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1 Sep 2010

Volume 2, Issue 5, Articles (05xxxx)

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Effects of global warming on wind energy availability

Diandong Ren

J. Renewable Sustainable Energy 2, 052301 (2010); http://dx.doi.org/10.1063/1.3486072 (5 pages) | Cited 7 times

Online Publication Date: 1 September 2010

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The use of wind energy reduces our greenhouse gas emissions into the atmosphere. In this study, we proposed a generic power-law relationship between global warming and the usable wind energy (Betz’s law). The power law index ( ∼ 4, region dependent) is then determined using simulated atmospheric parameters from eight global coupled ocean-atmosphere climate models (CGCMs). It is found that the power-law relationship holds across all eight climate models and also is time scale independent. Reduction of wind power scales with the degree of warming according to a generic power-law relationship. Thus, the earlier we switch to clean energy, and thereby decrease the global climate warming trend, the more cost-effective will be the harnessing of wind energy. This relationship is an area-averaged consequence of the reduced poleward temperature gradient as the climate warms during the 21st Century; it does not imply spatial uniformity over a region of interest.
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88.50.-k Wind energy
88.05.Np Environmental aspects
92.60.Ry Climatology, climate change and variability
92.60.Bh General circulation
92.70.Mn Impacts of global change; global warming
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Potential of bio-DME as a transportation fuel for India

M. Himabindu and R. V. Ravikrishna

J. Renewable Sustainable Energy 2, 052701 (2010); http://dx.doi.org/10.1063/1.3489529 (13 pages)

Online Publication Date: 21 September 2010

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This article discusses the potential of bio-dimethyl ether (DME) as a promising fuel for India in the transportation sector where a majority of imported petroleum in the form of diesel is used. Specifically, the suitability of DME in terms of its properties vis-à-vis those of diesel, ability to liquefy DME at low pressures similar to liquefied petroleum gas (LPG), and ease of production from renewable feedstock (biomass), and most importantly, very low emissions including near-zero soot levels are some of the features that make it an attractive option. A detailed review presents the state-of-the-art on various aspects such as estimates of potential bio-DME production, methods of synthesis of bio-DME, important physicochemical properties, fuel-injection system-related concerns (both conventional and common-rail system), fuel spray characteristics which have a direct bearing on the engine performance, and finally, exhaust emissions. Future research directions covering all aspects from production to utilization are summarized
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88.20.F- Renewable alternative fuels from biomass energy
88.85.M- Alternative fuels for advanced vehicles
89.20.Kk Engineering
89.40.-a Transportation
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Vertically aligned ZnO nanodisks and their uses in bulk heterojunction solar cells

Congkang Xu, Kaikun Yang, Liwei Huang, and Howard Wang

J. Renewable Sustainable Energy 2, 053101 (2010); http://dx.doi.org/10.1063/1.3478880 (7 pages) | Cited 2 times

Online Publication Date: 1 September 2010

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A new approach has been developed for fabricating vertically aligned ZnO nanodisks (ZONDs) on indium tin oxide coated glass for photovoltaic devices. ZONDs with a thickness of ∼ 40 nm and diameter from ∼ 150 nm to 2 μm have been synthesized via chemical vapor deposition at low temperatures of ∼ 320 °C. As-synthesized nanodisks are single crystalline and have broad photoluminescence emission. ZOND arrays have been used to construct bulk heterojunction photovoltaic devices together with neat poly(3-hexylethiophene) (P3HT) or (6,6)-phenyl C61 butyric acid methyl ester (PCBM) and P3HT blends, respectively. The P3HT/ZOND hybrid solar cell has a power conversion efficiency of up to 0.212%, a fill factor of 0.36, and an open circuit voltage of 341 mV, whereas the P3HT:PCBM/ZOND solar cell has a power conversion efficiency of 1.21%, a fill factor of 0.46, and a open circuit voltage of 445 mV.
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88.40.H- Solar cells (photovoltaics)

Experiments on solar absorption using a greenhouse-effect gas in a thermal solar collector

Abdul Hai M. B. Alami

J. Renewable Sustainable Energy 2, 053102 (2010); http://dx.doi.org/10.1063/1.3488789 (9 pages)

Online Publication Date: 16 September 2010

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This paper investigates an augmentation to the thermal solar absorption of solar collectors by introducing a greenhouse gas between the glazing and the absorber part of the solar collector. Experiments are designed and conducted to compare the effect of adding the gas on the efficiency of the collector without that addition. The maximum temperature rise of the absorber, the time of heat retention before reaching room temperature, and the energy conversion efficiency in heating up water for domestic use were all studied.
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88.40.-j Solar energy
42.79.Ek Solar collectors and concentrators
92.60.hv Pressure, density, and temperature

Systematic analysis of processing parameters on the ordering and performance of working poly(3-hexyl-thiophene):[6,6]-phenyl C61-butyric acid methyl ester solar cells

A. Turak, J. Hanisch, E. Barrena, U. Welzel, F. Widmaier, E. Ahlswede, and H. Dosch

J. Renewable Sustainable Energy 2, 053103 (2010); http://dx.doi.org/10.1063/1.3488381 (14 pages)

Online Publication Date: 21 September 2010

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In this study, we report a systematic investigation of the impact of various processing conditions on all features of the bulk polymer microstructure in working P3HT:PCBM solar cells. Unlike previous studies, which usually examine optimized films grown on Si, without an inorganic electrode layer, we directly examined films in working device architectures to understand the impact of the various steps commonly used in device manufacturing. Thermal treatments were observed to strongly impact the performance of devices produced at less than optimal conditions through changes to the bulk crystal structure; however, even when the production conditions are close to the optimal morphology and crystal structure, annealing is still necessary to improve the π-π overlap of adjacent polymer chains and to reduce the interfacial barrier at polymer-electrode interfaces. The annealing step is therefore crucial to yielding high performance through the control of both the bulk and interfacial properties. Our results suggest a new perspective on device manufacturing, showing that it is not necessary to achieve perfection in bulk crystal structure with the first production steps, potentially saving time in the manufacturing process.
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88.40.H- Solar cells (photovoltaics)
61.66.-f Structure of specific crystalline solids
85.30.-z Semiconductor devices

Use of an autonomous sensor to evaluate the biological performance of the advanced turbine at Wanapum Dam

Zhiqun Deng, Thomas J. Carlson, Joanne P. Duncan, Marshall C. Richmond, and Dennis D. Dauble

J. Renewable Sustainable Energy 2, 053104 (2010); http://dx.doi.org/10.1063/1.3501336 (11 pages) | Cited 4 times

Online Publication Date: 13 October 2010

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Hydropower is the largest renewable energy resource in the United States and the world. However, hydropower dams have adverse ecological impacts because migrating fish may be injured or killed when they pass through hydroturbines. In the Columbia and Snake River basins, dam operators and engineers are required to make those hydroelectric facilities more fish-friendly through changes in hydroturbine design and operation after fish population declines and the subsequent listing of several species of Pacific salmon under the Endangered Species Act of 1973. Public Utility District No. 2 of Grant County, Washington, requested authorization from the Federal Energy Regulatory Commission to replace the ten turbines at Wanapum Dam with advanced hydropower turbines designed to improve survival for fish passing through the turbines while improving operation efficiency and increasing power generation. As an additional measure to the primary metric of direct injury and mortality rates of juvenile Chinook salmon using balloon tag-recapture methodology, this study used an autonomous sensor device—the Sensor Fish—to provide insight into the specific hydraulic conditions and physical stresses experienced by the fish as well as the specific causes of fish biological response. We found that the new hydroturbine blade shape and the corresponding reduction of turbulence in the advanced hydropower turbine were effective in meeting the objectives of improving fish survival while enhancing operational efficiency of the dam. The frequency of severe events based on Sensor Fish pressure and acceleration measurements showed trends similar to those of fish survival determined by the balloon tag-recapture methodology. In addition, the new turbine provided a better pressure and rate of pressure change environment for fish passage. Overall, the Sensor Fish data indicated that the advanced hydroturbine design improved passage of juvenile salmon at Wanapum Dam.
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89.20.Kk Engineering
89.60.-k Environmental studies
88.60.K- Hydroturbines

A comparative evaluation of Al2O3 coated low heat rejection diesel engine performance and emission characteristics using fuel as rice bran and pongamia methyl ester

M. Mohamed Musthafa, S. P. Sivapirakasam, and M. Udayakumar

J. Renewable Sustainable Energy 2, 053105 (2010); http://dx.doi.org/10.1063/1.3480659 (15 pages)

Online Publication Date: 13 October 2010

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In this study, for the first time, a nanoceramic Al2O3 was used as a coating material in the low heat rejection engine concept. Experiments were conducted on single cylinder, four stroke, water cooled, and direct injection diesel engine. First, the engine was tested at different load conditions without coating. Then, combustion chamber surfaces (cylinder head, cylinder liner, valves, and piston crown face) were coated with nanoceramic material of Al2O3 using plasma spray method. Comparative evaluation on performance and emission characteristics using fuel as rice bran methyl ester, pongamia methyl ester, and biodiesel/diesel fuel mixtures was studied in the ceramic coated and uncoated engines under the same running conditions. An increase in engine power and a decrease in specific fuel consumption, as well as significant improvements in exhaust gas emissions (except NOx) and smoke density, were observed in the ceramic coated engines compared with those of the uncoated engine.
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89.20.Kk Engineering
88.05.Np Environmental aspects
88.20.F- Renewable alternative fuels from biomass energy
88.20.jj Combustion
81.65.-b Surface treatments

Solid state dye sensitized solar cells based on supersonic beam deposition of organic, inorganic cluster assembled, and nanohybrid materials

N. Coppedè, M. Nardi, T. Toccoli, M. Tonezzer, F. Siviero, V. Micheli, A. C. Mayer, and S. Iannotta

J. Renewable Sustainable Energy 2, 053106 (2010); http://dx.doi.org/10.1063/1.3501337 (8 pages) | Cited 1 time

Online Publication Date: 15 October 2010

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The growth of nanohybrids synthesized by supersonic beam codeposition of metal oxide clusters, produced by microplasma cluster source, and of aerodynamically accelerated molecules has been explored as a novel approach to the preparation of controlled dye sensitized materials for photovoltaic applications. The hybrid nanostructures are formed through deposition via supersonic expansion processes, controlling the kinetic energy of the precursors. With this approach, we developed prototype dye sensitized solar cells based on nanostructured TiO2 and CuPc with different architectures. To explore the viability of this approach, we compare cells made layer by layer with those where an intermediate codeposited layer is inserted between the two raw materials. This latter type of cells presents an enhancement of the photocurrent of a factor of 45 and of the efficiency of a factor of 40. This work opens a new viable perspective in the growth and in the control of the interfacial properties of nanohybrid materials, by direct codeposition of molecules and oxide nanostructures, with demonstrated useful applications in photovoltaic devices.
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88.40.H- Solar cells (photovoltaics)

A framework and methodology for reporting geographically and temporally resolved solar data: A case study of Texas

David M. Wogan, Michael Webber, and Alexandre K. da Silva

J. Renewable Sustainable Energy 2, 053107 (2010); http://dx.doi.org/10.1063/1.3496493 (22 pages) | Cited 1 time

Online Publication Date: 28 October 2010

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This paper presents a framework and methodology for reporting measured solar radiation data. Geographically and temporally resolved solar data have been calculated for all 254 counties in Texas using geospatial interpolation of data from 24 existing terrestrial measurement locations. Hourly global, direct, and diffuse horizontal radiation data have been obtained from 15 measurement sites at the Texas Solar Radiation Database, a project at The University of Texas at Austin, and from 9 sites at the National Solar Radiation Database. Average radiation fluxes and peak insolation have been calculated using daylight hours in addition to the total energy in kW h/m2 day. The methodology presented in this paper provides solar insolation data in a convenient format for engineers, scientists, policy-makers, homeowners, and consumers to assess the potential of solar energy at the county resolution. This methodology enables informed decisions about the economic viability of solar installations at particular locations and with useful diurnal and seasonal fidelity. These results are presented in a series of maps, figures, and tables included in this paper.
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88.40.-j Solar energy
93.85.Bc Computational methods and data processing, data acquisition and storage
02.60.Ed Interpolation; curve fitting
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Publisher’s Note: “Rapid characterization of biomass using fluorescence spectroscopy coupled with multivariate data analysis. II. Northern red oak (Quercus rubra)” [J. Renewable Sustainable Energy 2, 043101 (2010)]

K. Nkansah and B. Dawson-Andoh

J. Renewable Sustainable Energy 2, 059901 (2010); http://dx.doi.org/10.1063/1.3488982 (1 page)

Online Publication Date: 23 September 2010

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Abstract Unavailable
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88.20.D- Biomass energy sources
88.20.F- Renewable alternative fuels from biomass energy
88.20.R- Bioproducts from biomass
07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques
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