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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 1,459 records · Page 81
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Supporting the Transition from Grid-Scale to Emerging Market Wave Energy Converter Design and Assessment

In the past decade there has been increasing interest in emerging markets for wave energy, both as a stepping stone for development and as a way to create new opportunities for offshore markets such as ocean observation or desalination. Developers who were once focused exclusively on grid-scale development have begun to engage with more unique markets. This has led researchers to begin examining means of assessing emerging-market devices. In this paper, we analyze the Technology Performance Level (TPL) Assessment for its potential use in the assessment of emerging market wave energy converters (EM-WECs). We use Quality Function Deployment (QFD) and a question-by-question analysis of the TPL assessment to determine the changes necessary for such an assessment to be applicable in emerging markets. We discuss how the primary differences between the markets could impact the viable development pathways for developers hoping to succeed in multiple markets. We determine that the different stakeholders and stakeholder requirements of some emerging markets compared to gridscale applications should be met with changes to cost-toperformance metrics, prototype testing processes, recovery planning, materials selection, optimization objectives, and public engagement.

blue economy↗
DOE OSTI2022

Designing Resilience for Advanced Energy Systems

Advancements in energy technologies are making the grid more powerful, more efficient, and cleaner. As these promising innovations flourish across our communities, it is essential that our nation's infrastructure also becomes more resilient. Natural disasters, cyberattacks, user error, and a changing climate all present risks that could have devastating consequences. Individual emergencies are unique, but holistic planning and proactive measures can harden the grid and help anticipate and respond to any number of threats. The National Renewable Energy Laboratory (NREL) is at the forefront of this transition, establishing a vision for resilient energy systems today, and in the future.

energy disruption↗
DOE OSTI2023

The Department of Energy and IDEA team up to document industry best practices

This article describes a collaboration between the U.S. Department of Energy and the International District Energy Association (IDEA) to document best practices in district energy systems. The initiative focuses on analyzing real-world performance data and highlighting effective strategies for improving efficiency, integrating renewable energy, and supporting decarbonization efforts. It highlights case studies from the University of California, Davis, and Princeton University to show how long-term master planning, phased project implementation, and strong financial analysis can drive successful transitions to more sustainable energy systems. U.C. Davis emphasizes incremental, results-driven planning and pilot projects, while Princeton focuses on aligning climate goals with financially viable infrastructure investments and life-cycle cost analysis. Overall, the article demonstrates that combining strategic planning, data-driven decision-making, and financial accountability is essential for advancing sustainable district energy systems.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2021

The Role of Energy Storage in the Uptake of Renewable Energy: A Model Comparison Approach

The power sector needs to ensure a rapid transition towards a low-carbon energy system to avoid the dangerous consequences of greenhouse gas emissions. Storage technologies are a promising option to provide the power system with the flexibility required when intermittent renewables are present in the electricity generation mix. This paper focuses on the role of electricity storage in energy systems with high shares of renewable sources. The study encompasses a model comparison approach where four models (GENeSYS-MOD, MUSE, NATEM, and urbs - MX) are used to analyse the storage uptake in North America. The analysis addresses the conditions affecting storage uptake in each country and its dependence on resource availability, technology costs, and public policies. Results show that storage may promote emissions reduction at lower costs when renewable mandates are in place whereas in presence of carbon taxes, renewables may compete with other low-carbon options. The study also highlights the main modelling approach shortcomings in the modelling of electricity storage in integrated assessment models.

electricity storage↗
NASA NTRS1975

Proton collisional excitation in the ground configurations of Fe/+12/ and Fe/+13/. III - Transitions between magnetic sublevels

Values of proton collisional cross-sections at coronal energies have been computer for all transitions between magnetic sublevels of the Fe(+12) and Fe(+13) ground configurations. Semiclassical Coulomb excitation theory was used with the resulting truncated Schroedinger equations being directly integrated. The corresponding rate constants for coronal temperatures are presented and comparison is made with previous results.

Landman, D. A.↗
NASA NTRS1983

The threshold laws for electron-atom and positron-atom impact ionization

The Coulomb-dipole theory is employed to derive a threshold law for the lowest energy needed for the separation of three particles from one another. The study focuses on an electron impinging on a neutral atom, and the dipole is formed between an inner electron and the nucleus. The analytical dependence of the transition matrix element on energy is reduced to lowest order to obtain the threshold law, with the inner electron providing a shield for the nucleus. Experimental results using the LAMPF accelerator to produce a high energy beam of H- ions, which are then exposed to an optical laser beam to detach the negative H- ion, are discussed. The threshold level is found to be confined to the region defined by the upper bound of the inverse square of the Coulomb-dipole region. Difficulties in exact experimental confirmation of the threshold are considered.

Temkin, A.↗
DOE OSTI2024

Turbulence Transition in Magnetically Confined Hydrogen and Deuterium Plasmas

In this study, we discovered a turbulence transition in a large helical device. The turbulence level and turbulence-driven energy transport decrease to a specific transition density and increase above it. The ruling turbulences below and above the transition density were ion-temperature gradient (ITG) and resistive-interchange (RI) turbulences, consistent with the predictions of gyrokinetic theory and two-fluid MHD model, respectively. Isotope experiments on hydrogen (H) and deuterium (D) clarified the role of transitions. In the ITG regime, turbulence levels and energy transport were comparable in the H and D plasmas. In contrast, in the RI regime, they were clearly suppressed in the D plasma. The results provide crucial knowledge for understanding isotope effects and future optimization of stellarator and heliotron devices. Published by the American Physical Society 2024

Physics↗
NASA NTRS1977

High-energy cosmic-ray electrons - A new measurement using transition-radiation detectors

A new detector for cosmic-ray electrons, consisting of a combination of a transition-radiation detector and a shower detector, has been constructed, calibrated at accelerator beams, and exposed in a balloon flight under 5 g/sq cm of atmosphere. The design of this instrument and the methods of data analysis are described. Preliminary results in the energy range 9-300 GeV are presented. The energy spectrum of electrons is found to be significantly steeper than that of protons, consistent with a long escape lifetime of cosmic rays in the galaxy.

Hartmann, G.↗
DOE OSTI2021

Chirality-induced zigzag domain wall in in-plane magnetized ultrathin films

In this report the domain structure in in-plane magnetized Fe/Ni/W(110) films is investigated using spin-polarized low-energy electron microscopy. A novel transition of the domain wall shape from a zigzaglike pattern to straight is observed as a function of the film thickness, which is triggered by the transition of the domain wall type from the out-of-plane chiral wall to the in-plane Néel wall. The contribution of the Dzyaloshinskii-Moriya interaction to the wall energy is proposed to explain the transition of the domain wall shape, which is supported by Monte Carlo simulations.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Bio-inspired Bistable Piezoelectric Energy Harvester for Powering Animal Telemetry Tags: Concept Design and Preliminary Experimental Validation

This paper presents the concept design, preliminary experimental validation, and performance evaluation of a novel bio-inspired bi-stable piezoelectric energy harvester for self-powered animal telemetry tags. The overall concept design, which includes a bio-inspired attachment and a bi-stable piezoelectric energy harvester, is introduced firstly with a specific application example of marine fish tracking. The self-powered telemetry tag can be externally deployed on fish (dorsal fin) to monitor fish habitats, population, and underwater environment. Inspired by the Venus flytrap’s rapid shape transition, a bistable piezoelectric energy harvester is developed to scavenge energy from fish maneuvering and the surrounding fluid flow for a sustainable power supply. The bistability of the harvester is characterized by the measured force-displacement curve and double potential wells. A bluff body is integrated to the free end of the bistable piezoelectric energy harvester to enhance the structure-fluid interaction for the large-amplitude snap-through vibrations and higher voltage output. Controlled laboratory experiments are conducted in a water tank on the bio-inspired bi-stable piezoelectric energy harvester using a servo motor system to simulate fish swing motion at various conditions to evaluate the power generation performance. The preliminary underwater experimental results demonstrated that the proposed bio-inspired bi-stable piezoelectric could effectively converter fish swing motions into electricity. 17.25 mJ energy was obtained within 130 s under the peak-to-peak swing angle of 30o at 1.5 Hz in the capacitor charging experiments.

Qian, Feng↗
DOE OSTI2020

Ab Initio Study of Vibronic and Magnetic 5f-to-5f and Dipole-Allowed 5f-to-6d and Charge-Transfer Transitions in [UX 6 ] n – (X = Cl, Br; n = 1, 2)

The absorption spectra of the octahedral [UX 6 ] n– (X = Cl, Br; n = 1, 2) complexes in the near-infrared (NIR) and UV–vis spectral regions were studied theoretically, using a relativistic restricted active space second-order perturbation theory (RASPT2) wavefunction framework, with the spin–orbit (SO) coupling treated by state interaction, in conjunction with Kohn–Sham density functional theory calculations for determining the vibrational normal modes. The electric-dipole-allowed ligand-to-metal charge-transfer (LMCT) and 5f-to-6d transitions, and the electric-dipole-forbidden 5f-to-5f ligand field (LF) transitions, are thereby obtained within the same theoretical framework. For the 5f-to-5f LF transitions, the observed absorption intensity is mostly due to vibronic coupling with low-energy electric-dipole-allowed transitions, but in some cases, the magnetic dipole intensity of the purely electronic transition has comparable intensity to the vibronic transitions. Here, experimental LF spectra of 5f 2 open-shell systems have been reported decades back, but ab initio calculations of their vibronic intensity have not yet been reported in the literature. Although the LF spectra for the 5f 2 systems can be assigned in detail, based on the calculations, the spectra are very complex and the underlying electronic states are strongly multiconfigurational. Therefore, the usefulness of the LF spectra beyond serving as a “fingerprint” of the LF and the metal oxidation state appears to be limited.

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

Excitonic Dynamics in Janus MoSSe and WSSe Monolayers

We report here details of steady-state and time-resolved spectroscopy of excitonic dynamics for Janus transition metal dichalcogenide monolayers, including MoSSe and WSSe, which were synthesized by low-energy implantation of Se into transition metal disulfides. Absorbance and photoluminescence spectroscopic measurements determined the room-temperature exciton resonances for MoSSe and WSSe monolayers. Transient absorption measurements revealed that the excitons in Janus structures form faster than those in pristine transition metal dichalcogenides by about 30% due to their enhanced electron–phonon interaction by the built-in dipole moment. Here, by combining steady-state photoluminescence quantum yield and time-resolved transient absorption measurements, we find that the exciton radiative recombination lifetime in Janus structures is significantly longer than in their pristine samples, supporting the predicted spatial separation of the electron and hole wave functions due to the built-in dipole moment. These results provide fundamental insight in the optical properties of Janus transition metal dichalcogenides.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Prefabricated Zero Energy Retrofit Technologies: A Market Assessment

The U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy’s (EERE’s) mission is to “create and sustain American leadership in the transition to a global clean energy economy.” EERE’s vision is a strong and prosperous America powered by clean, affordable, and secure energy. In support of this vision, one of EERE’s strategic pillars is to stimulate the growth of a thriving domestic clean energy manufacturing industry. This report seeks to identify products in the European and U.S. markets that can enable a more integrated and standardized approach to conducting zero energy retrofits, leveraging off-site construction and manufacturing. Greater integration of energy conservation measures into prefabricated building components will further enable efficiency adoption, while reducing project complexity, risks, and costs.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
NASA NTRS1971

Analytic expression for the energy-transfer rate from photoelectrons to thermal-electrons.

An analytic form is given for the energy-transfer rate from photoelectrons to thermal electrons. The expression fits the classical formulation of Itakawa and Aono (1966) at low energies and gives a smooth transition to fit the quantum mechanical equation of Schunk and Hays (1971) at higher energies. The corresponding loss function or stopping power has a form that is convenient in auroral and dayglow calculations.

Swartz, W. E.↗
DOE OSTI2020

Magnetically driven phonon instability enables the metal–insulator transition in h-FeS

Hexagonal iron sulfide exhibits a fascinating coexistence of metal–insulator, structural and magnetic transitions, reflecting an intimate interplay of its spin, phonon and charge degrees of freedom. Here, we show how a subtle competition of energetic and entropic free-energy components governs its thermodynamics and the sequence of phase transitions it undergoes upon cooling. By means of comprehensive neutron and X-ray scattering measurements, and supported by first-principles electronic structure simulations, we identify the critical role of the coupling between antiferromagnetic ordering and instabilities of anharmonic phonons in the metallic phase in driving the metal–insulator transition. The antiferromagnetic ordering enables the emergence of two zone-boundary soft phonons, whose coupling to a zone-centre mode drives the lattice distortion opening the electronic bandgap. Simultaneously, spin–lattice coupling opens a gap in the magnon spectrum that controls the entropy component of the metal–insulator transition free energy. Furthermore, these results reveal the importance of spin–phonon coupling to tune anharmonic effects, thus opening new avenues to design novel technologically important materials harbouring the metal–insulator transition and magnetoelectric behaviours.

36 MATERIALS SCIENCE↗
NASA NTRS1995

Rotational Energy Transfer and Collisional Induced Raman Linewidths in N2 Gas: Energy Transfer Rates - 1

Rotationally inelastic transitions of N2 have been studied in the coupled state (CS) and infinite-order-sudden (IOS) approximations, using the N2-N2 rigidrotor potential of van der Avoird et al. For benchmarking purposes, close coupling (CC) calculations have also been carried out over a limited energy range. The CC and CS cross sections have been obtained both with and without identical molecule exchange symmetry, whereas exchange was neglected in the IOS calculations. The CS results track the CC cross sections rather well; between 113 - 219 cm(exp -1) the average deviation is 14%. Comparison between the CS and IOS cross sections at the high energy end of the CS calculation, 500 - 680 cm(exp -1), shows that IOS is sensitive to the amount of inelasticity and the results for large DELTA J transitions are subject to larger errors. It is found that the state-to-state cross sections with even and odd exchange symmetry agree to better than 2% and are well represented as a sum of direct and exchange cross sections for distinguishable molecules, an indication of the applicability of a classical treatment for this system. This result, however, does not apply to partial cross sections for given total J, but arises from a near cancellation in summing over partial waves. In order to use rigid-rotor results for the calculation of effective rotational excitation rates of N2 in the v=1 vibrational level colliding with bath N2 molecules in the v=0 level, it is assumed that exchange scattering between molecules in different vibrational levels is negligible and direct scattering is independent of Y. Good agreement with room temperature experimental data is obtained. The effective rates determined using the IOS and energy corrected sudden (ECS) approximations are also in reasonable agreement with experiment, with the ECS results being somewhat better. The problem with a degeneracy factor in earlier cross section expressions for collisions between identical molecules is pointed out and corrected.

Huo, Winifred M.↗
DOE OSTI2022

Hydrogen as Part of a 100% Clean Energy System: Exploring Its Decarbonization Roles

Today's energy system uses a variety of fuels and energy carriers in molecular forms, such as coal, oil, and natural gas, each contributing to CO2 emissions (Figure 1). As solar and wind levels grow and the energy system becomes more electrified, fossil molecular fuels will contribute a progressively smaller fraction of overall energy. As shown in Figure 2, hydroelectric storage and molecules, such as coal and natural gas, provide substantial storage and dispatch functionality today that will become increasingly critical for electricity operation and stability. Emerging low-carbon gases, such as hydrogen, can support the efficient integration of renewables in the transition from today's energy system to one that is 100% clean from a carbon emissions perspective.

clean energy system↗