Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “DIRECT ENERGY CONVERSION”

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 937 records · Page 52
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Commercial applications of new photovoltaic technologies

The National Renewable Energy Laboratory (NREL) has directed and managed photovoltaic (PV) research and development (R&D) activities for the Department of Energy for more than 13 years. The NREL budget for these activities is almost $33 million for FY 1991. With the world's increasing concern for the environment and the United States' renewed apprehension over secure and adequate energy supplies, the use of semiconducting materials for the direct conversion of sunlight to electricity - photovoltaics - is an excellent example of government-supported high technology ready for further development by U.S. companies. Some new PV technologies and their research progress, some commercial applications of PV, and NREL's technology transfer activities for helping U.S. industry in its efforts to bring new products or services to the marketplace are described.

Mcconnell, R.↗
NASA NTRS1984

Buoyant production and consumption of turbulence kinetic energy in cloud-topped mixed layers

It is pointed out that studies of the entraining planetary boundary layer (PBL) have generally emphasized the role of buoyancy fluxes in driving entrainment. The buoyancy flux is proportional to the rate of conversion of the potential energy of the mean flow into the kinetic energy of the turbulence. It is not unusual for conversion to proceed in both directions simultaneously. This occurs, for instance, in both clear and cloudy convective mixed layers which are capped by inversions. A partitioning of the net conversion into positive parts, generating turbulence kinetic energy (TKE), and negative parts (TKE-consuming), would make it possible to include the positive part in the gross production rate, and closure would be achieved. Three different approaches to partitioning have been proposed. The present investigation is concerned with a comparison of the three partitioning theories. Particular attention is given to the cloud-topped mixed layer because in this case the differences between two partitioning approaches are most apparent.

Randall, D. A.↗
DOE OSTI2025

InDEEP, DEEC-Tec, and Direct Generation Synergies for Ocean Wave Energy: Wave Energy Scotland's Direct Generation Programme Review

The presentation highlights: (i) how DEEC-Tec, advanced through the U.S. DOE's InDEEP Prize, holds the potential to redefine ocean wave energy conversion through modular, embedded energy conversion; (ii) a global scan that identified 158 participants and 35 promising concepts, showcasing strong international momentum; (iii) InDEEP's innovation-first approach and how it complements Wave Energy Scotland's structured Direct Generation research; and (iv) the ongoing and possible future collaborative pathways for co-funded trials, joint metric/standards developments, and maturation of these technologies toward and real-world deployment.

16 TIDAL AND WAVE POWER↗
DOE OSTI2021

Monte Carlo Modeling and Design of Photon Energy Attenuation Layers for >10× Quantum Yield Enhancement in Si-Based Hard X-ray Detectors

High-energy (>20 keV) X-ray photon detection at high quantum yield, high spatial resolution, and short response time has long been an important area of study in physics. Scintillation is a prevalent method but limited in various ways. Directly detecting high-energy X-ray photons has been a challenge to this day, mainly due to low photon-to-photoelectron conversion efficiencies. Commercially available state-of-the-art Si direct detection products such as the Si charge-coupled device (CCD) are inefficient for >10 keV photons. Here, we present Monte Carlo simulation results and analyses to introduce a highly effective yet simple high-energy X-ray detection concept with significantly enhanced photon-to-electron conversion efficiencies composed of two layers: a top high-Z photon energy attenuation layer (PAL) and a bottom Si detector. We use the principle of photon energy down conversion, where high-energy X-ray photon energies are attenuated down to ≤10 keV via inelastic scattering suitable for efficient photoelectric absorption by Si. Our Monte Carlo simulation results demonstrate that a 10–30× increase in quantum yield can be achieved using PbTe PAL on Si, potentially advancing high-resolution, high-efficiency X-ray detection using PAL-enhanced Si CMOS image sensors.

47 OTHER INSTRUMENTATION↗
DOE OSTI2021

Atomic/molecular layer deposition for energy storage and conversion

Energy storage and conversion systems, including batteries, supercapacitors, fuel cells, solar cells, and photoelectrochemical water splitting, have played vital roles in the reduction of fossil fuel usage, addressing environmental issues and the development of electric vehicles. The fabrication and surface/interface engineering of electrode materials with refined structures are indispensable for achieving optimal performances for the different energy-related devices. Atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques, the gas-phase thin film deposition processes with self-limiting and saturated surface reactions, have emerged as powerful techniques for surface and interface engineering in energy-related devices due to their exceptional capability of precise thickness control, excellent uniformity and conformity, tunable composition and relatively low deposition temperature. In the past few decades, ALD and MLD have been intensively studied for energy storage and conversion applications with remarkable progress. In this work, we give a comprehensive summary of the development and achievements of ALD and MLD and their applications for energy storage and conversion, including batteries, supercapacitors, fuel cells, solar cells, and photoelectrochemical water splitting. Moreover, the fundamental understanding of the mechanisms involved in different devices will be deeply reviewed. Furthermore, the large-scale potential of ALD and MLD techniques is discussed and predicted. Finally, we will provide insightful perspectives on future directions for new material design by ALD and MLD and untapped opportunities in energy storage and conversion.

25 ENERGY STORAGE↗
DOE OSTI2021

Direct Observation of Photoexcited Charge Carrier Dynamics and Electrostatic Fields at Photocatalytic Semiconductor/liquid Interfaces

Photoelectrochemical conversion of solar energy to fuels at semiconductor-liquid interfaces involves a complex set of processes, which include band bending, built-in electric fields, surface recombination of photoexcited carriers, and ultimately charge transfer to the ions in solution, in which the electrostatic fields within the depletion region of the semiconductor plays an important role. There are loss mechanisms associated with each of these key components in the overall photoelectrochemical conversion efficiency. Direct probe of these elementary processes is key to the rational improvement of photoeletrochemical cells and electrodes. In this collaborative project, Tianquan Lian at Emory University, Steve Cronin at University of Southern California and their students and postdoctoral fellows carried out a series of studies that are aimed at direct observation of photoexcited charge carrier dynamics at photocatalytic semiconductor/liquid interfaces. The collaborative work led to the development of transient reflectance spectroscopy as a tool for in situ probing of carrier dynamics in planar photoelectrode/electrode interface; and the demonstration that this tool can be used to study oxide protected GaP to identify key efficiency limiting factors in these photoelectrodes. This work has led to the development a tool for in situ probing of carrier dynamics in planar photoelectrodes, which will facilitate the mechanistic study of photoelectrochemical cells. This work informs the development of better photoelectrode materials for solar water splitting and CO 2 reduction. This work has contributed to the training of three PhD students in the area of photoelectrochemistry, ultrafast spectroscopy and solar energy conversion

14 SOLAR ENERGY↗
DOE OSTI2021

Ultra-high energy density relativistic plasmas from nanostructures: scaling to ultra-high intensities (Final Report)

This project investigated the ultra-high energy density (UHED) regime of matter found in the center of stars, using a compact PW-class laser. These extreme conditions are typically only obtained in the laboratory in the central hot-spot of spherically imploded capsules in inertial confinement fusion experiments driven by the world’s largest lasers. We have shown that near-solid density arrays of aligned nanostructures can be volumetrically heated to multi-keV temperatures by irradiation at relativistic intensity with ultrafast laser pulses of modest energy, opening a path for the generation of UHED plasmas with compact lasers. This new UHED plasma generation approach promises to create an environment with extreme energy densities and degrees of ionization, record conversion of optical laser light into ultrafast x-ray pulses, gigantic magnetic fields and pressures, and directed beams of high energy particles . In this project we achieved record degree of ionization in volumetric heating solid density and near-solid density plasmas. Gold plasmas which spectra is characterized by L shell transition emission from ions with charge up to the Ne-like state, Au+ 72 were generated using ultrafast laser pulses of less than 10 J of energy from a compact laser focused to an intensity of ~ 3x10 21 Wcm -2 . We also conducted measurements to determine the heat penetration depth in Ni nanowire arrays as compared to Ni foil targets by monitoring the line emission of a Co buried tracer underneath a variable amount of Ni. The measurements revealed that the nanowire plasmas are roughly six times larger in depth than the solid density target plasmas. A result of this increased plasma in nanowire arrays is a greatly increased conversion of optical laser light into > 1 KeV x-rays, a record conversion efficiency of 20 %. Critical to the realization of the proposed experiments was the generation of ultrafast laser pulses with ultra-high contrast that can deposit the energy deep into the nanowire arrays before the nanowires explode to create a continuous plasma. Supporting the proposed experiments was the recent demonstration at Colorado State University of a Petawatt-class laser that emits 30 fs pulses at high repetition rates. The experiments combined this unique laser tool with a variety of tailored nanowire arrays fabricated in house and with an extensive suite of diagnostics. The experiments were accompanied by 3-dimensional particle-in-cell simulations and detailed atomic physics simulations with transient kinetics and radiation transport. The proposed research allowed us to continue training Ph.D students and post-docs with broad experience in HEDP Science.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Building Artificial Layered Solids from the Bottom-up: Materials by Design to Enable New Energy Technologies

This final technical report summarizes the key accomplishments on this DOE Early Career Program award received by PI Guihua Yu at the University of Texas at Austin. The main goal of this ECP award was to develop synthetic methodologies, self-assembly approaches towards structurally controlled nanosheets-like solids from the bottom up, and to understand and characterize their chemical/physical characteristics for the design of future-generation energy devices with novel functions and properties, that will have direct implications for energy science and technologies such as energy storage and conversion, and catalysis. The project accomplished these goals by completing the following objectives: • Rational design, synthesis, and self-assembly of structurally-controlled molecular ‘nanosheets’ materials. Moving beyond conventional van der Waals two-dimensional crystals, this project enables new synthesis and processing strategies to develop ultrathin nanosheets materials, from inorganic transition-metal oxides-based, to hybrid organic-inorganic nanomaterials, with structural factors such as facet, thickness and pore structure being well controlled during synthesis or assembly processes. • Fundamental understanding and electrochemical characterization of these assembled molecular ‘nanosheets’ materials via charge/mass transport studies through electrochemical intercalation of different metal ions for next-generation energy storage, as well as electrocatalytic studies using this new material platform for understanding catalytic reaction kinetics and the roles of surface functionalization and interface interactions owing to atomic thickness, nanoscale porosity, and other structural factors.

36 MATERIALS SCIENCE↗
NASA NTRS1989

Power from space for use on earth: An emerging global option

The concept of the Earth as a closed ecological system is addressed from the point of view of the availability and use of energy from space and its potential influence on the economies of both developed and developing countries. The results of past studies of the solar power satellite (SPS) are reviewed, and the current international activities exploring various aspects of an SPS are mentioned. The functions of an SPS, including collection of solar energy in orbit, conversion to an intermediate form of energy, transmission of energy from orbit to Earth, and conversion to useful energy in the most appropriate form are discussed. Directions for future developments are addressed including a suggested planning framework. Salient aspects of SPS technologies are presented, and the potential benefits of the uses of lunar materials for the SPS construction are outlined. Scenarios within the context of international participation in a global SPS system are presented. The conclusion is drawn that an SPS system is one of the few promising, globally applicable power generation options that has the potential to meet energy demands in the 21st Century and to achieve the inevitable transition to inexhaustible and renewable energy sources.

Glaser, Peter E.↗
NASA NTRS2011

High Intensity Laser Power Beaming Architecture for Space and Terrestrial Missions

High Intensity Laser Power Beaming (HILPB) has been developed as a technique to achieve Wireless Power Transmission (WPT) for both space and terrestrial applications. In this paper, the system architecture and hardware results for a terrestrial application of HILPB are presented. These results demonstrate continuous conversion of high intensity optical energy at near-IR wavelengths directly to electrical energy at output power levels as high as 6.24 W from the single cell 0.8 cm2 aperture receiver. These results are scalable, and may be realized by implementing receiver arraying and utilizing higher power source lasers. This type of system would enable long range optical refueling of electric platforms, such as MUAV s, airships, robotic exploration missions and provide power to spacecraft platforms which may utilize it to drive electric means of propulsion.

Nayfeh, Taysir↗
DOE OSTI2022

The MU2E Experiment at FERMILAB: R&D, Design and Status

The Mu2e Experiment at Fermilab 1) will search for coherent, neutrinoless conversion of negative muons into electrons in the field of an aluminum nucleus, µ - + N (A, Z) → e - + N (A, Z). This is an example of Charged Lepton Flavour Violation (CLFV) never observed experimentally. The dynamics of such a process is well modelled by a two-body decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass (~104.967 MeV). If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between conversion and capture rate R µe ≤ 6 × 10 -17 (@ 90% C.L.). This will improve the current limit of a factor of 10 4 over previous experiments. The experiment complements and extends the current/planned searches (µ → eγdecay at MEG , mu3e) as well as the direct searches for new physics at the LHC. Indeed, such CLFV searches in the muon sector probe new physics at a mass scale inaccessible with direct searches at either present or planned high-energy colliders. To detect the muon conversion process, a very intense pulsed beam of negative muons is produced by means of a S-shape Superconducting Solenoid Magnet System that is organized into three subsystems: the Production Solenoid, the Transport Solenoid and the Detector Solenoid. The beam is stopped at 10 GHz on an Aluminum target inside the Detector Solenoid. The Mu2e detectors, also installed inside the Detector Solenoid, are a high-precision tracker made on ~20000 straw tubes, and a calorimeter composed of ~1500 pure CsI crystals organized in two disks and readout by two large area UV-extended Silicon Photomultipliers (SiPMs). The Detector Solenoid region is surrounded by a Cosmic Ray Veto based on scintillators readout by SiPMs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1976

Photoassisted electrolysis of water - Conversion of optical to chemical energy

A description is given of devices, termed photoelectrochemical cells, which can, in principle, be used to directly convert light to fuels and/or electricity. The fundamental principles on which the photoelectrochemical cell is based are related to the observation that irradiation of a semiconductor electrode in an electrochemical cell can result in the flow of an electric current in the external circuit. Attention is given to the basic mechanisms involved, the energy conversion efficiency, the advantages of photoelectrochemical cells, and the results of investigations related to the study of energy conversion via photoelectrochemical cells.

Wrighton, M. S.↗
DOE OSTI2025

A review on advances in oxidative coupling of methane (OCM) for industrial use and prospects of CO 2 –H 2 O splitting integration

The discovery of shale gas reserves has encouraged the development of direct methods for methane conversion into valuable chemicals, offering an alternative to indirect approaches that involve an energy-intensive and intermittent syngas production step, leading to high CO 2 emissions. Amongst the direct methods, the oxidative coupling of methane (OCM) is a potential pathway to reduce CO 2 emissions and can produce commodity chemicals such as ethylene, a chemical regarded as central to the petrochemical industry. Even though OCM has been studied for over four decades, the technology still has not found commercial application. Amongst the challenges regarding industrial deployment of OCM, the most significant one is the requirement of a high ethylene yield of 30 % which is currently reported to be around 20 %. Moreover, the highly exothermic nature of the process and controlling the carbon selectivity over oxides of carbon (COx) is the heart of the problem. Numerous researchers have presented promising results in terms of catalysts, reactor designs and feeding strategies for OCM. However, due to lack of inclusiveness in the results, none of the combination of catalysts, reactors and system optimizations has been able to bring about its industrial viability. The current paper presents an extensive review of the noteworthy attempts to achieve industrial targets for OCM. Moreover, a comprehensive criteria is presented which highlights the desired end state for the industrial deployment of OCM technology. Furthermore, the criteria is based on literature survey and a comparison with industrially deployed ethylene production plants i.e., naphtha or ethane steam cracker plants. Finally, a novel integration technology is presented which includes a combination of OCM and CO 2 -H 2 O splitting in a chemical looping reactor design to enable efficient energy utilization and minimal heat losses to the environment.

CO2 Splitting↗
DOE OSTI2025

Advanced Brine Processing to Enable U.S. Lithium Independence (CRADA Report)

Current production of LiOH, which is needed to make Li-ion battery cathode active materials, utilizes a multistep process including solar evaporation, precipitation with Na 2 CO 3 and then conversion to LiOH using Ca(OH) 2 . This process requires a large amount of land area for solar evaporation, the right weather conditions, and chemicals for the conversion process that result in NaCl and CaCO 3 waste products. The production of Ca(OH) 2 is very energy intensive and evolves significant quantities of CO 2 . An alternative process flow utilizing direct lithium extraction techniques, followed by a chemical free conversion process can have benefits in reducing the needed land requirements and chemicals for traditional brine processing. There are many potential direct lithium extraction technologies that are currently being developed. The direct lithium extraction process from typical brine sources will produce a LiCl solution with some impurities including typically high concentrations of Na. This brine then needs to be converted to LiOH for use in battery cathode production. Ideally this conversion could occur without the use of additional chemicals. Electrochemistry can do this conversion either via electrolysis or bipolar membrane electrodialysis (BPED) to produce LiOH and HCl in solution. BPED utilized bipolar membranes to split water, which has a reduced potential as compared to splitting water at electrodes into hydrogen and oxygen gas. This reduced potential required results in a significant energy savings for BPED over electrolysis methods. This CRADA project aimed to develop such an integrated process using direct lithium extraction followed by BPED to produce a LiOH solution. That solution can then be crystallized into battery grade LiOH. In particular, Albemarle utilized a direct lithium extraction process to produce a concentrated LiCl solution that could be used for the BPED process. The BPED process was first tested using various LiCl solutions with impurity ions added at bench scale to understand the effects of impurities and determine processing parameters. Then testing was performed using the direct lithium extracted brine at the bench scale before scaling the process up. After the process was scaled up a long duration test was carried out to estimate the lifetime of the membranes, which is key to the economics of the BPED process.

25 ENERGY STORAGE↗
NASA NTRS1981

Thermodynamic limits to the efficiency of solar energy conversion by quantum devices

The second law of thermodynamics imposes a strict limitation to the energy converted from direct solar radiation to useful work by a quantum device. This limitation requires that the amount of energy converted to useful work (energy in any form other than heat) can be no greater than the change in free energy of the radiation fields. Futhermore, in any real energy conversion device, not all of this available free energy in the radiation field can be converted to work because of basic limitations inherent in the device itself. A thermodynamic analysis of solar energy conversion by a completely general prototypical quantum device is presented. This device is completely described by two parameters, its operating temperature T sub R and the energy threshold of its absorption spectrum. An expression for the maximum thermodynamic efficiency of a quantum solar converter was derived in terms of these two parameters and the incident radiation spectrum. Efficiency curves for assumed solar spectral irradiance corresponding to air mass zero and air mass 1.5 are presented.

Buoncristiani, A. M.↗
DOE OSTI2020

Coal direct chemical looping process: 250 kW pilot-scale testing for power generation and carbon capture

Chemical looping combustion (CLC) is an energy conversion technology that can produce concentrated CO 2 stream without the need for a gas separation step, and thus, has the potential to drastically reduce the energy consumption and cost associated with CO 2 capture in power generation. The coal-direct chemical looping (CDCL) process is a CLC technology that uses a moving bed reducer configuration that can directly consume coal as a feedstock without requiring an upstream gasification step. An integrated 250 kW th CDCL pilot unit using iron-based oxygen carriers was constructed and demonstrated for over 1000 h of testing. The principles for the CDCL pilot unit design and operation are summarized in this article. During the 288-hour continuous operation testing, the CDCL pilot unit achieved >96% coal conversion with a CO 2 purity of >97%. Low carbon carryover into the combustor, i.e. <2%, was also confirmed during the test, which shows the capability of the moving bed reactor to retain and convert coal using the oxygen available on the iron-based oxygen carrier. The results from the pilot unit testing confirms the CDCL concept as a promising coal combustion technology for heat and power generation with CO 2 capture.

10 SYNTHETIC FUELS↗