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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Characterization of Natural Consolidated Halloysite Nanotube Structures

Halloysite is a unique 1:1 clay mineral frequently appearing with nanotubular morphology, and having surfaces of different polarity with interesting and important technological applications. HNTs can be consolidated naturally in the earth by pressure and thermal flows. In this study of natural consolidated HNTs, the strength and hardness of these materials were found to be dependent on the presence of impurities (gibbsite, alunite, quartz, and other silica minerals), which accounted for the increased stability of such samples. In the absence of impurities, the strength of consolidated HNTs was significantly lower. The first 3D mapping of the pore structure of natural consolidated HNT is provided. The contributions of the porosity within the nanotubes and between the nanotubes were delineated using a combination of non-invasive ultra-small and small-angle X-ray scattering (USAXS/SAXS) analyses, BET/BJH pore size analyses, and computed tomography studies. A total porosity of 40%, as determined by X-ray attenuation and He porosimetry, was found for the natural consolidated HNTs, of which about one-third was due to the inter-HNT porosity. Nano-X-ray computed tomography (nano-XCT) analyses also indicated that 76% of the inter-HNT pores were smaller than 150 nm in diameter. The intra-HNT pore size determined by combined USAXS/SAXS and BET/BJH was about 10 nm. This pore network information is essential for the utilization of natural consolidated HNTs as a model geomaterial to investigate the effects of surface characteristics on confined fluid flow.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Nature-GL: A Revolutionary Learning Paradigm Unleashing Nature’s Power in Real-World Spatial-Temporal Graph Learning

Spatial-Temporal Graph Learning (ST-GL) is a prominent research area due to its unique capability to effectively learn real-world graphs. Applications of ST-GL pose stringent and various demands on not only real-time inference with low energy cost and high ac- curacy but also fast training. Unfortunately, as Moore’s Law approaches its limits and ST-GL model complexity drastically grows, the gap between digital hardware’s computational power and ST- GL application demands is widening. In response, this paper introduces Nature-GL, a nature-powered graph learning paradigm that exploits the principle of entropy increase to advance graph learning. In particular, Nature-GL transforms both the training and inference of real-valued ST-GL into electron-speed natural anneal- ing processes of a parameterized dynamical system that represents the target graphs. Experimental results across four real-world ap- plications with six datasets demonstrate that Nature-GL achieves orders-of-magnitude speedups in both training and inference, delivering higher accuracy compared to Graph Neural Networks.

Liu, Chuan [University of Rochester]↗
DOE OSTI2017

Aggregation control in natural brush-printed conjugated polymer films and implications for enhancing charge transport

Shear-printing of electroactive polymers using natural brushes is a promising film deposition technique for printed electronics capable of microstructure control and electrical properties enhancement over large areas. Nevertheless, the interplay between film printing parameters, microstructure development, and charge transport is not well-understood. We report that natural brush-printing greatly enhances charge transport by as much as 5.7× through control of polymer nanofibril aggregate growth and backbone alignment, attributable to the oriented squamae of the natural hair. However, while brush shear-induced aggregation enhances charge transport, we show that backbone alignment alone does not guarantee charge transport anisotropy. These results provide additional understanding of shear-induced enhanced charge transport and set processing guidelines for high-performance printed organic circuitry.

natural brush-printing↗
DOE OSTI2025

Economic and environmental performance of biomass gasification for renewable natural gas production in the context of the U.S. natural gas supply

Bioenergy technologies offer potential for reducing greenhouse gas (GHG) emissions. One such promising technology is biomass gasification, which is the conversion of biomass into renewable natural gas (RNG) for use with a natural gas combined-cycle power generation system. However, the associated economic and emission effects need to be better understood to enable optimal decision-making and avoid missed opportunities for enhancing efficiency and increasing system circularity. This analysis explores opportunities to (1) decarbonize natural-gas-based systems and (2) leverage the extensive US natural gas infrastructure to mobilize biomass resources to achieve environmental and economic benefits. Here, in this analysis, the research team used a spatially explicit biomass logistics model (integrated with relevant biomass availability, technoeconomic analysis, and life cycle assessment information) to simulate economically optimal biomass allocation for RNG production and use for decarbonization in the United States. Results show that the United States has the potential to produce 9203 million GJ of RNG within the expected range of $\$$12–30/GJ. Further analyses tested the overall RNG production system's sensitivity to economic and emissions parameters of nine different processes. The sensitivity analysis results indicate that the median carbon abatement cost of RNG is most sensitive to changes in emissions associated with conversion processes and land use changes. These findings provide a deeper understanding of RNG's economic and emission potential for decision-making and guiding future research.

09 BIOMASS FUELS↗
DOE OSTI2019

Characterizing Regional Methane Emissions from Natural Gas Liquids Unloading

A “bottom-up” probabilistic model was developed using engineering first-principles to quantify annualized throughput normalized methane emissions (TNME) from natural gas liquid unloading activities for 18 basins in the United States in 2016. For each basin, six discrete liquid-unloading scenarios are considered, consisting of combinations of well types (conventional and unconventional) and liquid-unloading systems (nonplunger, manual plunger lift, and automatic plunger lift). While previous work has advocated that operational malfunctions and abnormal process conditions explain the existence of super-emitters in the natural gas supply chain, this work finds that super-emitters can arise naturally due to variability in underlying component processes. Additionally, average cumulative methane emissions from liquids unloading, attributed to the natural gas supply chain, across all basins are ~4.8 times higher than those inferred from the 2016 Greenhouse Gas Reporting Program (GHGRP).

Zaimes, George G.↗
DOE OSTI2015

Review of Sector and Regional Trends in U.S. Electricity Markets. Focus on Natural Gas. Natural Gas and the Evolving U.S. Power Sector Monograph Series. Number 1 of 3

This study explores dynamics related to natural gas use at the national, sectoral, and regional levels, with an emphasis on the power sector. It relies on a data set from SNL Financial to analyze recent trends in the U.S. power sector at the regional level. The research aims to provide decision and policy makers with objective and credible information, data, and analysis that informs their discussions of a rapidly changing energy system landscape. This study also summarizes regional changes in natural gas demand within the power sector. The transition from coal to natural gas is occurring rapidly along the entire eastern portion of the country, but is relatively stagnant in the central and western regions. This uneven shift is occurring due to differences in fuel price costs, renewable energy targets, infrastructure constraints, historical approach to regulation, and other factors across states.

03 NATURAL GAS↗
DOE OSTI2016

Novel poly(imide dioxime) sorbents: Development and testing for enhanced extraction of uranium from natural seawater

We synthesized a new series of amidoxime-based polymer adsorbents at the Oak Ridge National Laboratory (ORNL) by electron beam induced grafting of acrylonitrile and itaconic acid onto polyethylene fiber. We also demonstrate hydroxylamine derivatives of poly(acrylonitrile) (PAN) moiety to possess two kinds of functional groups: open-chain amidoxime and cyclic imide dioxime. The open-chain amidoxime is shown to convert to imide dioxime on heat treatment in the presence of an aprotic solvent, like dimethylsulfoxide (DMSO). Furthermore, the formation of amidoxime and imide dioxime was confirmed by 13C CP-MAS spectra. The adsorbents were evaluated for uranium adsorption efficiency at ORNL with simulated seawater spiked with 8 ppm uranium and 5 gallon seawater in a batch reactor, and in flow-through columns with natural seawater at the Marine Science Laboratory (MSL) of Pacific Northwest National Laboratory (PNNL) at Sequim Bay, WA. The DMSO-heat-treated sorbents adsorbed uranium as high as 4.48 g-U/kg-ads. from seawater. Experimental evidence is presented that the poly(imide dioxime) is primarily responsible for enhanced uranium adsorption capacity from natural seawater. The conjugated system in the imide dioxime ligand possesses increased electron donation ability, which is believed to significantly enhance the uranyl coordination in seawater.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Characterization and Testing of Amidoxime-Based Adsorbent Materials to Extract Uranium from Natural Seawater

Extraction of uranium (U) from seawater for use as a nuclear fuel is a significant challenge due to the low concentration of U in seawater (~3.3 ppb) and difficulties to selectively extract U from the background of major and trace elements in seawater. The Pacific Northwest National Laboratory (PNNL)’s Marine Sciences Laboratory (MSL) has been serving as a marine test site for determining performance characteristics (adsorption capacity, adsorption kinetics, and selectivity) of novel amidoxime-based polymeric adsorbents developed at Oak Ridge National Laboratory (ORNL) under natural seawater exposure conditions. This manuscript describes the performance of three formulations (38H, AF1, AI8) of amidoxime-based polymeric adsorbents produced at ORNL in MSL’s ambient seawater testing facility. The adsorbents were produced in two forms, fibrous material (40-100 mg samples) and braided material (5-10 g samples), and exposed to natural seawater using flow-through columns and recirculating flumes. All three formulations demonstrated high 56 day uranium adsorption capacity (>3 g U/kg adsorbent). The AF1 formulation had the best uranium adsorption performance, with a 56 day capacity of 3.9 g U/ kg adsorbent, a saturation capacity of 5.4 g U/kg adsorbent, and ~25 days half-saturation time. The two exposure methods, flowthrough columns and flumes, were demonstrated to produce similar performance results, providing confidence that the test methods were reliable, that scaling up from 10’s of mg quantities of exposure in flow-through columns to gram quantities in flumes produced similar results, and confirm that the manufacturing process produces a homogeneous adsorbent. Adsorption kinetics appear to be element specific, with half-saturation times ranging from minutes for the major cations in seawater, to 8-10 weeks for V and Fe. Reducing the exposure time provides a potential pathway to improve the adsorption capacity of U by reducing the V/U ratio on the adsorbent.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2012

Constraining the Influence of Natural Variability to Improve Estimates of Global Aerosol Indirect Effects in a Nudged Version of the Community Atmosphere Model 5

Natural modes of variability on many timescales influence aerosol particle distributions and cloud properties such that isolating statistically significant differences in cloud radiative forcing due to anthropogenic aerosol perturbations (indirect effects) typically requires integrating over long simulations. For state-of-the-art global climate models (GCM), especially those in which embedded cloud-resolving models replace conventional statistical parameterizations (i.e. multi-scale modeling framework, MMF), the required long integrations can be prohibitively expensive. Here an alternative approach is explored, which implements Newtonian relaxation (nudging) to constrain simulations with both pre-industrial and present-day aerosol emissions toward identical meteorological conditions, thus reducing differences in natural variability and dampening feedback responses in order to isolate radiative forcing. Ten-year GCM simulations with nudging provide a more stable estimate of the global-annual mean aerosol indirect radiative forcing than do conventional free-running simulations. The estimates have mean values and 95% confidence intervals of -1.54 ± 0.02 W/m2 and -1.63 ± 0.17 W/m2 for nudged and free-running simulations, respectively. Nudging also substantially increases the fraction of the world’s area in which a statistically significant aerosol indirect effect can be detected (68% and 25% of the Earth's surface for nudged and free-running simulations, respectively). One-year MMF simulations with and without nudging provide global-annual mean aerosol indirect radiative forcing estimates of -0.80 W/m2 and -0.56 W/m2, respectively. The one-year nudged results compare well with previous estimates from three-year free-running simulations (-0.77 W/m2), which showed the aerosol-cloud relationship to be in better agreement with observations and high-resolution models than in the results obtained with conventional parameterizations.

aerosol↗
DOE OSTI2017

Modeling Electric Power and Natural Gas Systems Interdependencies: Application to Natural Hazards

To assist the evaluation of infrastructure assets from an all-hazards perspective, this paper describes the 16 progress of continuing infrastructure modeling and integration efforts underway by researchers at 17 Argonne National Laboratory under its Resilient Infrastructure Initiative. A unique approach is adopted 18 that integrates existing and proven electric power and natural gas infrastructure models used for impact 19 assessment analyses to aid and enhance the design of resilient energy systems. Significant benefits of the 20 combined electric power-natural gas model (EP-NG Model) are that the generalized framework permits 21 the integration and automation of the entire process, including threat and hazard identification and data 22 acquisition, impact zone estimation and projection, simulation of the initial effects on the initiating 23 infrastructure, evaluation of propagating effects within each infrastructure, and simulation of the influence 24 of cascading effects of the disruption on interdependent infrastructure. Two state-level case studies 25 demonstrate the approach’s effectiveness in simulating the propagation of disruptions between the natural gas and electric power systems, and the usefulness for designing resilient energy systems considering 27 hazards related to climate change and other natural hazards.

all-hazards↗
DOE OSTI2014

Environment management conflict in Mount Tangkuban Perahu Nature Reserve and Nature Park, North Bandung, West Java

Nature Park Mount Tangkuban Perahu is part of the Nature Reserve that defined as utilization zone. Until now the nature park continues to experience disruption and threat caused by human activities such as tourists, local peoples, and administrators so that giving rise to the area conflict. The number of rules did not guarantee high protection of the area and even can lead conflict. The evaluation performance of stakeholder and analysis environmental sustainablity, seems that there are not sustainable. The performance score of stakeholders in conservation efforts in the field of preservation and protection are 1.5 and 2 respectively (low category), while the area of utilization is 2 (low category). Total score condition of management area are 1.75 (low category). Visitors assume that Tangkuban Perahu was categorized as cheap attraction (< Rp. 100,000 pervisit), but the benefits, comfort and safety are considerable (> 50%). Most visitors have a good perception of the facilities (66.2%), ticket price (64.6%), and ecosystems (78.5%). However this is not followed by magnitude of willingness to pay from the visitor to keep the preserved area (61.5% of visitors want to pay < 100,000). Most argue that the management of the area classified as good (78.5%), but approximately 38.5% of visitors said that need additional facilities such as children's play facilities in the area. This shows the lack of understanding of visitor of the meaning of natural recreation. Some visitors (47.69%) mentioned the need of management system implementation to ensure the region sustainability. The causes and alternative conflict resolution also discussed in this study.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2019

Investigating instabilities in a Rotating Detonation Combustor Operating with Natural Gas-Hydrogen Fuel Blend – Effect of Air Preheat and Annulus Width

Propagation characteristics of a detonation wave in an air-breathing Rotating Detonation Combustor (RDC) using natural gas-hydrogen fuel blends is presented in this paper. Short duration (~up to 6s) experiments were performed on a 152.4mm OD uncooled RDC with two different annulus gap widths (5.08mm and 7.62mm) over a range of equivalence ratios (0.6–1.0) at varying inlet air temperatures (~65°C-204°C) and natural gas content (up to 15%) with pre-combustion operating pressure slightly above ambient.It was observed that the RDC, with an annulus gap width of 5.08mm, was inherently unstable when natural gas (NG) was added to the hydrogen fuel while operating at pre-combustion pressures near ambient and at an inlet air temperature of 65°C. Increasing the annulus gap width to 7.62mm improved the stability of the detonation wave at similar temperatures and pressure permitting operation with as much as 5% NG by volume. While observed speeds of the detonation waves were still below theoretical values, an increase in inlet air temperature reduced the variability in wave speed. The frequency analysis thus explored in this study is an effort to quantify detonation instability in an RDC under varying operational envelope. The data presented is relevant towards developing strategies to sustain a stable detonation wave in an RDC using natural gas for land based power generation.

Roy, Arnab↗
DOE OSTI2019

Pressure-induced velocity softening in natural orthopyroxene at mantle temperature

In this study, we have measured the compressional and shear wave velocities of (Mg 1.77 Fe 0.22 Ca 0.01 )Si 2 O 6 natural orthopyroxene up to 13.5 GPa and 873 K using ultrasonic interferometry in conjunction with in situ synchrotron X-ray diffraction and imaging techniques. Previous acoustic experiments on orthoenstatite (OEn) MgSiO 3 indicated that both compressional and shear velocities (V P and V S ) of OEn undergo continuous velocity softening above 9 GPa at room temperature, which has been attributed to the phase transition from OEn to the metastable, high-pressure clinoenstatite HPCEn2. For the first time, our results suggest that pressure-induced velocity softening can occur in natural orthopyroxene at high-temperature conditions relevant to the Earth's cold subduction zones. As a result, estimates of the impedance and velocity contrasts between orthopyroxene (Opx) and high-pressure clinopyroxene (HPCpx) have been calculated, and the possibility of this phase transformation being a plausible candidate for seismic X-discontinuities at depth around 250–350 km is re-evaluated.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Climate Change Impacts on Natural Sulfur Production: Ocean Acidification and Community Shifts

Utilizing the reduced-complexity model Hector, a regional scale analysis was conducted quantifying the possible effects climate change may have on dimethyl sulfide (DMS) emissions within the oceans. The investigation began with a review of the sulfur cycle in modern Earth system models. We then expanded the biogeochemical representation within Hector to include a natural ocean component while accounting for acidification and planktonic community shifts. The report presents results from both a latitudinal and a global perspective. This new approach highlights disparate outcomes which have been inadequately characterized via planetary averages in past publications. Our findings suggest that natural sulfur emissions (ESN) may exert a forcing up to 4 times that of the CO 2 marine feedback, 0.62 and 0.15 Wm –2 , respectively, and reverse the radiative forcing sign in low latitudes. Additionally, sensitivity tests were conducted to demonstrate the need for further examination of the DMS loop. As a result, the present work attempts to include dynamic ESN within reduced-complexity simulations of the sulfur cycle, illustrating its impact on the global radiative budget.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2004

Formations Near the Libration Points: Design Strategies Using Natural and Non-Natural Arcs

Space based observatory and interferometry missions, such as Terrestrial Planet Finder (TPF), Stellar Imager, and MAXIM, have sparked great interest in multi-spacecraft formation flight in the vicinity of the Sun-Earth/Moon (SEM) libration points. The initial phase of this research considered the formation keeping problem from the perspective of continuous control as applied to non-natural formations. In the present study, closer inspection of the flow, corresponding to the stable and center manifolds near the reference orbit, reveals some interesting natural relative motions as well as some discrete control strategies for deployment. A hybrid control strategy is also employed that combines both the natural formation dynamics with non-natural motions via input feedback linearization techniques.

Howell, K. C.↗