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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Improving EV Charger Resiliency for MW Charging Systems

In this paper, the resiliency of a megawatt-scale EV charging station is investigated. Fault detection and tolerance methodologies are presented, based on monitoring the voltage offsets in DABs and switch-level currents in three-phase inverters, with the goal of maintaining operation at rated power during single faults and at reduced power under multiple fault conditions. To validate the effectiveness of the proposed strategy, simulation results at the rated 1 MW power of the charging station are carried out, followed by controller hardware-in-the-loop (CHIL) experiments on a 250 kW section of the station. The results highlight the feasibility of the integrated fault-tolerant methods for resilient, high-power EV charging infrastructure.

Adib, Aswad [ORNL] (ORCID:000000020997056X)↗
DOE OSTI2022

Ensuring a Nuclear Power Plant Safe State Following an EMP Event - Task 7 Deliverable: EMP Testing of Secondary Coupling to Instrumentation Cables

Sandia National Laboratories performed tests to address the potential vulnerability concerns of a coupled High-Altitude Electromagnetic Pulse (HEMP) inducing secondary coupling onto critical instrumentation and control cables in a nuclear power plant, with specific focus on early-time HEMP. Three types of receiving cables in nine configurations were tested to determine transfer functions between two electrically separated cables referenced to the common mode input current on the transmitting cable. One type of transfer function related the input short circuit current and resulting open circuit voltage on the receiving cable. The other transfer function related the input short circuit current and the resulting short circuit current on the receiving cable. A 500 A standard HEMP waveform was input into the transfer functions to calculate peak coupling values on the receiving cables. The highest level of coupling using the standard waveform occurred when cables were in direct contact, with a peak short circuit current of 85 A and open circuit voltage of 9.8 kV, while configurations with separated cables predicted coupling levels of less than 5 A or 500 V.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2026

Anion-exchange membrane water electrolysis: insights from round-robin testing

As research and industrial interest in anion-exchange membrane water electrolysis (AEMWE) grows, there is an increasing need for reliable baselines and cross-lab validation of results. The wide variety of material sets and operating conditions under consideration for AEMWE has thus far limited efforts for standardization. In this study, round-robin testing was conducted in deionized water and KOH-based supporting electrolyte by 5 institutions from academia, national laboratories, and industry to provide baseline performance data and identify sources of cross-lab variability. Baseline membrane electrode assemblies were fabricated with commercial catalysts, membranes, and transport layers using standard techniques and tested using reagent-grade electrolytes, aiming for accessibility rather than state-of-the-art performance. From all tests, the average voltage at 1 A/cm 2 was 2.72 ± 0.17 V and 1.87 ± 0.03 V in deionized water and 0.1 M KOH, respectively. The maximum in-house and cross-lab variations at this current density were 118 mV and 476 mV in water and 60 and 88 mV in 0.1 M KOH. The KOH purity, station contamination, and temperature control were identified as possible factors affecting performance between labs, with in-house specific variation attributed to sample-to-sample differences in fabrication, cell assembly, and station contamination. This work provides a commercial baseline for the field and highlights the need for improved standardization and reproducibility in AEMWE research.

08 HYDROGEN↗
DOE OSTI2021

Preventing Voltage Divergence in Series-Stacked Bidirectional Battery Energy Storage DC-DC Converter under Asymmetrical Operating Conditions

DC stacked topologies have gained popularity for interfacing individual photovoltaic panels to a high-voltage DC bus. A similar approach can be used to interface individual battery packs to the same DC bus, which allows active balancing of battery substrings and the use of lower voltage switches. Any imbalance in battery current, however, can cause the converter output voltages to diverge. This paper describes the source of voltage divergence and demonstrates a solution that allows seamless stacking of multiple battery packs to be interfaced to a high voltage DC bus. To prevent the voltage divergence phenomenon and allow asymmetrical battery charging for efficient battery state of charge management, the PI-based decentralized voltage control enabling both capacitor voltage sharing and asymmetrical capacitor voltage control is proposed. The effectiveness of the decentralized voltage control strategy is demonstrated through controller hardware-in-the-loop test results.

Kim, Namwon↗
DOE OSTI2023

Electrochemical conversion of methane to ethylene, olefins, and paraffins using metal-supported solid oxide cells

Electrochemical oxidative coupling of methane (E-OCM) with Sr 2 Fe 1·5 Mo 0·5 O 6–δ (SFM) catalyst is demonstrated with metal-supported solid oxide cells (MS-SOC). SFM anode and Pr 6 O 11 cathode catalysts are loaded into a porous symmetric-architecture cell by infiltration and firing. The most effective chelating agent (citric acid/ethyl glycol) and optimal firing/reducing temperatures (850 °C/750 °C) for the SFM catalyst precursor solution are selected and confirmed by cell testing. Operating temperature, cell voltage, and oxygen concentration at the cathode greatly affect the methane conversion rate and product selectivity by controlling the oxygen ion flow. CH 4 conversion of 85.8% is obtained, with C 2 H 4 , C 2 H 6 , and H 2 concentrations of 10.5%, 12.3%, and 25.6% at 800 °C, respectively, in the product exhaust gas. Reasonable stability of the current density and methane conversion is demonstrated during 200 h operation. Furthermore, this research demonstrates technical progress in catalyst and device development for the E-OCM reaction to synthesize valuable chemicals.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2020

Ultrathin high- κ antimony oxide single crystals

Ultrathin oxides have been reported to possess excellent properties in electronic, magnetic, optical, and catalytic fields. However, the current and primary approaches toward the preparation of ultrathin oxides are only applicable to amorphous or polycrystalline oxide nanosheets or films. Here, we successfully synthesize high-quality ultrathin antimony oxide single crystals via a substrate-buffer-controlled chemical vapor deposition strategy. The as-obtained ultrathin antimony oxide single crystals exhibit high dielectric constant (~100) and large breakdown voltage (~5.7 GVm -1 ). Such a strategy can also be utilized to fabricate other ultrathin oxides, opening up an avenue in broadening the applicaitons of ultrathin oxides in many emerging fields.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Using AI to predict calibration constants for the central drift chamber in GlueX at Jefferson Lab

The AI for Experimental Controls project team at Jefferson Lab has developed an AI system to control and calibrate a large drift chamber system in near-real time. The AI system will monitor environmental and experimental variables to recommend voltage settings that maintain consistent dE/dx gain and optimal resolution throughout the experiment. At present, calibrations are performed after data have been recorded and require a considerable amount of time and attention from experts. The calibrations currently require multiple iterations and depend on accurate tracking information. Our approach uses environmental data, such as atmospheric pressure and gas temperature, and beam conditions, such as the flux of incident particles, as inputs to a Gaussian Process Regression (GPR) model. For the data taken during the GlueX 2020 run period, the GPR is able to predict the existing gain correction factors to within 3.5%. This talk will briefly describe the development, testing, and future plans for this system at Jefferson Lab.

Jeske, Torri↗
DOE OSTI2022

Observation of Vector Spin Seebeck Effect in a Noncollinear Antiferromagnet

Spintronic phenomena to date have been established in magnets with collinear moments, where the spin injection through the spin Seebeck effect (SSE) is always along the out-of-plane direction. Here, we report the observation of a vector SSE in a noncollinear antiferromagnet (AF) LuFeO 3 , where temperature gradient along the out-of-plane and also the in-plane directions can both inject a pure spin current and generate a voltage in the heavy metal via the inverse spin Hall effect (ISHE). We show that the thermovoltages are due to the magnetization from canted spins in LuFeO 3 . Furthermore, in contrast to the challenges of generating, manipulating, and detecting spin current in collinear AFs, the vector SSE in LuFeO 3 is readily viable in zero magnetic field and can be controlled by a small magnetic field of about 150 Oe at room temperature. Furthermore, the noncollinear AFs expand new realms for exploring spin phenomena and provide a new route to low-field antiferromagnetic spin caloritronics and magnonics.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Fault Clearing Operation in Low-Frequency High-Voltage AC Systems

Abstract—Low-frequency high-voltage ac (LF-HVac) system has been proposed as an alternative to HVdc and HVac systems to reduce transmission losses and improve grid flexibility. LF-HVac system employs back-to-back (BTB) converters to interconnect and control the voltage and power interchange between two power grid operating at different frequencies. While there are multiple studies on LF-HVac system in the literature, the fault clearing method in the LF-HVac system has not been analyzed. Therefore, this paper focuses on fault clearing operation in LFHVac system and proposes a novel method to reduce fault current by changing operating frequency of power source and converter. The performance of the proposed method is validated using detailed models of BTB converters developed in PSCAD/EMTDC. The ability to change operating frequency at the onset of a fault condition allows breakers to rapidly clear the fault and recloses. The results obtained by using the proposed method substantially diminish the fault current.

Kim, Woosung↗
DOE OSTI2023

In-Situ Detection and Prediction of WAAM Cross Feature Geometry

Abstract Wire arc additive manufacturing (WAAM) is increasingly used by manufacturers due to its relatively low cost and high deposition rate compared to other metal AM methods, but the parts produced by WAAM can be subject to localized variations in part quality. One such variation is the cross-feature defect, whereby a localized part height increase occurs due to the crossing of deposition toolpaths. Mitigation of this defect is typically achieved using manual path planning strategies, but closed-loop control is underutilized. Since the nature of this defect and of the WAAM process is such that the previous layer’s geometry influences that of the subsequent layer’s, the cross-feature defect geometry changes throughout the deposition. Therefore, any closed-loop control strategy will need to incorporate the dynamic trait of this defect. The present work seeks to implement an in-situ process modeling approach where a regression model can be continuously updated to predict the defect geometry of the subsequent deposition layer based on the historical process data. Several multi-layer cross-feature geometries are deposited and current, voltage, and optical camera data is taken for each layer. The resulting cross-feature geometries are characterized using 3D scanning and the performance and accuracy of the in-situ modeling approach is evaluated.

Thien, Austen↗
DOE OSTI2021

Optoelectronic memristor devices including one or more solid electrolytes with electrically controllable optical properties

An optoelectronic memristor includes a first electrode, a second electrode, and a solid electrolyte in between that is in electrical communication with the first electrode and the second electrode. The solid electrolyte has an electronic conductivity of about 10 −10 Siemens/cm to about 10 −4 Siemens/cm at room temperature. The first electrode, and optionally the second electrode, can be optically transparent at a specific wavelength and/or a wavelength range. A direct current (DC) voltage source is employed to apply an electric field across the solid electrolyte, which induces a spatial redistribution of ionic defects in the solid electrolyte. In turn, this causes a change in electrical resistance of the solid electrolyte. The application of the electric field can also cause a change in an optical property of the solid electrolyte at the specific wavelength, and/or at the wavelength range (or a portion thereof).

Defferriere, Thomas↗
DOE OSTI2023

1.2-kV Vertical GaN PIN Rectifier With Ion-Implanted Floating Guard Rings

Here, this work reports on the fabrication and properties of a homojunction gallium nitride (GaN) p-i-n (PIN) rectifier fabricated on a free-standing GaN substrate. Uniform device performance is achieved with breakdown voltage (BV) >1.2 kV and low ON-resistance × area ( R ON A ). The statistics of the BV measurements show 58.5% of devices achieve BV >1.3 kV, and 71.1% of devices achieve BV >1.2 kV, as attributed to high quality and control in both epitaxial growth and device process. At room temperature, R ON A is 0.23 mΩ∙ cm 2 at a current density ( J ) of 6.9 kA/cm2. The corresponding Baliga’s figure of merit is >5.97 GW/cm 2 . Temperature-dependent reverse I – V measurements were performed and show a positive temperature coefficient of 0.42 V/K, indicating the avalanche capability of reverse breakdown. Further analysis with the Poole-Frenkel model on the temperature-dependent measurement suggested that a trap-assisted tunneling process contributed to the reverse leakage current. Floating guard rings (FGRs) formed by nitrogen implantation serve as an effective edge termination technique in these GaN PIN rectifiers, resulting in uniform performance in both forward and reverse bias.

42 ENGINEERING↗
DOE OSTI2020

Carbon Support Microstructure Impact on High Current Density Transport Resistances in PEMFC Cathode

Cell voltages at high current densities (HCD) of an operating proton-exchange membrane fuel cell (PEMFC) cathode suffer from losses due to the local-O 2 and bulk-H + transport resistances in the catalyst layer. Particularly, the microstructure of high surface area carbon (HSC) support upon which both the platinum catalyst and ionomer are dispersed play a pivotal role in controlling the reactant transport to the active site in the catalyst layer. In this study, we perform a systematic analysis of the underlying microstructure of platinum-cobalt catalyst dispersed on various HSC supports in terms of their surface area and pore-size distribution. The carbon microstructure was found to strongly influence the PtCo nanoparticle dispersion, catalyst layer ionomer distribution and transport losses governing the performance at HCD. Catalyst layer electrochemical diagnostics carried out to quantify local-O 2 transport resistance and bulk-H + transport resistance in the cathode were found to be directly correlated to the micropore (<2 nm) and macropore (>8 nm) surface areas of the carbon support, respectively. Finally, a 1D-performance model has been developed to assimilate our understanding of the catalyst layer microstructure and transport resistances at HCD.

25 ENERGY STORAGE↗
DOE OSTI2022

The Demonstration of Power over Ethernet (PoE) Technologies in Commercial and Institutional Buildings

Power over Ethernet (PoE) technologies are currently ubiquitous in offices in the form of phones, access points, and IP security cameras. They are systems that are familiar to and managed by on-site IT staff. As low voltage DC-power capabilities have increased with the advancement of IT network switches within offices, PoE devices are now being integrated across additional building systems, including lighting, computers, and HVAC controls. The connection of PoE devices to network switches offers the opportunity for energy monitoring and management to be performed through IT network management software. Data and results from technology validations of PoE equipment remain very limited. This lack of information hinders expansion of PoE as an energy management strategy as its benefits and challenges have been insufficiently quantified in real-world scenarios. This final report presents the findings of a DOE/State of Minnesota-funded project that demonstrated and assessed the energy and non-energy benefits of Power over Ethernet (PoE) technologies at six sites: two offices, three schools, and a hotel. The goals of the demonstrations were to: (1) assess the receptiveness of commercial and institutional markets to these new technologies, (2) demonstrate the feasibility of PoE technologies within standard design/construction practices and commercial codes, (3) assess the energy and cost savings opportunities of these technologies, (4) provide energy management opportunities where not typically available, and (5) formulate approaches to spur adoption of these technologies in the marketplace.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

SiC-Based 5-kV Universal Modular Soft-Switching Solid-State Transformer (M-S4T) for Medium-Voltage DC Microgrids and Distribution Grids

Medium-voltage DC (MVDC) grids are attractive for electric aircraft and ship power systems, battery energy storage system (BESS), fast charging electric vehicle (EV), etc. Such EV or BESS applications need isolated bidirectional MVDC to LVDC or LVAC converters. However, the existing Si-based solutions cannot fulfill the requirements of a high-efficiency and robust converter for MVDC grids. This paper presents a 5 kV SiC-based universal modular solid-state transformer (SST). This universal current-source SST can interface either a LVAC or LVDC grid with a MVDC grid in single-stage power conversion, while the conventional dual active bridge (DAB) converter needs an additional inverter. The proposed SST module using 3.3 kV SiC MOSFETs and diodes is bidirectional and can serve as a building block in series or parallel for higher-voltage higher-power systems. The topology of each module is based on the soft-switching solid-state transformer (S4T) with reduced conduction loss, which features reduced EMI through controlled dv/dt, and high efficiency with full-range ZVS for main devices and ZCS for auxiliary devices. Operation principle of the modular S4T (M-S4T), capacitor voltage balancing control between the cascaded modules, design of components including a medium-voltage (MV) medium-frequency transformer (MFT) to realize a 50 kVA 5 kV DC to 600 V DC or 480 V AC M-S4T are presented. Importantly, the MV MFT prototype achieves very low leakage inductance (0.13%) and 15 kV insulation with coaxial cables and nanocrystalline cores. Here, the proposed universal modular SST is compared against the DAB solution and verified with DC-DC and DC-AC simulation and 4 kV experimental results. Significantly, the MV experimental results of a modular DC transformer with each module at MVDC are rarely covered in the literature and reported for the first time.

14 SOLAR ENERGY↗
DOE OSTI2020

Spin Rectification and Electrically Controlled Spin Transport in Molecular-Ferroelectrics-Based Spin Valves

We report a spin-rectification effect in a spin-valve structure consisting of ferroelectric croconic acid (C 5 H 2 O 5 ) sandwiched between ferromagnetic electrodes La 0.7 Sr 0.3 MnO 3 and Co, which can be switched between a high-resistance (off ) and a low-resistance (on) state by a poling voltage. In the off state, the magnetoresistance (MR) sign reverses with the measurement voltage with a 0.1-V offset, suggesting a spin-rectification behavior, while in the on state the MR remains negative. These observations can be understood in terms of electrically controlled interfacial energy-band alignment either from the electrostatic effect or from the interfacial redox process. In conclusion, the observed spin-rectification effect suggests thepossibility of diodelike devices for spin-polarized current.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Making Better Use of On-Site PV Generation: Direct Distribution of DC Power in Buildings

With the increasing availability of Direct Current (DC) power from on-site solar systems, building designers now have the option of direct distribution of DC power to energy storage systems and end-use loads such as lighting, electronics, and motors. Research shows that direct-DC can reduce building distribution losses by 5-15%, while improving power reliability. A readily available way to implement direct-DC distribution is Power over Ethernet (PoE), which typically has provided low-voltage DC to power office equipment such as WiFi access points. With recent updates to the PoE standard, equipment such as network-controlled LED lighting, thin client and computer workstations, HVAC controllers, fans, motors, and actuators can now be powered by PoE and are commercially available. This paper presents results from a DOE-funded project that is demonstrating PoE technologies and describes a DC modeling and design tool that is intended to help building designers properly evaluate and design DC distribution systems in buildings. The tool provides designers of DC power systems with estimates of both power system losses and indirect effects on building heating and cooling. The results of this research demonstrate that the design methods and products are available to implement DC power in buildings today.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗