Bulletin of the American Physical Society
APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010; Portland, Oregon
Session T14: Energy Resources Followed by Energy Production, Sustainability and Environment |
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Sponsoring Units: GERA Chair: Terry Tritt, Clemson University Room: B113 |
Wednesday, March 17, 2010 2:30PM - 2:42PM |
T14.00001: Visible light photoreduction of CO$_{2}$ using CdSe/Pt/TiO$_{2}$ heterostructured catalysts Christopher Matranga, Congjun Wang, Robert Thompson, John Baltrus A series of CdSe quantum dot (QD) sensitized TiO$_{2}$ heterostructures have been synthesized, characterized, and tested for the photocatalytic reduction of CO$_{2 }$in the presence of H$_{2}$O. ~Our results show that these heterostructured materials are capable of catalyzing the photoreduction of CO$_{2}$ using visible light illumination ($\lambda \quad >$ 420 nm) only. The effect of removing surfactant caps from the CdSe QDs by annealing and using a hydrazine chemical treatment have also been investigated. The photocatalytic reduction process is followed using infrared spectroscopy to probe the gas phase reactants and gas chromatography to detect the products. Gas chromatographic analysis shows that the primary reaction product is CH$_{4}$, with CH$_{3}$OH, H$_{2}$, and CO observed as secondary products. Typical yields of the gas phase products after visible light illumination ($\lambda \quad >$ 420 nm) were 48 ppm g$^{-1}$ h$^{-1}$ of CH$_{4}$, 3.3 ppm g$^{-1}$ h$^{-1}$ of CH$_{3}$OH (vapor), and trace amounts of CO and H$_{2}$. [Preview Abstract] |
Wednesday, March 17, 2010 2:42PM - 2:54PM |
T14.00002: First-Principles Modeling of ThO$_{2}$ Solid Solutions with Oxides of Trivalent Cations Vitaly Alexandrov, Mark Asta, Niels Gronbech-Jensen Solid solutions formed by doping ThO$_{2}$ with oxides of trivalent cations, such as Y$_{2}$O$_{3}$ and La$_{2}$O$_{3}$, are suitable for solid electrolyte applications, similar to doped zirconia and ceria. ThO$_{2}$ has also been gaining much attention as an alternative to UO$_{2}$ in nuclear energy applications, the aforementioned trivalent cations being important fission products. In both cases the mixing energetics and short-range ordering/clustering are key to understanding structural and transport properties. Using first-principles atomistic calculations, we address intra- and intersublattice interactions for both cation and anion sublattices in ThO$_{2}$-based fluorite-type solid solutions and compare the results with similar modeling studies for related trivalent-doped zirconia systems. [Preview Abstract] |
Wednesday, March 17, 2010 2:54PM - 3:06PM |
T14.00003: Energy Security: From Deal Killers to Game Changers Raymond L Orbach Five ``deal killers'' for achieving energy security will be addressed: 1) Global warming and CO$_{2}$ emissions from fossil fuel combustion, 2) Intermittent energy sources (wind, solar) and the presence and stability of the grid, 3) Penetration of plant defenses to produce transportation fuels from biomass, 4) Mimicking nature: artificial photosynthesis for solar energy-to-fuels, and 5) Spent fuel from nuclear power reactors. Basic research can lead to ``game changers'' for these five fields: 1) Carbon capture and storage through enhanced oil and gas recovery, 2) Electrical energy storage for base-load electricity through batteries and supercapacitors, 3) Genetic modification of the plant cell wall, and catalytic methods for conversion of plant sugars to fuels, 4) Separation of solar-induced electrons from holes, and catalysis to produce fuels, and 5) Closing the nuclear fuel cycle. The present state for each of these game changers will be summarized, and future research opportunities discussed. [Preview Abstract] |
Wednesday, March 17, 2010 3:06PM - 3:18PM |
T14.00004: Proper orthogonal decomposition analysis of the turbulence characteristics in a 3$\times$3 wind turbine array boundary layer Max Gibson, Hyung-Suk Kang, Charles Meneveau, Raul Cal Large wind-turbine arrays have been shown to depend on vertical entrainment to remediate the downstream momentum deficit. The largest scales of the flow are responsible for this entrainment. In addition, it has been determined that the large scale structures control the drop in coherence from the top to bottom of the wind turbine wake. Such large scale dependence lends itself to reduced-order analysis. Proper orthogonal decomposition will be used to analyze the flow over a wind turbine array. The data is taken from particle image velocimetry measurements of a wind- tunnel experiment on the flow within a 3$\times$3 array of lightly loaded wind turbine models operating inside a turbulent boundary layer over a rough surface. It is expected that a limited number of energetic modes will sufficiently recapture the turbulent wake structures and give further insight into the vertical entrainment of momentum as well as the organized coherent structures. [Preview Abstract] |
Wednesday, March 17, 2010 3:18PM - 3:30PM |
T14.00005: Defect Stability and Xe in UO2: Comparison between first-principles and classical potential calculations Alexander Thompson, Dilpuneet Aidhy, Chris Wolverton We have investigated defect stability and noble gas impurities in uranium dioxide (UO2) using a combination of Density Functional Theory and classical potential calculations. We consider a wide array of defects types, such as intrinsic vacancies and Schottky defects, as well as noble gas impurities such as Xe. We also consider the interaction between Xe and the vacancy clusters. We find Xe in an interstitial is a very high energy defect. It is energetically favorable to create a Schottky defect cluster for the Xe to incorporate into. We also examine transition states of point defect migration in UO2. We compare our results from DFT+U with several existing classical potentials, including potentials which are fit to first principles calculation. For our DFT+U calculations, we consider the problem of metastable orbital occupation that occurs in the DFT+U methodology. [Preview Abstract] |
Wednesday, March 17, 2010 3:30PM - 3:42PM |
T14.00006: A fast and flexible reactor physics model for simulating neutron spectra and depletion in fast reactors Geoff Recktenwald, Mark Deinert Determining the time dependent concentration of isotopes within a nuclear reactor core is central to the analysis of nuclear fuel cycles. We present a fast, flexible tool for determining the time dependent neutron spectrum within fast reactors. The code (VBUDS: visualization, burnup, depletion and spectra) uses a two region, multigroup collision probability model to simulate the energy dependent neutron flux and tracks the buildup and burnout of 24 actinides, as well as fission products. While originally developed for LWR simulations, the model is shown to produce fast reactor spectra that show high degree of fidelity to available fast reactor benchmarks. [Preview Abstract] |
Wednesday, March 17, 2010 3:42PM - 3:54PM |
T14.00007: Irradiation Response of Nanocrystalline Cubic Zirconia William Weber, Yanwen Zhang, Weilin Jiang, Philip Edmondson, Fereydoon Namavar Cubic zirconia is a potential inert matrix phase for burning actinides in some advanced fuel cycles. We have investigated the irradiation response of nanocrystalline cubic zirconia. The nanocrystalline zirconia films were prepared by ion-beam-assisted deposition that produced nanostructurally-stabilized pure cubic zirconia with an average grain size of 7.7 nm. The films were irradiated with 2 MeV Au$^{ }$ions at 160 K and 400 K to doses up to 35 displacements per atom. The average grain size determined by grazing incident X-ray diffraction increases with dose and saturates at high doses. Under irradiation at 160 K, the increase in grain size saturates at about 30 nm; while under irradiation at 400 K, slower grain growth is observed. The decrease in saturation value with increasing temperature indicates thermal grain growth does not contribute to the observed grain growth. While the cubic phase is retained, some reduction of O in the irradiated films is indicated from the Rutherford backscattering spectroscopy measurements. The ratio of O to Zr decreases from close to 2.0 for the as-deposited films to about 1.65 at the highest doses. Transmission electron microscopy observations and selected area electron diffraction have also confirmed the grain growth and phase stability. [Preview Abstract] |
Wednesday, March 17, 2010 3:54PM - 4:06PM |
T14.00008: Comparison of actinide transmutation using deep burn in an inert matrix fuel and recycle in a low conversion fast burner reactor Mark Deinert, Geoff Recktenwald Because of their non-fertile matrices, inert matrix fuels (IMF) could allow light-water reactors to achieve a significant burn down of the actinides that they themselves produce. However, the extent to which this is possible is not yet fully understood and must be compared to the other future options for actinide transmutation. We consider a ZrO$_{2}$ based IMF with a moderate transuranic loading and compare the endpoint actinide inventories that would result from recycling actinides from spent UOX fuel using IMF with a deep burn, and continuous recycle in a low conversion ratio fast burner reactor, both over a 100 year time frame. The results show that for IMF with a burnup beyond 750 MWd/kgIHM the residual actinide inventories would be similar. [Preview Abstract] |
Wednesday, March 17, 2010 4:06PM - 4:18PM |
T14.00009: Carbon-negative Fuel from Stranded Energy with Carbon Sequestration James Van Vechten, Robert Graupner Stranded energy can be captured as nitrogen based fuels (ammonia, urea, guanidine) produced from hydrogen from saltwater electrolysis. The use of electrodialysis enables the co-production of NaOH(aq) and HCl(aq) together with oxygen and hydrogen. The NaOH can capture atmospheric CO2 as sodium carbonate or sodium bicarbonate and together with HCl and basaltic local rocks can produce a range of valuable commodity chemicals. Depending on the form of the sequestered carbon, either 2 or 4 moles of CO2 can be captured for each mole of hydrogen gas produced. The nitrogen based fuels can be used to power conventional thermal engines or solid oxide fuel cells. They can also be used as fertilizers, thereby avoiding the release of CO2 during their conventional production using natural gas or coal. With care the produced NaOH or carbonates may be used to counter ocean acidification [Preview Abstract] |
Wednesday, March 17, 2010 4:18PM - 4:30PM |
T14.00010: Adsorption of Nanoplastics on Algal Photosynthesis James Turner , Priyanka Bhattacharya , Sijie Lin , Pu Chun Ke The rapid accumulation of disposed plastics in the environment, especially in the Pacific Ocean, has become a global concern in recent years. Photo, chemical and physical degradations constantly fragment these plastics into a wide array of macroscopic to microscopic particles. As a result, marine organisms such as algae may be exposed to plastic particles through ingestion, adsorption and other forms of uptake. Such interactions, currently little understood, could potentially impact on the health state of the entire food chain. Here we report on polystyrene-algae interaction and its impact on algal photosynthesis. We first investigated the adsorption of polystyrene beads (20 nm) on a cellulose film coated on a 96-well plate. We derived a supralinear increase of the adsorption with the beads concentration for both positively and negatively charged polystyrene beads, with a saturation observed for the negatively charged polystyrene beads of concentration above 1.6 mg/mL. Using a bicarbonate indicator we discovered decreased carbon dioxide depletion due to polystyrene-algae binding. Since polystyrene beads also mediated algae aggregation, nanoplastics may alternatively be harnessed for waste water treatment. [Preview Abstract] |
Wednesday, March 17, 2010 4:30PM - 4:42PM |
T14.00011: Modeling property evolution of container materials used in nuclear waste storage Dongsheng Li, Hamid Garmestani, Moe Khaleel, Xin Sun Container materials under irradiation for a long time will raise high energy in the structure to generate critical structural damage. This study investigated what kind of mesoscale microstructure will be more resistant to radiation damage. Mechanical properties evolution during irradiation was modeled using statistical continuum mechanics. Preliminary results also showed how to achieve the desired microstructure with higher resistance to radiation. [Preview Abstract] |
Wednesday, March 17, 2010 4:42PM - 4:54PM |
T14.00012: Cobalamin Catalytic Centers for Stable Fuels Generation from Carbon Dioxide Wesley D. Robertson, BenMaan I. Jawdat, Nathan M. Ennist, Kurt Warncke Our aim is to design and construct protein-based artificial photosynthetic systems that reduce carbon dioxide (CO$_{2})$ to stable fuel forms within the robust and adaptable ($\beta \alpha )_{8}$ TIM-barrel protein structure. The EutB subunit of the adenosylcobalamin-dependent enzyme, ethanolamine ammonia-lyase, from \textit{Salmonella typhimurium}, was selected as the protein template. This system was selected because the Co$^{I}$ forms of the native cobalamin (Cbl) cofactor, and the related cobinamide (Cbi), possess redox properties that are commensurate with reduction of CO$_{2}$. The kinetics of photo- (excited 5'-deazariboflavin electron donor) and chemical [Ti(III)] reduction, and subsequent reaction, of the Cbl and Cbi with CO$_{2}$ are measured by time-resolved UV/visible absorption spectroscopy. Products are quantified by NMR spectroscopy. The results address the efficacy of the organocobalt catalytic centers for CO$_{2}$ reduction to stable fuels, towards protein device integration. [Preview Abstract] |
Wednesday, March 17, 2010 4:54PM - 5:06PM |
T14.00013: Kinetic Analysis of Gas Splitting on Oxide Surfaces for Solar Thermochemical Fuel Production Heine Hansen, Bryce Meredig, Chris Wolverton Solar thermochemical cycles have the potential to convert solar energy into chemical fuels at high thermodynamic efficiency. This can be done by reducing an oxide at high temperature and oxidizing the reduced oxide at a lower temperature in H$_{2}$O or CO$_{2}$ to produce H$_{2}$ or CO. The gas splitting reaction at low temperature is kinetically limited, possibly from slow kinetics of the surface processes. For example, the rate of H$_{2}$O splitting over CeO$_{2}$ is increased by the addition of a rhodium catalyst.~ Little is known about the gas splitting reactions at the atomic level. In this work we use density functional theory to investigate the mechanism for the gas splitting reactions on oxide surfaces such as CeO$_{2 }$(111) or on precious metal catalyst particles such as Rh or Pt.~ [Preview Abstract] |
Wednesday, March 17, 2010 5:06PM - 5:18PM |
T14.00014: Comparative study of metal-organic frameworks for carbon capture applications Jason Simmons, Wei Zhou, Hui Wu, Taner Yildirim With the current prevalence of hydrocarbon-based energy sources, carbon capture and sequestration are essential technologies for minimizing the emission of carbon dioxide and the resulting increased atmospheric concentration of CO2. Current technologies based on absorption require high temperature regeneration of the solvent, ultimately leading to significantly decreased efficiency and increased cost. Development of an adsorption-based technology, based on physical adsorption in optimized porous media, would greatly reduce the regeneration costs. Here we discuss the carbon capture performance of a range of metal-organic frameworks (MOFs), including both high surface area materials as well as those with sites that have been engineered to have enhanced binding. In particular, we demonstrate that MOFs can capture significant amounts of CO2 and that the CO2 can be readily removed from the MOF using standard pressure/vacuum swing techniques, yielding cyclic capture capacities in excess of 5 mmol/g. Further, we discuss the role of pore geometry and surface chemistry in the capacity of CO2 that can be removed in order to best optimize these materials. Lastly, we will address the effect of flue gas impurities on the carbon capture performance of these MOFs. [Preview Abstract] |
Wednesday, March 17, 2010 5:18PM - 5:30PM |
T14.00015: Designing Energy-Efficient Heat Exchangers--- Creating Micro-Channels on the Aluminum Fin Surface Jia Ying, Andrew Sommers, Khalid Eid In this research, a method for patterning micro-channels on aluminum surfaces is described for the purpose of exploiting those features to affect the surface wettability. Minimizing water retention on aluminum is important in the design of energy-efficient heat exchangers because water retention can deteriorate the performance of such devices. It increases the air-side pressure drop and can decrease the sensible heat transfer coefficient thereby increasing energy consumption and contributing to higher pollution levels in the environment. Photolithography is used to create the micro-scale channels and a hydrophobic polymer is used to reduce the surface energy of the aluminum plates. Droplets are both injected on the surface using a micro-syringe and condensed on the surface using an environmentally-controlled chamber. A ram\'{e}-hart goniometer is used to determine the advancing and receding contact angles of water droplets on these modified surfaces, and a tilt-table assembly is used to measure the critical inclination angle for sliding. Our results show that droplets placed on these patterned surfaces not only have significantly lower critical inclination angles for sliding but are easier to remove from the surface at low air flow rates. Efforts to model the onset of droplet movement on these surfaces using a simple force balance relationship are currently underway. [Preview Abstract] |
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