Results for “Alternating Current” — Page 61

DOE OSTI2022

Unconventional Highly Active and Stable Oxygen Reduction Catalysts Informed by Computational Design Strategies

As conventional strategies of engineering new MIEC materials for SOFCs over the past few decades would have eliminated a material like BFCZ75 from contention, this work suggests there is a need to re-think existing design criteria and develop and understand new rational materials design strategies that challenge conventional wisdom and chemical intuition. The ultimate goal of cathode design of SOFCs is to achieve a balance among electrical conductivity, ionic conductivity, oxygen exchange activity and long-term stability. Instead of searching for a replacement for unstable MIEC like LSCF, which works well in a ceria based composite electrode, some stable composites contain a highly conductive material mixing with a less conductive but highly ORR active and stable MIEC such as BFCZ75 or even triple-phase composites could be an alternative way to advance the current SOFC technology. (This work is published in May 2022 issue of Advanced Energy Materials. https://doi.org/10.1002/aenm.202201203 -->)<br>

Liu, Jian↗

DOE OSTI2017

Evaluating the Performance of the IEEE Standard 1366 Method for Identifying Major Event Days

IEEE Standard 1366 offers a method for segmenting reliability performance data to isolate the effects of major events from the underlying year-to-year trends in reliability. Recent analysis by the IEEE Distribution Reliability Working Group (DRWG) has found that reliability performance of some utilities differs from the expectations that helped guide the development of the Standard 1366 method. This paper proposes quantitative metrics to evaluate the performance of the Standard 1366 method in identifying major events and in reducing year-to-year variability in utility reliability. The metrics are applied to a large sample of utility-reported reliability data to assess performance of the method with alternative specifications that have been considered by the DRWG. We find that none of the alternatives perform uniformly 'better' than the current Standard 1366 method. That is, none of the modifications uniformly lowers the year-to-year variability in System Average Interruption Duration Index without major events. Instead, for any given alternative, while it may lower the value of this metric for some utilities, it also increases it for other utilities (sometimes dramatically). Thus, we illustrate some of the trade-offs that must be considered in using the Standard 1366 method and highlight the usefulness of the metrics we have proposed in conducting these evaluations.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2014

Reactor Physics Scoping and Characterization Study on Implementation of TRIGA Fuel in the Advanced Test Reactor

The Advanced Test Reactor (ATR), under the Reduced Enrichment for Research and Test Reactors (RERTR) Program and the Global Threat Reduction Initiative (GTRI), is conducting feasibility studies for the conversion of its fuel from a highly enriched uranium (HEU) composition to a low enriched uranium (LEU) composition. These studies have considered a wide variety of LEU plate-type fuels to replace the current HEU fuel. Continuing to investigate potential alternatives to the present HEU fuel form, this study presents a preliminary analysis of TRIGA® fuel within the current ATR fuel envelopes and compares it to the functional requirements delineated by the Naval Reactors Program, which includes: greater than 4.8E+14 fissions/s/g of 235 U, a fast to thermal neutron flux ratio that is less than 5% deviation of its current value, a constant cycle power within the corner lobes, and an operational cycle length of 56 days at 120 MW. Other parameters outside those put forth by the Naval Reactors Program which are investigated herein include axial and radial power profiles, effective delayed neutron fraction, and mean neutron generation time.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2018

A novel heme oxygenase-1 splice variant, 14kDa HO-1, promotes cell proliferation and increases relative telomere length

Alternative splicing is a routine phenomenon which greatly increases the diversity of proteins in eukaryotic cells. In humans, most multi-exonic genes are alternatively spliced and their splice variants confer distinct functions. Heme oxygenase-1 (HO-1, 32 kDa) is an inducible stress responsive protein, which possesses multiple functions in many cellular processes. In the current study, we identified a novel alternative splice isoform of 14 kDa HO-1 generated through exclusion of exon 3, and it is highly expressed in immortalized cells. In contrast to nuclear accumulation of the full-length 32 kDa HO-1, the novel 14 kDa HO-1 isoform is retained in the cytoplasm under ultraviolet (UV) irradiation. Interestingly, the 14 kDa HO-1 is shown to promote cell proliferation and an increase in relative telomere lengths in vivo and in vitro. Thus, we are pioneer to report and confirm the presence of a novel splice form of HO-1 and its distinct role in modulating telomere length and tumor growth.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2024

Investigation of Ammonia Carrier Materials for Next Generation Ammonia Dosing System - CRADA 334 (Abstract)

Lean-burn gasoline and diesel engines can offer substantially higher fuel efficiency, good driving performance, and reduced carbon dioxide emission compared to stoichiometric gasoline engines. Various catalyst technologies have been developed to remove the pollutants from these engines. For example, a three-way catalyst (TWC) is used to remove hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) from gasoline engines during the stoichiometric conditions. During the lean-burn conditions, a TWC or a diesel oxidation catalyst (DOC) is used to control HC and CO emissions. NOx is removed by either lean NOx trap catalyst (LNT) that can store NOx under lean conditions and reduce NOx under rich conditions, or selective catalytic reduction catalyst (SCR) that can selectively remove NOx with a reducing agent. Among the NOx reduction catalyst technologies, SCR offers a number of advantages, including excellent NOx reduction efficiency over a wide range of temperatures and overall lower system cost. In fact, the SCR technology using ammonia (NH3) as reductant has been proven effective and used commercially for the removal of NOx emissions from stationary sources since the 1970s. Currently, SCR is being used to meet the NOx emission standards for diesel engines in Europe and North America, and also being considered for meeting the future NOx emission standards for lean-burn gasoline engines. Because of the challenges associated with storage, handling and transportation of ammonia on a vehicle, aqueous urea solution (e.g., Diesel Exhaust Fluid, AdBlue) has been developed as ammonia storage compound for mobile applications. When the aqueous urea solution is sprayed into exhaust gas stream, urea is decomposed to release ammonia, which then reduces NOx over the downstream SCR catalyst. Although aqueous urea solution technology has enabled automakers and engine manufacturers to meet the current NOx emission standards, this process of releasing ammonia requires a hot exhaust gas and sufficient mixing, creating challenges for low temperature NOx emission control and aftertreatment system packaging. For these reasons, alternative technologies have been developed as ammonia sources (e.g., solid urea, ammonium carbamate, metal ammine chloride) during the past few years. These technologies promise more convenient handling and distribution of ammonia sources, and help maximize the low-temperature performance of SCR catalysts and reduce the overall system volume and weight. However, none of these alternative technologies can be successfully implemented without the industry consensus. Therefore, the USCAR SCR work group, which is comprised of representatives from GM, Ford, and Chrysler, has decided to investigate the potential alternative ammonia carriers, define common standard vehicle interfaces, and address personal and environmental safety concerns with part suppliers and chemical companies. Under this CRADA Project, USCAR and Battelle will investigate alternative ammonia carrier materials that are currently under development. Based on the data and information derived under the CRADA project, the USCAR SCR work group plans to build the consensus and make recommendations for the industry.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2024

Investigation of Ammonia Carrier Materials for Next Generation Ammonia Dosing System - CRADA 334 (Abstract)

Lean-burn gasoline and diesel engines can offer substantially higher fuel efficiency, good driving performance, and reduced carbon dioxide emission compared to stoichiometric gasoline engines. Various catalyst technologies have been developed to remove the pollutants from these engines. For example, a three-way catalyst (TWC) is used to remove hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) from gasoline engines during the stoichiometric conditions. During the lean-burn conditions, a TWC or a diesel oxidation catalyst (DOC) is used to control HC and CO emissions. NOx is removed by either lean NOx trap catalyst (LNT) that can store NOx under lean conditions and reduce NOx under rich conditions, or selective catalytic reduction catalyst (SCR) that can selectively remove NOx with a reducing agent. Among the NOx reduction catalyst technologies, SCR offers a number of advantages, including excellent NOx reduction efficiency over a wide range of temperatures and overall lower system cost. In fact, the SCR technology using ammonia (NH3) as reductant has been proven effective and used commercially for the removal of NOx emissions from stationary sources since the 1970s. Currently, SCR is being used to meet the NOx emission standards for diesel engines in Europe and North America, and also being considered for meeting the future NOx emission standards for lean-burn gasoline engines. Because of the challenges associated with storage, handling and transportation of ammonia on a vehicle, aqueous urea solution (e.g., Diesel Exhaust Fluid, AdBlue) has been developed as ammonia storage compound for mobile applications. When the aqueous urea solution is sprayed into exhaust gas stream, urea is decomposed to release ammonia, which then reduces NOx over the downstream SCR catalyst. Although aqueous urea solution technology has enabled automakers and engine manufacturers to meet the current NOx emission standards, this process of releasing ammonia requires a hot exhaust gas and sufficient mixing, creating challenges for low temperature NOx emission control and aftertreatment system packaging. For these reasons, alternative technologies have been developed as ammonia sources (e.g., solid urea, ammonium carbamate, metal ammine chloride) during the past few years. These technologies promise more convenient handling and distribution of ammonia sources, and help maximize the low-temperature performance of SCR catalysts and reduce the overall system volume and weight. However, none of these alternative technologies can be successfully implemented without the industry consensus. Therefore, the USCAR SCR work group, which is comprised of representatives from GM, Ford, and Chrysler, has decided to investigate the potential alternative ammonia carriers, define common standard vehicle interfaces, and address personal and environmental safety concerns with part suppliers and chemical companies. Under this CRADA Project, USCAR and Battelle will investigate alternative ammonia carrier materials that are currently under development. Based on the data and information derived under the CRADA project, the USCAR SCR work group plans to build the consensus and make recommendations for the industry.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2015

Geologic Investigation of Alternative Flight Testing Sites

Sandia National Laboratories is evaluating alternative gravity bomb flight test (GBFT) options that might be more cost effective in the 2025 timeframe than the current Tonopah Test Range (TTR) facility. The alternate ranges being considered are White Sands Missile Range (WSMR) and the Nevada National Security Site (NNSS). One of the factors considered in the decision process is if the geology of the alternative sites is suitable for gravity bomb flight testing. The study looked at seven specific sites within the three test ranges, including the TTR. Those seven sites are Main Lake and Antelope Lake at TTR, Trinity Lake at WSMR, and Yucca Lake, an area west of Frenchman Flat, Pahute Mesa, and the Pahute Airstrip all at NNSS. The four lakes studied are playas. In general the findings indicate that the playa lakes (Main, Antelope, Trinity, and Yucca) consist of fine-grained lacustrine sediments with inter-bedded stringers of coarse grains and gravels towards the shorelines. Frenchman Flat and Pahute Airstrip are both located within basins filled with poorly sorted gravel alluviums. Pahute Mesa consists of volcanic tuff. The seven sites are listed in order from the most favorable location to least favorable based on the suitability of the geology for GBFT. An ideal test site would consist of a succession of soft sediments devoid of hard layers. WSMR Lake Trinity is the most suitable site, exhibiting solely find-grained sediments across the study region. The lakes at TTR follow next with Antelope Lake and Main Lake, Antelope lake being finer grained and more homogeneous than Main Lake. The four NNSS sites are considered the least favorable due the heterogenetic character of Yucca Lake, Pahute Airstrip, and Frenchman Flat. The geology of Pahute Mesa is considered the least favorable consisting of volcanic tuff too hard for current test operations.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

NASA NTRS2007

Cost-Benefit Analysis for Alternatives to Aliphatic Isocyanate Polyurethanes

NASA and Air Force Space Command (AFSPC) have similar missions and therefore similar facilities and structures in similar environments. The standard practice for protecting metallic substrates in atmospheric environments is the application of an applied coating system. The most common topcoats used in coating systems are polyurethanes that contain isocyanates. Isocyanates are classified as potential human carcinogens and are known to cause cancer in animals. The primary objective of this effort was to demonstrate and validate alternatives to aliphatic isocyanate polyurethanes resulting in one or more isocyanate-free coatings qualified for use at AFSPC and NASA installations participating in this project. This Cost-Benefit Analysis (CBA) quantifies the estimated capital and process costs of coating alternatives and cost savings relative to the current coatings. The estimates in this CBA are to be used for assessing the relative merits of the selected alternatives. The actual economic effects at any specific facility will depend on the alternative material or technology implemented, the number of actual applications converted, future workloads, and other factors . The participants initially considered eighteen (18) alternative coatings as described in the Potential Alternatives Report entitled Potential Alternatives Report for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes, prepared by ITB. Of those, 8 alternatives were selected for testing in accordance with the Joint Test Protocol entitled Joint Test Protocol for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes, and the Field Test Plan entitled Field Evaluations Test Plan for Validation of Alternatives 10 Aliphatic Isocyanate Polyurethanes, both of which were prepared by ITB. A joint Test Report entitled Joint Test Report for Validation of Alternatives to Aliphatic Isocyanate Polyurethanes, prepared by ITB, documents the results of the laboratory and field testing, as well as any test modifications made during the execution of the testing. The coatings selected for evaluation in this CBA are shown in the table below. Only one control coating system is considered in this analysis. These coatings were either downselected for Phase II or performed well enough to be included in the Qualified Products List in the NASA technical standard NASA-STD-5008, Protective Coating of Carbon Steel, Stainless Steel, and Aluminum on Launch Structures, Facilities, and Ground Support Equipment.

Lewis, Pattie↗

DOE OSTI2020

Left-right canted-cosine-theta magnets

Disclosed herein are superconducting gantry magnets that include multiple quadrupole winding sections placed in sequence on a curve such that the effective current direction is reversed between sections. This produces alternating quadrupole field regions along the length of the bend whose individual integral strengths can be tuned by the location of the current polarity transitions. A simple transition scheme to reverse the current between sections can be implemented to allow for the use of one continuous winding and power supply. Dipole windings can be included in the superconducting gantry magnets so that the magnets produce superposed dipole and alternating quadrupole fields. The disclosed design for the windings and transition scheme to reverse current polarity can be implemented for higher order multipoles as well.

43 PARTICLE ACCELERATORS↗

DOE OSTI2018

Self-Powered Flexible Displays

Wearable technology is the new frontier in the tech industry. To be wearable, a device must be flexible, durable, and bio-compatible. As all electronics, these devices are going to consume energy. Currently, the world uses lithium ion batteries for its energy needs. The demand for lithium has become so high that the world reserves are threatening to run out far quicker than expected. This makes it imperative that we find a suitable alternative material to keep up with current power demands and, while we are at it, address the drive for low-cost, flexible power sources that the flexible electronics industry will surely need. The answer to this need can be potentially found in Triboelectric Nanogenerators (TENGs). Not only are TENGs flexible, they are also low-cost and stand-alone power sources, meaning that they have no need for bulky or rigid batteries. TENGs work based on the triboelectrification effect.

25 ENERGY STORAGE↗

DOE OSTI2023

Life-cycle costing assessment of back contact doping and encapsulation alternatives for increasing the life expectancy of CdTe PV modules (Final Report)

Contribution of Research to the State-of-Knowledge This research produced comparative sustainability evaluations of back contact doping and encapsulation alternatives considered by First Solar for decreasing degradation and increasing the life of the cadmium telluride (CdTe) photovoltaic (PV) modules. Technical Effectiveness and Economic Feasibility of Methods Investigated A holistic life-cycle-assessment of the alternatives considered for longer module operational lives, showed that they add between 0.2% and 2% to environmental impact indicators at the cradle-to-gate module level, but at the cradle-to-grave system level, alternative materials offer only benefits (i.e., environmental impact indicator decreases) to the public and the environment. Parallel experimental studies at First Solar showed that the use of the considered alternative materials did not impact the effectiveness of the current module recycling separations and material recovery processes. Furthermore, the increment on the module manufacturing cost due to using alternative materials was estimated to be negligible (i.e., >1%) and longer module lives more than compensate cost increases. Specifically, increase of the current warranted module life of 30 years to 50 years, would decrease the levelized cost of electricity (LCOE) from $40/MWh to $24/MWh for utility-scale installations in the US-SW, the economic feasibility of the considered alternatives is assured. Benefit to the Public With decreasing degradation from the current ~0.3%/year of Series 6 modules to less than 0.2%/year, the public will be benefited by longer photovoltaic operational lives, and therefore. In addition, the requirement for end-of-life management is shifted from 30 years to 40 or 50 years, with profound benefits to the public and the environment.

14 SOLAR ENERGY↗

NASA NTRS1990

Scientific Assessment of Stratospheric Ozone: 1989, volume 2. Appendix: AFEAS Report

The results are presented of the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS), which was organized to evaluate the potential effects on the environment of alternate compounds targeted to replace fully halogenated chlorofluorocarbons (CFCs). All relevant current scientific information to determine the environmental acceptability of the alternative fluorocarbons. Special emphasis was placed on: the potential of the compounds to affect stratospheric ozone; their potential to affect tropospheric ozone; their potential to contribute to model calculated global warming; the atmospheric degradation mechanisms of the compounds, in order to identify their products; and the potential environmental effects of the decomposition products. The alternative compounds to be studied were hydrofluorocarbons (HFCs) with one or two carbon atoms and one or more each of fluorine and hydrogen.

Source record↗

NASA NTRS1993

Eddy-Current Monitoring Of Composite Layups

Eddy-current-probe apparatus used to determine predominant orientations of fibers in fiber/matrix composite materials. Apparatus nondestructive, noninvasive means for monitoring composite prepregs and layups during fabrication to ensure predictable and repeatable mechanical properties of finished composite panels. Consists essentially of electromagnet coil wrapped around horseshoe-shaped powdered-iron or ferrite ore. Optionally, capacitor included in series or parallel with coil to form resonant circuit. Impedance monitor excites radio-frequency current in coil and measures impedance of probe circuit. Affected by whatever material placed near ends of core, where material intercepts alternating magnetic field excited in core by current in coil.

Fox, Robert L.↗

NASA NTRS1985

A preliminary investigation of the dynamic force-calibration of a magnetic suspension and balance system

The aerodynamic forces and moments acting upon a magnetically suspended wind tunnel model are derived from calibrations of suspension electro magnet currents against known forces. As an alternative to the conventional calibration method of applying steady forces to the model, early experiences with dynamic calibration are outlined, that is a calibration obtained by oscillating a model in suspension and deriving a force/current relationship from its inertia force and the unsteady components of currents. Advantages of dynamic calibration are speed and simplicity. The two methods of calibration applied to one force component show good agreement.

Goodyer, M. J.↗

DOE OSTI2021

Experimental and computational study of the microporous layer and hydrophobic treatment in the gas diffusion layer of a proton exchange membrane fuel cell

Enabling fuel cell operation at high current density is critical for developing competitive alternative power system to replace internal combustion engine. However, liquid water management continues to be a challenge for high humidity or high current density operation. Water condensation in the porous media hinders efficient oxygen transport to the catalyst layer, which in turns, reduces fuel cell performance. To improve water management capability, the gas diffusion layer is often impregnated with Polytetrafluoroethylene (PTFE) and coated with a thin microporous layer, which have shown to improve fuel cell performance, especially under wet conditions. However, the fundamental mechanism that drives the performance enhancement is still not well understood. In this work, the effects of PTFE impregnation and MPL were studied using both experimental and computational techniques. Both limiting current and polarization tests under dry and wet operating condition are conducted to study the oxygen transport resistance and fuel cell performance. In addition, a 2-D, two-phase, multi-physics PEMFC model is developed to simulate performance and gain a fundamental understanding of local water saturation and oxygen concentration. The combined results show that 5 wt% PTFE impregnation with MPL significantly enhances liquid water management, which enables higher current density operation of a fuel cell.

25 ENERGY STORAGE↗

DOE OSTI2012

Commercial Building Energy Asset Score System: Program Overview and Technical Protocol (Version 1.0)

The U.S. Department of Energy (DOE) is developing a national voluntary energy asset score system that includes an energy asset score tool to help building owners evaluate their buildings with respect to the score system. The goal of the energy asset score system is to facilitate cost-effective investment in energy efficiency improvements of commercial buildings. The system will allow building owners and managers to compare their building infrastructure against peers and track building upgrade progress over time. The system can also help other building stakeholders (e.g., building operators, tenants, financiers, and appraisers) understand the relative efficiency of different buildings in a way that is independent from their operations and occupancy. This report outlines the technical protocol used to generate the energy asset score, explains the scoring methodology, and provides additional details regarding the energy asset score tool. This report also describes alternative methods that were considered prior to developing the current approach. Finally, this report describes a few features of the program where alternative approaches are still under evaluation.

building energy use↗

DOE OSTI2013

Selection and properties of alternative forming fluids for TRISO fuel kernel production

Current Very High Temperature Reactor (VHTR) designs incorporate TRi-structural ISOtropic (TRISO) fuel, which consists of a spherical fissile fuel kernel surrounded by layers of pyrolytic carbon and silicon carbide. An internal sol-gel process forms the fuel kernel using wet chemistry to produce uranium oxyhydroxide gel spheres by dropping a cold precursor solution into a hot column of trichloroethylene (TCE). Over time, gelation byproducts inhibit complete gelation, and the TCE must be purified or discarded. The resulting TCE waste stream contains both radioactive and hazardous materials and is thus considered a mixed hazardous waste. Changing the forming fluid to a non-hazardous alternative could greatly improve the economics of TRISO fuel kernel production. Selection criteria for a replacement forming fluid narrowed a list of ~10,800 chemicals to yield ten potential replacement forming fluids: 1-bromododecane, 1- bromotetradecane, 1-bromoundecane, 1-chlorooctadecane, 1-chlorotetradecane, 1-iododecane, 1-iodododecane, 1-iodohexadecane, 1-iodooctadecane, and squalane. The density, viscosity, and surface tension for each potential replacement forming fluid were measured as a function of temperature between 25 °C and 80 °C. Calculated settling velocities and heat transfer rates give an overall column height approximation. 1-bromotetradecane, 1-chlorooctadecane, and 1-iodododecane show the greatest promise as replacements, and future tests will verify their ability to form satisfactory fuel kernels.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2023

Heat pumps in the United States: Market potentials, challenges and opportunities, technology advances

The US heat pump market has been affected by the socioeconomic impacts of the COVID-19 pandemic. However, the Biden administration’s goal of net-zero greenhouse gas emissions by 2050 through electrification and clean energy technologies is accelerating the research, development, and deployment of heat pumps in the United States for improved energy performance, reduced greenhouse gas emissions, and wider adoption. The US heat pump market has experienced steady growth since 2010. In 2020, heat pumps surpassed gas furnace shipments for the first time, and the trend maintains through 2022. The current priority is to improve the affordability of energy and equitable access to heat pump technologies through cost reductions and further accelerate this trend. In addition, current R&D includes emphases on alternative refrigeration technology and lower–global warming potential refrigerants to reduce direct emissions. Heat pump market share is expected to grow as regulatory policies and financial incentives steer the building sector toward decarbonization. This paper reviews policies and market trends, discusses the challenges and opportunities in the current policy landscape, and reviews current research in the United States.

Malhotra, Mini↗