$-Ge/In x Ga 1-x -Ge/In x Ga 1-x As quantum well (QW) laser through self-consistent physical solvers calibrated using in-house experimental results. A separate confinement heterostructure QW design is proposed to enable lasing from tensile strained germanium ($\varepsilon$-Ge/In x Ga 1-x -Ge) in the range of 1.55 um to 4 um wavelengths as a function of QW thickness and indium (In) composition. Different recombination mechanisms were analyzed as a function of tensile strain in $\varepsilon$-Ge/In x Ga 1-x -Ge QW. Minority carrier lifetime and band alignment are key attributes of a QW laser, which were measured using microwave photoconductive decay and x-ray photoelectron spectroscopy (as a function of In composition), respectively. The transition point of Ge to a direct bandgap material is re-affirmed to be at $\varepsilon$-Ge/In x Ga 1-x = 1.6% (In ~24%) and the transition from type I to type II for $\varepsilon$-Ge/In x Ga 1-x -Ge/In x Ga 1-x As QW is found to be at In ~55%. Also, the transition to a TM mode dominant laser is identified at In ~15%. Using a tunable waveguide design to optimize confinement as a function of In composition, strain, wavelength, QW thickness, refractive index, and geometry, the $\varepsilon$-Ge/In x Ga 1-x -Ge QW laser design provided a net material gain of ~2000 cm -1 and a threshold current density of ~5 kA/cm 2 , which is an improvement over existing Ge based lasers. In conclusion, the impact of In composition and QW thickness on the band structure, polarized gain spectra, and various lasing metrics were analyzed to show $\varepsilon$-Ge/In x Ga 1-x -Ge/InGaAs QW lasers as promising for integrated photonics.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Well‐to‐wheels analysis of greenhouse gas emissions for passenger vehicles in Middle East and North Africa

Battery electric vehicles (BEVs) are widely considered a pathway to achieve low carbon mobility. BEVs emit zero emissions from the tailpipe, but their life cycle carbon reduction compared to gasoline vehicles varies based on primary energy sources, electricity generation, and use efficiency. The Middle East and North Africa (MENA) region is an area rich in fossil fuels, meriting a detailed comparison between the emissions from BEV and other powertrains. We developed a MENA‐specific life cycle model that estimates well‐to‐wheel (WTW) greenhouse gas (GHG) emissions from passenger transport with internal combustion engine vehicles (ICEVs), hybrid electric vehicles (HEVs), plug‐in hybrid electric vehicles, and BEVs. MENA's average WTW GHG emissions for all supply chain steps including combustion emissions from vehicle operation are 767 g/kWh and 84 g CO 2 eq/MJ for electricity and gasoline, respectively, but are highly variable due to heterogeneity in upstream supply chains. The use of hybrid gasoline ICEVs provides the largest emission reduction opportunity for existing vehicle fleets in 9 of the 16 MENA countries. For these nine countries, replacing gasoline ICEVs with HEVs could, on average, reduce country‐level life cycle GHG emissions by 47%. There is a similar emission reduction opportunity for 14 of the 16 MENA countries when normalizing vehicle efficiencies irrespective of the powertrain shares and other trends in existing vehicle fleets. Future scenario analysis shows that BEVs would have the lowest WTW GHG emissions among all powertrains in most MENA countries only if significantly reduced electricity transmission losses and cleaner grid mix are realized, although a high cost of infrastructure developments is expected.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

Design of InGaN-ZnSnGa 2 N 4 quantum wells for high-efficiency amber light emitting diodes

A novel type-II InGaN-ZnSnGa 2 N 4 quantum well (QW) structure is proposed based on recent experimental achievements for the successful epitaxy of ZnSnN 2 -GaN alloys and the determination of their band offsets with GaN. The simulation results indicate that this structure is promising as the active region for high-efficiency InGaN-based amber (λ ~ 590 nm) light-emitting diodes (LEDs). The hole wavefunction in the valence band is better confined with the insertion of a monolayer scale of ZnSnGa 2 N 4 into the InGaN QW while the electron wavefunction in the conduction band is better confined with the incorporation of an AlGaN layer in the GaN quantum barrier. The band structure of the InGaN-ZnSnGa 2 N 4 QW is numerically simulated based on the experimentally measured band offsets between ZnSnGa 2 N 4 and GaN. With the InGaN-ZnSnGa 2 N 4 QW design, a low In content (20%) is required in the InGaN layer to reach a peak emission wavelength of ~590 nm, yet an In composition of 25% is needed to reach the same emission wavelength for a conventional InGaN QW with the same layer thicknesses. Moreover, the electron-hole wavefunction overlap (Гe1-hh1) for the InGaN-ZnSnGa 2 N 4 QW design reaches 18% for an emission wavelength at ~590 nm. This result is much improved over the conventional InGaN QW overlap of 5% emitting at the same wavelength. The increase in electron-hole wavefunction overlap results in an approximately 14 times enhancement in the predicted spontaneous emission radiative recombination rate of the InGaN-ZnSnGa 2 N 4 QW as compared to that of the conventional InGaN QW. This InGaN-ZnSnGa 2 N 4 QW structure design can be promising to pave a new way to achieve high efficiency amber LEDs.

42 ENGINEERING↗
DOE OSTI2022

Optimization of InGaN quantum well interfaces for fast interwell carrier transport and low nonradiative recombination

Efficient high-power operation of light emitting diodes based on InGaN quantum wells (QWs) requires rapid interwell hole transport and low nonradiative recombination. The transport rate can be increased by replacing GaN barriers with that of InGaN. Introduction of InGaN barriers, however, increases the rate of the nonradiative recombination. In this work, we have attempted to reduce the negative impact of the nonradiative recombination by introducing thin GaN or AlGaN interlayers at the QW/barrier interfaces. The interlayers, indeed, reduce the nonradiative recombination rate and increase the internal quantum efficiency by about 10%. Here, the interlayers do not substantially slow down the interwell hole transport; for 0.5 nm Al 0.10 Ga 0.90 N interlayers the transport rate has even been found to increase. Another positive feature of the interlayers is narrowing of the QW PL linewidth, which is attributed to smoother QW interfaces and reduced fluctuations of the QW width.

carrier transport↗
DOE OSTI2023

Utah FORGE: Well 16B(78)-32 Core Photographs

This dataset includes images of core samples collected from Utah FORGE well 16B(78)-32. The images are stitched photographs showing the circumferential view of the cores exterior in two dimensions and the individual photos of the core taken at multiple angles used to construct the stitched photos.

15 GEOTHERMAL ENERGY↗
DOE OSTI2023

Utah FORGE: Neubrex Well 16B(78)-32 Circulation Test Fiber Optics Monitoring Data and Reports - July, 2023

This dataset features Distributed Acoustic Sensing (DAS) and fiber optics monitoring data acquired by Neubrex Energy Services during the Utah FORGE Well 16B(78)-32 circulation test in July 2023. DAS and fiber optic monitoring data include absolute strain, strain change, strain change rate, distributed temperature sensing (DTS), and frequency band extraction (FBE). Data processing was completed between September and October 2023. The dataset includes the fiber optic sensing data collected during these operations, along with a data collection report, descriptions of the data, and instructions for reading the data files.

15 GEOTHERMAL ENERGY↗
DOE OSTI2024

Utah FORGE: Wells 16A(78)-32 and 16B(78)-32 Circulation Test Daily Reports from August 2024

These are the daily reports created during and around the August 2024 circulation test done on wells 16A(78)-32 and 16B(78)-32 at the Utah FORGE site. Information about the rig activity during this period includes details on rig up, depths, pumping, water temperature, safety, and cleanout. The reports span all rig activities from July 29th, 2024 through September 5th, 2024.

15 GEOTHERMAL ENERGY↗
DOE OSTI2024

Utah FORGE: Well 16A(78)-32 Perforation Images and Raw Data

This archive contains raw data of visual and acoustic mapping of perforations in Utah FORGE well 16A(78)-32 acquired during the August 2024 circulation program. The dataset includes downhole images captured by EV, a downhole visual analytics company, providing visual records of each perforation. Images are organized in two folders: one set with perforation visualization overlays and one without. An included Excel spreadsheet provides the organized raw data.

15 GEOTHERMAL ENERGY↗
DOE OSTI2025

Surface water and groundwater FTICR-MS, NPOC, and TN from nine wetlands and three upland wells at the Tanglewood Biological Station, Alabama

This dataset supports a broader study examining wetland hydrobiogeochemical responses to flood disturbance and the subsequent impacts on watershed nutrient export. The study was designed following ICON (integrated, coordinated, open, and networked) principles. Samples were collected from nine wetlands and three upland wells at the Tanglewood Biological Station, Alabama in August 2024 and February 2025, during the dry and wet season, respectively. The contents include geochemistry (dissolved organic carbon measured as non-purgeable organic carbon; total dissolved nitrogen) and organic matter characterization (FTICR-MS). Related water level data from the same locations can be found at https://data.ess-dive.lbl.gov/view/doi:10.15485/2530253. Additional geochemistry will be published in a separate data package. For details on how to navigate this data package, see this infographic from the River Corridor SFA https://data.ess-dive.lbl.gov/portals/PNNLRiverCorridorSFA/About. In addition to a readme, this data package also includes a file-level metadata (FLMD) file that describes each file and a data dictionary (DD) that describes all column/row headers and variable definitions.This dataset is comprised of (1) a folder containing environmental context photos; (2) file-level metadata; (3) data dictionary; (4) field metadata; (5) readme; (6) international generic sample number (IGSN) mapping file; (7) the field protocol; and (8) a subfolder with sample data. The sample data subfolder contains (1) dissolved organic carbon (DOC, measured as non-purgeable organic carbon, NPOC) data and averages; (2) total nitrogen data and averages; (3) methods codes; and (4) a subfolder of 12 Tesla (12T) Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) data. All files are .csv, .pdf, .jpeg, or .jpg.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Citizen Green #1 Well: Drilling, Deviation, Mud, Whole Core, and Observation Logs

This submission includes drilling logs, mud log, deviation survey, site observation notes, and whole core scans from the Citizen Green #1 well drilled on King Island, CA (API 07720688) as part of the WESTCARB partnership basin characterization effort. These datasets were gathered by JAF but created and compiled by a variety of WESTCARB operations team members and contractors including Sandia Resources, Stratagraphic Corp, John Henry Beyer, Paul Graham Drilling, and Core Labs.

Core CT↗
DOE OSTI2022

ML4Geo: Machine Learning based Well Design to Enhance Unconventional Energy Production

This project aimed at using artificial intelligence and machine learning methods to improve oil and gas operations. On the machine learning front, this focused on the development of differentiable programming methods that are relevant in this application area, such as incorporating physical simulations into machine learning workflows. On the oil and gas front, the focus was on optimizing well performance.

02 PETROLEUM↗
DOE OSTI2021

Hydrophobic Lightweight Cement with Thermal Shock Resistance and Thermal Insulating Properties for Energy-Storage Geothermal Well Systems

This study assessed the possibility of using polymethylhydrosiloxane (PMHS)-treated fly ash cenospheres (FCS) for formulating a thermally insulating and thermal shock (TS)-resistant cementitious blend with calcium aluminate cement. To prevent FCS degradation in an alkaline cement environment at high temperatures, the cenospheres were pre-treated with sodium metasilicate to form silanol and aluminol groups on their surface. These groups participated in a dehydrogenation reaction with the functional ≡Si–H groups within PMHS with the formation of siloxane oxygen-linked M-FCS (M: Al or Si). At high hydrothermal temperatures of 175 and 250 °C, some Si–O–Si and SiCH 3 bonds ruptured, causing depolymerization of the polymer at the FCS surface and hydroxylation of the raptured sites with the formation of silanol groups. Repolymerization through self-condensation between the silanol groups followed, resulting in the transformation of siloxane to low crosslinked silicon-like polymer as a repolymerization-induced product (RIP) without carbon. The RIP provided adequate protection of FCS from pozzolanic reactions (PR), which was confirmed by the decline in zeolites as the products of PR of FCS. Cements with PMHS-treated FCS withstood both hydrothermal and thermal temperature of 250 °C in TS tests, and they also showed improved compressive strength, toughness, and water repellency as well as decreased thermal conductivity. The lubricating properties of PMHS increased the fluidity of lightweight slurries.

15 GEOTHERMAL ENERGY↗
DOE OSTI2024

Volumetric carrier injection in InGaN quantum well light emitting diodes

InGaN/GaN quantum well (QW) light emitting diodes (LEDs) are essential components of solid-state lighting and displays. However, the efficiency of long wavelength (green to red) devices is inferior to that of blue LEDs. To a large degree, this occurs because the equilibration of injected holes between multiple QWs of the active region is hindered by GaN quantum confinement and polarization barriers. This drawback could be overcome by volumetric hole injection into all QWs through semipolar QWs present on the facets of V-defects that form at threading dislocations in polar GaN-based structures. In this work, we have tested the viability of this injection mechanism and studied its properties by time-resolved and near-field spectroscopy techniques. Here, we have found that indeed the hole injection via the V-defects does take place, the mechanism is fast, and the hole spread from the V-defect is substantial, making this type of injection feasible for efficient long wavelength GaN LEDs.

InGaN/GaN quantum wells↗
DOE OSTI2024

Grid Resilience Analysis on Geothermal District Heating and Cooling Implementation Alongside Four Existing Oil and Gas Wells in Tuttle, Oklahoma: Preprint

This study builds on the existing techno-economic and environmental life cycle assessments performed for a geothermal district heating and cooling system implementation in Tuttle Oklahoma with four existing oil and gas wells. Its resilience in meeting the peak annual heating and cooling loads of the district assuming a temporary disconnection from the electrical grid is assessed both qualitatively and quantitatively. Attributes of resilience and qualitative criteria established by Kolker et al. (2022) for geothermal district heating systems are applied to the proposed case to highlight its vulnerabilities. Results indicate that increasing the redundancy and diversity in the physical configuration of the distributional piping can considerably increase the system’s resilience. A quantitative assessment executed via the REopt tool predicts that the ancillary electricity required to power the geothermal system’s heating and cooling can be met by an onsite emergency diesel generator during times of grid outages for over 28 days.

district heating and cooling↗
DOE OSTI2025

Grid Resilience Analysis on Geothermal District Heating and Cooling Implementation Alongside Four Existing Oil and Gas Wells in Tuttle, Oklahoma

This study builds on the existing techno economic and environmental life cycle assessments performed for a geothermal district heating and cooling system implementation in Tuttle Oklahoma with four existing oil and gas wells. Its resilience in meeting the peak annual heating and cooling loads of the district assuming a temporary disconnection from the electrical grid is assessed both qualitatively and quantitatively. Attributes of resilience and qualitative criteria established by Kolker et al. (2022) for geothermal district heating systems are applied to the proposed case to highlight its vulnerabilities. Results indicate that increasing the redundancy and diversity in the physical configuration of the distributional piping can considerably increase the system's resilience. A quantitative assessment executed via the REopt tool predicts that the ancillary electricity required to power the geothermal system's heating and cooling can be met by an onsite emergency diesel generator during times of grid outages for over 28 days.

district heating and cooling↗
DOE OSTI2021

Risk-based area of review estimation in overpressured reservoirs to support injection well storage facility permit requirements for CO 2 storage projects

This paper by the Energy & Environmental Research Center presents a workflow and modeling approach for delineating a risk-based area of review (AOR) to support a U.S. Environmental Protection Agency (EPA) Class VI permit for a carbon dioxide (CO 2 ) storage project. The approach combines semianalytical solutions for estimating formation fluid leakage through a hypothetical leaky wellbore with the results of numerical reservoir simulations to define the AOR. The modeling utilizes 1) semianalytical solutions from the peer-reviewed literature for formation fluid leakage through abandoned wellbores by Raven (1990) and Avci (1994), 2) a FORTRAN model compiled and described in Cihan et al. (2011, 2012) called ASLMA (Analytical Solution for Leakage in Multilayered Aquifers), and 3) a computational framework for estimating a risk-based AOR first proposed by Oldenburg et al. (2014, 2016). Therefore, the approach builds upon well-established research and underlying hydrogeological principles that have been upheld for nearly three decades. Moreover, the ASLMA model has been broadly applied to an array of storage projects. The work presented herein extends these earlier works using a custom wrapper written in the software environment, R (R Core Team, 2020), which was developed to perform multiple runs of the ASLMA model using given ranges for one or more input parameters. In addition, the current work simulates the pressure buildup within the storage reservoir in response to CO 2 injection using a compositional simulator to better accommodate the temporospatial evolution of pressure buildup within the storage reservoir that is more accurately modeled using a heterogeneous geologic model and a compositional simulator that accounts for the multiphase interactions. The workflow is demonstrated using a case study for a 180,000-metric-ton-per-year storage project located in the PCOR (Plains CO 2 Reduction) Partnership region. For the storage project evaluated here, under the scenario where the leaky wellbore is open to a saline aquifer (thief zone) between the overlying seal (cap rock) and the underground sources of drinking water (USDW), the risk-based AOR essentially collapses to the areal extent of the CO 2 plume in the storage reservoir because the pressure buildup in the storage reservoir beyond the CO 2 plume is insufficient to drive formation fluids up a hypothetical leaky wellbore into the USDW. However, even under the conservative assumption that the leaky wellbore is not open to a thief zone, beyond the areal extent of the CO 2 plume, the incremental leakage is less than 400 m 3 over 20 years, which represents ~0.0001% or less of the total volume of water contained within the USDW rock volume. As discussed in the text, the threshold criterion for defining the risk-based AOR is site-specific and should be informed by the results of the sensitivity analysis and available site characterization data. The approach outlined in this paper is designed to be protective of USDWs and, therefore, comply with the Safe Drinking Water Act requirements and provisions for the U.S. EPA Class VI Underground Injection Control (UIC) Program (Class VI Rule) and North Dakota Administrative Code Chapter 43-05-01.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

1,4-cineole: a bio-derived solvent for highly stable graphene nanoplatelet suspensions and well-dispersed UHMWPE nanocomposite fibers

The exceptional properties of carbon nanoparticles, such as graphene, promise to expand the performance and functionality of many materials. The reinforcement of polymers is of keen interest due to their low density and flexible manufacturing methods. However, dispersing graphene in them has proven to be an enduring challenge due to the particles’ propensity to form performance degrading agglomerations. Furthermore, effective solvents for nanoparticle dispersion are commonly harmful, non-renewable, petrochemicals. In this work, a bio-derived solvent, 1,4-cineole, is demonstrated as a renewable alternative to these solvents that can be used to form highly stable graphene nanoplatelet (GnP) suspensions and used to gel spin well-dispersed UHMWPE/GnP nanocomposite fibers. The GnP concentration in the fibers was varied across three orders of magnitude, 0.01 wt% to 1 wt%, to examine its effect on fiber microstructure and properties. At low concentrations the particles act as point defects without affecting the fiber microstructure, and poor particle/matrix interfacial adhesion results in significantly reduced mechanical properties. At 1 wt% GnPs, a network effect takes hold thereby reinforcing the fibers, but the particles also impede the growth and orientation of crucial load-carrying crystalline structures in the fiber. Furthermore, unveiling the microstructural effects of GnPs on highly oriented and crystalline polymers in this study provides crucial insights for future work developing high-performance polymer nanocomposite fibers.

36 MATERIALS SCIENCE↗