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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Diverse electron carriers drive syntrophic interactions in an enriched anaerobic acetate-oxidizing consortium

Abstract In many anoxic environments, syntrophic acetate oxidation (SAO) is a key pathway mediating the conversion of acetate into methane through obligate cross-feeding interactions between SAO bacteria (SAOB) and methanogenic archaea. The SAO pathway is particularly important in engineered environments such as anaerobic digestion (AD) systems operating at thermophilic temperatures and/or with high ammonia. Despite the widespread importance of SAOB to the stability of the AD process, little is known about their in situ physiologies due to typically low biomass yields and resistance to isolation. Here, we performed a long-term (300-day) continuous enrichment of a thermophilic (55 °C) SAO community from a municipal AD system using acetate as the sole carbon source. Over 80% of the enriched bioreactor metagenome belonged to a three-member consortium, including an acetate-oxidizing bacterium affiliated with DTU068 encoding for carbon dioxide, hydrogen, and formate production, along with two methanogenic archaea affiliated with Methanothermobacter_A. Stable isotope probing was coupled with metaproteogenomics to quantify carbon flux into each community member during acetate conversion and inform metabolic reconstruction and genome-scale modeling. This effort revealed that the two Methanothermobacter_A species differed in their preferred electron donors, with one possessing the ability to grow on formate and the other only consuming hydrogen. A thermodynamic analysis suggested that the presence of the formate-consuming methanogen broadened the environmental conditions where ATP production from SAO was favorable. Collectively, these results highlight how flexibility in electron partitioning during SAO likely governs community structure and fitness through thermodynamic-driven mutualism, shedding valuable insights into the metabolic underpinnings of this key functional group within methanogenic ecosystems.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Manipulating the oxygen reduction reaction pathway on Pt-coordinated motifs

Electrochemical oxygen reduction could proceed via either 4e - -pathway toward maximum chemical-to-electric energy conversion or 2e - -pathway toward onsite H 2 O 2 production. Bulk Pt catalysts are known as the best monometallic materials catalyzing O 2 -to-H 2 O conversion, however, controversies on the reduction product selectivity are noted for atomic dispersed Pt catalysts. Here, we prepare a series of carbon supported Pt single atom catalyst with varied neighboring dopants and Pt site densities to investigate the local coordination environment effect on branching oxygen reduction pathway. Manipulation of 2e - or 4e - reduction pathways is demonstrated through modification of the Pt coordination environment from Pt-C to Pt-N-C and Pt-S-C, giving rise to a controlled H 2 O 2 selectivity from 23.3% to 81.4% and a turnover frequency ratio of H 2 O 2 /H 2 O from 0.30 to 2.67 at 0.4 V versus reversible hydrogen electrode. Energetic analysis suggests both 2e - and 4e - pathways share a common intermediate of *OOH, Pt-C motif favors its dissociative reduction while Pt-S and Pt-N motifs prefer its direct protonation into H 2 O 2 . By taking the Pt-N-C catalyst as a stereotype, we further demonstrate that the maximum H 2 O 2 selectivity can be manipulated from 70 to 20% with increasing Pt site density, providing hints for regulating the stepwise oxygen reduction in different application scenarios.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Visible core spectroscopy at Wendelstein 7-X

This paper presents an overview of recent hardware extensions and data analysis developments to the Wendelstein 7-X visible core spectroscopy systems. These include upgrades to prepare the in-vessel components for long-pulse operation, nine additional spectrometers, a new line of sight array for passive spectroscopy, and a coherence imaging charge exchange spectroscopy diagnostic. Progress in data analysis includes ion temperatures and densities from multiple impurity species, a statistical comparison with x-ray crystal spectrometer measurements, neutral density measurements from thermal passive Balmer-alpha emission, and a Bayesian analysis of active hydrogen emission, which is able to infer electron density and main ion temperature profiles.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Prediction of hydration energies of adsorbates at Pt(111) and liquid water interfaces using machine learning

Aqueous phase heterogeneous catalysis is important to various industrial processes, including biomass conversion, Fischer–Tropsch synthesis, and electrocatalysis. Accurate calculation of solvation thermodynamic properties is essential for modeling the performance of catalysts for these processes. Explicit solvation methods employing multiscale modeling, e.g., involving density functional theory and molecular dynamics have emerged for this purpose. Although accurate, these methods are computationally intensive. This study introduces machine learning (ML) models to predict solvation thermodynamics for adsorbates on a Pt(111) surface, aiming to enhance computational efficiency without compromising accuracy. In particular, ML models are developed using a combination of molecular descriptors and fingerprints and trained on previously published water–adsorbate interaction energies, energies of solvation, and free energies of solvation of adsorbates bound to Pt(111). These models achieve root mean square error values of 0.09 eV for interaction energies, 0.04 eV for energies of solvation, and 0.06 eV for free energies of solvation, demonstrating accuracy within the standard error of multiscale modeling. Feature importance analysis reveals that hydrogen bonding, van der Waals interactions, and solvent density, together with the properties of the adsorbate, are critical factors influencing solvation thermodynamics. Furthermore, these findings suggest that ML models can provide rapid and reliable predictions of solvation properties. This approach not only reduces computational costs but also offers insights into the solvation characteristics of adsorbates at Pt(111)–water interfaces.

Adsorption↗
DOE OSTI2024

Secondary structure determines electron transport in peptides

Proteins play a key role in biological electron transport, but the structure–function relationships governing the electronic properties of peptides are not fully understood. Despite recent progress, understanding the link between peptide conformational flexibility, hierarchical structures, and electron transport pathways has been challenging. Here, we use single-molecule experiments, molecular dynamics (MD) simulations, nonequilibrium Green’s function-density functional theory (NEGF-DFT), and unsupervised machine learning to understand the role of secondary structure on electron transport in peptides. Our results reveal a two-state molecular conductance behavior for peptides across several different amino acid sequences. MD simulations and Gaussian mixture modeling are used to show that this two-state molecular conductance behavior arises due to the conformational flexibility of peptide backbones, with a high-conductance state arising due to a more defined secondary structure (beta turn or 3 10 helices) and a low-conductance state occurring for extended peptide structures. These results highlight the importance of helical conformations on electron transport in peptides. Conformer selection for the peptide structures is rationalized using principal component analysis of intramolecular hydrogen bonding distances along peptide backbones. Molecular conformations from MD simulations are used to model charge transport in NEGF-DFT calculations, and the results are in reasonable qualitative agreement with experiments. Projected density of states calculations and molecular orbital visualizations are further used to understand the role of amino acid side chains on transport. Overall, our results show that secondary structure plays a key role in electron transport in peptides, which provides broad avenues for understanding the electronic properties of proteins.

Science & Technology - Other Topics↗
DOE OSTI2021

Structure and mechanism of Staphylococcus aureus oleate hydratase (OhyA)

Flavin adenine dinucleotide (FAD)-dependent bacterial oleate hydratases (OhyAs) catalyze the addition of water to isolated fatty acid carbon–carbon double bonds. Staphylococcus aureus uses OhyA to counteract the host innate immune response by inactivating antimicrobial unsaturated fatty acids. Mechanistic information explaining how OhyAs catalyze regiospecific and stereospecific hydration is required to understand their biological functions and the potential for engineering new products. In this study, we deduced the catalytic mechanism of OhyA from multiple structures of S. aureus OhyA in binary and ternary complexes with combinations of ligands along with biochemical analyses of relevant mutants. The substrate-free state shows Arg81 is the gatekeeper that controls fatty acid entrance to the active site. FAD binding engages the catalytic loop to simultaneously rotate Glu82 into its active conformation and Arg81 out of the hydrophobic substrate tunnel, allowing the fatty acid to rotate into the active site. FAD binding also dehydrates the active site, leaving a single water molecule connected to Glu82. This active site water is a hydronium ion based on the analysis of its hydrogen bond network in the OhyA•PEG400•FAD complex. We conclude that OhyA accelerates acid-catalyzed alkene hydration by positioning the fatty acid double bond to attack the active site hydronium ion, followed by the addition of water to the transient carbocation intermediate. Structural transitions within S. aureus OhyA channel oleate to the active site, curl oleate around the substrate water, and stabilize the hydroxylated product to inactivate antimicrobial fatty acids.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

$\rm {H\,\small {I}}$ constraints from the cross-correlation of eBOSS galaxies and Green Bank Telescope intensity maps

We present the joint analysis of Neutral Hydrogen ($\rm {H\,\small {I}}$) Intensity Mapping observations with three galaxy samples: the Luminous Red Galaxy (LRG) and Emission Line Galaxy (ELG) samples from the eBOSS survey, and the WiggleZ Dark Energy Survey sample. The $\rm {H\,\small {I}}$ intensity maps are Green Bank Telescope observations of the redshifted $21\rm cm$ emission on $100 \, {\rm deg}^2$ covering the redshift range 0.6 < z < 1.0. We process the data by separating and removing the foregrounds present in the radio frequencies with FastI ICA. We verify the quality of the foreground separation with mock realizations, and construct a transfer function to correct for the effects of foreground removal on the $\rm {H\,\small {I}}$ signal. We cross-correlate the cleaned $\rm {H\,\small {I}}$ data with the galaxy samples and study the overall amplitude as well as the scale dependence of the power spectrum. We also qualitatively compare our findings with the predictions by a semianalytical galaxy evolution simulation. The cross-correlations constrain the quantity $\Omega _{\rm {H\,\small {I}}} b_{\rm {H\,\small {I}}} r_{\rm {H\,\small {I}},{\rm opt}}$ at an effective scale k eff , where $\Omega _\rm {H\,\small {I}}$ is the $\rm {H\,\small {I}}$ density fraction, $b_\rm {H\,\small {I}}$ is the $\rm {H\,\small {I}}$ bias, and $r_{\rm {H\,\small {I}},{\rm opt}}$ the galaxy–hydrogen correlation coefficient, which is dependent on the $\rm {H\,\small {I}}$ content of the optical galaxy sample. At $k_{\rm eff}=0.31 \, h\,{\rm Mpc^{-1}}$ we find $\Omega _{\rm {H\,\small {I}}} b_{\rm {H\,\small {I}}} r_{\rm {H\,\small {I}},{\rm Wig}} = [0.58 \pm 0.09 \, {\rm (stat) \pm 0.05 \, {\rm (sys)}}] \times 10^{-3}$ for GBT-WiggleZ, $\Omega _{\rm {H\,\small {I}}} b_{\rm {H\,\small {I}}} r_{\rm {H\,\small {I}},{\rm ELG}} = [0.40 \pm 0.09 \, {\rm (stat) \pm 0.04 \, {\rm (sys)}}] \times 10^{-3}$ for GBT-ELG, and $\Omega _{\rm {H\,\small {I}}} b_{\rm {H\,\small {I}}} r_{\rm {H\,\small {I}},{\rm LRG}} = [0.35 \pm 0.08 \, {\rm (stat) \pm 0.03 \, {\rm (sys)}}] \times 10^{-3}$ for GBT-LRG, at z ≃ 0.8. We also report results at $k_{\rm eff}=0.24$ and $k_{\rm eff}=0.48 \, h\,{\rm Mpc^{-1}}$. With little information on $\rm {H\,\small {I}}$ parameters beyond our local Universe, these are amongst the most precise constraints on neutral hydrogen density fluctuations in an underexplored redshift range.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Numerical calculation of Coulomb corrections in forward elastic 𝑝↑⁢𝑝 and 𝑝↑⁢𝐴 scattering

The analysis of RHIC hydrogen gas jet target polarimeter measurements of transverse analyzing powers 𝐴 N ⁡(𝑡) in proton-nucleus scattering requires accurate Coulomb corrections to both spin-flip and nonflip amplitudes. These corrections must cover a wide range of nuclear charges 𝑍 and form factor slopes, with flexibility to vary form factors during data fitting. To avoid technically challenging calculations involving a small but finite fictitious photon mass, the Coulomb correction to the nonflip electromagnetic amplitude with an exponential form factor was related to the corresponding correction for the spin-flip amplitude. This approach allows soft photon contributions to all amplitudes, including those with nonexponential form factors, to be calculated in the massless photon limit using only analytical expressions and numerically stable integrals with nonsingular integrands and finite integration limits. In addition, an absorptive correction to the spin-flip electromagnetic amplitude, which plays a critical role in spin effects in forward polarized proton-nucleus scattering, was accurately evaluated.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Transitions between Rydberg states in two-color corotating circularly polarized laser pulses

We present a study of higher-order Raman (Λ, V, and S) transitions between Rydberg states involving the absorption and emission of at least three photons in the interaction of two-color corotating circularly polarized laser pulses with the hydrogen atom. Our analysis is based on results of numerical solutions of the corresponding time-dependent Schrödinger equation. Here, the results for the interaction with (ω,2ω) fields show that the simultaneous interaction with both fields results in an excited state distribution over a broad range of magnetic quantum numbers. Indications of the impact of the Λ, V, and S transitions are found via the analysis of final distributions resulting from the preparation of the atom in specific Rydberg states. Furthermore, we show that similar mechanisms for the redistribution of population between Rydberg states are present in two-color fields with larger differences in the central frequencies, i.e., (ω,3ω) and (ω,4ω) fields.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2023

Status Update on NETL Techno-Economic Analysis of Solid Oxide Cells

This is a presentation delivered at the Solid Oxide Fuel Cell Project Review Meeting portion of the 2023 FECM / NETL Spring R&D Project Review Meeting on April 19, 2023. The presentation highlights recently completed techno-economic analysis of solid oxide cell systems including a brief overview of pairing SOFC technology with energy storage, an analysis of the tradeoffs associated with reversible SOC technology versus paired SOFC/SOEC, and highlights of the recently released NGFC and IGFC pathway studies. A more detailed description of analysis conducted on hydrogen fueled SOFC systems is also included.

Hackett, Gregory↗
DOE OSTI2022

Exploring the potential of hydrogen in decarbonizing China's light-duty vehicle market

The Chinese government has pledged to achieve overall carbon neutrality by 2060. Currently, the transportation sector contributes to about 10% of total greenhouse gas (GHG) emissions in China. Hence, China has created a well-defined energy vehicle development strategy to reduce GHG emissions from the transportation sector, further expanding into hydrogen vehicle technologies. In this study, the Transportation Energy Analysis Model (TEAM) investigates the potential of hydrogen internal combustion engine vehicles (H2- ICEVs) and fuel cell vehicles (FCEVs) as a reliable pathway towards the government's aspiration of carbon neutrality in the transportation sector. According to TEAM, by adopting FCEVs and H2-ICEVs in the vehicle market, hydrogen demand could reach 25% of the total light-duty transportation energy demand in 2050. Consequently, this will lead to an annual reduction of more than 35 million tons GHG compared to only counting on the electrification pathway in the decarbonization task. Besides, FCEVs would take longer to penetrate the light-duty vehicle market compared to H2-ICEVs, as the current fuel cell technology still requires much improvement to attain a competitive vehicle cost of production.

Life cycle analysis↗
DOE OSTI2023

Availability Estimates of Low-Cost, Dispatch-Constrained Electricity (LDE)

This dataset accompanies the report "Potential Availability of and Supply Curves for Low-Cost, Dispatch-Constrained Electricity", which provides initial estimates of the quantity and availability of the potential low-cost, dispatch-constrained electricity (LDE) resource in the United States under scenarios with high variable renewable energy (VRE) penetrations. The analysis also estimates supply curves that can be used in subsequent analysis of the opportunity to use the LDE. The estimated LDE resource could be used for various applications that value low-cost electricity and can operate at reduced capacity factors, including electrolytic hydrogen production and carbon capture. The analysis accompanying this dataset was performed in 2018-2019 to support an analysis of "The Technical and Economic Potential of the H2@Scale Concept within the United States" ( https://www.nlr.gov/docs/fy21osti/77610.pdf ). This dataset includes the quantity of estimated LDE resource for each hour of the year in 2050, aggregated to both the national level and the ReEDS balancing area level. As described in the accompanying report, the ReEDS model was used to project the evolution of the power sector over time. Links to the mapping of ReEDS balancing areas to states and ReEDS balancing area shape files are provided. This dataset also includes the report figure data.

08 HYDROGEN↗
DOE OSTI2024

Quantification of Hydrogen Isotopes Utilizing Raman Spectroscopy Paired with Chemometric Analysis for Application across Multiple Systems

On-line and real-time analysis of a chemical process is a major analytical challenge that can drastically change the way the chemical industry or chemical research operates. With in situ analyses, new and powerful understanding of chemistry can be gained; however, building robust tools for long-term monitoring faces many challenges that include compensating for instrument drift, instrument replacement, and sensor or probe replacement. Accounting for these changes by recollecting calibration data and rebuilding quantification models can be costly and time consuming. Here, in this study, methods to overcome these challenges are demonstrated with an application of Raman spectroscopy to monitoring hydrogen isotopes with varied speciation within dynamic gas streams. Specifically, chemical data science tools such as chemometric modeling are leveraged along with several examples of calibration transfer approaches. Furthermore, the optimization of instrument and sensors cell parameters for targeted gas phase analyses is discussed. While the particular focus on hydrogen is highly beneficial within the nuclear energy sector, mechanisms built and demonstrated here are widely applicable to optical spectroscopy monitoring in numerous other chemical systems that can be leveraged in other hazardous processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Technoeconomic Analysis of Steel Production with Electric Thermal Energy Storage

The iron and steel industry is an important manufacturing sector and one of the largest energy consumers in the United States and globally. Hydrogen direct reduction of iron ore (H2DRI) is considered a promising process that could enhance domestic steel production. This process requires hydrogen inlet temperatures up to 950 degrees C to drive the endothermic reduction of the iron ore pellets. In this work we investigate the technoeconomic performance of an H2DRI plant using electric thermal energy storage (ETES) technologies for the hydrogen heating, compared to conventional natural gas fired heaters, hydrogen fired heaters, and electric hydrogen heaters. A technoeconomic analysis framework for the plant is developed and used in multiple case studies, covering different hydrogen prices, grid electricity profiles, and financing scenarios. The levelized cost of steel production is found out to be in the range of $775-950/mt, which is mostly inside the benchmarked steel price of $941/mt. ETES-based hydrogen heating is found to be in par with conventional natural gas fired heaters, and cheaper than hydrogen fired heaters and electric hydrogen heaters. The major cost drivers are the iron ore and hydrogen feedstock, followed by the hydrogen compression and heating capital. Several insights and suggested future directions are identified.

08 HYDROGEN↗
DOE OSTI2020

Empirically verified analysis of dual pre-cooling system for hydrogen refuelling station

The dual cooling system at the California State University Los Angeles Hydrogen Research and Fueling Facility is analysed to predict the output hydrogen temperature in different ambient conditions. Initially, the facility was built with a coil chiller T20 cooling, sufficient for occasional fuelings. A flat plate evaporator system was added in series to resolve any issues for multiple fuelings even in the hottest weather. This study was commenced to verify the set points and determine the control requirements for the dual setup in order to inform future designs. A numerical-empirical model of the cooling system was developed by reverse engineering, using the station experimental measurements and database records. The subsystems are characterized separately but validated as a whole system imposing specific and standard operating conditions. The cooling model is tested with different inputs to validate the pre-set parameter variation of the cooling components. Ten scenarios were investigated to evaluate the fueling output parameters, testing two hydrogen temperature input trends (according to the facility initial conditions) and five ambient temperatures (from 15 °C to 35 °C). In closing, the simulation results have confirmed that the hydrogen output temperature remains within the range imposed by the SAE J2601 for each scenario studied, around -22 °C and -25 °C.

08 HYDROGEN↗