Department Of Energy Requirements Research Articles

New insights from DFT analysis: Mg vacancies and hydrogen doping in enhancing thermodynamic properties and hydrogen storage performance of Li2BeMgH6

To identify effective hydrogen storage materials, a novel study employing first-principles calculations based on density functional theory DFT on the lithium-based double perovskite hydride Li2BeMgH6. This material, with its innovative and significant attributes, emerges as a potential candidate for hydrogen storage, inspiring experimental researchers to pursue its synthesis for the experimental fabrication of hydrogen storage devices. Notably, it boasts a remarkable gravimetric capacity of 11.35 wt%, coupled with exceptional stability and desorption temperature, surpassing the standards set by the U.S. Department of Energy (DOE) for solid-state hydrogen storage (ΔH = −40 kJ/mol.H2 and Td = 289 K–393 K), with respective values of ΔH = −77.37 kJ/mol H2 and Td = 591 K for the cubic phase and ΔH = −84.64 kJ/mol H2, Td = 647 K for the rhombohedral structure. This comprehensive research aims to demonstrate the thermodynamic stability of this innovative material and improve its hydrogen storage properties in line with DOE requirements. The results obtained highlight the significant impact of two strategies for enhancing hydrogen storage properties in two stable phases (face-centered cubic (fcc) and rhombohedral (R3)): the creation of magnesium vacancy defects and hydrogen doping in the Mg vacancies in the studied system. The first strategy, involving the generation of 6 % defects in the Mg atoms, resulted in a notable improvement in storage properties, with a gain of 50.75 % for the cubic structure and 50.46 % for the rhombohedral structure. The second strategy, which consists of doping the vacant Mg sites with hydrogen, also demonstrated remarkable efficiency, leading to an increase of 50.05 % and 53.07 % in storage performance for the two phases, respectively.

Carbon Material-Reinforced Polymer Composites for Bipolar Plates in Polymer Electrolyte Membrane Fuel Cells.

Bipolar plates (BPs) are one of the most important components of polymer electrolyte membrane fuel cells (PEMFCs) because of their important role in gas and water management, electrical performance, and mechanical stability. Therefore, promising materials for use as BPs should meet several technical targets established by the United States Department of Energy (DOE). Thus far, in the literature, many materials have been reported for possible applications in BPs. Of these, polymer composites reinforced with carbon allotropes are one of the most prominent. Therefore, in this review article, we present the progress and critical analysis on the use of carbon material-reinforced polymer composites as BPs materials in PEMFCs. Based on this review, it is observed that numerous polymer composites reinforced with carbon allotropes have been produced in the literature, and most of the composites synthesized and characterized for their possible application in BPs meet the DOE requirements. However, these composites can still be improved before their use for BPs in PEMFCs.

An Economic Analysis of Rewind, Premium, and Standard Efficiency Vertical Hollow Shaft Motors for Irrigation

Abstract. Vertical hollow shaft motors are commonly used for vertical turbine pumps for irrigation. They are a specialty motor which has been exempt from the Department of Energy (DOE) requirement for improved energy efficiency. We evaluated the payback and net present value (NPV) of standard efficiency, energy efficient, and premium efficiency motors for motor sizes used in irrigation. For motor sizes between 22 and 56 kW (30 and 75 hp), the NPV and payback analysis indicated that premium efficient motors are more advantageous than standard efficiency. In motor sizes greater than 75 kW (100 hp) standard efficient motors are more cost effective than replacing a motor with a premium efficiency motor. When considering a repair or rewind of a motor, the result is highly dependent on the quality, and the resulting efficiency expected after the repair. If a repaired motor nameplate efficiency could be attained after rewinding and repair, then rewinding is most cost effective. However, if original nameplate efficiency is not attained, then it may be more cost effective to purchase a premium efficiency motor over rewinding. New DOE requirements may be advantageous for irrigators even though capital costs will be higher for new motors. Keywords: Motor rewind, Net present value (NPV), Payback period, Premium efficiency motor.

The future of scientific workflows

Today’s computational, experimental, and observational sciences rely on computations that involve many related tasks. The success of a scientific mission often hinges on the computer automation of these workflows. In April 2015, the US Department of Energy (DOE) invited a diverse group of domain and computer scientists from national laboratories supported by the Office of Science, the National Nuclear Security Administration, from industry, and from academia to review the workflow requirements of DOE’s science and national security missions, to assess the current state of the art in science workflows, to understand the impact of emerging extreme-scale computing systems on those workflows, and to develop requirements for automated workflow management in future and existing environments. This article is a summary of the opinions of over 50 leading researchers attending this workshop. We highlight use cases, computing systems, workflow needs and conclude by summarizing the remaining challenges this community sees that inhibit large-scale scientific workflows from becoming a mainstream tool for extreme-scale science.

Surface modification of 316 stainless steel with platinum for the application of bipolar plates in high performance proton exchange membrane fuel cells

316 stainless steel has been regarded as one of the promising candidates to replace graphite for bipolar plate application. However, the relatively high electrical resistance caused by the formation of passive oxide film and the insufficient corrosion resistance in long-term operation are two main concerns of 316 stainless steel bipolar plates. Low temperature active screen plasma alloying technology shows the ability to reduce electrical resistance and enhance corrosion resistance of 316 stainless steel bipolar plates to some extent, but still can not satisfy the Department of Energy (DOE) requirements. In this paper, active screen plasma co-alloying treatments with nitrogen and platinum are conducted to modify the surface of 316 stainless steel. The surface morphology, phase constitute, chemical composition and layer structure of treated 316 stainless steel are fully studied. A dense, columnar structured and single phase Pt3Fe deposition layer is produced on the surface of 316 stainless steel after treatments. Thanks to the excellent electrical conductivity and corrosion resistance of Pt3Fe, the surface electrical conductivity and corrosion resistance are greatly enhanced and satisfies the DOE requirements, contributing to the significant improvement of single cell performances.

CO2 capture from dry flue gas by vacuum swing adsorption: A pilot plant study

The capture and concentration of CO2 from a dry flue gas by vacuum swing adsorption (VSA) has been experimentally demonstrated in a pilot plant. The pilot plant has the provision for using two coupled columns that are each packed with approximately 41 kg of Zeochem zeolite 13X. Breakthrough experiments were first carried out by perturbing a N2 saturated bed with 15% CO2 and 85% N2 feed, which is representative of a dry flue gas from coal‐fired power plants. The breakthrough results showed long plateaus in temperature profiles confirming a near adiabatic behavior. In the process study, a basic four‐step vacuum swing adsorption (VSA) cycle comprising the following steps: pressurization with feed, adsorption, forward blowdown, and reverse evacuation was investigated first. In the absence of any coupling among the steps, a single bed was used. With this cycle configuration, CO2 was concentrated to 95.9 ± 1% with a recovery of 86.4 ± 5.6%. To improve the process performance, a four‐step cycle with light product pressurization (LPP) using two beds was investigated. This cycle was able to achieve 94.8 ± 1% purity and 89.7 ± 5.6% recovery. The Department of Energy requirements are 95% purity and 90% recovery. The proposed underlying physics of performance improvement of the four‐step cycle with LPP has also been experimentally validated. The pilot plant results were then used for detailed validation of a one‐dimensional, nonisothermal, and nonisobaric model. Both transient profiles of various measured variables and cyclic steady state performance results were compared with the model predictions, and they were in good agreement. The energy consumptions in the pilot plant experiments were 339–583 ± 36.7 kWh tonne−1 CO2 captured and they were significantly different from the theoretical power consumptions obtained from isentropic compression calculations. The productivities were 0.87–1.4 ± 0.07 tonne CO2 m−3 adsorbent day−1. The results from our pilot plant were also compared with available results from other pilot plant studies on CO2 capture from flue gas. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1830–1842, 2014

A TECHNICAL BASIS FOR THE CONTINUED USE OF EXPOSURE AS AN ACCEPTABLE OPERATIONAL QUANTITY IN RADIATION PROTECTION

Within the tabulated values of the new [to U.S. Department of Energy (DOE)] radiation weighting factors, it can be seen that a doubling of the neutron factor occurs for the 0.1 to 2 MeV neutron energy range. Hence, with the effective replacement of the quality factor by these new radiation weighting factors (for the protection quantities), it has been widely understood that the new changes will most definitely impact neutron dosimetry. However, it is less well understood that the new changes could also affect photon (and beta) dosimetry, i.e., photon reference fields, instrument design, and instrument calibrations. This paper discusses the ramifications, and ultimately concludes that the use of exposure for workplace measurements complies with both current and amended DOE requirements.

Development of fuel cell bipolar plates from graphite filled wet-lay thermoplastic composite materials

A method with the potential to produce economical bipolar plates with high electrical conductivity and mechanical properties is described. Thermoplastic composite materials consisting of graphite particles, thermoplastic fibers and glass or carbon fibers are generated by means of a wet-lay (paper-making) process to yield highly formable sheets. The sheets are then stacked and compression molded to form bipolar plates with gas flow channels. Poly(phenylene sulfide) (PPS) based wet-lay composite plates have in-plane conductivity of 200–300 S cm −1, tensile strength of 57 MPa, flexural strength of 96 MPa and impact strength (unnotched) of 81 J m −1 (1.5 ft-lb in. −1). These values well exceed industrial as well as Department of Energy requirements or targets and have never been reached before for composite bipolar plates. The use of wet-lay sheets also makes it possible to choose different components including polymer, graphite particle and reinforcement for the core and outer layers of the plate, respectively, to optimize the properties and/or reduce the cost of the plate. The through-plane conductivity (around 20 S cm −1) and half-cell resistance of the bipolar plate indicate that the through-plane conductivity of the material needs some improvement.

An algorithm for source checking continuous air monitors using radon progeny.

Department of Energy requirements contained within 10CFR835 require that continuous air monitors be periodically checked for operability. The DOE air monitoring implementation guide for 10CFR835 allows the use of radon progeny to perform the recommended weekly source check. The Defense Waste Processing Facility located at the Savannah River Site has demonstrated that, through the use of the Hypotheses Concerning Two Means, diurnal change in the radon progeny detected by the monitors meets the requirements for weekly source checks. The use of the diurnal change in radon progeny has replaced the person-hours expended performing direct weekly source checking with an automated system requiring minimal person-hour expenditure.

Teraflops supercomputer: architecture and validation of the fault tolerance mechanisms

Intel Corporation developed the Teraflops supercomputer for the US Department of Energy (DOE) as part of the Accelerated Strategic Computing Initiative (ASCI). This is the most powerful computing machine available today, performing over two trillion floating point operations per second with the aid of more than 9,000 Intel processors. The Teraflops machine employs complex hardware and software fault/error handling mechanisms for complying with DOE's reliability requirements. This paper gives a brief description of the system architecture and presents the validation of the fault tolerance mechanisms. Physical fault injection at the IC pin level was used for validation purposes. An original approach was developed for assessing signal sensitivity to transient faults and the effectiveness of the fault/error handling mechanisms. Dependency between fault/error detection coverage and fault duration was also determined. Fault injection experiments unveiled several malfunctions at the hardware, firmware, and software levels. The supercomputer performed according to the DOE requirements after corrective actions were implemented. The fault injection approach presented in this paper can be used for validation of any fault-tolerant or highly available computing system.