During the development of a solar photovoltaic (PV) energy project, predicting expected energy production from a system is a key part of understanding system value. System energy production is a function of the system design and location, the mounting configuration, the power conversion system, and the module technology, as well as the solar resource. Even if all other variables are held constant, annual energy yield (kWh/kWp) will vary among module technologies because of differences in response to low-light levels and temperature. A number of PV system performance models have been developed and are in use, but little has been published on validation of these models or the accuracy and uncertainty of their output. With support from the U.S. Department of Energy's Solar Energy Technologies Program, Sandia National Laboratories organized a PV Performance Modeling Workshop in Albuquerque, New Mexico, September 22-23, 2010. The workshop was intended to address the current state of PV system models, develop a path forward for establishing best practices on PV system performance modeling, and set the stage for standardization of testing and validation procedures for models and input parameters. This report summarizes discussions and presentations from the workshop, as well as examines opportunities for collaborative efforts to develop objective comparisons between models and across sites and applications.
This report describes the status of research being performed under CRADA No. SC10/01771.00 (Lead/Carbon Functionality in VRLA Batteries) between Sandia National Laboratories and East Penn Manufacturing, conducted for the U.S. Department of Energy's Energy Storage Systems Program. The Quarter 1 Milestone was completed on time. The milestone entails conducting a thorough literature review to establish the current level of understanding of the mechanisms through which carbon additions to the negative active material improve valve-regulated lead-acid (VRLA) batteries. Most studies have entailed phenomenological research observing that the carbon additions prevent/reduce sulfation of the negative electrode; however, no understanding is available to provide insight into why certain carbons are successful while others are not. Impurities were implicated in one recent review of the electrochemical behavior of carbon additions. Four carbon samples have been received from East Penn Manufacturing and impurity contents have been analyzed. Carbon has been explored as an addition to lead-acid battery electrodes in a number of ways. Perhaps the most notable to date has been the hybrid 'Ultrabattery' developed by CSIRO where an asymmetric carbon-based electrochemical capacitor is combined with a lead-acid battery into a single cell, dramatically improving high-rate partial-state-of-charge (HRPSoC) operation. As illustrated below, the 'Ultrabattery' is a hybrid device constructed using a traditional lead-acid battery positive plate (i.e., PbO{sub 2}) and a negative electrode consisting of a carbon electrode in parallel with a lead-acid negative plate. This device exhibits a dramatically improved cycle life over traditional VRLA batteries, as well as increased charge power and charge acceptance. The 'Ultrabattery' has been produced successfully by both The Furukawa Battery Co. and East Penn Manufacturing. An example illustrating the dramatic improvement in cycle life of the Ultrabattery over a conventional VRLA battery is shown in the graph.
This report describes the status of research being performed under CRADA No. SC10/01771.00 (Lead/Carbon Functionality in VRLA Batteries) between Sandia National Laboratories and East Penn Manufacturing, conducted for the U.S. Department of Energy's Energy Storage Systems Program. The Quarter 2 Milestone was completed on time. The milestone entails an ex situ analysis of the four carbons that have been added to the negative active material of valve-regulated lead-acid (VRLA) batteries for the purposes of this study. The four carbons selected for this study were a graphitic carbon, a carbon black, an activated carbon, and acetylene black. The morphology, crystallinity, and impurity contents of each of the four carbons were analyzed; results were consistent with previous data. Cycling on a subset of the received East Penn cells containing different carbons (and a control) has been initiated. Carbon has been explored as an addition to lead-acid battery electrodes in a number of ways. Perhaps the most notable to date has been the hybrid 'Ultrabattery' developed by CSIRO where an asymmetric carbon-based electrochemical capacitor is combined with a lead-acid battery into a single cell, dramatically improving high-rate partial-state-of-charge (HRPSoC) operation. As illustrated below, the 'Ultrabattery' is a hybrid device constructed using a traditional lead-acid battery positive plate (i.e., PbO{sub 2}) and a negative electrode consisting of a carbon electrode in parallel with a lead-acid negative plate. This device exhibits a dramatically improved cycle life over traditional VRLA batteries, as well as increased charge power and charge acceptance. The 'Ultrabattery' has been produced successfully by both The Furukawa Battery Co. and East Penn Manufacturing. An example illustrating the dramatic improvement in cycle life of the Ultrabattery over a conventional VRLA battery is shown.
The Joint Architecture Standard (JAS) program at Sandia National Laboratories requires the use of a reliable data delivery protocol over SpaceWire. The National Aeronautics and Space Administration at the Goddard Spaceflight Center in Greenbelt, Maryland, developed and specified a reliable protocol for its Geostationary Operational Environment Satellite known as GOES-R Reliable Data Delivery Protocol (GRDDP). The JAS program implemented and tested GRDDP and then suggested a number of modifications to the original specification to meet its program specific requirements. This document details the full RDDP specification as modified for JAS. The JAS Reliable Data Delivery Protocol uses the lower-level SpaceWire data link layer to provide reliable packet delivery services to one or more higher-level host application processes. This document specifies the functional requirements for JRDDP but does not specify the interfaces to the lower- or higher-level processes, which may be implementation-dependent.
This study examines the meandering phenomenon as it occurs in media throughout terrestrial, glacial, atmospheric, and aquatic environments. Analysis of the minimum energy principle, along with theories of Coriolis forces (and random walks to explain the meandering phenomenon) found that these theories apply at different temporal and spatial scales. Coriolis forces might induce topological changes resulting in meandering planforms. The minimum energy principle might explain how these forces combine to limit the sinuosity to depth and width ratios that are common throughout various media. The study then compares the first order analytical solutions for flow field by Ikeda, et al. (1981) and Johannesson and Parker (1989b). Ikeda's et al. linear bank erosion model was implemented to predict the rate of bank erosion in which the bank erosion coefficient is treated as a stochastic variable that varies with physical properties of the bank (e.g., cohesiveness, stratigraphy, or vegetation density). The developed model was used to predict the evolution of meandering planforms. Then, the modeling results were analyzed and compared to the observed data. Since the migration of a meandering channel consists of downstream translation, lateral expansion, and downstream or upstream rotations several measures are formulated in order to determine which of the resulting planforms is closest to the experimental measured one. Results from the deterministic model highly depend on the calibrated erosion coefficient. Since field measurements are always limited, the stochastic model yielded more realistic predictions of meandering planform evolutions. Due to the random nature of bank erosion coefficient, the meandering planform evolution is a stochastic process that can only be accurately predicted by a stochastic model.
The objective of the U.S. Department of Energy Office of Nuclear Energy Advanced Modeling and Simulation Nuclear Waste Management Integrated Performance and Safety Codes (NEAMS Nuclear Waste Management IPSC) is to provide an integrated suite of computational modeling and simulation (M&S) capabilities to quantitatively assess the long-term performance of waste forms in the engineered and geologic environments of a radioactive-waste storage facility or disposal repository. These M&S capabilities are to be managed, verified, and validated within the NEAMS Nuclear Waste Management IPSC quality environment. M&S capabilities and the supporting analysis workflow and simulation data management tools will be distributed to end-users from this same quality environment. The same analysis workflow and simulation data management tools that are to be distributed to end-users will be used for verification and validation (V&V) activities within the quality environment. This strategic decision reduces the number of tools to be supported, and increases the quality of tools distributed to end users due to rigorous use by V&V activities. This report documents an evaluation of the needs, options, and tools selected for the NEAMS Nuclear Waste Management IPSC quality environment. The objective of the U.S. Department of Energy (DOE) Office of Nuclear Energy Advanced Modeling and Simulation Nuclear Waste Management Integrated Performance and Safety Codes (NEAMS Nuclear Waste Management IPSC) program element is to provide an integrated suite of computational modeling and simulation (M&S) capabilities to assess quantitatively the long-term performance of waste forms in the engineered and geologic environments of a radioactive-waste storage facility or disposal repository. This objective will be fulfilled by acquiring and developing M&S capabilities, and establishing a defensible level of confidence in these M&S capabilities. The foundation for assessing the level of confidence is based upon the rigor and results from verification, validation, and uncertainty quantification (V&V and UQ) activities. M&S capabilities are to be managed, verified, and validated within the NEAMS Nuclear Waste Management IPSC quality environment. M&S capabilities and the supporting analysis workflow and simulation data management tools will be distributed to end-users from this same quality environment. The same analysis workflow and simulation data management tools that are to be distributed to end-users will be used for verification and validation (V&V) activities within the quality environment. This strategic decision reduces the number of tools to be supported, and increases the quality of tools distributed to end users due to rigorous use by V&V activities. NEAMS Nuclear Waste Management IPSC V&V and UQ practices and evidence management goals are documented in the V&V Plan. This V&V plan includes a description of the quality environment into which M&S capabilities are imported and V&V and UQ activities are managed. The first phase of implementing the V&V plan is to deploy an initial quality environment through the acquisition and integration of a set of software tools. An evaluation of the needs, options, and tools selected for the quality environment is given in this report.
Eight cycles in a coordinated set of projects for Solar Thermochemical Cycles for Hydrogen production (STCH) were self-evaluated for the DOE-EERE Fuel Cell Technologies Program at a Working Group Meeting on October 8 and 9, 2008. This document reports the initial selection process for development investment in STCH projects, the evaluation process meant to reduce the number of projects as a means to focus resources on development of a few most-likely-to-succeed efforts, the obstacles encountered in project inventory reduction and the outcomes of the evaluation process. Summary technical status of the projects under evaluation is reported and recommendations identified to improve future project planning and selection activities.
Today, researchers, engineers, and policy makers are seeking ways to meet the world's growing demand for energy while addressing critical issues such as energy security, reliability, and sustainability. Many believe that distributed generators operating within a microgrid have the potential to address most of these issues. Sandia National Laboratories has developed a concept called energy surety in which five of these 'surety elements' are simultaneously considered: energy security, reliability, sustainability, safety, and cost-effectiveness. The surety methodology leads to a new microgrid design that we call an energy surety microgrid (ESM). This paper discusses the unique control requirement needed to produce a microgrid system that has high levels of surety, describes the control system from the most fundamental level through a real-world example, and discusses our ideas and concepts for a complete system.
An updated algorithm for the EXTRAD 4100S extremity dosimeter has been derived. This algorithm optimizes the binning of dosimeter element ratios and uses a quadratic function to determine the response factors for low response ratios. This results in lower systematic bias across all test categories and eliminates the need for the 'red strap' algorithm that was used for high energy beta/gamma emitting radionuclides. The Radiation Protection Dosimetry Program (RPDP) at Sandia National Laboratories uses the Thermo Fisher EXTRAD 4100S extremity dosimeter, shown in Fig 1.1 to determine shallow dose to the extremities of potentially exposed individuals. This dosimeter consists of two LiF TLD elements or 'chipstrates', one of TLD-700 ({sup 7}Li) and one of TLD-100 (natural Li) separated by a tin filter. Following readout and background subtraction, the ratio of the responses of the two elements is determined defining the penetrability of the incident radiation. While this penetrability approximates the incident energy of the radiation, X-rays and beta particles exist in energy distributions that make determination of dose conversion factors less straightforward in their determination.
We describe the design of pixelated filter arrays for hyperspectral monitoring of CO2 and H2O absorption in the midwave infrared (centered at 4.25μm and 5.15μm, respectively) using resonant subwavelength gratings (RSGs), also called guided-mode resonant filters (GMRFs). For each gas, a hyperspectral filter array of very narrowband filters is designed that spans the absorption band on a single substrate. A pixelated geometry allows for direct registration of filter pixels to focal plane array (FPA) sensor pixels and for non-scanning data collection. The design process for narrowband, low-sideband reflective and transmissive filters within fabrication limitations will be discussed.
Microsystem-Enabled Photovoltaic (MEPV) cells allow solar PV systems to take advantage of scaling benefits that occur as solar cells are reduced in size. We have developed MEPV cells that are 5 to 20 microns thick and down to 250 microns across. We have developed and demonstrated crystalline silicon (c-Si) cells with solar conversion efficiencies of 14.9%, and gallium arsenide (GaAs) cells with a conversion efficiency of 11.36%. In pursuing this work, we have identified over twenty scaling benefits that reduce PV system cost, improve performance, or allow new functionality. To create these cells, we have combined microfabrication techniques from various microsystem technologies. We have focused our development efforts on creating a process flow that uses standard equipment and standard wafer thicknesses, allows all high-temperature processing to be performed prior to release, and allows the remaining post-release wafer to be reprocessed and reused. The c-Si cell junctions are created using a backside point-contact PV cell process. The GaAs cells have an epitaxially grown junction. Despite the horizontal junction, these cells also are backside contacted. We provide recent developments and details for all steps of the process including junction creation, surface passivation, metallization, and release.
Circuit simulation tools (e.g., SPICE) have become invaluable in the development and design of electronic circuits in radiation environments. These codes are often employed to study the effect of many thousands of devices under transient current conditions. Device-scale simulation tools (e.g., MEDICI) are commonly used in the design of individual semiconductor components, but require computing resources that make their incorporation into a circuit code impossible for large-scale circuits. Analytic solutions to the ambipolar diffusion equation, an approximation to the carrier transport equations, may be used to characterize the transient currents at nodes within a circuit simulator. We present new transient 1D excess carrier density and photocurrent density solutions to the ambipolar diffusion equation for low-level radiation pulses that take into account a finite device geometry, ohmic fields outside the depleted region, and an arbitrary change in the carrier lifetime due to neutron irradiation or other effects. The solutions are specifically evaluated for the case of an abrupt change in the carrier lifetime during or after, a step, square, or piecewise linear radiation pulse. Noting slow convergence of the raw Fourier series for certain parameter sets, we use closed-form formulas for some of the infinite sums to produce 'partial closed-form' solutions for the above three cases. These 'partial closed-form' solutions converge with only a few tens of terms, which enables efficient large-scale circuit simulations.
The goal of the 7X performance testing was to assure Sandia National Laboratories, Cray Inc., and the Department of Energy that Red Storm would achieve its performance requirements which were defined as a comparison between ASCI Red and Red Storm. Our approach was to identify one or more problems for each application in the 7X suite, run those problems at multiple processor sizes in the capability computing range, and compare the results between ASCI Red and Red Storm. The first part of this report describes the two computer systems, the applications in the 7X suite, the test problems, and the results of the performance tests on ASCI Red and Red Storm. During the course of the testing on Red Storm, we had the opportunity to run the test problems in both single-core mode and dual-core mode and the second part of this report describes those results. Finally, we reflect on lessons learned in undertaking a major head-to-head benchmark comparison.
Minimum detectable velocity (MDV) is a fundamental consideration for the design, implementation, and exploitation of ground moving-target indication (GMTI) radar imaging modes. All single-phase-center air-to-ground radars are characterized by an MDV, or a minimum radial velocity below which motion of a discrete nonstationary target is indistinguishable from the relative motion between the platform and the ground. Targets with radial velocities less than MDV are typically overwhelmed by endoclutter ground returns, and are thus not generally detectable. Targets with radial velocities greater than MDV typically produce distinct returns falling outside of the endoclutter ground returns, and are thus generally discernible using straightforward detection algorithms. This document provides a straightforward derivation of MDV for an air-to-ground single-phase-center GMTI radar operating in an arbitrary geometry.
We performed measurements of the prompt radiation induced conductivity in thin samples of Alumina and Sapphire at the Little Mountain Medusa LINAC facility in Ogden, UT. Five mil thick samples were irradiated with pulses of 20 MeV electrons, yielding dose rates of 1E7 to 1E9 rad/s. We applied variable potentials up to 1 kV across the samples and measured the prompt conduction current. Analysis rendered prompt conductivity coefficients between 1E10 and 1E9 mho/m/(rad/s), depending on the dose rate and the pulse width for Alumina and 1E7 to 6E7 mho/m/(rad/s) for Sapphire.
The Sandia National Laboratories, California (SNL/CA) Environmental Management System (EMS) Program Manual documents the elements of the site EMS Program. The SNL/CA EMS Program conforms to the International Standard on Environmental Management Systems, ISO 14001:2004and Department of Energy (DOE) Order 450.1. Sandia National Laboratories, California (SNL/CA) has maintained functional environmental programs to assist with regulatory compliance for more than 30 years. During 2005, these existing programs were rolled into a formal environmental management system (EMS) that expands beyond the traditional compliance focus to managing and improving environmental performance and stewardship practices for all site activities. An EMS is a set of inter-related elements that represent a continuing cycle of planning, implementing, evaluating, and improving processes and actions undertaken to achieve environmental policy and goals. The SNL/CA EMS Program conforms to the International Standard for Environmental Management Systems, ISO 14001:2004 (ISO 2004). The site received ISO 14001 certification in September 2006. SNL/CA's EMS Program is applicable to the Sandia, Livermore site only. Although SNL/CA operates as one organizational division of the overall Sandia National Laboratories, the EMS Program is site-specific, with site-specific objectives and targets. SNL/CA (Division 8000) benefits from the organizational structure as it provides corporate level policies, procedures, and standards, and established processes that connect to and support elements of the SNL/CA EMS Program. Additionally, SNL/CA's EMS Program benefits from two corporate functional programs (Facilities Energy Management and Fleet Services programs) that maintain responsibility for energy management and fleet services for all Sandia locations. Each EMS element is further enhanced with site-specific processes and standards. Division 8000 has several groups operating at Sandia National Laboratories, New Mexico (SNL/NM). Although these groups, from an organizational perspective, are part of Division 8000, they are managed locally and fall under the environmental requirements specific to their New Mexico location. The New Mexico groups in Division 8000 follow the corporate EMS Program for New Mexico operations.
The CASL Level 2 Milestone VUQ.Y1.03, 'Enable statistical sensitivity and UQ demonstrations for VERA,' was successfully completed in March 2011. The VUQ focus area led this effort, in close partnership with AMA, and with support from VRI. DAKOTA was coupled to VIPRE-W thermal-hydraulics simulations representing reactors of interest to address crud-related challenge problems in order to understand the sensitivity and uncertainty in simulation outputs with respect to uncertain operating and model form parameters. This report summarizes work coupling the software tools, characterizing uncertainties, selecting sensitivity and uncertainty quantification algorithms, and analyzing the results of iterative studies. These demonstration studies focused on sensitivity and uncertainty of mass evaporation rate calculated by VIPRE-W, a key predictor for crud-induced power shift (CIPS).