• Energy Research
• 7. Clean energy close
• 13. Climate action close
• DE close
• University of North Texas close

Progress in science often follows or parallels the development of new techniques. The optical microscope helped convert medicine and biology from a speculative activity in old times to today's sophisticated scientific disciplines. The telescope changed the study and interpretation of heavens from mythology to science. X-ray diffraction enabled the flourishing of solid state physics and materials science. The technique object of this review, Ambient Pressure Photoelectron Spectroscopy or APPES for short, has also the potential of producing dramatic changes in the study of liquid and solid surfaces, particularly in areas such as atmospheric, environment and catalysis sciences. APPES adds an important missing element to the host of techniques that give fundamental information, i.e., spectroscopy and microscopy, about surfaces in the presence of gases and vapors, as encountered in industrial catalysis and atmospheric environments. APPES brings electron spectroscopy into the realm of techniques that can be used in practical environments. Decades of surface science in ultra high vacuum (UHV) has shown the power of electron spectroscopy in its various manifestations. Their unique property is the extremely short elastic mean free path of electrons as they travel through condensed matter, of the order of a few atomic distances in the energy rangemore » from a few eV to a few thousand eV. As a consequence of this the information obtained by analyzing electrons emitted or scattered from a surface refers to the top first few atomic layers, which is what surface science is all about. Low energy electron diffraction (LEED), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), Ultraviolet photoelectron spectroscopy (UPS), and other such techniques have been used for decades and provided some of the most fundamental knowledge about surface crystallography, composition and electronic structure available today. Unfortunately the high interaction cross section of electrons with matter also prevents them from traveling long distances unscattered in gas environments. Above the millibar pressure range this distance is reduced to less that a millimeter, effectively preventing its use in the most relevant environments, usually between millibars and atmospheric pressures. There is therefore a large gap of several orders of magnitude where information about surfaces is scarce because these powerful electron spectroscopies cannot operate. One characteristic of surfaces in ambient pressure environments is that they are covered by dense layers of molecules, even when their binding energy is weak. Water for example is known to form layers several molecules thick at room temperature in humid environments. Metals readily form oxide films several layers thick in oxygen atmospheres. Dense layers of adsorbed molecules can also be produced in ultra high vacuum, often by the simple and expedient method of cooling the sample to cryogenic temperatures. A large amount of data has been obtained in the past in UHV by surface scientists using this method. While this has provided valuable information it begs the question of whether the structures formed in this manner represent equilibrium structures or metastable ones, kinetically trapped due to high activation energies that cannot be overcome at low temperature. From a thermodynamic point of view is interesting to consider the entropic contribution to the Gibbs free energy, which we can call 'the pressure factor', equal to kT.logP. This factor amounts to a sizeable 0.3 eV difference at room temperature between UHV (<10{sup -8} Pascal) and atmospheric pressures. Such change if free energy can definitely result in changes in surface structure and stability. Entire areas of the phase diagram are out of reach due to the pressure gap. Even when cooling is not necessary, many surface treatments and most chemical reactions necessitate the presence of gases at pressures ranging from millibar to bars. What is the structure and chemical nature of the species formed on the surface in equilibrium with such gases? As we shall illustrate in this review, APPES provides a much needed electron spectroscopy to analyze surface electronic structure and composition in equilibrium with gases.« less

High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore, they are considered an interesting solution for final focus and beam transport in a heavy ion beam fusion reactor. At the Gesellschaft fuer Schwerionenforschung accelerator facility, 50 cm long, free-standing discharge channels were created in a 60 cm diameter metallic chamber. Discharges with currents of 45 kA in 2 to 25 mbar ammonia (NH3) gas are initiated by a CO2 laser pulse along the channel axis before the capacitor bank is triggered. Resonant absorption of the laser, tuned to the v2 vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. The influence of an electric prepulse on the high current discharge was investigated. This article describes the laser–gas interaction and the discharge initiation mechanism. We found that channels are magnetohydrodynamic stable up to currents of 45 kA, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a one-dimensional Lagrangian fluid code (CYCLOPS) and is identified as the dominant initiation mechanism of the discharge.

Voltage on the North American bulk system is normally regulated by synchronous generators, which typically are provided with voltage schedules by transmission system operators. In the past, variable generation plants were considered very small relative to conventional generating units, and were characteristically either induction generator (wind) or line-commutated inverters (photovoltaic) that have no inherent voltage regulation capability. However, the growing level of penetration of non-traditional renewable generation - especially wind and solar - has led to the need for renewable generation to contribute more significantly to power system voltage control and reactive power capacity. Modern wind-turbine generators, and increasingly PV inverters as well, have considerable dynamic reactive power capability, which can be further enhanced with other reactive support equipment at the plant level to meet interconnection requirements. This report contains a set of recommendations to the North-America Electricity Reliability Corporation (NERC) as part of Task 1-3 (interconnection requirements) of the Integration of Variable Generation Task Force (IVGTF) work plan. The report discusses reactive capability of different generator technologies, reviews existing reactive power standards, and provides specific recommendations to improve existing interconnection standards.

A multinational test program is in progress to quantify the aerosol particulates produced when a high energy density device, HEDD, impacts surrogate material and actual spent fuel test rodlets. This program provides needed data that are relevant to some sabotage scenarios in relation to spent fuel transport and storage casks, and associated risk assessments; the program also provides significant political benefits in international cooperation. We are quantifying the spent fuel ratio, SFR, the ratio of the aerosol particles released from HEDD-impacted actual spent fuel to the aerosol particles produced from surrogate materials, measured under closely matched test conditions. In addition, we are measuring the amounts, nuclide content, size distribution of the released aerosol materials, and enhanced sorption of volatile fission product nuclides onto specific aerosol particle size fractions. These data are crucial for predicting radiological impacts. This document includes a thorough description of the test program, including the current, detailed test plan, concept and design, plus a description of all test components, and requirements for future components and related nuclear facility needs. It also serves as a program status report as of the end of FY 2003. All available test results, observations, and analyses - primarily for surrogate material Phasemore » 2 tests using cerium oxide sintered ceramic pellets are included. This spent fuel sabotage - aerosol test program is coordinated with the international Working Group for Sabotage Concerns of Transport and Storage Casks, WGSTSC, and supported by both the U.S. Department of Energy and Nuclear Regulatory Commission.« less

This final report describes results achieved under a 20-month NREL subcontract to develop and understand thin-film solar cell technology associated to CuInSe{sub 2} and related alloys, a-Si and its alloys, and CdTe. Modules based on all these thin films are promising candidates to meet DOE's long-range efficiency, reliability and manufacturing cost goals. The critical issues being addressed under this program are intended to provide the science and engineering basis for the development of viable commercial processes and to improve module performance. The generic research issues addressed are: (1) quantitative analysis of processing steps to provide information for efficient commercial-scale equipment design and operation; (2) device characterization relating the device performance to materials properties and process conditions; (3) development of alloy materials with different bandgaps to allow improved device structures for stability and compatibility with module design; (4) development and improved window/heterojunction layers and contacts to improve device performance and reliability; and (5) evaluation of cell stability with respect to device structure and module encapsulation.

Les herbivores peuvent avoir un accès indirect au carbone récalcitrant présent dans les parois des cellules végétales grâce à des associations symbiotiques avec des microbes lignocellulolytiques. Un exemple paradigmatique est la fourmi coupeuse de feuilles (Tribu : Attini), qui utilise des feuilles fraîches pour cultiver un champignon pour se nourrir dans des jardins spécialisés. En utilisant une combinaison d'analyses de la composition du sucre, de la métagénomique et du séquençage du génome entier, nous révélons que le microbiome du champignon de jardin des fourmis coupeuses de feuilles est composé d'une communauté diversifiée de bactéries ayant une capacité élevée de dégradation de la biomasse végétale. La comparaison du profil enzymatique prédit de dégradation des glucides de ce microbiome avec d'autres métagénomes montre une similitude plus étroite avec le rumen bovin, indiquant une convergence évolutive du potentiel de dégradation de la biomasse végétale entre deux animaux herbivores importants. La caractérisation génomique et physiologique de deux bactéries dominantes dans le microbiome fongique du jardin fournit des preuves de leur capacité à dégrader la cellulose. Compte tenu de l'intérêt récent pour les biocarburants cellulosiques, comprendre comment la dégradation rapide et à grande échelle de la biomasse végétale se produit chez un insecte herbivore très évolué est particulièrement important pour la bioénergie. Los herbívoros pueden obtener acceso indirecto al carbono recalcitrante presente en las paredes celulares de las plantas a través de asociaciones simbióticas con microbios lignocelulolíticos. Un ejemplo paradigmático es la hormiga cortadora de hojas (Tribu: Attini), que utiliza hojas frescas para cultivar un hongo como alimento en jardines especializados. Usando una combinación de análisis de composición de azúcar, metagenómica y secuenciación del genoma completo, revelamos que el microbioma del jardín de hongos de las hormigas cortadoras de hojas está compuesto por una comunidad diversa de bacterias con alta capacidad de degradación de la biomasa vegetal. La comparación del perfil enzimático de degradación de carbohidratos predicho de este microbioma con otros metagenomas muestra la mayor similitud con el rumen bovino, lo que indica una convergencia evolutiva del potencial de degradación de la biomasa vegetal entre dos animales herbívoros importantes. La caracterización genómica y fisiológica de dos bacterias dominantes en el microbioma del jardín de hongos proporciona evidencia de su capacidad para degradar la celulosa. Dado el reciente interés en los biocombustibles celulósicos, la comprensión de cómo se produce la degradación rápida y a gran escala de la biomasa vegetal en un insecto herbívoro altamente evolucionado es de particular relevancia para la bioenergía. Herbivores can gain indirect access to recalcitrant carbon present in plant cell walls through symbiotic associations with lignocellulolytic microbes. A paradigmatic example is the leaf-cutter ant (Tribe: Attini), which uses fresh leaves to cultivate a fungus for food in specialized gardens. Using a combination of sugar composition analyses, metagenomics, and whole-genome sequencing, we reveal that the fungus garden microbiome of leaf-cutter ants is composed of a diverse community of bacteria with high plant biomass-degrading capacity. Comparison of this microbiome's predicted carbohydrate-degrading enzyme profile with other metagenomes shows closest similarity to the bovine rumen, indicating evolutionary convergence of plant biomass degrading potential between two important herbivorous animals. Genomic and physiological characterization of two dominant bacteria in the fungus garden microbiome provides evidence of their capacity to degrade cellulose. Given the recent interest in cellulosic biofuels, understanding how large-scale and rapid plant biomass degradation occurs in a highly evolved insect herbivore is of particular relevance for bioenergy. يمكن للحيوانات العاشبة الوصول بشكل غير مباشر إلى الكربون المتمرد الموجود في جدران الخلايا النباتية من خلال الارتباطات التكافلية مع الميكروبات المحللة للخلايا. ومن الأمثلة النموذجية على ذلك نملة قطع الأوراق (القبيلة: أتيني)، التي تستخدم أوراقًا طازجة لزراعة فطر للطعام في الحدائق المتخصصة. باستخدام مزيج من تحليلات تركيبة السكر، وعلم الوراثة، وتسلسل الجينوم الكامل، نكشف أن ميكروبيوم حديقة الفطريات من النمل القاطع للأوراق يتكون من مجموعة متنوعة من البكتيريا ذات القدرة العالية على تحلل الكتلة الحيوية للنبات. تُظهر مقارنة ملف تعريف إنزيم تحلل الكربوهيدرات المتوقع لهذا الميكروبيوم مع الميتاجينومات الأخرى أقرب تشابه مع الكرش البقري، مما يشير إلى التقارب التطوري لإمكانات تحلل الكتلة الحيوية النباتية بين اثنين من الحيوانات العاشبة المهمة. يوفر التوصيف الجيني والفسيولوجي لبكتيريا مهيمنة في ميكروبيوم حديقة الفطريات دليلاً على قدرتها على تحلل السليلوز. بالنظر إلى الاهتمام الأخير بالوقود الحيوي السليولوزي، فإن فهم كيفية حدوث تدهور الكتلة الحيوية النباتية على نطاق واسع وسريع في الحيوانات العاشبة الحشرية المتطورة للغاية له أهمية خاصة بالنسبة للطاقة الحيوية.

This report addresses the Asia-Pacific Economic Cooperation (APEC) organization’s desire to minimize the learning time required to understand the implications of smart-grid concepts so APEC members can advance their thinking in a timely manner and advance strategies regarding smart approaches that can help meet their environmental-sustainability and energy-efficiency policy goals. As significant investments are needed to grow and maintain the electricity infrastructure, consideration needs to be given to how information and communications technologies can be applied to electricity infrastructure decisions that not only meet traditional needs for basic service and reliability, but also provide the flexibility for a changing the mix of generation sources with sensitivity to environmental and societal impacts.

The costs for carbon dioxide (CO2) capture and storage (CCS) in geologic formations is estimated to be $6–75/t CO2 .I n the absence of a mandate to reduce greenhouse gas emissions or some other significant incentive for CCS deployment, this cost effectively limits CCS technology deployment to small niche markets and stymies the potential for further technological development through learning by doing until these disincentives for the free venting of CO2 are in place. By far, the largest current fraction of these costs is capture (including compression and dehydration), commonly estimated at $25–60/t CO2 for power plant applications, followed by CO2 transport and storage, estimated at $0–15/t CO2. Of the storage costs, only a small fraction of the cost will go to accurate geological characterization. These one time costs are probably on the order of $0.1/t CO2 or less as these costs are spread out over the many millions of tons likely to be injected into a field over many decades. Geologic assessments include information central to capacity prediction, risk estimation for the target intervals and development facilities engineering. Since assessment costs are roughly two orders of magnitude smaller than capture costs, and assessment products carry other tangible societal benefits, such as improved accuracy in fossil fuel and ground water reserves estimates, government or joint private–public funding of major assessment initiatives should underpin early policy choices regarding CO2 storage deployment and should serve as a point of entry for policy makers and regulators. Early assessment is also likely to improve the knowledge base upon which the first commercial CCS deployments will rest. 2005 Elsevier Ltd. All rights reserved.