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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Production of low-oxygen bio-oil via ex situ catalytic fast pyrolysis and hydrotreating

Catalytic fast pyrolysis (CFP) bio-oils with different organic oxygen contents (4-18 wt%) were prepared in a bench-scale dual fluidized bed reactor system by ex situ CFP of southern pine over HZSM-5, and the oils were subsequently hydrotreated over a sulfided CoMo catalyst at 170 bar. The goal was to determine the impact of the CFP oil oxygen content on hydrotreating requirements. The CFP oils with higher oxygen contents included a variety of oxygenates (phenols, methoxyphenols, carbonyls, anhydrosugars) whereas oxygenates in the 4 wt% oxygen oil were almost exclusively phenols. Phenols were the most recalcitrant oxygenates during hydrotreating as well, and the hydrotreated oils consisted mainly of aromatic and partially saturated ring hydrocarbons. The temperature required to produce oil with <1% oxygen was approximately 350 °C for the CFP oil with the lowest oxygen content whereas temperatures around 400 °C were required for the other CFP oils. The carbon efficiency during hydrotreating slightly decreased as the CFP oil oxygen content increased but remained above 90% in all cases, and the carbon efficiency for the integrated process was dominated by the efficiency of the CFP process. In conclusion, a preliminary technoeconomic evaluation suggested that with the current zeolite-based CFP catalysts, it is economically beneficial to preserve carbon during CFP, at the expense of higher oxygen contents in the CFP oil.

09 BIOMASS FUELS↗
DOE OSTI2013

Minimizing the formation of coke and methane on Co nanoparticles in steam reforming of biomass-derived oxygenates

Fundamental understanding and control of chemical transformations are essential to the development of technically feasible and economically viable catalytic processes for efficient conversion of biomass to fuels and chemicals. Using an integrated experimental and theoretical approach, we report high hydrogen selectivity and catalyst durability of acetone steam reforming (ASR) on inert carbon supported Co nanoparticles. The observed catalytic performance is further elucidated on the basis of comprehensive first-principles calculations. Instead of being considered as an undesired intermediate prone for catalyst deactivation during bioethanol steam reforming (ESR), acetone is suggested as a key and desired intermediate in proposed two-stage ESR process that leads to high hydrogen selectivity and low methane formation on Co-based catalysts. The significance of the present work also sheds a light on controlling the chemical transformations of key intermediates in biomass conversion such as ketones. We gratefully acknowledge the financial support from U. S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, and the Laboratory directed research and development (LDRD) project of Pacific Northwest National Laboratory (PNNL). Computing time was granted by the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). The EMSL is a U.S. DOE national scientific user facility located at PNNL, and sponsored by the U.S. DOE’s Office of Biological and Environmental Research.

biomass↗
DOE OSTI2022

ThunderSecure: deploying real-time intrusion detection for 100G research networks by leveraging stream-based features and one-class classification network

Nowadays, data generated by large-scale scientific experiments are on the scale of petabytes per month. These data are transferred through dedicated high-bandwidth networks (40/100G) across distributed sites for processing, storage, and analysis. Like general purpose networks, research networks experience intrusions. However, monitoring anomalies in such high-speed network traffics is challenging given current cyber-infrastructure. Moreover, traditional network intrusion detection systems (NIDS) are signature based. However, anomaly patterns are difficult to define and that rulesets are often not updated frequently enough to reflect the changes of attack behaviors. We present ThunderSecure, a high-throughput, unsupervised learning-based intrusions detection system for 100G research networks. ThunderSecure implements an efficient packet processing and detection pipeline using multi-cores and GPUs. It extracts statistical and temporal features from real-time network data streams and feeds them to a one-class anomaly detection network. A baseline of normal distribution will be created based on the training observation. Testing traffic deviated from the learned profile will be marked as anomalies. We trained ThunderSecure on hundreds of billions of science data packets mirrored from two 100G network connections at Fermi National Accelerator Laboratory. The detection performance was evaluated on traffic captured from the same research network days and weeks after the training with different types of attack flows injected. Results show that ThunderSecure can recognize science data traffic captured long after the training and made nearly certain detection on the segment of the streams where anomalous flows were injected.

100G research network↗
DOE OSTI2024

Mapping use cases and dataset needs for benchmarking buildings data

A perennial challenge in buildings research is the lack of high-quality datasets that can be relied upon for a wide array of tasks, including model calibration and improving energy efficiency and load flexibility. Instrumenting a building for data collection is resource intensive, so it is important to be methodical in the approach and ensure that resulting data are flexible and useful for a broad range of analyses. This study aims to fill the gaps in characterizing potential use cases for buildings datasets and mapping them to dataset needs using a well-defined data infrastructure. Here, we have developed a systematic mapping strategy between buildings dataset needs and use cases to help streamline the processes of efficiently targeting datasets, designing building sensing systems, and determining buildings research use cases. We selected 14 prospective use cases and 11 refined buildings data categories for developing the preliminary dataset-needs-to-use-cases mapping matrix (‘DN-UC mapping matrix’) with generic ‘Tags’—a detailed sub-level of data categories extracted by justifying the needs of an aspect of the datasets to use cases. We present two example applications of the developed mapping matrix to demonstrate use of the mapping matrix and its effectiveness.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

New Catalyst Reduces Wasted Carbon in Biofuel Process, Lowers Cost

Researchers at NREL recently developed a catalyst formulation that incorporates more hydrogen into the DME-to-high-octane gasoline process, resulting in a higher yield to gasoline-range products. Further, the researchers developed a secondary process that efficiently couples a portion of the gasoline-range product to yield jet/diesel fuels. The modified catalyst doubles the conversion rate of DME, which can be produced from biomass, to the high-octane gasoline product and significantly decreases the formation of wasted byproducts. For the distillate-range product, 80% of the mixture is in line with ASTM standards for use as a jet fuel blendstock. The increased productivity of high-octane gasoline and the development of a value-added distillate blendstock process further improve the economic viability toward commercially implementing this renewable fuels process.

09 BIOMASS FUELS↗
DOE OSTI2017

How systems engineering and human factors can assist SMR vendors with the licensing process - 345

There is growing interest in the development of small modular reactors (SMRs) as a cost-effective renewable source of energy. Most of the current conceptual designs propose advanced and automated control and monitoring technologies which would require complex human system interfaces. The proposals also include a reduction in the number of staff, and partial or full remote control of the facilities. The human factors challenges of such a design philosophy range from identification of information requirements of users to assessing workload to deciding on best information visualization techniques to ensure situation awareness is maintained in a remote control facility. Addressing these challenges will require a systems engineering approach where user requirements are identified through a systematic approach for various contexts, including normal, abnormal, and accident conditions. A systems engineering process will integrate human factors as well as other specialty disciplines such as reliability and design optimization in a coherent fashion that would lead to realization of a successful system that addresses user requirements. The licensing model in Canada is based upon a graded approach and is largely technology neutral. A key factor in ensuring effective licensing effort is identification of regulatory requirements. This paper discusses how adopting a systems engineering approach and early consideration of human factors principles and requirements will not only ensure an efficient design process, but will also help with developing a design that meets the regulatory requirements. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2016

Review on first-principles study of defect properties of CdTe as a solar cell absorber

CdTe is one of the leading materials for high-efficiency, low-cost, and thin-film solar cells. In this work, we review the recent first-principles study of defect properties of CdTe and present that: (1) When only intrinsic defects are present, p-type doping in CdTe is weak and the hole density is low due to the relatively deep acceptor levels of Cd vacancy. (2) When only intrinsic defects present, the dominant non-radiative recombination center in p-type CdTe is Te-2+/Cd, which limits the carrier lifetime to be around 200 ns. (3) Extrinsic p-type doping in CdTe by replacing Te with group V elements generally will be limited by the formation of AX centers. This could be overcome through a non-equilibrium cooling process and the hole density can achieve 10^17 cm-3. However, the long-term stability will be a challenging issue. (4) Extrinsic p-type doping by replacing Cd with alkaline group I elements is limited by alkaline interstitials and a non-equilibrium cooling process can efficiently enhance the hole density to the order of 10^17 cm-3. (5) Cu and Cl treatments are discussed. In bulk CdTe, Cu can enhance p-type doping, but Cl is found to be unsuitable for this. Both Cu and Cl show segregation at grain boundaries, especially at those with Te-Te wrong bonds. (6) External impurities are usually incorporated by diffusion. Therefore, the diffusion processes in CdTe are investigated. We find that cation interstitial (Nai, Cui) diffusion follows relatively simple diffusion paths, but anion diffusion (Cli, Pi) follows more complicated paths due to the degenerated defect wavefunctions.

14 SOLAR ENERGY↗
DOE OSTI2021

An Enzymatic Platform for Primary Amination of 1-Aryl-2-alkyl Alkynes

Propargyl amines are versatile synthetic intermediates with numerous applications in the pharmaceutical industry. An attractive strategy for efficient preparation of these compounds is nitrene propargylic C(sp 3 )–H insertion. However, achieving this reaction with good chemo-, regio-, and enantioselective control has proven to be challenging. Here, we report an enzymatic platform for the enantioselective propargylic amination of alkynes using a hydroxylamine derivative as the nitrene precursor. Cytochrome P450 variant PA-G8 catalyzing this transformation was identified after eight rounds of directed evolution. A variety of 1-aryl-2-alkyl alkynes are accepted by PA G8, including those bearing heteroaromatic rings. This biocatalytic process is efficient and selective (up to 2610 total turnover number (TTN) and 96% ee) and can be performed on preparative scale.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Twisted MoSe 2 Homobilayer Behaving as a Heterobilayer

Heterostructures (HSs) formed by the transition-metal dichalcogenides materials have shown great promise in next-generation (opto)electronic applications. An artificially twisted HS, allows us to manipulate the optical, and electronic properties. In this work, we introduce the understanding of the energy transfer (ET) process governed by the dipolar interaction in a twisted molybdenum diselenide (MoSe 2 ) homobilayer without any charge-blocking interlayer. We fabricated an unconventional homobilayer (i.e., HS) with a large twist angle by combining the 2 chemical vapor deposition (CVD) and mechanical exfoliation (Exf.) techniques to fully exploit the lattice parameters mismatch and indirect/direct (CVD/Exf.) bandgap nature. These effectively weaken the interlayer charge transfer and allow the ET to control the carrier recombination channels. Our experimental and theoretical results explain a massive HS photoluminescence enhancement due to an efficient ET process. This work shows that the electronically decoupled MoSe 2 homobilayer is coupled by the ET process, mimicking a 'true' heterobilayer nature.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Experimental confirmation of the standard magnetorotational instability mechanism with a spring-mass analogue

Abstract The magnetorotational instability (MRI) has long been considered a plausibly ubiquitous mechanism to destabilize otherwise stable Keplerian flows to support radially outward transport of angular momentum. Such an efficient transport process would allow fast accretion in astrophysical objects such as stars and black holes to release copious kinetic energy that powers many of the most luminous sources in the universe. But the standard MRI under a purely vertical magnetic field has heretofore never been directly measured despite numerous efforts over more than a decade. Here we report an unambiguous laboratory demonstration of the spring-mass analogue to the standard MRI by comparing motion of a spring-tethered ball within different rotating flows. The experiment corroborates the theory: efficient outward angular momentum transport manifests only for cases with a weak spring in quasi-Keperian flow. Our experimental method accomplishes this in a new way, thereby connecting solid and fluid mechanics to plasma astrophysics.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

Biotic degradation of acetonitrile. Limitations, controls and conversion rates

This document has been prepared to support Washington River Protection Solutions (WRPS) in their evaluation of technologies to remediate organic compounds in the Liquid Effluent Retention Facility (LERF)/Effluent Treatment Facility (ETF) during direct feed low activity waste (DFLAW) operations at Hanford. This report summarizes the results of a review of the available literature describing aerobic and anaerobic biological treatment of acetonitrile and proposes a test matrix to evaluate microbial degradation rates of acetonitrile. Numerous studies describe acetonitrile degradation by pure culture strains of bacteria, fungi, and yeast; however, the purpose of this review was to provide estimations of degradation under conditions that more closely approximate the Liquid Effluent Retention Facility (LERF) basins at the Hanford Site. To this end, documented limitations, controls, and conversion rates are summarized for mixed and natural microbial communities being maintained or operated as a biological treatment for wastewater processing. Based on the literature evaluation, the inherent capacity and rates of microbial degradation of acetonitrile are sufficiently high that if applied in the LERF basins, acetonitrile removal would be achieved. To be clear, though, published studies have not been conducted under conditions that approximate or that could be directly related to the LERF basins. Thus, a focused test matrix the encompasses LERF relevant conditions to specifically measure microbial degradation of acetonitrile is proposed and the results would provide the strong technical justification for use of this low-cost efficient biological process at LERF during DFLAW operations and beyond.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Lead-Halide Perovskites for Photocatalytic α-Alkylation of Aldehydes

Here, cost-effective and efficient photocatalysis are highly desirable in chemical synthesis. Here we demonstrate that readily prepared suspensions of APbBr 3 (A = Cs or methylammonium (MA)) type perovskite colloids (ca. 2-100 nm) can selectively photocatalyze carbon-carbon bond formation reactions, i.e., ..alpha..-alkylations. Specifically, we demonstrate ..alpha..-alkylation of aldehydes with a turnover number (TON) of over 52,000 under visible light illumination. Hybrid organic/inorganic perovskites are revolutionizing photovoltaic research and are now impacting other research fields, but their exploration in organic synthesis is rare. Our low-cost, easy-to-process, highly efficient and bandedge-tunable perovskite photocatalyst is expected to bring new insights in chemical synthesis.

14 SOLAR ENERGY↗
DOE OSTI2015

Enhanced chemical CRUD decontamination combined with electrokinetic process - 15242

This study has tested about the deposition and dissolution of Chalk River Unidentified Deposit (CRUD), and investigated the remediation of CRUD. CRUD is an accumulated corrosion product on external fuel rod cladding surfaces and composed of either dissolved ions or solid particles such as Ni and Co. As nuclear power plants are getting older, decontaminating process has been concerned due to increased contamination. Corrosion product can be activated through nuclear reaction to form radionuclide such as Co-60. Because the CRUD is formed at cladding surface and radionuclides can be contained in CRUD, it can affect to human health and environment. Therefore CRUD needs to be removed safely during NPP's decontaminating process by efficient. In order to decontaminate the CRUD, first thing it has to be dissolved and removed. Deposition behavior of corrosion products has been well studied, but the study about behavior of CRUD dissolution is required in various environments. In this study, the CRUD synthesis, the dissolution method of CRUD, and the CRUD decontamination method was investigated. There are three major approaches the remediation of CRUD. First one is well synthesized the CRUD, second one is finding the optimum condition for CRUD dissolution, and last one is applying the Electro-Kinetic (EK) process to CRUD remediation. Synthesis of simulated CRUD for the decontamination experiments was successful. The combination of EK process with chemical decontamination of CRUD proved to be a more economical method for removing CRUD; it can be directly applied to the NPP decommissioning and decontamination process, and it can decrease the volume of secondary radioactive waste as well. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Frontiers, Opportunities, and Challenges in Biochemical and Chemical Catalysis of CO2

Our central premise is that catalytic scientists can learn by studying how these important metabolic processes occur in nature. Complementarily, biochemists can learn by studying how catalytic scientists view these same chemical transformations promoted by synthetic catalysts. From these studies, hypotheses can be developed and tested through manipulation of enzyme structure and by synthesizing simple molecular catalysts to incorporate different structural features of the enzymes. It is hoped that these studies will lead to new and useful concepts in catalyst design for fuel production and utilization. This paper describes the results of a workshop held to explore these concepts in regard to the development of new and more efficient catalytic processes for the conversion of CO2 to a variety of carbon-based fuels. The organization of this overview/review is as follows: 1) The first section briefly explores how interactions between the catalysis and biological communities have been fruitful in developing new catalysts for the reduction of protons to hydrogen, the simplest fuel generation reaction. 2) The second section assesses the state of the art in both biological and chemical reduction of CO2 by two electrons to form either carbon monoxide (CO) or formate (HCOO-). It also attempts to identify common principles between biological and synthetic catalysts and productive areas for future research. 3) The third section explores both biological and chemical processes that result in the reduction of CO2 beyond the level of CO and formate, again seeking to identify common principles and productive areas of future research. 4) The fourth section explores the formation of carbon-carbon bonds in biological and chemical systems in the same vein as the other sections. 5) A fifth section addresses the role of non-redox reactions of CO2 in biological systems and their role in carbon metabolism, with a parallel discussion of chemical systems. 6) In section 6, the topics of electrode modification, photochemical systems, and tandem catalysis are briefly discussed. These areas may be important for developing practical systems for CO2 reduction, and they share the common theme of coupling chemical reactions. 7) Section 7 describes some of the crosscutting activities that are critical for advancing the science underpinning catalyst development. 8) The last section attempts to summarize common issues in biological and chemical catalysis and to identify challenges that must be addressed to achieve practical catalysts that are suitable for the reduction of CO2 to fuels.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2014

Comparative study of beam losses and heat loads reduction methods in MITICA beam source

In negative ion electrostatic accelerators a considerable fraction of extracted ions is lost by collision processes causing efficiency loss and heat deposition over the components. Stripping is proportional to the local density of gas, which is steadily injected in the plasma source; its pumping from the extraction and acceleration stages is a key functionality for the prototype of the ITER Neutral Beam Injector, and it can be simulated with the 3D code AVOCADO. Different geometric solutions were tested aiming at the reduction of the gas density. The parameter space considered is limited by constraints given by optics, aiming, voltage holding, beam uniformity, and mechanical feasibility. The guidelines of the optimization process are presented together with the proposed solutions and the results of numerical simulations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Defect formation in Cu(In,Ga)Se{sub 2} thin films due to the presence of potassium during growth by low temperature co-evaporation process

Doping the Cu(In,Ga)Se{sub 2} (CIGS) absorber layer with alkaline metals is necessary to process high efficiency solar cells. When growth of CIGS solar cells is performed on soda-lime glass (SLG), the alkaline elements naturally diffuse from the substrate into the absorber layer. On the other hand, when CIGS is grown on alkaline free substrates, the alkaline metals have to be added from another source. In the past, Na was believed to be the most important dopant of the alkaline elements, even though K was also observed to diffuse into CIGS from the SLG. Recently, the beneficial effect of a post deposition treatment with KF was pointed out and enabled the production of a 20.4% CIGS solar cell grown at low substrate temperature (<500 °C). However, possible negative effects of the presence or addition of the alkaline impurities during the low temperature growth process were observed for Na, but were not investigated for K so far. In this study, we investigate in detail the role of K on the defect formation in CIGS layers deposited at low temperature on alkaline free polyimide with intentional addition of K during selected time intervals of the CIGS layer growth. By means of admittance spectroscopy and deep level transient spectroscopy, we identify a deep minority carrier trap at around 280 meV below the conduction band E{sub C} in CIGS layers grown with K. Its influence on recombination and minority carrier lifetime in the absorber layer is investigated with external quantum efficiency measurements and time-resolved photoluminescence. Furthermore, to support the experimental findings device simulations were performed using the software SCAPS.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Atmospheric processing of iron in mineral and combustion aerosols: development of an intermediate-complexity mechanism suitable for Earth system models

Abstract. Atmospheric processing of iron in dust and combustion aerosols is simulated using an intermediate-complexity soluble iron mechanism designed for Earth system models. The solubilization mechanism includes both a dependence on aerosol water pH and in-cloud oxalic acid. The simulations of size-resolved total, soluble and fractional iron solubility indicate that this mechanism captures many but not all of the features seen from cruise observations of labile iron. The primary objective was to determine the extent to which our solubility scheme could adequately match observations of fractional iron solubility. We define a semi-quantitative metric as the model mean at points with observations divided by the observational mean (MMO). The model is in reasonable agreement with observations of fractional iron solubility with an MMO of 0.86. Several sensitivity studies are performed to ascertain the degree of complexity needed to match observations; including the oxalic acid enhancement is necessary, while different parameterizations for calculating model oxalate concentrations are less important. The percent change in soluble iron deposition between the reference case (REF) and the simulation with acidic processing alone is 63.8 %, which is consistent with previous studies. Upon deposition to global oceans, global mean combustion iron solubility to total fractional iron solubility is 8.2 %; however, the contribution of fractional iron solubility from combustion sources to ocean basins below 15∘ S is approximately 50 %. We conclude that, in many remote ocean regions, sources of iron from combustion and dust aerosols are equally important. Our estimates of changes in deposition of soluble iron to the ocean since preindustrial climate conditions suggest roughly a doubling due to a combination of higher dust and combustion iron emissions along with more efficient atmospheric processing.

Scanza, Rachel A.↗
DOE OSTI2013

IONIZATION IN ATMOSPHERES OF BROWN DWARFS AND EXTRASOLAR PLANETS. V. ALFVÉN IONIZATION

Observations of continuous radio and sporadic X-ray emission from low-mass objects suggest they harbor localized plasmas in their atmospheric environments. For low-mass objects, the degree of thermal ionization is insufficient to qualify the ionized component as a plasma, posing the question: what ionization processes can efficiently produce the required plasma that is the source of the radiation? We propose Alfvén ionization as a mechanism for producing localized pockets of ionized gas in the atmosphere, having sufficient degrees of ionization (≥10{sup –7}) that they constitute plasmas. We outline the criteria required for Alfvén ionization and demonstrate its applicability in the atmospheres of low-mass objects such as giant gas planets, brown dwarfs, and M dwarfs with both solar and sub-solar metallicities. We find that Alfvén ionization is most efficient at mid to low atmospheric pressures where a seed plasma is easier to magnetize and the pressure gradients needed to drive the required neutral flows are the smallest. For the model atmospheres considered, our results show that degrees of ionization of 10{sup –6}-1 can be obtained as a result of Alfvén ionization. Observable consequences include continuum bremsstrahlung emission, superimposed with spectral lines from the plasma ion species (e.g., He, Mg, H{sub 2}, or CO lines). Forbidden lines are also expected from the metastable population. The presence of an atmospheric plasma opens the door to a multitude of plasma and chemical processes not yet considered in current atmospheric models. The occurrence of Alfvén ionization may also be applicable to other astrophysical environments such as protoplanetary disks.

79 ASTRONOMY AND ASTROPHYSICS↗