Variability of the data for CO2 absorption on coal reported by different research groups suggests that it strongly depends on experimental conditions. We investigated the effects of moisture content and pressure cycling history on temporal changes in the coal sorptive capacity for Pocahontas #3, Illinois #6, and Beulah Zap powders of Argonne premium coals. The samples were tested as received and moisture equilibrated at 96-97% RH and 55°C for 48 hours. It was demonstrated that the magnitude and dynamics of the changes are affected by the coal type (maceral) and rank. Correlation between the sample volume change (swelling/shrinkage) and the variations in absorption-desorption patterns may indicate the relationship between coal structural relaxation and kinetics of CO2 absorption. Experimental and theoretical methods are proposed to study these effects.

The Solargenix Advanced Trough Development Project was initiated in the Year 2000 with the support of the DOE CSP Program and, more recently, with the added support of the Nevada Southwest Energy Partnership. Parabolic trough plants are the most mature solar power technology, but no large-scale plants have been built in over a decade. Given this lengthy lull in deployment, our first Project objective was development of improved trough technology for near-term deployment, closely patterned after the best of the prior-generation troughs. The second objective is to develop further improvements in next-generation trough technology that will lead to even larger reductions in the cost of the delivered energy. To date, this Project has successfully developed an advanced trough, which is being deployed on a 1-MW plant in Arizona and will soon be deployed in a 64-MW plant in Nevada. This advanced trough offers a 10% increase in performance and over an 20% decrease in cost, relative to prior-generation troughs.

This article introduces a novel phase shifting pixelated interferometer based on a liquid crystal spatial light modulator and simulates the expected performance. The phase shifted frames are captured simultaneously which reduces the problems arising from vibrations and air turbulence. The liquid crystal spatial light modulator is very flexible and can be configured to provide a large number of phase shift levels and geometries to reduce the measurement error.

We report the effect of the hydrogen (H) content (CH) on the crystallization kinetics, surface morphology and grain growth for Hot Wire CVD a-Si:H films containing 12.5 and 2.7 at.% H which are crystallized by rapid thermal anneal (RTA). For the high CH film we observe explosive H evolution, with a resultant destruction of the film for RTA temperatures >750 deg C. At RTA temperatures ~600 deg C, both films remain intact with similar morphologies. At this same lower RTA, the incubation and crystallization times decrease, and the grain size as measured by X-Ray Diffraction increases with decreasing film CH. SIMS measurements indicate that a similar film CH (<0.5 at.%) exists in both films when crystallization commences. The benefits of a two-step annealing process for the high CH film are documented.

Our analyses show that defect clusters can lower the efficiency of multicrystalline silicon (mc-Si) solar cells by 2 to 4 absolute percentage points. This large loss can be recovered if impurities precipitated at the defect cluster sites can be gettered. We describe a new technique for gettering precipitated impurities.

The National Renewable Energy Laboratory (NREL) Solar Radiometry and Metrology task provides traceable optical radiometric calibrations and measurements to photovoltaic (PV) researchers and the PV industry. Traceability of NREL solar radiometer calibrations to the World Radiometric Reference (WRR) was accomplished during Pyrheliometer Comparison at NREL in October 2004. Ten spectral and more than 200 broadband radiometers for solar measurements were calibrated this year. We measured detailed spectral distributions of the NREL and PV industry Pulsed Solar Simulators and are analyzing the influence of environmental variables on radiometer uncertainty. New systems for indoor and outdoor solar radiometer calibrations and ultraviolet (UV) spectral measurements and UV radiometer calibrations were purchased and tested. Optical metrology functions support the NREL Measurement and Characterization Task effort for ISO 17025 accreditation of NREL Solar Reference Cell Calibrations and have been integrated into the NREL quality system and audited for ISO17025 compliance.

Thin hydrogenated amorphous silicon (a-Si:H) layers deposited by hot-wire chemical vapor deposition (HWCVD) are used as both emitters and back contacts in silicon heterojunction solar cells. Low interface recombination velocity and high open-circuit voltage are achieved by a low substrate temperature (<150 deg C) intrinsic a-Si:H deposition which ensures immediate amorphous silicon deposition. This is followed by deposition of doped a-Si:H at a higher temperature (>200 deg C) which appears to improve dopant activation. With an i/n a-Si:H emitter, we obtain a confirmed efficiency of 17.1% on textured p-type float-zone (FZ) silicon with a screen-printed aluminum back-surface-field (Al-BSF) contact. Employing a-Si:H as both the front emitter and the back contact, we achieve a confirmed efficiency of 17.5%, the highest reported efficiency for a p-type c-Si based heterojunction solar cell.

This paper presents a brief overview of the status and accomplishments during fiscal year (FY) 2005 of the Photovoltaic (PV) Exploratory Reliability and Performance R&D Subtask, which is part of the PV Module Reliability R&D Project (a joint NREL-Sandia project).

Arizona Public Service (APS) is currently installing new power facilities to generate a portion of its electricity from solar resources that will satisfy its obligation under the Arizona Environmental Portfolio Standard (EPS). During FY04, APS began construction on a 1-MWe parabolic trough concentrating solar power plant. This plant represents the first parabolic trough plant to begin construction since 1991. Site preparation and construction activities continued throughout much of FY05, and startup activities are planned for Fall 2005 (with completion early in FY06). The plant will be the first commercial deployment of the Solargenix parabolic trough collector technology developed under contract to the National Renewable Energy Laboratory. The plant will use an organic Rankine cycle (ORC) power plant, provided by Ormat. The ORC power plant is much simpler than the conventional steam Rankine cycle plant and allows unattended operation of the facility.

A poster presentation for AWEA's WindPower 2005 conference in Denver, Colorado, May 15 -18, 2005 that provides an outline of the approach and process used for validating U.S. wind resource maps.

We illustrate the capabilities of the High Voltage Stress Test (HVST) which operates continuously in the array field east of the Outdoor Test Facility at the National Renewable Energy Laboratory. Because we know that photovoltaic (PV) modules generating electrical power in both residential and utility-scale array installations will develop high-voltage biases approaching 600 VDC and 1,000 VDC, respectively, we expect such high voltages will result in current leakage between cells and ground, typically through the frames or mounts. We know that inevitably such leakage currents are capable of producing electrochemical corrosion that adversely impacts long-term module performance. With the HVST, we stress or operate PV modules under high-voltage bias, to characterize their leakage currents under all prevailing ambient conditions and assess performance changes emanating from high-voltage stress. We perform this test both on single modules and an active array.

The objective of this research is to determine the operational characteristics key to efficient, low-cost, stable solar cells based on dye-sensitized mesoporous films (in collaboration with DOE's Office of Science Program). Toward this end, we have investigated the mechanism by which the adsorbent chenodeoxycholate, cografted with a sensitizer onto TiO2 nanocrystals, improves the open-circuit photovoltage (VOC) and short-circuit photocurrent density (JSC). We find that adding chenodeoxycholate not only shifts the TiO2 conduction-band edge to negative potentials but also accelerates the rate of recombination. The net effect of these opposing phenomena is to produce a higher photovoltage. It is also found that chenodeoxycholate reduces the dye loading significantly but has only a modest effect on JSC. Implications of these results to developing more efficient cells are discussed.

Crystallization of hydrogenated amorphous silicon (a-Si:H) films deposited on low-cost substrates shows potential for solar cell applications. Secondary ion mass spectrometry (SIMS) was used to study impurity incorporation, hydrogen evolution, and dopant diffusion during the crystallization process

High quality electron beams with hundreds of picoCoulombs ofcharge inpercent energy spread above 80 MeV were produced for the firsttime in high gradient laser wakefield accelerators by guiding the drivelaser pulse.

As part of the work conducted in the PV Systems Reliability and Performance R&D Task, a 1.5-kWdc photovoltaic (PV) array consisting of 36 Solarex MST-43MV dual-junction a-Si modules was installed and its performance monitored for almost six years (September 1999 through May 2005) at the National Renewable Energy Laboratory (NREL) Outdoor Test Facility (OTF). This paper describes the system and its performance based on the PV for Utility-Scale Applications (PVUSA) power rating method.

The authors present a search for the standard model Higgs boson decaying into b{bar b} and produced in association with W bosons in p{bar p} collisions at {radical}s = 1.96 TeV. This search uses 320 pb{sup -1} of the dataset accumulated by the upgraded Collider Detector at Fermilab. Events are selected that have a high-transverse momentum electron or muon, missing transverse energy, and two jets, at least one of which is consistent with the hadronization of a b quark. Both the number of events and the dijet mass distribution are consistent with standard model background expectations, and they set 95% confidence level upper limits on the production cross section times branching ratio for the Higgs boson or any new particle with similar decay kinematics. These upper limits range from 10 pb for m{sub H} = 110 GeV/c{sup 2} to 3 pb for m{sub H} = 150 GeV/c{sup 2}.

Poster presentation on Macro-System Model for the 2005 Hydrogen, Fuel Cells & Infrastructure Technologies Program Annual Review held in Arlington, Virginia on May 23-26, 2005

Pyrochemical processing has been implemented for the treatment of spent fuel from the Experimental Breeder Reactor-II (EBR-II) at Idaho National Laboratory since 1996. This report summarizes technical advancements made in electrorefining of spent EBR-II driver fuel in the Mk-IV electrorefiner since the pyrochemical processing was integrated into the AFCI program in 2002. The significant advancements include improving uranium dissolution and noble metal retention from chopped fuel segments, increasing cathode current efficiency, and achieving co-collection of zirconium along with uranium from the cadmium pool.

The combined sensitivity of CDF's current Standard Model Higgs boson searches is presented. The expected 95% CL limits on the production cross section times the relevant Higgs boson branching ratios are computed for the W{sup {+-}}H {yields} {ell}{sup {+-}}{nu}b{bar b}, ZH {yields} {nu}{bar {nu}}b{bar b}, gg {yields} H {yields} W{sup +}W{sup -} W{sup {+-}}H {yields} W{sup {+-}}W{sup +}W{sup -} channels as they stand as of the October 2005, using results which were prepared for Summer 2005 conferences and a newer result form the gg {yields} H {yields} W{sup +}W{sup -} channel. Correlated and uncorrelated systematic uncertainties are taken into account, and the luminosity requirements for 95% CL exclusion, 3{sigma} evidence, and 5{sigma} discovery are computed for median experimental outcomes. A list of improvements required to achieve the sensitivity to a SM Higgs boson as quantified in the Higgs Sensitivity Working Group's report is provided.

Dual-continuum models have been widely used in modeling flowand transport in fractured porous rocks. Among many other applications,dual-continuum approaches were utilized in predictive models of thethermal-hydrological conditions near emplacement tunnels (drifts) atYucca Mountain, Nevada, the proposed site for a radioactive wasterepository in the U.S. In unsaturated formations such as those at YuccaMountain, the magnitude of mass and heat exchange between the twocontinua fracture network and matrix is largely dependent on the flowcharacteristics in the fractures, because channelized finger-type flowstrongly reduces the interface area between the matrix surfaces and theflowing liquid. This effect may have important implications, for example,during the time period that the fractured rock near the repository driftswould be heated above the boiling point of water. Depending on themagnitude of heat transfer from the matrix, water percolating down thefractures will either boil off in the hot rock region above drifts or maypenetrate all the way to the drift walls and possibly seep into the opencavities. In this paper, we describe a sensitivity analysis using avariety of approaches to treat fracture-matrix interaction in athree-dimensional dual-continuum setting. Our simulation example is alaboratory heater experiment described in the literature that providesevidence of rapid water flow in fractures, leading to drift seepagedespite above-boiling …

We present a digest of our research on the thin-film material components that comprise the top and bottom cells of three different material systems and the tandem devices constructed from them.

Stress/Strain fields associated with thin film buckling induced by compressive stresses or blistering due to the presence of gas bubbles underneath single crystal surfaces are difficult to measure owing to the microscale dimensions of these structures. In this work, we show that micro Scanning X-ray diffraction is a well suited technique for mapping the strain/stress tensor of these damaged structures.

Higher-efficiency solar cells improve the likelihood that concentrator photovoltaic systems will become cost effective. A four-junction GaAs- and Ge-based solar cell incorporating a 1-eV bandgap material has an ideal AM0 efficiency of ~40% and could also be used in a terrestrial concentrator module. The dilute-N GaAsN alloy's bandgap can be reduced to near 1 eV when the nitrogen content is 2% - 3%. Indium can also be added to the alloy to improve lattice matching to GaAs and Ge. We have used deep-level transient spectroscopy (DLTS) to characterize traps in both p-type and n-type GaAsN. For each type of material, the dominant DLTS signal corresponds to an electron trap having an activation energy of about 0.35 eV for p-type GaAsN and about 0.45 eV for n-type GaAsN. In both types of materials, the trap concentrations, modified by ..lambda..-effect factors, increase with both increasing N content and increased doping.

Symbioses between cnidarians and dinoflagellates in the genus Symbiodinium are widespread in the marine environment. The importance of this symbiosis to reef-building corals and reef nutrient and carbon cycles is well documented, but little is known about the mechanisms by which the partners establish and regulate the symbiosis. Because the dinoflagellate symbionts live inside the cells of their host coral, the interactions between the partners occur on cellular and molecular levels, as each partner alters the expression of genes and proteins to facilitate the partnership. These interactions can examined using high-throughput techniques that allow thousands of genes to be examined simultaneously. We are developing the groundwork so that we can use DNA microarray profiling to identify genes involved in the Montastraea faveolata and Acropora palmata symbioses. Here we report results from the initial steps in this microarray initiative, that is, the construction of cDNA libraries from 4 of 16 target stages, sequencing of 3450 cDNA clones to generate Expressed Sequenced Tags (ESTs), and annotation of the ESTs to identify candidate genes to include in the microarrays. An understanding of how the coral-dinoflagellate symbiosis is regulated will have implications for atmospheric and ocean sciences, conservation biology, the study and diagnosis of …