Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “favorability”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

DEEPEN 3D PFA Favorability Models and 2D Favorability Maps at Newberry Volcano

DEEPEN stands for DE-risking Exploration of geothermal Plays in magmatic ENvironments. Part of the DEEPEN project involved developing and testing a methodology for a 3D play fairway analysis (PFA) for multiple play types (conventional hydrothermal, superhot EGS, and supercritical). This was tested using new and existing geoscientific exploration datasets at Newberry Volcano. This GDR submission includes images, data, and models related to the 3D favorability and uncertainty models and the 2D favorability and uncertainty maps. The DEEPEN PFA Methodology is based on the method proposed by Poux et al. (2020), which uses the Leapfrog Geothermal software with the Edge extension to conduct PFA in 3D. This method uses all available data to build a 3D geodata model which can be broken down into smaller blocks and analyzed with advanced geostatistical methods. Each data set is imported into a 3D model in Leapfrog and divided into smaller blocks. Conditional queries can then be used to assign each block an index value which conditionally ranks each block's favorability, from 0-5 with 5 being most favorable, for each model (e.g., lithologic, seismic, magnetic, structural). The values between 0-5 assigned to each block are referred to as index values. The final step of the process is to combine all the index models to create a favorability index. This involves multiplying each index model by a given weight and then summing the resulting values. The DEEPEN PFA Methodology follows this approach, but split up by the specific geologic components of each play type. These components are defined as follows for each magmatic play type: 1. Conventional hydrothermal plays in magmatic environments: Heat, fluid, and permeability 2. Superhot EGS plays: Heat, thermal insulation, and producibility (the ability to create and sustain fractures suitable for and EGS reservoir) 3. Supercritical plays: Heat, supercritical fluid, pressure seal, and producibility (the proper permeability and pressure conditions to allow production of supercritical fluid) More information on these components and their development can be found in Kolker et al., 2022. For the purposes of subsurface imaging, it is easier to detect a permeable fluid-filled reservoir than it is to detect separate fluid and permeability components. Therefore, in this analysis, we combine fluid and permeability for conventional hydrothermal plays, and supercritical fluid and producibility for supercritical plays. More information on this process is described in the following sections. We also project the 3D favorability volumes onto 2D surfaces for simplified joint interpretation, and we incorporate an uncertainty component. Uncertainty was modeled using the best approach for the dataset in question, for the datasets where we had enough information to do so. Identifying which subsurface parameters are the least resolved can help qualify current PFA results and focus future efforts in data collection. Where possible, the resulting uncertainty models/indices were weighted using the same weights applied to the respective datasets, and summed, following the PFA methodology above, but for uncertainty. There are two different versions of the Leapfrog model and associated favorability models: - v1.0: The first release in June 2023 - v2.1: The second release, with improvements made to the earthquake catalog (included additional identified events, removed duplicate events), to the temperature model (fixed a deep BHT), and to the index models (updated the seismicity-heat source index models for supercritical and EGS, and the resistivity-insulation index models for all three play types). Also uses the jet color map rather than the magma color map for improved interpretability. - v2.1.1: Updated to include v2.0 uncertainty results (see below for uncertainty model versions) There are two different versions of the associated uncertainty models: - v1.0: The first release in June 2023 - v2.0: The se...

15 GEOTHERMAL ENERGY↗
DOE OSTI2024

DEEPEN: Final 3D PFA Favorability Models and 2D Favorability Maps at Newberry Volcano

Part of the DEEPEN (DE-risking Exploration of geothermal Plays in magmatic ENvironments) project involved developing and testing a methodology for a 3D play fairway analysis (PFA) for multiple play types (conventional hydrothermal, superhot EGS, and supercritical). This was tested using new and existing geoscientific exploration datasets at Newberry Volcano. This GDR submission includes images, data, and models related to the 3D favorability and uncertainty models and the 2D favorability and uncertainty maps. The DEEPEN PFA Methodology, detailed in the journal article below, is based on the method proposed by Poux & O'brien (2020), which uses the Leapfrog Geothermal software with the Edge extension to conduct PFA in 3D. This method uses all available data to build a 3D geodata model which can be broken down into smaller blocks and analyzed with advanced geostatistical methods. Each data set is imported into a 3D model in Leapfrog and divided into smaller blocks. Conditional queries can then be used to assign each block an index value which conditionally ranks each block's favorability, from 0-5 with 5 being most favorable, for each model (e.g., lithologic, seismic, magnetic, structural). The values between 0-5 assigned to each block are referred to as index values. The final step of the process is to combine all the index models to create a favorability index. This involves multiplying each index model by a given weight and then summing the resulting values. The DEEPEN PFA Methodology follows this approach, but split up by the specific geologic components of each play type. These components are defined as follows for each magmatic play type: 1. Conventional hydrothermal plays in magmatic environments: Heat, fluid, and permeability 2. Superhot EGS plays: Heat, thermal insulation, and producibility (the ability to create and sustain fractures suitable for and EGS reservoir) 3. Supercritical plays: Heat, supercritical fluid, pressure seal, and producibility (the proper permeability and pressure conditions to allow production of supercritical fluid) More information on these components and their development can be found in Kolker et al., (2022). For the purposes of subsurface imaging, it is easier to detect a permeable fluid-filled reservoir than it is to detect separate fluid and permeability components. Therefore, in this analysis, we combine fluid and permeability for conventional hydrothermal plays, and supercritical fluid and producibility for supercritical plays. We also project the 3D favorability volumes onto 2D surfaces for simplified joint interpretation, and we incorporate an uncertainty component. Uncertainty was modeled using the best approach for the dataset in question, for the datasets where we had enough information to do so. Identifying which subsurface parameters are the least resolved can help qualify current PFA results and focus future efforts in data collection. Where possible, the resulting uncertainty models/indices were weighted using the same weights applied to the respective datasets, and summed, following the PFA methodology above, but for uncertainty.

15 GEOTHERMAL ENERGY↗
DOE OSTI2023

Edge radiated temperature fluctuations across confinement regime transitions in favorable and unfavorable drift configurations at ASDEX Upgrade

Abstract The physics behind the difference in heating power threshold for the low to high confinement (L–H) transition between favorable ion B × ∇ B drift (toward active X -point) and unfavorable ion B × ∇ B drift (away from active X -point) magnetic configurations is a longstanding open question. In this work we show differences in edge ( ρ p o l = 0.95 –1.0) turbulence in matched heating power favorable and unfavorable magnetic configuration discharges using a correlation electron cyclotron emission diagnostic to measure radiated temperature ( T r a d ) fluctuations. During power matched L-mode phases, the edge T r a d fluctuations have higher amplitude in the unfavorable configuration plasma as compared to the favorable configuration plasma. The lower fluctuation amplitude in favorable configuration is observed concomitant with increased E × B shear, as compared to the unfavorable case. Although this turbulence is different in amplitude, it is similar in radial and frequency structure between favorable and unfavorable configurations and grows to the weakly coherent mode during the I-mode phase of the unfavorable configuration discharge. A broadband pedestal fluctuation is seen during an inter-ELM H-mode period of the favorable configuration discharge.

Physics↗
DOE OSTI2025

Machine learning guided search for energetically favorable metal borocarbide ternary compounds

In this work, we employ machine-learning (ML) combined with first principles calculations to efficiently search for the energetically favorable metal borocarbide (M-B-C) ternary compounds with M being the group 1–3 metal elements. Using a crystal graph convolutional neural network (CGCNN) ML approach followed by first-principles calculations, we predicted 47 energetically favorable stable and metastable ternary Na-B-C, Ca-B-C, and La-B-C ternary compounds with their decomposition energy (E d ) below or within 100 meV/atom from the currently known convex hulls. Phonon spectra and electronic structures of the 14 energetically favorable stable structures are also investigated by first-principles calculations. By substituting the metal atoms in the 29 energetically favorable non-equivalent template structures of Na (Ca, La)-B-C with other group 1–3 elements in the periodic table, we further obtain 22 stable structures and 52 metastable structures (E d ≤100 meV/atom with respect to the known convex hulls) for Li-B-C, K-B-C, Rb-B-C, Mg-B-C, Sr-B-C, Ba-B-C, Sc-B-C and Y-B-C ternary compounds. New convex hulls including our newly predicted stable ternary structures and the known stable structures are constructed for the M-B-C systems. The results obtained by our ML guided first-principles calculations enrich our knowledge in the structure and energy landscape of metal borocarbide ternary compounds and provide useful guidance for further experimental synthesis and discovery.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Current data are consistent with flat spatial hypersurfaces in the Λ CDM cosmological model but favor more lensing than the model predicts

Here, we study the performance of three pairs of tilted, and a pair of untilited, ΛCDM cosmological models, with three of these four pairs allowing for non-flat spatial hypersurfaces, against cosmic microwave background (CMB) temperature and polarization power spectrum data (P18), measurements of the Planck 2018 lensing potential power spectrum (lensing), and a large compilation of non-CMB data (non-CMB). For the eight models, we measure cosmological parameters and study whether or not pairs of the data sets (as well as subsets of them) are mutually consistent in these models. Half of these models allow the lensing consistency parameter A L , which re-scales the gravitational potential power spectrum, to be an additional free parameter to be determined from data, while the other three have A L = 1 which is the theoretically expected value. The pair of untilted non-flat ΛCDM models are incompatible with P18 data. The tilted spatially-flat models assume the usual primordial spatial inhomogeneity power spectrum that is a power law in wave number. The tilted non-flat models assume either the primordial power spectrum used in the Planck group anal yses [Planck P(q)], that has recently been numerically shown to be a good approximation to what is quantum-mechanically generated from a particular choice of closed inflation model initial conditions, or a recently computed power spectrum [new P(q)] that quantum-mechanically follows from a different set of non-flat inflation model initial conditions. In the tilted non-flat models with A L = 1 we find differences between P18 data and non-CMB data cosmological parameter constraints, which are large enough to rule out the Planck P(q) model at 3σ but not the new P(q) model. No significant differences are found when cosmological parameter constraints obtained with two different data sets are compared within the standard tilted flat ΛCDM model. While both P18 data and non-CMB data separately favor a closed geometry, with spatial curvature density parameter Ω k < 0, when P18+non-CMB data are jointly analyzed the evidence in favor of non-flat hypersurfaces subsides. Differences between P18 data and non-CMB data cosmological constraints subside when A L is allowed to vary. From the most restrictive P18+lensing+non-CMB data combination we get almost model-independent constraints on the cosmological parameters and find that the A L > 1 option is preferred over the Ω k < 0 one, with the A L parameter, for all models, being larger than unity by ~ 2.5σ. According to the deviance information criterion, in the P18+lensing+non-CMB analysis, the varying A L option is on the verge of being strongly favored over the A L = 1 one, which could indicate a problem for the standard tilted flat ΛCDM model. These data are consistent with flat spatial hypersurfaces but more and better data could improve the constraints on Ω k and might alter this conclusion. Error bars on some cosmological parameters are significantly reduced when non-CMB data are used jointly with P18+lensing data. For example, in the tilted flat ΛCDM model for P18+lensing+non-CMB data the Hubble constant H 0 = 68.09 ± 0.38 km s -1 Mpc -1 , which is consistent with that from a median statistics analysis of a large compilation of H 0 measurements as well as with a number of local measurements of the cosmological expansion rate. This H 0 error bar is 31% smaller than that from P18+lensing data alone.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

Chemical trends favoring interstitial cluster formation in bcc high-entropy alloys from first-principles calculations

Achieving high strength and ductility is a common goal in structural alloy design. Body-centered cubic high-entropy alloys (HEAs) commonly highlight the conflict between these properties, with stronger alloys being brittle and vice versa. Recent reports suggest interstitial solutes can be used to overcome this trade-off, in some cases providing both strength and ductility enhancements. This effect has been correlated with interstitial cluster formation, although the conditions favoring their formation remain incompletely understood. Using first-principles calculations of solution energies and diffusivities, we provide insights into thermodynamic and kinetic factors favoring interstitial solute clusters. Among C, N and O solutes, O interstitials display most desirable diffusion kinetics. Further, the results highlight the importance of local composition fluctuations in the HEAs to enable the formation of clusters of appreciable size. The results are explained in terms of bonding and distortion trends across solutes and HEA compositions to provide guidelines for alloy design.

Borges, Pedro P P O↗
DOE OSTI2023

CO 2 electroreduction favors carbon isotope 12 C over 13 C and facilitates isotope separation

We discovered that CO 2 electroreduction strongly favors the conversion of the dominant isotope of carbon ( 12 C) and discriminates against the less abundant, stable carbon 13 C isotope. Both absorption of CO 2 in the alkaline electrolyte and CO 2 electrochemical reduction favor the lighter isotopologue. As a result, the stream of unreacted CO 2 leaving the electrolyzer has an increased 13 C content, and the depletion of 13 C in the product is several times greater than that of photosynthesis. Using a natural abundance feed, we demonstrate enriching of the 13 C fraction to ~1.3% (i.e., +18%) in a single-pass reactor and propose a scalable and economically attractive process to yield isotopes of a commercial purity. Our finding opens pathways to both cheaper and less energy-intensive production of stable isotopes ( 13 C, 15 N) essential to the healthcare and chemistry research, and to an economically viable, disruptive application of electrolysis technologies developed in the context of sustainability transition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Creating Favorable Pt/Co Interfaces via a Two‐Step Approach for Constructing Highly Durable PtCo Intermetallic Fuel Cell Catalysts

Structurally ordered PtCo intermetallics are one of the most promising oxygen-reduction catalysts in proton exchange membrane fuel cells (PEMFCs) due to their intrinsically improved catalytic activity and stability relative to PtCo solid-solution alloys. However, increasing the heating temperature to achieve a desirable high degree of ordering results in severe particle agglomeration and low mass activity and stability. Herein, a two-step synthesis approach is developed to create an L1 2 -Pt 3 Co intermetallic structure with an increased ordering degree and well-dispersed ultrafine particles. The first step of the synthesis yields ultrafine Pt nanoparticles that are well-dispersed on the ZIF-8-derived carbon support. The second adsorption step enables us to fine-tune the Pt and Co interfaces, assisted by optimal amino acids, to establish a favorable Co-rich environment around fine Pt nanoparticles, facilitating Co diffusion into the Pt crystalline under mild thermal conditions (<800 °C). In conclusion, this two-step ordered L1 2 -Pt 3 Co catalyst is systematically evaluated using membrane electrode assemblies under heavy-duty vehicle (HDV) conditions and demonstrated exceptional performance and durability, retaining 1.35 A cm -2 only a 7% loss in current density at 0.7 V after an extensive accelerated stress test of 150,000 voltage cycles.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2021

Flavor SU(3) in Cabibbo-favored D -meson decays

Model-independent description of nonleptonic decays of charmed mesons is a challenging task due to large nonperturbative effects of strong interactions on the transition amplitudes. We discuss the equivalence of two different flavor-SU(3)-based descriptions of Cabibbo-favored non-leptonic decays of charmed mesons to two-pseudoscalars final states including the η and η' mesons.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Observations of the Cabibbo-Suppressed decays $Λ^{+}_{c}$ → $\mathcal{n}$$π$ + $π$ 0 , $\mathcal{n}$$π$ + $π$ - $π$ + and the Cabibbo-Favored decay $Λ^{+}_{c}$ → $\mathcal{n}$$K$ - $π$ + $π$ + *

Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb -1 , collected by the BESIII detector in the energy region between $4599.53$ $MeV$ and $4698.82$ $MeV$ we report the first observations of the Cabibbo-suppressed decays $Λ^{+}_{c}$ → $\mathcal{n}$$π$ + $π$ 0 , $Λ^{+}_{c}$ → $\mathcal{n}$$π$ + $π$ - $π$ + , and the Cabibbo-favored decay $Λ^{+}_{c}$ → $\mathcal{n}$$K$ - $π$ + $π$ + with statistical significances of $7.9σ$, $7.8σ$, and Misplaced &, respectively. The branching fractions of these decays are measured to be $\mathcal{B}$($Λ^{+}_{c}$ → $\mathcal{n}$$π$ + $π$ 0 ) = ($0.64 ± 0.09 ± 0.02$)%, $\mathcal{B}$($Λ^{+}_{c}$ → $\mathcal{n}$$π$ + $π$ - $π$ + ) = ($0.45 ± 0.07 ± 0.03$)%, and $\mathcal{B}$ $Λ^{+}_{c}$ → $\mathcal{n}$$K$ - $π$ + $π$ + ) = ($1.90 ± 0.08 ± 0.09$)% where the first uncertainties are statistical and the second are systematic. We find that the branching fraction of the decay $Λ^{+}_{c}$ → $\mathcal{n}$$π$ + $π$ 0 is about one order of magnitude higher than that of $Λ^{+}_{c}$ → $\mathcal{n}$ $π$ + .

$Λ^{+}_{c}$ baryon↗
DOE OSTI2021

Progress toward favorable landscapes in quantum combinatorial optimization

The performance of variational quantum algorithms relies on the success of using quantum and classical computing resources in tandem. Here, we study how these quantum and classical components interrelate. In particular, we focus on algorithms for solving the combinatorial optimization problem MaxCut, and study how the structure of the classical optimization landscape relates to the quantum circuit used to evaluate the MaxCut objective function. In order to analytically characterize the impact of quantum features on the critical points of the landscape, we consider a family of quantum circuit ansätze composed of mutually commuting elements. We identify multiqubit operations as a key resource and show that overparameterization allows for obtaining favorable landscapes. Namely, we prove that an ansatz from this family containing exponentially many variational parameters yields a landscape free of local optima for generic graphs. However, we further prove that these ansätze do not offer superpolynomial advantages over purely classical MaxCut algorithms. Here, we then present a series of numerical experiments illustrating that noncommutativity and entanglement are important features for improving algorithm performance.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

A High-Ceramic-Loading LATP–PVDF–Al 2 O 3 Composite Film for Lithium-Ion Batteries With Favorable Porous Microstructure and Enhanced Thermal Stability

A separator plays a crucial role in a Li-ion battery to carry liquid electrolytes while preventing short-circuiting between electrodes. Nevertheless, conventional commercial separators often exhibit poor wettability and are prone to shrink at elevated temperatures due to their limited thermal stability. Herein, we report a heat-resistant LATP–PVDF–Al 2 O 3 composite film with outstanding wetting performance. The thin film was prepared using ball mill mixing and tape-casting processes. Two solvents, NMP and glycerol, were applied to prepare the slurry, and a favorable microstructure in the film was created after drying. Here, the ionic conductivity of the film was tested at 1.39 mS cm –1 when paired with liquid electrolyte, almost double that of the commercial counterpart. The high ceramic loading of 70% improved both the thermal shrinkage resistance and dendrite inhibition of the membrane. When assembled in an NMC half-cell, the cycling capacity retentions of 92.8% and 92.1% are achieved after 50 cycles at 0.5 C and 1 C, demonstrating its capability to be used in Li-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

Identifying Regions Favorable for Geothermal Heating and Cooling Storage

Space heating and cooling represents the single largest category of in building energy use for U.S. residential and commercial buildings, with heating representing 61% of residential and 46% commercial energy consumption. Building heating technologies are dominated by natural gas technologies, and are an important opportunity for building electrification to enable a transition to a low CO 2 energy system. FLXenabler study is a joint analysis effort among multiple analysis teams at NREL and focused on examining the role of geothermal heating and cooling (GHC) system with thermal energy storage (TES) providing flexibility. Utilizing information from ResStock the amount of energy consumption associated with heating and cooling by state was calculated. We applied adjusted load shapes to estimate the a maximum grid savings potential of using TES to address building space conditioning. Normalizing grid, fuel, and emissions impacts locations with higher favorability for further study in FLXenabler were identified.

15 GEOTHERMAL ENERGY↗
DOE OSTI2024

Accelerating CO2 Storage Site Characterization through a New Understanding of Favorable Formation Properties and the Impact of Core-Scale Heterogeneities

CO2 sequestration in deep geologic formations can permanently reduce atmospheric CO2 emissions and help to abate climate change. Target formations must undergo a time- and resource-intensive site evaluation process, assessing storage capacity, environmental safety, and suitability for CO2 trapping via reactive transport models based on data from a limited number of core samples. As such, simulations are often simplified and omit heterogeneities in formation properties that may be significant but are not well understood. To facilitate more rapid site assessment, this work first defines the aquifer properties of favorable storage formations through the analysis of promising and active storage sites. Data show quartz is the most prevalent formation mineral with carbonate minerals, highly reactive with injected CO2, present in over 75% of formations. Porosity and permeability data are highly clustered at 10–30% and 10–1000 mD. Field-scale reactive transport simulations are then constructed and used to analyze CO2 trapping efficiency. The models consider porosity and carbonate mineral heterogeneity as well as the impacts of typical temperature gradients. Simulated sequestration efficiencies are compared to results from a comparable homogenous model to understand the implications of aquifer non-uniformities. The results show a lower sequestration efficiency in the homogeneous model during the injection phase. During the post-injection phase, the homogenization of porosity and carbonate mineralogy results in a higher sequestration efficiency. Incorporating the temperature gradient also increases the sequestration efficiency. Importantly, the maximum deviation between the homogeneous and heterogeneous simulations at the end of the 50-year study period is only ~10%. Larger impacts may be incurred for properties outside the defined, promising ranges suggested here.

Environmental Sciences & Ecology↗
DOE OSTI2024

Multifrequency Analysis of Favored Models for the Messier 87* Accretion Flow

Abstract The polarized images of the supermassive black hole Messier 87* (M87*) produced by the Event Horizon Telescope (EHT) provide a direct view of the near-horizon emission from a black hole accretion and jet system. The EHT theoretical analysis of the polarized M87* images compared thousands of snapshots from numerical models with a variety of spins, magnetization states, viewing inclinations, and electron energy distributions, and found a small subset consistent with the observed image. In this article, we examine two models favored by EHT analyses: a magnetically arrested disk with moderate retrograde spin and a magnetically arrested disk with high prograde spin. Both have electron distribution functions that lead to strong depolarization by cold electrons. We ray trace five snapshots from each model at 22, 43, 86, 230, 345, and 690 GHz to forecast future very long baseline interferometry (VLBI) observations and examine limitations in numerical models. We find that even at low frequencies where optical and Faraday rotation depths are large, approximately rotationally symmetric polarization persists, suggesting that shallow depths dominate the polarization signal. However, morphology and spectra suggest that the assumed thermal electron distribution is not adequate to describe emission from the jet. We find 86 GHz images show a ringlike shape determined by a combination of plasma and spacetime imprints, smaller in diameter than recent results from the Global mm-VLBI Array. We find that the photon ring becomes more apparent with increasing frequency, and is more apparent in the retrograde model, leading to large differences between models in asymmetry and polarization structure.

Astronomy & Astrophysics↗
DOE OSTI2021

Can magnetogenesis driven by dynamo instabilities in chiral fermion plasmas, favor Einstein–Cartan AdS cosmology?

In this letter we show that the magnetic field (MF) bounds induced by Einstein–Cartan–de Sitter (EC) with AdS anti-de Sitter spacetime geometry and fermionic torsion with chiral dynamo plasmas instabilities, with inhomogeneous uniform chiral chemical potential, indicates that there is a possibility, as far as magnetogenesis is concerned, that we may obtain more stringent results within ECAdS gravity, compared with general relativity (GR) limits obtained by Tsagas using torsionless magnetogenesis. Spinorial fermionic source with torsion induces a chiral plasmas oscillation. The time dependent chiral chemical potential, sometimes associated formally with torsion, (de Andrade, 2018), is obtained from chiral flipping equation. The MFs obtained from the present universe ECdS chiral dynamo model, meet the criteria of galactic seed fields with better limits within Tsagas range (Tsagas, 2015) seed galactic magnetic fields for dynamo mechanisms, than the bound obtained by chiral dynamos in torsionless AdS cosmology. Majorana neutrinos are used as spatial components of axial spin-torsion source of dynamo instability from neutrino asymmetry.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Formation of hydrocarbons favored by high pressure at subduction zone conditions

Subduction zones enable carbon transport to the deep Earth. Inorganic and organic carbon in fluids released from the subducted slab are important in water-rock interactions. However, the potential role of reduced carbon species in fluids during subduction is still unclear. In particular, the pressure, temperature, and oxidation state conducive to the formation of fluid hydrocarbons are poorly understood. Here we focused on the role of pressure influencing the formation of hydrocarbons using diamond anvil cell experiments starting with 0.5 M Ca-acetate solutions over a broad range of pressures, from 1.6 to 4.6 GPa at temperatures of 300 and 350°C. Droplets of immiscible hydrocarbon fluid coexisting with aqueous carbonate or bicarbonate and crystals of calcite or aragonite were formed at peak pressure and temperature conditions in the experiments. Furthermore, greater quantities of hydrocarbons formed at higher pressure as revealed by measuring the in situ volume percent of the droplets. Measurement of the in situ Raman spectra of the co-existing aqueous solutions and analysis of the peak area ratios of acetate to HCO 3 – showed faster decrease at higher pressure, which indicated that the reactions forming hydrocarbons were accelerated by pressure. Compared to previous Na-acetate experiments at 300°C and 3.0 GPa, this study found hydrocarbons that were more methane-rich and had more propane and less isobutane. In experiments at 350°C, isobutane transformed to one or more aromatic hydrocarbons in an immiscible fluid. The air-dried aromatic hydrocarbons were measured using a UV laser, and show peaks of bitumen. Overall, our study supports the hypothesis that high pressures and high temperatures facilitate the possible occurrence of immiscible hydrocarbon fluids in the deep carbon cycle.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗