Documents published in 2017 : Scipedia

The remarkable impact of renewable energy generation in Sicily onto electricity price formation in Italy
F. Meneguzzo, R. Ciriminna, L. Albanese, M. Pagliaro

Energy Sci Eng (2016).

Abstract
During the first half of 2015, for the first time, the zonal electricity price in Sicily decreased below than the national wholesale price in Italy. Showing the unique pattern of electricity consumption in Italys largest region at different time scales, we identify the effectiveness of the impact of renewable power generation on utility-scale in Sicily upon the whole of Italys electricity market. Increasing the electrification of the energy end uses, as it is happening despite prolonged reduction in electricity demand, will lead to further benefits for power consumers throughout the whole country.
Abstract
During the first half of 2015, for the first time, the zonal electricity price in Sicily decreased below than the national wholesale price in Italy. Showing the unique pattern [...]
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The great solar boom: a global perspective into the far reaching impact of an unexpected energy revolution
F. Meneguzzo, R. Ciriminna, L. Albanese, M. Pagliaro

Energy Sci Eng (2015).

Abstract
This study offers a unified perspective into the unexpected solar energy photovoltaic revolution, and its far reaching impact onto both energy generation and electricity markets. Practically relevant aspects, such as those related to the value of solar PV electricity, land consumption, energy return on energy invested, reliability of the technology, the structure of the global PV industry, the cost of Li ion batteries and related market trends are clarified. We identify the main barriers to overcome for solar PV to expand beyond a niche market (say,
Abstract
This study offers a unified perspective into the unexpected solar energy photovoltaic revolution, and its far reaching impact onto both energy generation and electricity markets. [...]
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Coevaporated calcium-silver metal alloys as contact for highly transparent organic solar cells
J. Meiss, H. Ziehlke, S. Schubert, K. Leo, M. Riede

Energy Sci Eng (2014). Vol. 77

Abstract
We present 10-nm thick metal alloys created by coevaporation of calcium and silver as transparent top electrode for inverted bulk heterojunction small-molecule organic solar cells (SMOSC). It is shown that such alloys exhibit sufficiently high conductivity to replace previously used thicker (>14 nm) pure Ag contacts. At the same time, Ca:Ag alloys have higher transmittance compared to pure Ag, which is desirable for semitransparent SMOSC where the light passes through the device and the metal contact. We find that a metal contact consisting of 1 nm Ag underlayer and 10 nm Ca:Ag of 1:1 mixing ratio (total Ag content by volume of 6 nm) on glass has an average transmittance in the visible range of 76% with a sheet resistance of 27.1 Ω/□, approaching the performance of ITO while being applied by a much gentler deposition method. Application of 10-nm thick alloys in semitransparent SMOSC lead to transmittance in the visible range Tvis of up to 49% and efficiency η of up to 2.3%, showing superior performance compared to devices with pure Ag top contacts.
Abstract
We present 10-nm thick metal alloys created by coevaporation of calcium and silver as transparent top electrode for inverted bulk heterojunction small-molecule organic solar [...]
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Biodiesel from grease interceptor to gas tank
A. Ragauskas, Y. Pu, A. Ragauskas

Energy Sci Eng (2013). Vol. 42

Abstract
The need for sustainable biofuels has initiated a global search for innovative technologies that can sustainably convert nonfood bioresources to liquid transportation fuels. While 2nd generation cellulosic ethanol has begun to address this challenge, other resources including yellow and brown grease are rapidly evolving commercial opportunities that are addressing regional biodiesel needs. This review examines the technical and environmental factors driving the collection of trap FOG (Fats, Oils, and Greases), its chemical composition and technologies currently available and future developments that facilitate the conversion of FOG into biodiesel.
Abstract
The need for sustainable biofuels has initiated a global search for innovative technologies that can sustainably convert nonfood bioresources to liquid transportation fuels. [...]
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Design, operation, and performance evaluation of a cable-drawn dual-axis solar tracker compared to a fixed-tilted system
S. Lo, F. Cheng, V. Chang, W. Liu, L. Chang, O. Adurodija, E. Chou, C. Lung, J. Liu, T. Lu, J. Su, E. Cheng

Energy Sci Eng (2015).

Abstract
This article discusses the design, operation, and performance evaluation of a unique cable-operated 6.24 kWp commercial-size solar tracking system called iPV dual-axis tracker or iPV DAT with a position detector to gain the maximum power from the sunlight. Compared with other solar tracking systems, low cost, simplified hardware structure, and controlling algorithm are the advantages of this system. The operating method of the 6.24 kWp iPV DAT follow a simple pull and release of the steel cables connecting the corners of the PV module frame to the electric motors and directed by an electronic control system. The steel cables attached to the corners of the module frame also provide an extra stability in the event of high wind of up to 220 km/h. The accuracy of the tracking effect is managed by an astronomical algorithm that enables a full 360° azimuth rotation and altitude tilt of −40° to 40° (0 = horizontal). The controller algorithm also includes backtracking capability that allows optimization of ground cover ratio. Performance evaluation of the iPV DAT installed and operated in Taiwan for 12 months is compared with a fixed-tilt PV system. An average electricity gain of 30.1% and performance ratio of 93% are realized using iPV DAT.
Abstract
This article discusses the design, operation, and performance evaluation of a unique cable-operated 6.24 kWp commercial-size solar tracking system called iPV dual-axis tracker [...]
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Dynamic modeling of a small open Joule cycle reciprocating Ericsson engine: simulation results
F. Lontsi, O. Hamandjoda, K. Djanna, P. Stouffs, J. Nganhou

Energy Sci Eng (2013).

Abstract
Externally heated Joule cycle reciprocating engines, also known as Ericsson engines, are particularly suitable for small-scale solar energy conversion and microcogeneration using biomass or gas effluents at high temperatures. These types of engine have been developed in the context of the current issue of climate change, combined with a progressive depletion of fossil fuels. A dynamic model of a 1.67 kW small open Joule cycle engine has been developed in order to study operational stability and behavioral control, especially during transient phases. Models are implemented on a Matlab/Simulink platform where simulations of the dynamics of engine start-up and steady conditions are carried out. The optimal settings of valves and the key engine parameters have also been determined. Simulation results reveal a rapid transient phase. Hot starting is achieved in about 5.3 sec and the system is stabilized, with a thermal efficiency of approximately 29%. The system responds well when subjected to selected perturbations.
Abstract
Externally heated Joule cycle reciprocating engines, also known as Ericsson engines, are particularly suitable for small-scale solar energy conversion and microcogeneration [...]
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An A-CAES pilot installation in the distribution system: A technical study for RES integration
P. Lombardi, C. Röhrig, K. Rudion, R. Marquardt, M. Müller-Mienack, A. Estermann, Z. Styczynski, N. Voropai

Energy Sci Eng (2014).

Abstract
In the last decade in Europe, the power generated by Renewable Energy Sources (RES) has significantly increased. For the electric power system, the integration of a high amount of power generated by RES represents a big challenge. Energy Storage Systems (ESS) may help to solve problems related to the grid integration of RES. In this study, an analysis of the benefits that a planned and dedicated Adiabatic Compressed Air Energy Storage (A-CAES) system may provide to a distribution network with a high penetration of RES will be carried out. The A-CAES system, taken into account in this investigation, is based on the proposed German study so-called “ADELE project”. The technical benefits as well as the corresponding costs that A-CAES brings to the system which were analyzed using the load and RES generation time series for 2010 and 2020, and were based on technical data from a selected part of a German distribution power network, were evaluated and results of those broad investigations are presented in this study. The result of the investigations shows that the direct technical benefits are quite limited for the A-CAES technology as it exists today.
Abstract
In the last decade in Europe, the power generated by Renewable Energy Sources (RES) has significantly increased. For the electric power system, the integration of a high amount [...]
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Systematic study of aqueous monoethanolamine-based CO2 capture process: model development and process improvement
K. Li, A. Cousins, H. Yu, P. Feron, M. Tade, W. Luo, J. Chen

Energy Sci Eng (2016). Vol. 23

Abstract
In this paper, we present improvements to postcombustion capture (PCC) processes based on aqueous monoethanolamine (MEA). First, a rigorous, rate-based model of the carbon dioxide (CO2) capture process from flue gas by aqueous MEA was developed using Aspen Plus, and validated against results from the PCC pilot plant trials located at the coal-fired Tarong power station in Queensland, Australia. The model satisfactorily predicted the comprehensive experimental results from CO2 absorption and CO2 stripping process. The model was then employed to guide the systematic study of the MEA-based CO2 capture process for the reduction in regeneration energy penalty through parameter optimization and process modification. Important process parameters such as MEA concentration, lean CO2 loading, lean temperature, and stripper pressure were optimized. The process modifications were investigated, which included the absorber intercooling, rich-split, and stripper interheating processes. The minimum regeneration energy obtained from the combined parameter optimization and process modification was 3.1 MJ/kg CO2. This study suggests that the combination of a validated rate-based model and process simulation can be used as an effective tool to guide sophisticated process plant, equipment design and process improvement.
Abstract
In this paper, we present improvements to postcombustion capture (PCC) processes based on aqueous monoethanolamine (MEA). First, a rigorous, rate-based model of the carbon [...]
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Models and experiments for energy consumption and quality of green tea drying
N. Langat, T. Thoruwa, J. Wanyoko, J. Kiplagat, B. Plourde, J. Abraham

Energy Sci Eng (2015). Vol. 43

Abstract
An experimental apparatus has been developed to evaluate the drying process of green tea leaves. Tea drying is an energy-intensive process which results in the removal of leaf moisture, it is essential to the quality of the final product. In order to more efficiently use process energy, a prototype drying system has been built and tested. The prototype incorporates a rotating perforated drum which helps speed the drying process. Experiments were carried out with multiple temperatures, airflow rates, and drum rotation rates, a subset of those results is shown here. In particular, the impact of airflow rate on the process was studied. It was found that as the airflow increased, the drying rate increased, as expected. However, the efficiency of energy use, which was quantified by the Specific Energy Consumption rate, varied considerably with flow. While higher flows led to faster drying, it resulted in a lower energy efficiency. Also, a two parameter predictive model was developed that was able to accurately match the moisture removal rates for a very wide range of flows. This predictive model, which is based on thermal-fluid fundamentals, can be used to extrapolate the presented results to cases which were not considered.
Abstract
An experimental apparatus has been developed to evaluate the drying process of green tea leaves. Tea drying is an energy-intensive process which results in the removal of [...]
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Steady-state and transient voltage stability analysis of a weak distribution system with a remote doubly fed induction generator-based wind farm
A. Kunwar, R. Bansal, O. Krause

Energy Sci Eng (2014).

Abstract
In modern, stressed distribution system, voltage stability is a major concern from planning and operation perspectives. Remote wind farm connected to a weak distribution system through a long line could adversely affect the voltage stability of the respective distribution network. This paper investigates the transient and steady-state voltage issues of a distribution network with a distant doubly fed induction generator (DFIG)-based wind farm. Results show that a distant DFIG-based wind farm could improve the voltage stability of a distribution network with a large motor load in steady-state operating condition as well as following disturbances, like three-phase faults, sudden load tripping, and motor starting.
Abstract
In modern, stressed distribution system, voltage stability is a major concern from planning and operation perspectives. Remote wind farm connected to a weak distribution system [...]
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Various operating methods and parameters for SO2 electrolysis
A. Krüger, H. Krieg, S. Grigoriev, D. Bessarabov

Energy Sci Eng (2015).

Abstract
The application of PFSA-based proton exchange membranes was investigated for the production of hydrogen and sulfuric acid using a SO2-depolarized electrolyzer system. Parameters investigated included hot pressing pressure for the membrane electrode assembly (MEA) manufacturing, cell temperature, membrane thickness, catalyst loading, membrane type, and SO2 anode feed concentration. The effect of cell temperature, membrane thickness, and acid concentrations was also investigated when using a second method, where clean sulfuric acid as cathode and SO2 saturated sulfuric acid as anode were used. Electrochemical impedance spectroscopy showed that the pressure exerted in the MEA manufacturing step had a significant influence with 125 kg cm−2 yielding the highest current density. High temperatures (>80°C) and thin membranes (≈120 μm) showed the best performance while thicker membranes produced higher acid concentration when using the first system. The SO2 concentration in the anode had a significant influence with the over potential increasing with decreasing SO2 concentration. When using the second method, it was found that the SO2 solubility in sulfuric acid is important as the mass transport of the SO2 limits the overall reaction rate. From the two systems tested, the first method, that is, dry SO2 anode and liquid water cathode showed the best operational effectiveness reaching a maximum of 0.32 A cm−2 at 80°C using N115 coated with 1 mgPt cm−2 while the second system under the same conditions achieved a current density of 0.18 A cm−2 when using N117.
Abstract
The application of PFSA-based proton exchange membranes was investigated for the production of hydrogen and sulfuric acid using a SO2-depolarized electrolyzer system. Parameters [...]
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Influence of different adsorbates on the efficiency of thermochemical energy storage
T. Kohler, K. Müller

Energy Sci Eng (2017). Vol. 21

Abstract
The main influencing parameter on the efficiency of adsorptive thermochemical energy storage is the efficiency of the desorption process, which is influenced by the process conditions, for example, desorption time and desorption temperature, and the working pair (adsorbent–adsorbate). Due to constrained process requirements, for example, hours of sun shine and low desorption temperatures available from a flat plate solar collector (333–373 K), the only possibility to increase the efficiency is to change the working pair. The reference working pair water–zeolite 13X needs high desorption temperatures of 500 K and high heat inputs per mass adsorbent (1080 kJ kg−1) in the desorption process to reach the maximum efficiency of 79 % and maximum energy density of 844 kJ kg−1. Therefore, the goal is to reach efficiencies in the same range as the maximum efficiency of water–zeolite 13X for desorption temperatures lower than 500 K with the usage of different adsorbates. Four systems of alcohol as adsorbate on activated carbon are compared with the reference working pair. The usage of alcohols on activated carbon allows for highly efficient adsorptive storage even at low desorption temperatures between 360 and 450 K. The maximum efficiency is shifted to higher desorption temperatures with increasing carbon chain length of the alcohol. At low desorption temperatures, the energy density and efficiency of methanol, ethanol, and propanol are higher than the energy density of the reference system. Hence, the alcohol systems on activated carbon are viable alternative approaches for regulating these process parameters.
Abstract
The main influencing parameter on the efficiency of adsorptive thermochemical energy storage is the efficiency of the desorption process, which is influenced by the process [...]
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Engineering evaluation of direct methane to methanol conversion
A. Klerk

Energy Sci Eng (2015). Vol. 60

Abstract
Investigations into direct methane to methanol conversion are justified based on the avoidance of synthesis gas generation, which accounts for around 60% of the capital cost of synthesis gas to methanol conversion. A significant body of information already exists on the process chemistry, but little has been reported on the engineering of such a process. An engineering evaluation of the process was performed and the potential of this process as a platform technology for small-scale gas-to-liquids (GTL) applications was evaluated. It was found that direct methane to methanol conversion had 35% carbon efficiency and 28% thermal efficiency, which were about half of the process efficiencies of indirect methanol synthesis using synthesis gas. The poor process efficiency was mainly a consequence of the irreversible loss of carbon to CO x during conversion. The direct methane to methanol process also required an air separation unit, which eroded the stated benefit of avoiding a synthesis gas generation step in the process. The utility footprint was typical of GTL processes, with large gas compression duties and cooling duties. Overall, the engineering evaluation indicated there was no benefit to employ direct methane to methanol conversion instead of indirect methanol synthesis (the industry standard), and there was no specific benefit of direct methane to methanol conversion, irrespective of scale, for GTL applications.
Abstract
Investigations into direct methane to methanol conversion are justified based on the avoidance of synthesis gas generation, which accounts for around 60% of the capital cost [...]
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Multi angle laser light scattering evaluation of field exposed thermoplastic photovoltaic encapsulant materials
M. Kempe, D. Miller, J. Wohlgemuth, S. Kurtz, J. Moseley, D. Nobles, K. Stika, Y. Brun, S. Samuels, Q. Shah, G. Tamizhmani, K. Sakurai, M. Inoue, T. Doi, A. Masuda, C. Vanderpan

Energy Sci Eng (2016). Vol. 40

Abstract
As creep of polymeric materials is potentially a safety concern for photovoltaic modules, the potential for module creep has become a significant topic of discussion in the development of IEC 61730 and IEC 61215. To investigate the possibility of creep, modules were constructed, using several thermoplastic encapsulant materials, into thin-film mock modules and deployed in Mesa, Arizona. The materials examined included poly(ethylene)-co-vinyl acetate (EVA, including formulations both cross-linked and with no curing agent), polyethylene/polyoctene copolymer (PO), poly(dimethylsiloxane) (PDMS), polyvinyl butyral (PVB), and thermoplastic polyurethane (TPU). The absence of creep in this experiment is attributable to several factors of which the most notable one was the unexpected cross-linking of an EVA formulation without a cross-linking agent. It was also found that some materials experienced both chain scission and cross-linking reactions, sometimes with a significant dependence on location within a module. The TPU and EVA samples were found to degrade with cross-linking reactions dominating over chain scission. In contrast, the PO materials degraded with chain scission dominating over cross-linking reactions. Although we found no significant indications that viscous creep is likely to occur in fielded modules capable of passing the qualification tests, we note that one should consider how a polymer degrades, chain scission or cross-linking, in assessing the suitability of a thermoplastic polymer in terrestrial photovoltaic applications.
Abstract
As creep of polymeric materials is potentially a safety concern for photovoltaic modules, the potential for module creep has become a significant topic of discussion in the [...]
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Field testing of thermoplastic encapsulants in high-temperature installations
M. Kempe, D. Miller, J. Wohlgemuth, S. Kurtz, J. Moseley, Q. Shah, G. Tamizhmani, K. Sakurai, M. Inoue, T. Doi, A. Masuda, S. Samuels, C. Vanderpan

Energy Sci Eng (2015).

Abstract
Recently there has been increased interest in using thermoplastic encapsulant materials in photovoltaic modules, but concerns have been raised about whether these would be mechanically stable at high temperatures in the field. Recently, this has become a significant topic of discussion in the development of IEC 61730 and IEC 61215. We constructed eight pairs of crystalline-silicon modules and eight pairs of glass/encapsulation/glass thin-film mock modules using different encapsulant materials, of which only two were formulated to chemically crosslink. One module set was exposed outdoors with thermal insulation on the back side in Mesa, Arizona, in the summer (hot-dry), and an identical module set was exposed in environmental chambers. High-precision creep measurements (±20 μm) and electrical performance measurements indicate that despite many of these polymeric materials operating in the melt or rubbery state during outdoor deployment, no significant creep was seen because of their high viscosity, lower operating temperature at the edges, and/or the formation of chemical crosslinks in many of the encapsulants with age despite the absence of a crosslinking agent. Only an ethylene-vinyl acetate (EVA) encapsulant formulated without a peroxide crosslinking agent crept significantly. In the case of the crystalline-silicon modules, the physical restraint of the backsheet reduced creep further and was not detectable even for the EVA without peroxide. Because of the propensity of some polymeric materials to crosslink as they age, typical thermoplastic encapsulants would be unlikely to result in creep in the vast majority of installations.
Abstract
Recently there has been increased interest in using thermoplastic encapsulant materials in photovoltaic modules, but concerns have been raised about whether these would be [...]
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Esterification of hydrolyzed sea mango (Cerbera odollam) oil using various cationic ion exchange resins
J. Kansedo, K. Lee

Energy Sci Eng (2014). Vol. 31

Abstract
This study investigates the esterification of hydrolyzed sea mango (Cerbera odollam) oil using several cationic ion exchange resins. The best resins were selected based on their performance in a preliminary esterification process. The best resins were then subsequently used in the optimization of the process parameters. The esterification parameters studied were reaction temperature (40–160°C), reaction time (0–5 h), molar ratio of oil to methanol (0.5:1 to 1:14), and catalyst loading (1–14 wt%). Among the resins studied, Amberlyst 15 was found to be the most promising catalyst in the esterification of the hydrolyzed sea mango oil. Moderate reaction temperatures, 60–100°C, were found to be adequate in converting the hydrolyzed sea mango oil into esters. Further investigation revealed that the esterification reaction using the cationic ion exchange resins proceeds at a fast rate, whereby fatty acid methyl esters (FAME) yield of over 80% at moderate reaction temperature was achievable in less than 1 h of reaction time. Small amount of catalyst, which is less than 5 wt%, was also found to be sufficient in catalyzing the esterification process to an acceptable yield.
Abstract
This study investigates the esterification of hydrolyzed sea mango (Cerbera odollam) oil using several cationic ion exchange resins. The best resins were selected based on [...]
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Al2O3/TiO2 double layer anti-reflection coating film for crystalline silicon solar cells formed by spray pyrolysis
H. Kanda, A. Uzum, N. Harano, S. Yoshinaga, Y. Ishikawa, Y. Uraoka, H. Fukui, T. Harada, S. Ito

Energy Sci Eng (2016).

Abstract
An Al2O3/TiO2 double layer anti-reflection coating (ARC) film formed by spray pyrolysis was introduced for monocrystalline silicon solar cells as the nonvacuum processing method. The thickness of the Al2O3 layer and TiO2 compact layer was controlled by the volume of deposited precursor solution and confirmed by ellipsometry and scanning electron microscopy. The average photovoltaic properties of photocurrent density (Jsc), open-circuit photovoltage (Voc), fill factor (FF), and photo energy conversion efficiency (η) were 37.0 mA/cm2, 590 mV, 0.712, and 15.5%, respectively. A significant improvement on Jsc and η could be confirmed owing to the Al2O3/TiO2 ARC. The results of Fourier transform infrared (FTIR) spectroscopy and optical simulation with modeling for the reflectance properties confirmed that C-H-based organics remained after the deposition of thin films.
Abstract
An Al2O3/TiO2 double layer anti-reflection coating (ARC) film formed by spray pyrolysis was introduced for monocrystalline silicon solar cells as the nonvacuum processing [...]
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Ozone pretreatment of humid wheat straw for biofuel production
A. jibouri, G. Turcotte, J. Wu, C. Cheng

Energy Sci Eng (2015).

Abstract
In an attempt to maximize the amount of ozone reacting with lignin inside humid wheat straw, some of the ozone-reactive lignin degradation products were washed away before a second ozonolysis delignification stage. The total contact time for the two stages was kept the same as that for a one-stage process for comparison. A significant decrease in the Acid Insoluble Lignin (AIL) content of the straw resulted: from 13.04 wt. % (after a 30-min one-stage ozonolysis) to 9.34 wt. % (after a 30-min two-stage ozonolysis, separated by a washing step). This significant improvement was accompanied by an increase in released fermentable sugars from an enzymatic hydrolysis. The yield increased from 60% theoretical sugars to 80%. A further improvement in AIL (down to 7.36 wt. %) and released sugars (up to 90% theoretical) occurred when the moisture content (MC) of the straw entering the second stage was adjusted to the optimum value of the straw entering first stage (45 wt. %, predicted from an experimental design). The authors believe this is the first time results are published for the introduction of a two-stage process separated by a washing step.
Abstract
In an attempt to maximize the amount of ozone reacting with lignin inside humid wheat straw, some of the ozone-reactive lignin degradation products were washed away before [...]
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A new era of renewable power plants?
T. Kåberger

Energy Sci Eng (2017). Vol. 4
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Combining science and engineering for global health and prosperity
T. Kåberger

Energy Sci Eng (2016). Vol. 3
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Energy science during industrial transformation
T. Kåberger

Energy Sci Eng (2015). Vol. 1
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Discovering new energy solutions
T. Kåberger

Energy Sci Eng (2013). Vol. 1
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Capacity assessment of CO2 storage in deep saline aquifers by mineral trapping and the implications for Songliao Basin, Northeast China
C. Jin, L. Liu, Y. Li, R. Zeng

Energy Sci Eng (2017). Vol. 81

Abstract
Sequestrating CO2 in deep saline aquifers is maybe the most effective option to mitigate CO2 emission. The storage capacity of CO2 is the key factor for site selection before a project is carried out. Most of the existing methods are for assessment of CO2 sequestered by stratigraphic and structural trapping, as well as residual trapping and solubility trapping. In this study, we used a new method that considers CO2 consumption through geochemical reactions with minerals of reservoir rocks, mainly sandstones. Contribution of storage capacity from carbonate mineral mainly refers to calcite is excluded. That is because lifetime of calcite (the whole time from reaction starting to calcite running out) is very short contrast with geological time-scale or it is a temporary trapping. The geochemical reactions between CO2 and feldspar minerals with thousand-year lifetime are regarded as the permanent methods for trapping CO2. CO2 consumptions by K-feldspar, albite, and anorthite are assessed with volume method based on corresponding geochemical reactions. Storage efficiency factor is also considered as one of the most important parameters in the reaction formula and it depends on specific surface area of minerals contacting with formation water and kinetics of precipitation and dissolution of minerals. We assessed the CO2 storage capacity of mineral trapping in Baokang sedimentary system, south Songliao Basin through the detailed analysis of geological data in this area. The calculated results show the total CO2 storage capacity of mineral trapping of the study area is 457.5–5114.5 Mt and the corresponding storage efficiency factor is 1%. The CO2 consumed by albite makes up more than 60% of the total storage capacity and it is about 30% for anorthite.
Abstract
Sequestrating CO2 in deep saline aquifers is maybe the most effective option to mitigate CO2 emission. The storage capacity of CO2 is the key factor for site selection before [...]
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Numerical investigation of the effects of dwell time duration in a two-stage injection scheme on exergy terms in an IDI diesel engine by three-dimensional modeling
S. Jafarmadar, A. Zehni

Energy Sci Eng (2014). Vol. 1

Abstract
Dwell duration of multiple-injection scheme is an important parameter, which makes it possible to shift the tradeoff curve between soot and NOx closer to the origin. In this investigation, therefore, energy and exergy analyses are carried out for various two-step injection schemes in which 25% of the total fuel is injected during the second pulse and the dwell time is increased from 5°CA (crank angle) to 30°CA by 5°CA increments. The calculations are performed for a Lister 8.1 indirect injection (IDI) diesel engine at full load operation. The energy analysis for these schemes is performed during a closed cycle by using a three-dimensional CFD code. The cylinder pressure results for the baseline engine are compared with the corresponding experimental data and they show good agreement. For the exergy analysis, an in-house computational code has been developed, which uses the results of energy analysis in various cases. With crank angle positions and dwell durations set for different injection schemes, various rates of exergy are calculated and the cumulative exergy components are identified separately. The results show that the values of work exergy and exergy efficiency decrease when the dwell duration is changed from 5°CA to 30°CA. Also, there is a sharp change in the exergy parameters when the dwell time reaches 25°CA.
Abstract
Dwell duration of multiple-injection scheme is an important parameter, which makes it possible to shift the tradeoff curve between soot and NOx closer to the origin. In this [...]
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A simplified methodology for estimating solar spectral influence on photovoltaic energy yield using average photon energy
T. Ishii, K. Otani, A. Itagaki, K. Utsunomiya

Energy Sci Eng (2013). Vol. 18

Abstract
Nowadays, investors, customers, and even suppliers focus on the bankability of photovoltaic (PV) technologies. However, few studies have investigated the annual net effect of solar spectrum. In this study, we estimate the net effect of the solar spectrum on the annual energy yield of c-Si and a-Si modules by two parameters. One parameter is a direct calculation from spectral factor (SF). The other parameter uses average photon energy (APE) and a regression line or curve. The estimations by the two parameters are quite consistent, whereas there is 1.2% difference between the estimations at most. Therefore, APE would be a useful index to quantify the effect of the solar spectrum.
Abstract
Nowadays, investors, customers, and even suppliers focus on the bankability of photovoltaic (PV) technologies. However, few studies have investigated the annual net effect [...]
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A bridge to nowhere: methane emissions and the greenhouse gas footprint of natural gas
R. Howarth

Energy Sci Eng (2014). Vol. 47

Abstract
In April 2011, we published the first peer-reviewed analysis of the greenhouse gas footprint (GHG) of shale gas, concluding that the climate impact of shale gas may be worse than that of other fossil fuels such as coal and oil because of methane emissions. We noted the poor quality of publicly available data to support our analysis and called for further research. Our paper spurred a large increase in research and analysis, including several new studies that have better measured methane emissions from natural gas systems. Here, I review this new research in the context of our 2011 paper and the fifth assessment from the Intergovernmental Panel on Climate Change released in 2013. The best data available now indicate that our estimates of methane emission from both shale gas and conventional natural gas were relatively robust. Using these new, best available data and a 20-year time period for comparing the warming potential of methane to carbon dioxide, the conclusion stands that both shale gas and conventional natural gas have a larger GHG than do coal or oil, for any possible use of natural gas and particularly for the primary uses of residential and commercial heating. The 20-year time period is appropriate because of the urgent need to reduce methane emissions over the coming 15–35 years.
Abstract
In April 2011, we published the first peer-reviewed analysis of the greenhouse gas footprint (GHG) of shale gas, concluding that the climate impact of shale gas may be worse [...]
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University of Texas study underestimates national methane emissions at natural gas production sites due to instrument sensor failure
T. Howard

Energy Sci Eng (2015).

Abstract
The University of Texas reported on a campaign to measure methane (CH4) emissions from United States natural gas (NG) production sites as part of an improved national inventory. Unfortunately, their study appears to have systematically underestimated emissions. They used the Bacharach Hi-Flow® Sampler (BHFS) which in previous studies has been shown to exhibit sensor failures leading to underreporting of NG emissions. The data reported by the University of Texas study suggest their measurements exhibit this sensor failure, as shown by the paucity of high-emitting observations when the wellhead gas composition was less than 91% CH4, where sensor failures are most likely, during follow-up testing, the BHFS used in that study indeed exhibited sensor failure consistent with under-reporting of these high emitters. Tracer ratio measurements made by the University of Texas at a subset of sites with low CH4 content further indicate that the BHFS measurements at these sites were too low by factors of three to five. Over 98% of the CH4 inventory calculated from their own data and 41% of their compiled national inventory may be affected by this measurement failure. Their data also indicate that this sensor failure could occur at NG compositions as high as 97% CH4, possibly affecting other BHFS measurement programs throughout the entire NG supply chain, including at transmission sites where the BHFS is used to report greenhouse gas emissions to the United States Environmental Protection Agency Greenhouse Gas Reporting Program (USEPA GHGRP, U.S. 40 CFR Part 98, Subpart W). The presence of such an obvious problem in this high profile, landmark study highlights the need for increased quality assurance in all greenhouse gas measurement programs.
Abstract
The University of Texas reported on a campaign to measure methane (CH4) emissions from United States natural gas (NG) production sites as part of an improved national inventory. [...]
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Greenhouse gas emissions from domestic hot water: heat pumps compared to most commonly used systems
B. Hong, R. Howarth

Energy Sci Eng (2016).

Abstract
We estimate the emissions of the two most important greenhouse gasses (GHG), carbon dioxide (CO2) and methane (CH4), from the use of modern high-efficiency heat pump water heaters compared to the most commonly used domestic hot water systems: natural gas storage tanks, tankless natural gas demand heaters, electric resistance storage tanks, and tankless electric resistance heaters. We considered both natural gas-powered electric plants and coal-powered plants as the source of the electricity for the heat pumps, the thermal electric storage tanks, and the tankless electric demand heaters. The time-integrated radiative forcing associated with using a heat pump water heater was always smaller than any other means of heating water considered in this study across all time frames including at 20 and 100 years. The estimated amount of CH4 lost during its lifecycle was the most critical factor determining the relative magnitude of the climatic impact. The greatest net climatic benefit within the 20-year time frame was predicted to be achieved when a storage natural gas water heater (the most common system for domestic hot water in the United States) fueled by shale gas was replaced with a high efficiency heat pump water heater powered by coal-generated electricity, the heat pump system powered by renewable electricity would have had an even greater climatic benefit, but was not explicitly modeled in this study. Our analysis provides the first assessment of the GHG footprint associated with using a heat pump water heater, which we demonstrate to be an effective and economically viable way of reducing emissions of GHGs.
Abstract
We estimate the emissions of the two most important greenhouse gasses (GHG), carbon dioxide (CO2) and methane (CH4), from the use of modern high-efficiency heat pump water [...]
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Parametric analysis and systems design of dynamic photovoltaic shading modules
J. Hofer, A. Groenewolt, P. Jayathissa, Z. Nagy, A. Schlueter

Energy Sci Eng (2016).

Abstract
Shading systems improve building energy performance and occupant comfort by controlling glare, natural lighting, and solar gain. Integrating PV (photovoltaics) in shading systems opens new opportunities for BIPV (building integrated photovoltaics) on façades. A key problem of such systems is mutual shading among PV modules as it can lead to electrical mismatch losses and overheating effects. In this work, we present a new modeling framework, which couples parametric 3D with high-resolution electrical modeling of thin-film PV modules to simulate electric energy yield of geometrically complex PV applications. The developed method is able to predict the shading pattern for individual PV modules with high spatio-temporal resolution, which is of great importance for electrical system design. The methodology is applied to evaluate the performance of different dynamic BIPV shading system configurations, as well as its sensitivity to façade orientation and module arrangement. The analysis shows, that there is a trade-off between tracking performance and mutual shading of modules. Distance between modules is a critical parameter influencing the amount of mutual shading and hence limiting solar irradiation and electricity generation of PV shading systems using solar tracking. Planning of module string configuration, PV cell orientation, and location of bypass diodes according to partial shading conditions, reduces electrical mismatch losses and results in significantly higher electricity generation. The integration of parametric 3D and electrical modeling opens new possibilities for PV system design and dynamic control optimization. Though the analysis focuses on BIPV, the method is useful for the planning and operation of solar tracking systems in general.
Abstract
Shading systems improve building energy performance and occupant comfort by controlling glare, natural lighting, and solar gain. Integrating PV (photovoltaics) in shading [...]
- 433
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Turbine design and field development concepts for tidal, ocean, and river applications
D. Zeiner-Gundersen

Energy Sci Eng (2015).

Abstract
This paper discusses tidal, ocean, and river free turbine functional design parameters and general considerations associated with tidal field developments. A particular focus is on the importance of considering mechanical fatigue and the associated calculation method when designing a turbine for the challenging hydrodynamic environment. The balance between high-fatigue resistances, costs associated with designing components, and potential for reduced turbine efficiency is discussed in regards to the potential energy extracted from a field site. A novel flexible foil vertical turbine concept with high-fatigue resistance, and simple installation and retrieval methods is shown to have a low kWh cost per production output compared to other hydrodynamic turbine concepts. Three possible field development concepts for the flexible foil turbine are described herein for river, ocean current, and tidal applications.
Abstract
This paper discusses tidal, ocean, and river free turbine functional design parameters and general considerations associated with tidal field developments. A particular focus [...]
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Automatized analysis of IR-images of photovoltaic modules and its use for quality control of solar cells
J. Hepp, F. Machui, H. Egelhaaf, C. Brabec, A. Vetter

Energy Sci Eng (2016).

Abstract
It is well known that the performance of solar cells may significantly suffer from local electric defects. Accordingly, infrared thermography (i.p. lock-in thermography) has been intensely applied to identify such defects as hot spots. As an imaging method, this is a fast way of module characterization. However, imaging leads to a huge amount of data, which needs to be investigated. An automatized image analysis would be a very beneficial tool but has not been suggested so far for lock-in thermography images. In this manuscript, we describe such an automatized analysis of solar cells. We first established a robust algorithm for segmentation (or recognition) for both, the PV-module and the defects (hot spots). With this information, we then calculated a parameter from the IR-images, which could be well correlated with the maximal power (Pmpp) of the modules. The proposed automatized method serves as a very useful foundation for faster and more thorough analyses of IR-images and stimulates the further development of quality control on solar modules.
Abstract
It is well known that the performance of solar cells may significantly suffer from local electric defects. Accordingly, infrared thermography (i.p. lock-in thermography) has [...]
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MoS2 as a co-catalyst for photocatalytic hydrogen production from water
B. Han, Y. Hu

Energy Sci Eng (2016).

Abstract
Solar-to-hydrogen conversion based on photocatalytic water splitting is a promising pathway for sustainable hydrogen production. The photocatalytic process requires highly active, inexpensive, and earth-abundant materials as photocatalysts. As a presentative layer-structured transition metal dichalcogenides, molybdenum disulfide (MoS2) is attracting intensive attention due to its unique electro and photo properties. In this article, we comprehensively review the recent research efforts of exploring MoS2 as a co-catalyst for photocatalytic hydrogen production from water, with emphasis on its combination with CdS, CdSe, graphene, carbon nitride, TiO2, and others. It is shown that MoS2–semiconductor composites are promising photocatalysts for hydrogen evolution from water under visible light irradiation.
Abstract
Solar-to-hydrogen conversion based on photocatalytic water splitting is a promising pathway for sustainable hydrogen production. The photocatalytic process requires highly [...]
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Fe-Cu metastable material as a mesoporous layer for dye-sensitized solar cells
A. Alami, J. Abed, M. Almheiri, A. Alketbi, C. Aokal

Energy Sci Eng (2016).

Abstract
This study investigates the performance of dye-sensitized solar cells constructed with a Fe-Cu metastable material as the mesoporous layer on which a natural organic dye is applied. The synthesis of the Fe-Cu material is done via a high throughput process that produces nanosized particles from elemental metallic powders. Xanthophyll is singled out as the organic natural dye of choice among other dyes that were extracted, as it exhibited wider spectral absorptivity in terms of wavelength range and magnitude. Two compact solar cells were constructed and tested, one is a reference cell with a TiO2 working electrode and the other with a Fe-Cu working electrode. The results show a better power conversion efficiency for the Fe-Cu-based solar cell 0.943% compared to 0.638% for the TiO2, and the number of carriers in the former is found to be orders of magnitude higher than the latter (1019 vs. 1032, respectively). A thorough optical, electrical, and thermal analysis of the Fe-Cu material is conducted and used to explain the obtained results.
Abstract
This study investigates the performance of dye-sensitized solar cells constructed with a Fe-Cu metastable material as the mesoporous layer on which a natural organic dye is [...]
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Review of passive heating/cooling systems of buildings
N. Gupta, G. Tiwari

Energy Sci Eng (2016).

Abstract
In this review, an attempt has been made to analyze passive solar heating and cooling concepts along with their effects on performance of a buildings thermal management. The concepts of Trombe wall, solarium, evaporative cooling, ventilation, radiative cooling, wind tower, earth air heat exchanger, roof pond, solar shading for buildings, and building-integrated photovoltaic thermal (BiPVT) systems are extensively covered in this review. Comparison of results by various heating and cooling concepts has been made. It has been observed that direct heating through double-glazed window saves maximum conventional fuel for thermal heating during winter months. Further, an evaporative cooling is one of the best cooling concepts which is economical too in summer period.
Abstract
In this review, an attempt has been made to analyze passive solar heating and cooling concepts along with their effects on performance of a buildings thermal management. The [...]
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Offshore wind energy potential estimation using UPSCALE climate data
M. Gross, V. Magar

Energy Sci Eng (2015).

Abstract
Offshore and near-shore wind energy is one of the major renewable energy resources, which already make a substantial contribution to the energy supply in Europe. Nevertheless, development is still in the start-up phase, with new projects being planned and implemented continuously. This development needs to be informed, to enable deployment at the most suitable/ideal locations. However, in order to predict the potential energy yield, forecasts have to be made. In this paper the authors present a scoping study. This study uses high-resolution climate data to predict wind speeds at various heights, and various locations along the coast of Mexico. Several techniques for wind extrapolation are explored, alongside a new method based on data analysis. The results show clearly a strong sensitivity to the method chosen, and results have to be interpreted accordingly. Also, the impact of water vapor is shown, using a method that predicts the moist air density at the hub height. The paper indicates that valuable information can be gained from the analyses undertaken, prior to embarking on detailed, targeted studies. The paper concludes with recommendations for further work.
Abstract
Offshore and near-shore wind energy is one of the major renewable energy resources, which already make a substantial contribution to the energy supply in Europe. Nevertheless, [...]
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Influence of different SSF conditions on ethanol production from corn stover at high solids loadings
A. Gladis, P. Bondesson, M. Galbe, G. Zacchi

Energy Sci Eng (2015).

Abstract
In this study, three different kinds of simultaneous saccharification and fermentation (SSF) of washed pretreated corn stover with water-insoluble solids (WIS) content of 20% were investigated to find which one resulted in highest ethanol yield at high-solids loadings. The different methods were batch SSF, prehydrolysis followed by batch SSF and fed-batch SSF. Batch-SSF resulted in an ethanol yield of 75–76% and an ethanol concentration of 53 g/L. Prehydrolysis prior to batch SSF did not improve the ethanol yield compared with batch SSF. Fed-batch SSF, on the other hand, increased the yield, independent of the feeding conditions used (79–81%, 57–60 g/L). If the initial amount of solids during fed-batch SSF was lowered, the yield could be improved to some extent. When decreasing the enzyme dosage, the greatest decrease in yield was seen in the fed-batch mode (75%), while lower or the same yield was seen in batch mode with and without prehydrolysis (73%). This resulted in similar ethanol yields in all methods. However, the residence time to achieve the final ethanol yield was shorter using fed-batch. This shows that fed-batch can be a better alternative also at a lower enzyme loading.
Abstract
In this study, three different kinds of simultaneous saccharification and fermentation (SSF) of washed pretreated corn stover with water-insoluble solids (WIS) content of [...]
- 9
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High efficiency thin-film amorphous silicon solar cells
A. Ghahremani, A. Fathy

Energy Sci Eng (2016).

Abstract
Enhancing light absorption within thin film amorphous silicon (a-Si) solar cells should lead to higher efficiency. This improvement is typically done using various light trapping techniques such as utilizing textured back reflectors for pronounced light scattering within the cell thus achieving higher absorption. It is believed that embedding metallic nanoparticles (MNPs) inside the structure could increase light scattering. However, embedding MNPs can also cause significant structure defects and pronounced efficiency drop as well – it has been indicated by many experiments that disproved this belief. In search of ways to improve efficiency, we have investigated the impact of MNPs size, and location within the solar cell, in addition to the effect of defects, and doping levels on the overall efficiency. On the basis of our 3D multiphysics (optical-electric) modeling, we developed a design guideline for embedding these MNPs and reducing the impact of defects created in the embedding process. The results of simulations were compared to relevant measured data, and it showed a good agreement. Subsequently, models were used to predict performance, and over 30% improvement in solar cell efficiency (~13% is predicted), which is beyond the state of the art. This was predicted by optimizing the size and location of the MNPs and tailoring the doping levels to have better forward light trapping and absorption.
Abstract
Enhancing light absorption within thin film amorphous silicon (a-Si) solar cells should lead to higher efficiency. This improvement is typically done using various light trapping [...]
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A three-dimensional multiphysics modeling of thin-film amorphous silicon solar cells
A. Ghahremani, A. Fathy

Energy Sci Eng (2015).

Abstract
A 3D multiphysics simulation toolbox for thin-film amorphous silicon solar cells has been developed. The simulation is rigorous and is based on developing three modules: first to analyze light propagation using electromagnetic techniques, second to account for charge generation and transportation based on the physics of the semiconductor device, and third including electrode modeling by applying electrostatic techniques. Published results of a P-I-N thin-film amorphous silicon solar cell fabricated on a thick glass and experimentally evaluated was used as a vehicle to validate our 3D multiphysics toolbox and demonstrate its capabilities. The toolbox utilizes COMSOL for solving the partial differential equations describing the three modules, and MATLAB to input data, control the solver, and provides the coupling between the three modules. The developed toolbox was used to investigate both the effect of embedding Metallic Nanoparticles (MNPs) and the impact of defects on the external quantum efficiency. The simulator, besides being rigorous, is suitable to model various types of solar cells (organic, inorganic, thick film, thin film, heterojunction, or plasmonic) as well.
Abstract
A 3D multiphysics simulation toolbox for thin-film amorphous silicon solar cells has been developed. The simulation is rigorous and is based on developing three modules: first [...]
- 115
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Reservoir modeling for Wabamun lake sequestration project
S. Ghaderi, Y. Leonenko

Energy Sci Eng (2015).

Abstract
A study, entitled “Wabamun Lake Sequestration Project” or “WASP, ” was performed to evaluate large-scale CO2 storage opportunities in the Wabamun area including potential risks. The project examined the feasibility of storing 20 megatons (Mt) of CO2 per year over 50 years. This scale is one order of magnitude larger than the typical benchmark (1 Mt/year) used in academic research and commercial projects that are currently in place or under review. The study was conducted by a group of researchers from several universities as well as industry consultants. This study presents an overview of the reservoir modeling part of this study, which the authors were responsible for. The main objectives of the reservoir modeling for WASP project were as follows: (1) estimation of storage capacity (traditionally, this value is projected based on the available pore space, but we have an additional practical consideration: the maximum amount one can inject within short period of time [~50 years] and within a localized injection area [~30 km × 90 km]), (2) investigation of CO2 plume movement and pressure distribution during and after injection including the effect of formation dip angle on the plume shape and its migration, (3) investigation of the long-term fate of injection associated with free phase CO2 (risks of leakage) and aquifer pressurization (possible geomechanical changes and related phenomena), (4) investigation of the phase behavior of H2S initially available and dissolved in brine during CO2 sequestration process. The WASP reservoir modeling study mentioned above led to a few important findings. The most important one is that, when CO2 is being injected into a sour aquifer, initially dissolved H2S will release into the expanding CO2 plume and accumulate at the leading edge of the plume. Also, the large-scale injection scheme (20 Mt/year), which requires multi well injectors, provides very different pressure response compared to a one well (1 Mt/year) scenario.
Abstract
A study, entitled “Wabamun Lake Sequestration Project” or “WASP, ” was performed to evaluate large-scale CO2 storage opportunities in the Wabamun area including potential [...]
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Liquinert quartz crucible for the growth of multicrystalline Si ingots
K. Fujiwara, Y. Horioka, S. Sakuragi

Energy Sci Eng (2015).

Abstract
The growth of a multicrystalline silicon (mc-Si) ingot for solar cell applications was attempted using a Liquinert quartz crucible. A mc-Si ingot was also grown in a quartz crucible coated with Si3N4 powder for comparison with that from the Liquinert quartz crucible. The mc-Si ingot grown in the Liquinert quartz crucible had a shinier surface which has few impurity particles and higher minority carrier lifetime than the mc-Si ingot grown in a quartz crucible coated with Si3N4 powder. These results indicate that contamination with impurities was reduced with the Liquinert quartz crucible, therefore, this crucible has the potential to be a powerful tool for the production of high-quality mc-Si ingots for solar cell applications.
Abstract
The growth of a multicrystalline silicon (mc-Si) ingot for solar cell applications was attempted using a Liquinert quartz crucible. A mc-Si ingot was also grown in a quartz [...]
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Effect of oxomolybdate species dispersion on direct methanol oxidation to dimethoxymethane over MoO x /TiO2 catalysts
J. Faye, M. Capron, A. Takahashi, S. Paul, B. Katryniok, T. Fujitani, F. Dumeignil

Energy Sci Eng (2015).

Abstract
The one-step selective oxidation of methanol to dimethoxymethane (DMM) was demonstrated over titania-supported molybdenum oxide catalysts, containing different amounts of molybdenum and prepared using two different impregnation techniques, namely wet impregnation and incipient wetness impregnation. The corresponding catalysts exhibited both acidic and redox properties, which are necessary for the oxidation of methanol to formaldehyde with subsequent condensation of the latter with excess methanol to finally yield DMM. The formation of well-dispersed polyoxomolybdate species on the catalyst surface was evidenced using IR-Raman, X-ray diffraction, and nitrogen physisorption. Varying the amount of these polyoxomolydate species was associated with a modulation of the acidic and redox properties, as shown by NH3-TPD and H2-TPR. With respect to the catalytic performances, the best balance between acid and redox properties was observed over the samples containing 8 wt.% Mo, which corresponds to a theoretical MoO x species coverage close to a monolayer.
Abstract
The one-step selective oxidation of methanol to dimethoxymethane (DMM) was demonstrated over titania-supported molybdenum oxide catalysts, containing different amounts of [...]
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Optimization and comparison analysis for application of PV panels in three villages
M. Fadaeenejad, M. Radzi, M. Fadaeenejad, M. Zarif, Z. Gandomi

Energy Sci Eng (2015).

Abstract
In recent years, research about the application and optimization of PV panels has grown rapidly. Especially for stand-alone solar systems there have been some problems related to first stages of design and application. Finding the optimum slope of PV panels in order to maximize the absorbed solar radiation is considered as one of the major obstacles. Although in Malaysia there have been some research works about finding of optimal tilt angle, however, this research work aims to start investigation about slope of PV panels for three villages without electricity and prior research. The Liu and Jordan model is applied to find the monthly optimal tilt angle and fixed tilt angle for the application of solar energy in these rural locations. The results demonstrate that the optimal tilt angle in these locations is less than 5°.
Abstract
In recent years, research about the application and optimization of PV panels has grown rapidly. Especially for stand-alone solar systems there have been some problems related [...]
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Oxyfuel combustion in rotary kiln lime production
M. Eriksson, B. Hökfors, R. Backman

Energy Sci Eng (2014).

Abstract
The purpose of this article is to study the impact of oxyfuel combustion applied to a rotary kiln producing lime. Aspects of interest are product quality, energy efficiency, stack gas composition, carbon dioxide emissions, and possible benefits related to carbon dioxide capture. The method used is based on multicomponent chemical equilibrium calculations to predict process conditions. A generic model of a rotary kiln for lime production was validated against operational data and literature. This predicting simulation tool is used to calculate chemical compositions for different recirculation cases. The results show that an oxyfuel process could produce a high-quality lime product. The new process would operate at a lower specific energy consumption thus having also a reduced specific carbon dioxide emission per ton of product ratio. Through some processing, the stack gas from the new process could be suitable for carbon dioxide transport and storage or utilization. The main conclusion of this paper is that lime production with an oxyfuel process is feasible but still needs further study.
Abstract
The purpose of this article is to study the impact of oxyfuel combustion applied to a rotary kiln producing lime. Aspects of interest are product quality, energy efficiency, [...]
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Tip speed ratio control of a 200 kW VAWT with synchronous generator and variable DC voltage
S. Eriksson, J. Kjellin, H. Bernhoff

Energy Sci Eng (2013).

Abstract
A novel control method for a fixed-pitch variable speed wind turbine is introduced and experimental results are presented. The measured absorbed power and rotational speed, together with a look-up table for the aerodynamic efficiency, are used to estimate the wind speed reaching the turbine as well as the tip speed ratio. Thereby, the control is independent on wind speed measurements and the wind turbine itself is used as an anemometer. Tip speed ratio control is implemented by comparing the estimated tip speed ratio to a reference value and adjusting the DC voltage level accordingly. Tip speed ratio control benefits from that the aerodynamic efficiency hardly varies with changing tip speed ratio when close to its optimum value. Experimental results from a 200 kW vertical axis wind turbine are presented. The voltage from the permanent magnet generator is passively rectified and the alternating DC voltage is then inverted, filtered, transformed, and grid connected. The estimated wind speed is compared with the measured wind speed. The absorbed power when tip speed ratio control has been implemented is shown. It is concluded that the presented control method works and some future improvements are discussed.
Abstract
A novel control method for a fixed-pitch variable speed wind turbine is introduced and experimental results are presented. The measured absorbed power and rotational speed, [...]
- 17
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Cyclical hydrogen storage and retention in polyaniline
R. Ebrahim, A. Zomorrodian, N. Attia, K. Geckeler, A. Ignatiev

Energy Sci Eng (2016).

Abstract
Hydrogen adsorption in porous nanostructured polyaniline (PANI) has been investigated to determine its potential as a hydrogen storage media. Residual gas analysis and thermogravimetric analysis were used to investigate the cyclical hydrogen adsorption in PANI. A hydrogen storage capacity of up to 3 wt % was obtained by charging the polymers at up to 3.0 × 106 Pa hydrogen at elevated temperature. Multiple charge and discharge cycles have been shown, with good retention beyond 106 sec.
Abstract
Hydrogen adsorption in porous nanostructured polyaniline (PANI) has been investigated to determine its potential as a hydrogen storage media. Residual gas analysis and thermogravimetric [...]
- 7
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Renewable energy auctions in South Africa outshine feed-in tariffs
A. Eberhard, T. Kåberger

Energy Sci Eng (2016).

Abstract
South Africas Renewable Energy Independent Power Producer Procurement Program has run four competitive tenders/auctions since 2011, which have seen US$19 billion in private investment, and electricity prices of wind power falling by 46% and solar PV electricity prices by 71%, in nominal terms. Competitive tenders were introduced after an unsuccessful attempt to implement feed-in tariffs. The tenders incorporated standard, nonnegotiable contract documents, including 20-year Power Purchase Agreements and an Implementation Agreement whereby the Government of South Africa back-stops IPP payments by the national utility, Eskom. All of these projects have reached financial close to date and some are already delivering power to the grid. The financing success has been due in part to the requirements for commercial banks to undertake a thorough due diligence of projects prior to bids being offered. The details of the policy package described may be useful for other policy makers in countries developing policies for renewable energy deployment.
Abstract
South Africas Renewable Energy Independent Power Producer Procurement Program has run four competitive tenders/auctions since 2011, which have seen US$19 billion in private [...]
- 7
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Comprehensive study of performance degradation of field-mounted photovoltaic modules in India
R. Dubey, S. Chattopadhyay, V. Kuthanazhi, A. Kottantharayil, C. Solanki, B. Arora, K. Narasimhan, J. Vasi, B. Bora, Y. Singh, O. Sastry

Energy Sci Eng (2017). Vol. 51

Abstract
The All India Survey of Photovoltaic Module Reliability 2014 is an enhanced version of the survey conducted in the previous year, with detailed characterization of PV modules including current-voltage, infrared and electroluminescence imaging, visual inspection, insulation resistance test and interconnect breakage test. More than a thousand modules were inspected in the field and the main results of the survey are presented in this paper. The average Pmax degradation rate for the so-called ‘good’ modules (Group X) is 1.33%/year which is higher than that commonly projected by manufacturers, and widely employed in financial calculations. Modules falling in the ‘not-so-good’ category (Group Y) show even higher degradation rates, and it is at least partly due to higher number of micro-cracks in the modules, and increased degradation of the packaging materials like encapsulant, backsheet, etc. Modules in ‘Hot’ climates degrade faster than modules in the ‘Non-Hot’ climates. Degradation in fill factor is the primary cause for performance degradation in the young modules (ages
Abstract
The All India Survey of Photovoltaic Module Reliability 2014 is an enhanced version of the survey conducted in the previous year, with detailed characterization of PV modules [...]
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Performance analysis of a tower solar collector-aided coal-fired power generation system
L. Duan, X. Yu, S. Jia, B. Wang, J. Zhang

Energy Sci Eng (2017). Vol. 38

Abstract
In this paper, a tower solar collector-aided coal-fired power generation (TSCACPG) system is proposed and studied in order to save the fossil energy and protect the environment. The integration scheme of tower solar collector and conventional coal-fired power plant is proposed. Based on the simulation platform TRNSYS, the TSCACPG system model is established and the dynamic performance of the TSCACPG system with the operating mode of coal saving is studied. The TSCACPG system performances of 1 day and 1 year are all discussed by using the DNI data of typical year in Chinese typical city of Dunhuang. Then, the sensitivity analysis of the TSCACPG system is carried out by changing the heliostat field scale (the size of the molten salt tower also changes accordingly). The annual performance of the TSCACPG system is also acquired. In consideration of the economic costs, the heliostat field area with the maximum annual solar-to-electric efficiency is selected as the optimal value. The results show that, for the case studied, the optimal heliostat field area is 101, 400 m2, and the maximum annual solar-to-electric efficiency is 16.74%. And under the optimal situation, the standard coal consumption rate of the original coal-fired power plant is reduced from 301.5 g/kWh to 294.5 g/kWh.
Abstract
In this paper, a tower solar collector-aided coal-fired power generation (TSCACPG) system is proposed and studied in order to save the fossil energy and protect the environment. [...]
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Design and experimental execution of a microcontroller (μC)-based smart dual-axis automatic solar tracking system
S. Das, S. Chakraborty, P. Sadhu, O. Sastry

Energy Sci Eng (2015).

Abstract
Detail analysis of microcontroller (μC)-based smart dual-axis automatic solar tracking system utilizable for different purpose is presented in this paper. Working of the proposed smart tracking system is based on the automatic rotation of photovoltaic (PV) panel depending on the intensity of sun light. It will help in maintaining the alignment of PV panels with the Sunlight to obtain maximum solar power at any instance. Intensity of sunlight on a particular alignment of solar PV panel varies throughout the day. As the intensity of light on PV panel decreases the proposed smart tracking system has the intelligence to automatically redirect the panel alignment to get maximum intensity of light. Four Light Dependent Resistor (LDR) sensors are placed on the surface of the PV panel to detect the intensity of light. Two servomotors are employed in the back side of PV panel system to align the panel with maximum luminous intensity. Design and construction of the proposed tracking system is presented to measure the efficiency over the fixed PV panel. Experimental results indicate that the power output of the PV system, using the proposed tracking system is increased up to 19.73% compare to the traditional fixed PV panel. The efficiency of the proposed design is considerably higher and comparable to the existing design which has the average efficiency around 12–15%.
Abstract
Detail analysis of microcontroller (μC)-based smart dual-axis automatic solar tracking system utilizable for different purpose is presented in this paper. Working of the [...]
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Experimental study of the effect of inhibitors in wax precipitation by different techniques
B. Coto, C. Martos, J. Espada, M. Robustillo, J. Peña

Energy Sci Eng (2014).

Abstract
The blocking problems in equipment and flowlines caused by precipitation of wax solids is a well-known problem and large research efforts have been focused on developing procedures dealing with wax deposition. Among the different alternatives, the use of chemicals is frequently used to inhibit wax precipitation. The presence of these compounds modifies the size and/or the shape of the paraffinic solids, thus affecting their flow behavior and cold properties. In this work, a methodology based on different experimental techniques was developed to study the effect of different additives on the crude oil behavior at low temperature. Four commercial inhibitors were added to three crude oils in different concentrations. The effect of the inhibitors on wax precipitation was studied using differential scanning calorimetry (DSC) and cross-polarized microscopy (CPM). Obtained results for wax appearance temperature (WAT) using DSC do not show remarkable differences regarding the presence of inhibitor. However, CPM analyses revealed differences in both size and shape of paraffin solids. The results obtained in this work reveal that in some cases the inhibitor does not modify the WAT values, but the morphology of the precipitated particles. In these cases, it is necessary to combine DSC and CPM analyses to obtain reliable results.
Abstract
The blocking problems in equipment and flowlines caused by precipitation of wax solids is a well-known problem and large research efforts have been focused on developing procedures [...]
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Enhanced biogas production from coffee pulp through deligninocellulosic photocatalytic pretreatment
G. Corro, U. Pal, S. Cebada

Energy Sci Eng (2014).

Abstract
Production of biogas utilizing agricultural wastes is one of the most demanding technologies for generating energy in sustainable manner considering environmental concerns. However, though the agricultural wastes are available in abundance, the technologies used for the production of biogas such as biological and thermochemical processes are not very efficient. In the present article, we describe a process for the production of biogas from coffee pulp utilizing Cu/TiO2 as an efficient photocatalyst in its solar photocatalytic pretreatment, producing biogas of high caloric value at enhanced rate. The pretreatment process enhances the coffee pulp–cattle manure codigestion, producing increased amounts of methane, propane, and other combustible components of biogas. The photocatalytic pretreatment was performed using 10%Cu/TiO2 as photocatalyst, bubbling air as oxidizing agent, and solar radiation as light source. The process enhances the degradation rate of lignocellulosic components of coffee pulp, consequently increasing the biogas production through anaerobic codigestion. The mechanism of photocatalytic degradation of lignocelluloses has been discussed. The results presented in this work indicate the photocatalytic pretreatment is a useful process to increase biogas generation from lignocelluloses-rich natural wastes.
Abstract
Production of biogas utilizing agricultural wastes is one of the most demanding technologies for generating energy in sustainable manner considering environmental concerns. [...]
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Estimating the specific chemical exergy of municipal solid waste
F. Eboh, P. Ahlström, T. Richards

Energy Sci Eng (2016).

Abstract
A new model for predicting the specific chemical exergy of municipal solid waste (MSW) is presented, the model is based on the content of carbon, hydrogen, oxygen, nitrogen, sulfur, and chlorine on a dry ash-free basis (daf). The proposed model was obtained from estimations of the higher heating value (HHV) and standard entropy of MSW using statistical analysis. The ultimate analysis of 56 different parts of MSW was used for the derivation of the HHV expression. In addition, 30 extra parts were used for validation. One hundred and seventeen relevant organic substances that represented the main constituents in MSW were used for derivation of the standard entropy of solid waste. The substances were divided into different waste fractions, and the standard entropies of each waste fraction and for the complete mixture were calculated. The specific chemical exergy of inorganic matter in the waste was also investigated by considering the inorganic compounds in the ash. However, as a result of the extremely low value calculated, the exergy of inorganic matter was ignored. The results obtained from the HHV model show a good correlation with the measured values and are comparable with other recent and previous models. The correlation of the standard entropy of the complete waste mixture is less accurate than the correlations of each individual waste fraction. However, the correlations give similar results for the specific chemical exergy, indicating that HHV has a greater impact when estimating the specific exergy of solid waste than entropy.
Abstract
A new model for predicting the specific chemical exergy of municipal solid waste (MSW) is presented, the model is based on the content of carbon, hydrogen, oxygen, nitrogen, [...]
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Technical mapping of solar PV for ISM-an approach toward green campus
S. Chakraborty, P. Sadhu, N. Pal

Energy Sci Eng (2015).

Abstract
This paper aims toward the first step for green campus approach for Indian School of Mines (ISM) campus. Comparative study of the performances for nine different commercialized solar panels made of Maxeon Cell Technology, HIT (Heterojunction with Intrinsic Thin layer), monocrystalline silicon (Mono C-Si), polycrystalline silicon (Poly C-Si), Micromorph, SCHOTT, amorphous silicon (a-Si), CIGS, CdTe technologies in the environmental condition of ISM are presented in this paper. This system suggests to supply the daytime electricity demand of ISM campus as well as efficient use of the huge roof areas of different buildings to setting up the photovoltaic plant. This system ensures a daily mean reduction of 8 MWh electricity consumption from grid. The outcome of this study is that a superior performance is noted for modules made of amorphous silicon technology under the typical temperature variant and dry environmental condition of ISM campus.
Abstract
This paper aims toward the first step for green campus approach for Indian School of Mines (ISM) campus. Comparative study of the performances for nine different commercialized [...]
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Developing new perspectives on the energy trilemma
A. Carrick

Energy Sci Eng (2017). Vol. 68

Abstract
The energy group of SCI (Society of Chemical Industry) was host for an event on 28th March 2017 at SCI Headquarters in London (UK) with a meeting on the important topic of the energy trilemma (sustainable, affordable and secure supply of energy). Alexandra Carrick gives an overview of the event.
Abstract
The energy group of SCI (Society of Chemical Industry) was host for an event on 28th March 2017 at SCI Headquarters in London (UK) with a meeting on the important topic of [...]
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Heterogeneous and homogenous catalysts for hydrogen generation by hydrolysis of aqueous sodium borohydride (NaBH4) solutions
P. Brack, S. Dann, K. Wijayantha

Energy Sci Eng (2015).

Abstract
It is clear that in order to satisfy global energy demands whilst maintaining sustainable levels of atmospheric greenhouse gases, alternative energy sources are required. Due to its high chemical energy density and the benign by-product of its combustion reactions, hydrogen is one of the most promising of these. However, methods of hydrogen storage such as gas compression or liquefaction are not suitable for portable or automotive applications due to their low hydrogen storage densities. Accordingly, much research activity has been focused on finding higher density hydrogen storage methods. One such method is to generate hydrogen via the hydrolysis of aqueous sodium borohydride (NaBH4) solutions, and this has been heavily studied since the turn of the century due to its high theoretical hydrogen storage capacity (10.8 wt%) and relatively safe operation in comparison to other chemical hydrides. This makes it very attractive for use as a hydrogen generator, in particular for portable applications. Major factors affecting the hydrolysis reaction of aqueous NaBH4 include the performance of the catalyst, reaction temperature, NaBH4 concentration, stabilizer concentration, and the volume of the reaction solution. Catalysts based on noble metals, in particular ruthenium (Ru) and platinum (Pt), have been shown to be particularly efficient at rapid generation of hydrogen from aqueous NaBH4 solutions. However, given the scarcity and expense of such metals, a transition metal-based catalyst would be a desirable alternative, and thus much work has been conducted using cobalt (Co) and nickel (Ni)-based materials to attempt to source a practical option. “Metal free” NaBH4 hydrolysis can also be achieved by the addition of aqueous acids such as hydrochloric acid (HCl) to solid NaBH4. This review summarizes the various catalysts which have been reported in the literature for the hydrolysis of NaBH4.
Abstract
It is clear that in order to satisfy global energy demands whilst maintaining sustainable levels of atmospheric greenhouse gases, alternative energy sources are required. [...]
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An old solution to a new problem? Hydrogen generation by the reaction of ferrosilicon with aqueous sodium hydroxide solutions
P. Brack, S. Dann, K. Wijayantha, P. Adcock, S. Foster

Energy Sci Eng (2015).

Abstract
The chemical hydrogen storage properties of ferrosilicon were investigated. A hydrogen yield of ~4.75 wt.% (with respect to the mass of ferrosilicon) was estimated by the reaction of varying quantities of ferrosilicon with 5 mL of 40 wt.% sodium hydroxide solution. The reaction of ferrosilicon with aqueous sodium hydroxide solution to form hydrogen was found to have an activation energy of 90.5 kJ mol−1 by means of an Arrhenius plot. It was observed that the induction period of the hydrogen generation reaction varies exponentially with temperature. Although this combination of high activation energy and a lengthy induction period at low temperatures reduces the attractiveness of ferrosilicon for portable hydrogen storage applications unless methods can be developed to accelerate the onset and rate of hydrogen generation, its low cost and widespread availability make it attractive for further studies focused on higher temperature stationary applications.
Abstract
The chemical hydrogen storage properties of ferrosilicon were investigated. A hydrogen yield of ~4.75 wt.% (with respect to the mass of ferrosilicon) was estimated by the [...]
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Numerical computation of a large-scale jet fire of high-pressure hydrogen in process plant
C. Jang, S. Jung

Energy Sci Eng (2016).

Abstract
Due to numerous hazardous chemicals to handle, the process plant industry has a higher risk of fire, explosion, and toxic release than other industries. Reviewing the accidents at process plants in the past, it is clear that fire accidents occur with the highest frequency, leading this study to consider accidental fire scenarios at process plants. For the scenario of an incident, a jet fire involving a massive amount of hydrogen gas to be processed or delivered at the process plant has been selected. The analysis of incident outcome resulting from the hydrogen jet fire has been implemented through the computational fluid dynamics simulation methodology Kameleon FireEx. Based on the outcome of this simulation, the consequences of a jet fire with high temperature and heat radiation are analyzed and evaluated. In addition, the results from Phast ver. 7.11 simulation for the same scenario are presented for comparison and further validation.
Abstract
Due to numerous hazardous chemicals to handle, the process plant industry has a higher risk of fire, explosion, and toxic release than other industries. Reviewing the accidents [...]
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Energy harvesting for assistive and mobile applications
V. Bhatnagar, P. Owende

Energy Sci Eng (2015).

Abstract
Technology advances have enabled modification of the size and shape of the electronic components to the microscale, with commensurate scaling down of their power requirements to milliwatts and microwatt range. Consequently, many complex electronic systems and devices such as wearable medical and autonomous devices consume power in the range less than 200 μW, and wireless sensor networks in the range μW to 100 mW are operated on battery power. Due to the salient limitations of battery power, such as longevity of charge and where applicable, the requirement for periodic recharging, possibilities for utilization of autonomous energy sources is critical for operation of such devices. Ambient energy sources, such as vibrations (1 μW to 20 mW), motion (wide range in power outputs), temperature gradient (0.5–10 mW), radiofrequency waves (>180 μW/cm2), light (100 μW/cm2 to 100 mW/cm2), acoustics (0.003–0.11 μW/cm2), and many other, have the potential to directly power the electronic device. Ambient energy harvesting, when used separately or in conjunction with batteries, will enhance the longevity of equipment operations requiring portable or autonomous power supply. This paper reviews the state of the art in energy-harvesting techniques, power conversion, and characterization of mini- and microscale self-sustaining power generation systems in the range 600 μW to 5 W, specifically focusing on low-power system applications, for personal assistive and mobile technology devices.
Abstract
Technology advances have enabled modification of the size and shape of the electronic components to the microscale, with commensurate scaling down of their power requirements [...]
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Photovoltaics: between a bright outlook and uncertainty
P. Berberi, S. Thodhorjani, P. Hoxha, V. Muda

Energy Sci Eng (2013). Vol. 72

Abstract
There is “breakneck” growth in the global photovoltaics market, with the global market of photovoltaic cells growing by about 47% in 2009, 72% in 2010, and 74% in 2011. Global installed capacity in 2011 was three times more than 2009. Italy and Germany are leading with a 57% share of the global market. Costs are dropping rapidly and photovoltaic (PV) power generation is an attractive option for investors. Increasing support of European Union (EU) for renewable energy in general and PV aims to diversify sources of energy and reduce reliance on fossil fuels, on nuclear and on imported energy. Energy security is an important dimension for the EU. Almost all experts agree that there is no single technology that will provide a sustainable global supply of cleaner energy. However, the scale, the cost of the change needed and supporting policy and legislation are often subject to debate. High costs could be counterbalanced by economic yields from new businesses, the creation of new jobs, and economic growth from clean energy investments. The current situation in which Germany and Italy account for almost 2/3 of global PV market growth and, also, the strong reliance on supporting policies is unstable. If PV power generation is to continue growing, the balance of development will have to shift to new markets – both inside and outside of Europe. Fixed price policy is a game to be played with caution. This article highlights examples of Spain, Italy, and Germany that illustrate that without robust policy the system can be easily misbalanced. When – or even if – photovoltaic power does become cheap enough to compete without subsidies against more established energy sources, depends upon a number of uncertainties, including the continuing political will to provide financial support, and how readily developing nations such as China and India embrace renewable energies.
Abstract
There is “breakneck” growth in the global photovoltaics market, with the global market of photovoltaic cells growing by about 47% in 2009, 72% in 2010, and 74% in 2011. [...]
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Potential induced degradation of n-type crystalline silicon solar cells with p front junction
S. Bae, W. Oh, K. Lee, S. Kim, H. Kim, N. Park, S. Chan, S. Park, Y. Kang, H. Lee, D. Kim

Energy Sci Eng (2017). Vol. 30

Abstract
N-type silicon-based solar cells are currently being used for achieving high efficiency. However, most of the photovoltaic modules already constructed are based on p-type silicon solar cells, and there are few studies on potential induced degradation (PID) in n-type solar cells. In this study, we investigated PID in n-type silicon solar cells with a front p+ emitter. Further, the PID characteristics of n-type solar cells are compared with those of p-type solar cells. The electrical properties of PID in solar cells are observed with the light I-V, quantum efficiency (QE), and electroluminescence (EL). The possible causes for the change in the external quantum efficiency (EQE) after PID are interpreted using PC1D and are discussed by comparing the experimental results with the simulation results.
Abstract
N-type silicon-based solar cells are currently being used for achieving high efficiency. However, most of the photovoltaic modules already constructed are based on p-type [...]
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Fuel-mix and energy utilization analysis of Port Harcourt Refining Company, Nigeria
I. Badmus, R. Fagbenle, O. Oyewola

Energy Sci Eng (2013).

Abstract
This study analyses the fuel-mix and energy utilization patterns in Port Harcourt Refining Company from 2000 to 2011. The average fuel mix over the study period is 43% refinery fuel gas, 0% liquefied petroleum gas (LPG), 44% low pour fuel oil (LPFO), 8% Coke, and 5% automotive gas oil (AGO). The present ratio of high-carbon fuel consumption to low-carbon fuel consumption adversely influences the specific fuel consumption by increasing it. Our proposal is that the present AGO and LPFO consumption levels are totally replaced with equivalent amounts of natural gas. This would yield the following fuel mix: 46% refinery fuel gas, 46% natural gas, and 8% coke. This, in effect, would result in a proportion of 92% low-carbon fuels and 8% coke. It would also lead to a specific fuel consumption that is averagely unaffected by high-carbon/low-carbon fuel consumption ratios. Natural gas utilization has its main advantage in its flare/waste and consequent environmental degradation reduction. Finally, the proposed fuel mix would generally lead to a reduction in specific fuel consumption, thus saving energy and reducing costs.
Abstract
This study analyses the fuel-mix and energy utilization patterns in Port Harcourt Refining Company from 2000 to 2011. The average fuel mix over the study period is 43% refinery [...]
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Response surface methodology for optimization of bio-lubricant basestock synthesis from high free fatty acids castor oil
V. Borugadda, V. Goud

Energy Sci Eng (2015).

Abstract
In this paper, an eco-friendly single-step process for the synthesis of biolubricant basestock from high free fatty acid (FFA) castor oil (CO) via epoxidation reaction was investigated. Influence of various process parameters on the structural modification of CO and their interaction with the maximum oxirane oxygen content (OOC) was optimized. Central composite design (CCD) as one of the tools in response surface methodology (RSM) was used to evaluate the effects of process variables on maximum OOC. Iodine value (IV) and OOC was used to monitor the progress of epoxidation. From the RSM study, the optimal condition inferred was H2O2, 1.65 mol, catalyst loading, 15.14 wt%, temperature, 52.81°C, and reaction time, 2.81 h. At this optimum condition, OOC was found to be 3.85 mass%. Further, the epoxide product was confirmed by 1H, 13C NMR spectral technique and OOC was determined by the standard HBr method. Finally, the significant physico-chemical properties for the prepared epoxide were determined and compared with the castor oil.
Abstract
In this paper, an eco-friendly single-step process for the synthesis of biolubricant basestock from high free fatty acid (FFA) castor oil (CO) via epoxidation reaction was [...]
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Spectral response measurements of multijunction solar cells with low shunt resistance and breakdown voltages
J. Babaro, K. West, B. Hamadani

Energy Sci Eng (2016).

Abstract
Spectral response measurements of germanium-based triple-junction solar cells were performed under a variety of light and voltage bias conditions. Two of the three junctions exhibited voltage and light bias-dependent artifacts in their measured responses, complicating the true spectral response of these junctions. To obtain more insight into the observed phenomena, a set of current-voltage measurement combinations were also performed on the solar cells under identical illumination conditions, and the data were used in the context of a diode-based analytical model to calculate and predict the spectral response behavior of each junction as a function of voltage. The analysis revealed that both low shunt resistance and low breakdown voltages in two of the three junctions influenced the measured quantum efficiency of all three junctions. The data and the modeling suggest that combination of current-voltage measurements under various light bias sources can reveal important information about the spectral response behavior in multijunction solar cells.
Abstract
Spectral response measurements of germanium-based triple-junction solar cells were performed under a variety of light and voltage bias conditions. Two of the three junctions [...]
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Advances on waste valorization: new horizons for a more sustainable society
R. Arancon, C. Lin, K. Chan, T. Kwan, R. Luque

Energy Sci Eng (2013). Vol. 53

Abstract
Increasingly tighter regulations regarding organic waste, and the demand for renewable chemicals and fuels, are pushing the manufacturing industry toward higher sustainability to improve cost-effectiveness and meet customers’ demand. Food waste valorization is one of the current research areas that has attracted a great deal of attention over the past few years as a potential alternative to the disposal of a wide range of residues in landfill sites. In particular, the development of environmentally sound and innovative strategies to process such waste is an area of increasing importance in our current society. Landfill, incineration and composting are common, mature technologies for waste disposal. However, they are not satisfactory to treating organic waste due to the generation of toxic methane gas and bad odor, high energy consumption and slow reaction kinetics. In fact, research efforts have also been oriented on novel technologies to decompose organic waste. However, no valuable product is generated from the decomposition process. Instead of disposing and decomposing food waste, recent research has focused on its utilization as energy source (e.g., for bioethanol and biodiesel production). Organic waste is also useful to generate useful organic chemicals via biorefinery or white biotechnology (e.g., succinic acid and/or bio-plastics). This article is aimed to summarize recent development of waste valorization strategies for the sustainable production of chemicals, materials, and fuels through the development of green production strategies. It will also provide key insights into recent legislation on management of waste worldwide as well as two relevant case studies (the transformation of corncob residues into functionalized biomass-derived carbonaceous solid acids and their utilization in the production of biodiesel-like biofuels from waste oils in Philippines, as well as the development of a bakery waste based biorefinery for succinic acid and bioplastic production in Hong Kong) to illustrate the enormous potential of biowaste valorization for a more sustainable society. Future research directions and possible sustainable approaches will also be discussed with their respective proofs of concept.
Abstract
Increasingly tighter regulations regarding organic waste, and the demand for renewable chemicals and fuels, are pushing the manufacturing industry toward higher sustainability [...]
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Comparison of the indoor performance of 12 commercial PV products by a simple model
G. Apostolou, A. Reinders, M. Verwaal

Energy Sci Eng (2016). Vol. 69

Abstract
This article presents a simple comparative model which has been developed for the estimation of the performance of photovoltaic (PV) products' cells in indoor environments. The model predicts the performance of PV solar cells, as a function of the distance from a spectrum of artificial (fluorescent light, halogen light, and light-emitting diodes) and natural light. It intends to support designers, while creating PV-integrated products for indoor use. For the models validation, PV cells of 12 commercially available PV-powered products with power ranging from 0.8 to 4 mWp were tested indoors under artificial illumination and natural light. The model is based on the physical measurements of natural and artificial irradiance indoors, along with literature data of PV technologies under low irradiance conditions. The input data of the model are the surface of the solar cell (in m2), the wavelength-dependent spectral response (SR) of the PV cell, the spectral irradiance indoors, and solar cells distance from light sources. The model calculates solar cells' efficiency and power produced under the specific indoor conditions. If using the measured SR of a PV cell and the irradiance as measured indoors, the model can predict the performance of a PV product under mixed indoor light with a typical inaccuracy of around 25%, which is sufficient for a design process. Measurements revealed that under mixed indoor lighting of around 20 W/m2, the efficiency of solar cells in 12 commercially available PV products ranges between 5% and 6% for amorphous silicon (a-Si) cells, 4–6% for multicrystalline silicon (mc-Si) cells, and 5–7% for the monocrystalline silicon (c-Si) cells.
Abstract
This article presents a simple comparative model which has been developed for the estimation of the performance of photovoltaic (PV) products' cells in indoor environments. [...]
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Hydrotreating reactions of tall oils over commercial NiMo catalyst
J. Anthonykutty, J. Linnekoski, A. Harlin, J. Lehtonen

Energy Sci Eng (2015).

Abstract
Catalytic hydrotreating is an attractive method for upgrading bio-derived oils into renewable feedstocks with less oxygen content, suitable for producing valuable hydrocarbons through various petro-refinery processes. This study evaluates the catalytic activity of a commercial alumina (Al2O3) supported NiMo catalyst for hydrotreating tall oil feeds such as crude tall oil (CTO), distilled tall oil (DTO), and tall oil fatty acid (TOFA). Catalytic experiments carried out in a bench-scale fixed bed reactor set-up at different process conditions [space velocity (1–3 h−1), temperature (325–450°C), and H2 pressure (5 MPa)] produced a wide-range of products from tall oil feeds. Hydrotreating of TOFA produced highest yield of n-alkanes (>80 wt%) compared to DTO and CTO hydrotreating. A high conversion of fatty acids and resin acids was obtained in DTO hydrotreating. In CTO hydrotreating, a drop in conversion of fatty acids and resin acids was observed especially at the lowest temperature tested (325°C). The study revealed that there are various deoxygenation pathways preferential at different hydrotreating temperatures. As an example for TOFA, the decarboxylation route is dominant over the hydrodeoxygenation route at high temperatures (>400°C).
Abstract
Catalytic hydrotreating is an attractive method for upgrading bio-derived oils into renewable feedstocks with less oxygen content, suitable for producing valuable hydrocarbons [...]
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Performance testing of thermal and photovoltaic thermal solar collectors
J. Allan, Z. Dehouche, S. Stankovic, L. Mauricette

Energy Sci Eng (2015).

Abstract
This work details a methodology to characterize the performance of solar thermal and photovoltaic thermal (PVT) collectors using an indoor solar simulator. In this study, several cases have been compared to show that the methodology can be used to extract fundamental performance characteristics from a solar collector. In the first case, a serpentine collector was compared against a header riser collector using the same mass flow rate. It was found that the header riser was less efficient, with a 34% increase in the overall loss coefficient. The experimental results were compared with commonly used empirical models and showed a close agreement. In the second case, the impact on performance of using a polycarbonate cover is presented. The results show that the optical efficiency of the collector is reduced by 12% when using a cover, however, because the loss coefficient is reduced by 53%, the covered collector performs better when there is a large temperature difference between the absorber and the ambient. The third case investigates the combined performance of a PVT collector, that produces both heat and electricity from a single device. By placing photovoltaic (PV) laminates on top of the serpentine absorber, the thermal efficiency is reduced by 15%. When electricity is generated by laminates, the thermal efficiency is reduced by a further 3.5%, this drop in thermal efficiency is a result of the incident radiation producing electricity before reaching the thermal absorber. The combined efficiency of the PVT collectors was compared at controlled inlet temperatures. The serpentine design had the highest combined efficiency of 61% with 8% electricity at the lowest inlet temperature (21°C). The dominant form of loss in the PVT system is temperature driven, as the thermal efficiency decreases, electricity generation makes up a larger percentage of the combined output. This study highlights the potential for manufacturers of bespoke thermal absorbers and PV devices to combine their products into a single PVT device that could achieve improved efficiency over a given roof area.
Abstract
This work details a methodology to characterize the performance of solar thermal and photovoltaic thermal (PVT) collectors using an indoor solar simulator. In this study, [...]
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Energy efficient inactivation of Saccharomyces cerevisiae via controlled hydrodynamic cavitation
L. Albanese, R. Ciriminna, F. Meneguzzo, M. Pagliaro

Energy Sci Eng (2015).

Abstract
We investigate hydrodynamic cavitation to inactivate commonly employed Saccharomyces cerevisiae yeast strains in an aqueous solution using different reactors and hydraulic circuit selected to demonstrate the process feasibility on the industrial scale. The target to achieve an useful lethality of the yeast at lower temperature when compared with standard thermal and even with other cavitation processes was achieved, with 90% yeast strains lethality at lower temperature (6.3–9.5°C), and about 20% lower energy input. A separate model simulating the combined thermal and cavitational effects on yeast lethality allows to accommodate the data into a comprehensive framework providing a tool to design further targeted experiments and to predict results when changing the process parameters.
Abstract
We investigate hydrodynamic cavitation to inactivate commonly employed Saccharomyces cerevisiae yeast strains in an aqueous solution using different reactors and hydraulic [...]
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The impact of electric vehicles on the power market
L. Albanese, R. Ciriminna, F. Meneguzzo, M. Pagliaro

Energy Sci Eng (2015).

Abstract
We investigate the impact of massive electric vehicle (EV) adoption onto the power market, both in the presence and in the absence of significant photovoltaic (PV) generation. Although results are derived taking into consideration Italys power market, results are of relevance also to other industrialized countries. One of the most important outcomes of the analysis, that is, the synergistic and beneficial effect on the overall energy bill of the concomitant expansion of EVs utilization and the growth of the renewable energy generation, particularly solar photovoltaics. The Conclusions provide arguments for policymakers for further support to sustainable mobility in their regions.
Abstract
We investigate the impact of massive electric vehicle (EV) adoption onto the power market, both in the presence and in the absence of significant photovoltaic (PV) generation. [...]
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Theoretical investigation about the optical characterization of cone-shaped pin-Si nanowire for top cell application
M. Khan, P. Sichanugrist, S. Kato, Y. Ishikawa

Energy Sci Eng (2016).

Abstract
Cone-shaped semiconductor silicon nanowires (CS-Si-NWs) grown in vapor liquid solid mode are promising for the fabrication of low-cost high-performance solar cells because of their low processing cost and lower use of Si materials, as compared to planar devices. In this article, the effect of injected charge carriers on the refractive indices and extinction coefficient values in a cone-shaped pin Si NW (CS-pin-Si NW) were considered. Then, the influence of top diameters and periods on the optical absorption was investigated using a finite difference time-domain (FDTD) modeling method. The absorption increased when we decreased the period from 300 to 150 nm for a light wave with a wavelength of 700 nm. However, in the case of incident light at a wavelength of 500 nm, the absorption significantly increased by up to 100% and was found to be independent of the period. On the other hand, we varied the period and the top diameter of the NWs with a fixed bottom diameter. In this case, we found that the period did not significantly affect the absorption value. A high value of the short circuit current density of 19.5 mA/cm2 was found in the case of NWs with a top diameter of 110 nm and a period of 150 nm. Combined with the analysis of the ultimate photocurrents, an optimum geometric structure with a top diameter of 70 nm and a period of 150 nm for a CS-pin-Si NW-based top cell for tandem solar cell applications was proposed.
Abstract
Cone-shaped semiconductor silicon nanowires (CS-Si-NWs) grown in vapor liquid solid mode are promising for the fabrication of low-cost high-performance solar cells because [...]
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Effects of temperature and equivalence ratio on mass balance and energy analysis in loblolly pine oxygen gasification
N. Abdoulmoumine, A. Kulkarni, S. Adhikari

Energy Sci Eng (2016).

Abstract
The purpose of this study was to evaluate the effects of temperature and equivalence ratios (ERs) on the distribution of products (primary gases carbon monoxide [CO], H2, CH4, CO2), gas phase contaminants (tar, NH3, HCN, H2S, HCl), char, carbon, and inorganics), and energy flows on an oxygen-blown bubbling fluidized bed gasifier system using loblolly pine. The goal and value of this study was to provide quantitative and qualitative performance analysis and data for process engineering and optimization of these fledgling biomass conversion systems. As temperature and ER increased, mass balance closures also increased from 94.73% to 96.72% for temperature and 89.82–96.93% for ER. In addition, the carbon closures ranged from 80.77% to 92.29% and from 79.09% to 87.13% as temperature and ER increased, respectively. Carbon conversion efficiency to gas product ranged from 72.26% to 84.32% as temperature increased and from 72.26% to 84.66% as ER increased. Carbon flow analysis showed that the char product streams retained 10.26–6.94% and 8.82–2.13% of the carbon fed to the gasifier as temperature and ER increased, respectively. The carbon content in the liquid condensate was minimal compared to the carbon in other product streams and accounted for less than 0.1% of the carbon input to the gasifier at all conditions. The cold and hot gas efficiencies increased from 56.12% to 67.45% and from 67.51% to 83.83% as temperature increased due to higher production of CO and hydrogen (H2). In contrast, cold and hot gas efficiencies decreased from 63.85% to 52.84% and from 78.06% to 73.00% as ER increased, respectively, due to enhanced oxidation of gas products resulting in a net decrease in heating value.
Abstract
The purpose of this study was to evaluate the effects of temperature and equivalence ratios (ERs) on the distribution of products (primary gases carbon monoxide [CO], H2, [...]
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Sliding Loads and their Effect on the Stress Triaxiality and Lode Parameter Responses of Plates and Frames
B. Quinton

Presentations to the VII International Conference on Computational Methods in Marine Engineering (Marine 2017).

Abstract
Much research has been done on the fracture of ship hulls due to collision or grounding; especially over the past two decades, where emphasis has been on advancing relevant nonlinear finite element analysis techniques. These simulations typically involve prediction of hull fracture/rupture, and may be validated against laboratory or field trials experiments ranging in complexity from uniaxial tensile tests to large-scale grillage fracture. Generally, validation efforts ignore the sliding motion of the “struck object;” with the notable exception of Rodd [8], who mounted 1/5th scale hull side-shell modules to a sled and impacted them against a cone-shaped “rock” composed of steel. For the case of steady-state plate cutting, which is typical of stranding, grounding, and oblique collision events, the sliding motion is intrinsic to the nature of the structural response (i.e. without sliding motion, there is no plate cutting), and is captured by existing analysis tools. There has been, however, comparatively little focus (except [1], [5], [6], and [7]) on the case of sliding hull loads resulting from grounding on a soft/wide bottom, or due to hull impact with ice. Both scenarios do not implicitly assume that fracture occurs, and the development of the hull structural response from initial impact to the (potential) point of fracture is of great interest. Typically, these scenarios – particularly impacts with ice features – are simplified to exclude tangential load motion. [1] and [6] predicted numerically that this simplification is unrealistic and unconservative, and [7] confirmed these predictions experimentally. Numerically, the development of fracture due to sliding loads depends on the damage history from the sliding load, the fracture model chosen, and the method of implementation of that fracture model. Quinton [7], using laboratory experiments, showed that nonlinear hull response due to sliding loads (without fracture) exhibits a significantly reduced hull capacity when compared with stationary loads of similar magnitude. This “capacity loss” increased with increasing plastic damage on the trailing side of the sliding load (i.e. increasing damage history). Regarding the fracture model, it is presently common in nonlinear finite element analysis to assume that the ductile fracture of steel (aluminum and some other marine materials) occurs at some equivalent strain that is: 1. a constant (i.e. a point), 2. a function of stress triaxiality (i.e. a line) [3], or 3. a function of stress triaxiality and Lode parameter (i.e. a surface) [2]. Additionally, considering temperature and/or strain-rate effects changes the point, line or surface (as appropriate to the fracture model). Implementation of a fracture model in finite element simulations is non-trivial, and numerous methods are available (e.g. the GISSMO model, the cohesive element approach [4], and the phenomenological approach (e.g. [9]). The application of these approaches to sliding induced fracture, however, is well beyond the scope of this paper; which instead focuses on the development of (i.e. changes in) stress triaxiality and Lode parameter in plates and frames subject to sliding loads; and hence the development of the point of onset of fracture based on the initial choice of fracture model. REFERENCES [1] Alsos, Hagbart S. "Ship Grounding - Analysis of Ductile Fracture, Bottom Damage and Hull Girder Response." PhD Norwegian University of Science and Technology (NTNU), 2008. [2] Bai, Yuanli, and Tomasz Wierzbicki. "A New Model of Metal Plasticity and Fracture with Pressure and Lode Dependence." International Journal of Plasticity 24.6 (2008). [3] Bao, Yingbin, and Tomasz Wierzbicki. "On Fracture Locus in the Equivalent Strain and Stress Triaxiality Space." International Journal of Mechanical Sciences 46.1 (2004). [4] Cirak, Fehmi, Michael Ortiz, and Anna Pandolfi. "A Cohesive Approach to Thin-Shell Fracture and Fragmentation." Computer Methods in Applied Mechanics and Engineering 194.21–24 (2005). [5] Hong, L., and J. Amdahl. "Rapid Assessment of Ship Grounding Over Large Contact Surfaces." Ships and Offshore Structures 7.1 (2012). [6] Quinton, B. W. T. "Progressive Damage to a Ship’s Structure due to Ice Loading." Master of Engineering Memorial University of Newfoundland, 2008. Print.St. John's, Newfoundland. [7] Quinton, B. W. T. "Experimental and Numerical Investigation of Moving Loads on Hull Structures." PhD Memorial University of Newfoundland, 2015. St. John's, NL. [8] Rodd, James L. "Large Scale Tanker Grounding Experiments". Proceedings of the Sixth (1996) International Offshore and Polar Engineering Conference. May 26-31, 1996, Los Angeles. [9] Woelke, Pawel B., and Najib N. Abboud. "Modeling Fracture in Large Scale Shell Structures." Journal of the Mechanics and Physics of Solids 60.12 (2012).
Abstract
Much research has been done on the fracture of ship hulls due to collision or grounding; especially over the past two decades, where emphasis has been on advancing relevant [...]
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Radiofrequency ablation of varicose veins improves venous clinical severity score despite failure of complete closure of the saphenous vein after 1 year
H. Yong Jin, H. Jin Ohe, J. Kye Hwang, S. Dong Kim, J. Yong Kim, S. Cheol Park, J. Kim, Y. Sung Won, S. Seob Yun, I. Sung Moon

Asian Journal of Surgery (2017). Vol. 40

Abstract
Endovenous treatment is increasingly supplanting open surgery for the treatment of varicose veins. Among emerging endovenous techniques, radiofrequency ablation (RFA) with a ClosureFast catheter is popular in Korea. The objective of this study was to evaluate and compare the efficacy and patient-reported outcomes of RFA of varicose veins. This is a retrospective study of a prospectively registered database of patients who underwent RFA for varicose veins from 2012 to 2013 in St. Marys Hospital in Seoul. Korea. Efficient ClosureFast RFA catheters (Medtronic, San Jose, CA, USA) were used. The techniques used for RFA of varicose veins were performed according to the manufacturers recommendations. Duplex scans and venous clinical severity scores (VCSSs) were used to document treatment outcome and patient symptoms before and after the procedures. Treatment outcomes were estimated before the procedure and 3 months, 6 months, and 12 months after the procedure. Outcomes were analyzed by paired t test, chi-square test, or Fishers exact test as well as by logistical regression. A total of 117 patients were evaluated for 183 consecutive RFA procedures (183 limbs). The initial technical success was 97.3% (178/183). The estimated mean VCSS changed over time from 4.0 ± 1.67 at preprocedure to 0.6 ± 1.05, 0.5 ± 1.02, and 0.6 ± 1.14 at 3 months, 6 months, and 12 months after the procedure, respectively. The improved VCSS was maintained 1 year after the procedure (p < 0.001). Recanalization of the saphenous vein was detected in 20 limbs at the 1-year follow up. The treatment failure group also exhibited a significant decline in the VCSS between preprocedure and 12 months (4.8 ± 1.76 vs. 1.8 ± 2.04, p < 0.001). Specifically, in the treatment failure group, 65% of limbs with episodic recanalization (13/20) were reoccluded or recanalized without venous reflux at the 1-year follow up. In this study, RFA of varicose veins had an initial success rate of 97.7% and a significantly improved patient VCSS at 1 year. Patients with episodic recanalization of the saphenous vein also exhibited an improved VCSS with favorable duplex findings at 1 year.
Abstract
Endovenous treatment is increasingly supplanting open surgery for the treatment of varicose veins. Among emerging endovenous techniques, radiofrequency ablation (RFA) with [...]
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Evolution of video-assisted thoracic surgery (VATS) techniques for Lung cancer; Minimizing surgical injury and Expanding applications
E. Yi, . Dongjin Kim, . Kwhanmien Kim, . Yu-Jen Cheng

Asian Journal of Surgery (2016). Vol. 39
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Recurrence factors and prevention of complications of pediatric differentiated thyroid cancer
. Changyuan Wang, . Xiaohua Chen, X. Wei, F. Chen, Y. Wang, . Zhiyong Shen

Asian Journal of Surgery (2017). Vol. 40

Abstract
To investigate the factors associated with recurrence of differentiated thyroid cancer in children. We combined the clinical and pathological features to guide surgical treatment options, ensure efficacy, and reduce complications. A prospective analysis of clinical data of 43 cases of pediatric differentiated thyroid cancer from March 2008 to June 2014 admitted in our department, including 38 cases of papillary cancers and five cases of follicular cancer, 40 cases were Stage I and three cases were Stage II (Union for International Cancer Control [UICC] Tumor Node Metastasis classification [TNM] staging). We performed the operations according to the condition of lesions and lymph nodes. Operations included subtotal resection in 36 cases, total resection in seven cases. We applied statistical methods to investigate the risk factors of recurrence and postoperative complications. The pathologic lymph node metastasis rate was 67.44% (29/43): Area VI lymph nodes metastases in 20 cases and Area III/IV or Area II/V lymph nodes metastases in nine cases. Postoperative hypocalcemia symptoms were seen in three cases and hoarseness in three cases, for a total rate of 13.95% (6/43). Until December 2015, patients were followed up from 1.5 years to 8.7 years, with a median of 4.9 years. There were three cases of cervical lymph node recurrence, one case of local recurrence, and one case of lung metastasis, for a total recurrence rate of 11.63% (5/43), all patients survived. Log-rank test of Kaplan-Meier curves and Cox stepwise regression analysis showed that lesion number, extrathyroidal extension, and lymph nodes metastases were the risk factors for postoperative recurrence, the relative risk values were, respectively, 3.117, 2.816, and 4.628 (p = 0.041, p = 0.048, and p = 0.031, respectively) and the 95% confidence intervals (CI) were, respectively, 1.094∼8.735, 1.046∼7.932, and 1.189∼10.205. However, the lesion excision approach was not a risk factor for postoperative recurrence (p = 0.107). The logistic stepwise regression model showed that lesion excision approach was a risk factor for postoperative hypocalcemia and hoarseness, the odds ratio value was 2.537 (p = 0.037) and the 95% CI was 1.034∼6.983. Pediatric differentiated thyroid cancer has a high metastatic rate to lymph nodes and distant organs, but the total prognosis is good. Application of total resection cannot necessarily reduce the relapse rate of pediatric differentiated thyroid cancer, but it may increase the postoperative hypocalcemia and hoarseness. The authors propose strictly adhering to various operation indicators, and carrying out various operations with a full understanding of the local lesion and lymph nodes in order to reduce relapse and postoperative complications.
Abstract
To investigate the factors associated with recurrence of differentiated thyroid cancer in children. We combined the clinical and pathological features to guide surgical treatment [...]
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Is the new comer always better?
. Yao-Chou Tsai, S. Chueh, . Shogo Inoue

Asian Journal of Surgery (2016). Vol. 39
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Surgical complications after simultaneous pancreas–kidney transplantation: A single-center experience
M. Khubutia, A. Pinchuk, I. Dmitriev, A. Balkarov, R. Storozhev, Y. Anisimov

Asian Journal of Surgery (2016). Vol. 39

Abstract
We investigated the rate of early surgical complications after simultaneous pancreas–kidney transplantation (SPKT) and their impact on both grafts and recipient survival. The retrospective analysis of typical pancreas-related complications, different methods of correction, and their efficacy were performed. Data describing pancreas transplant recipients were drawn from our SPKT waiting list. The overall surgical complications rate was 37.5%. The 1-year pancreas graft survival was 82.5% and 1-year recipient survival was 90%. Surgical complications based on the graft loss rate did not exceed 2.5%. Direct surgical complications did not account for the loss of a single patient. We conclude that the high rate of surgical complications is a major obstacle to widespread application of pancreas transplantation, early recognition and appropriate treatment of graft-related complications is fundamental for graft survival.
Abstract
We investigated the rate of early surgical complications after simultaneous pancreas–kidney transplantation (SPKT) and their impact on both grafts and recipient survival. [...]
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Donor site morbidity in buccinator-based myomucosal flaps: A retrospective study
. Amin Rahpeyma, . Saeedeh Khajehahmadi

Asian Journal of Surgery (2017). Vol. 40

Abstract
Buccinator-based myomucosal flaps can be used as a lining in oral cavity, pharyngeal, esophageal, and nasal reconstructions. Donor site morbidity is an important factor in selecting a flap, therefore, it was decided that donor site morbidity of this type of flap should be evaluated. In a retrospective study, patients for whom this flap had been used for oral, nasal, or pharyngeal reconstruction in 2008–2012 were recalled. Donor site morbidity including reduction in maximal interincisal opening (MIO), obliteration of the mandibular vestibule, injury to the Stensen duct, and vertical fibrous band in buccal mucosa were evaluated. Twenty-two buccinator-based myomucosal flaps (20 patients) had been used for oral, nasal, or oropharyngeal reconstruction. The most common flap used was the Facial Artery Musculomucosal (FAMM) flap (50%), and the commonest cause for flap use was the presence of a cleft lip/palate sequel in patients (45%). Four patients had developed complications (minimal reduction in MIO) related to the donor site. Donor site morbidity associated with buccinator-based myomucosal flaps is low. However, minimal reduction of mouth opening occurred in 20% of the patients.
Abstract
Buccinator-based myomucosal flaps can be used as a lining in oral cavity, pharyngeal, esophageal, and nasal reconstructions. Donor site morbidity is an important factor in [...]
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Thromboprophylaxis with dabigatran after total hip arthroplasty in Indian patients: A subanalysis of a double-blind, double-dummy, randomized RE-NOVATE II study
. Rajesh Malhotra, . Sushrut Babhulkar, K. Sanjib, . Andreas Clemens, . Akhil Dadi, . Rajagopalan Iyer, . Surendra Kamath, . Bharat Mody, . Satish Mutha, . Gurava Reddy, . Vikram Shah, . Vrajesh Shah, . Naresh Shetty, . Sachin Tapasvi, . Manuj Wadhwa

Asian Journal of Surgery (2017). Vol. 40

Abstract
In the Re-NOVATE II study, oral dabigatran provided thromboprophylaxis after total hip arthroplasty and improved compliance postdischarge in a global population. This article aims to identify trends (if any) in the Indian population. In this prospective, double-blind, double-dummy study, patients scheduled for primary, unilateral, elective total hip arthroplasty were randomized to 220 mg oral dabigatran once daily, starting with a 110 mg half-dose, 1–4 hours after surgery, or subcutaneous enoxaparin 40 mg once daily, starting the evening before surgery. Each group received a placebo of the other study drug. The primary efficacy outcome was the composite of total venous thromboembolism (VTE) and all-cause mortality. Secondary outcome measures were composite of major VTE and VTE-related mortality during the treatment period. The major safety outcome was incidence of bleeding events. Of the 179 Indian patients randomized, 91 received oral dabigatran and 88 received subcutaneous enoxaparin for 28–35 days. Total VTE and all-cause mortality occurred in 18.7% of patients in the dabigatran group and 13.7% in the enoxaparin group [odds ratio = 1.4 (95% confidence interval 0.6, 3.5)]. Major VTE and VTE-related mortality was numerically lower in the dabigatran group (7.9%) compared with the enoxaparin group (9.9%). Safety outcomes were comparable between both groups. Dabigatran is an effective oral alternative to enoxaparin for thromboprophylaxis as demonstrated by the RE-NOVATE II study global results. Data analyzed in Indian patients indicate comparable effects of dabigatran etexilate for major efficacy and safety outcomes.
Abstract
In the Re-NOVATE II study, oral dabigatran provided thromboprophylaxis after total hip arthroplasty and improved compliance postdischarge in a global population. This article [...]
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Factors associated with reoperation in hypospadias surgery — A nationwide, population-based study
. Yu-Chuan Lu, . Wei-Yi Huang, . Yu-Fen Chen, . Hong-Chiang Chang, . Yuan-Hung Pong, . Tsung-Hsien Shih, . Kuo-How Huang

Asian Journal of Surgery (2017).

Abstract
To analyze the preoperative factors associated with the need for secondary surgery following primary urethroplasty. This study utilized a subset of the National Health Insurance Research Database, which includes the data on all paid medical benefit claims from 1997 to 2007, for 1 million beneficiaries in 2005. We analyzed the claims data for all patients with hypospadias who had undergone primary urethroplasty. The characteristics of the patients, surgeons, and hospitals associated with surgical outcomes were analyzed to investigate possible associations with the need for secondary surgery. Among 52, 705 live male newborn babies, 218 were diagnosed with hypospadias, of whom 89 received repair surgery. A total of 75 (84.3%) male newborn babies received single hypospadias surgery, and 14 (15.7%) underwent more than two surgical procedures. Univariate analysis demonstrated that the type of hypospadias and the surgeon caseload volume were significantly associated with the need for additional hypospadias surgery (p = 0.02 and p = 0.03, respectively). In multivariate analysis, the type of hypospadias (distal vs. proximal, odds ratio, 0.25, p = 0.03) and the surgeon caseload volume (high vs. low, odds ratio, 0.04, p = 0.05) were significantly correlated with secondary operation. The type of hypospadias and the surgeon caseload volume were significantly associated with the need for secondary hypospadias surgery. The findings of this study provide important information on the outcomes of hypospadias repair for parents and specialists.
Abstract
To analyze the preoperative factors associated with the need for secondary surgery following primary urethroplasty. This study utilized a subset of the National Health Insurance [...]
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Surgery remains the best option for the management of pain in patients with chronic pancreatitis: A systematic review and meta-analysis
Z. A.R. Jawad, . Charis Kyriakides, . Madhava Pai, . Chris Wadsworth, . David Westaby, . Panagiotis Vlavianos, L. R. Jiao

Asian Journal of Surgery (2017). Vol. 40

Abstract
Controversy related to endoscopic or surgical management of pain in patients with chronic pancreatitis remains. Despite improvement in endoscopic treatments, surgery remains the best option for pain management in these patients.
Abstract
Controversy related to endoscopic or surgical management of pain in patients with chronic pancreatitis remains. Despite improvement in endoscopic treatments, surgery remains [...]
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Management for pilonidal disease: Before you compare, use a classification system
. Oktay Irkörücü, . Zulfu Bayhan, . Sezgin Zeren, S. Duzgun, B. Ucar

Asian Journal of Surgery (2016). Vol. 39
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Perforation of the colon in end colostomy
. Tetsunori Ikegami, . Akira Kuriyama, K. Lyn Ng, W. Kit Cheong

Asian Journal of Surgery (2016). Vol. 39

Abstract
We would like to heartily congratulate the authors Akira Kuriyama and Tetsunori Ikegami for the successful publication of their case report on Perforation of the colon in end colostomy. 1 We read with interest about their experience regarding that of a stercoral perforation occurring proximal to a colostomy in an elderly patient secondary to pressure necrosis from fecal masses. This has enhanced our overall understanding of this rare cause of spontaneous colonic perforation, and we humbly thank them for their citation of our article Surgical pitfalls in patients with Ehlers–Danlos type IV: a case of spontaneous sigmoid perforation in a 17-year-old male.
Abstract
We would like to heartily congratulate the authors Akira Kuriyama and Tetsunori Ikegami for the successful publication of their case report on Perforation of the colon in [...]
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Dexmedetomidine reduces neuropathic pain in a rat model of skin/muscle incision and retraction
. Xizhao Huang, . Rongfang Deng, . Weifeng Tu, . Zurong Hu

Asian Journal of Surgery (2017). Vol. 40

Abstract
Dexmedetomidine has been proposed as a novel anesthetic adjuvant. However, it remains unclear whether peripheral administration of dexmedetomidine is safe and effective to reduce acute postoperative pain. This study aimed to examine the effects of dexmedetomidine on neuropathic pain. Adult male Sprague-Dawley rats were anaesthetized and randomly allocated into four groups (n = 8): Groups S, R, RD1, and RD5 were injected with saline, 0.5% ropivacaine, 0.5% ropivacaine combined with 1 μg dexmedetomidine, and 0.5% ropivacaine combined with 5 μg dexmedetomidine, respectively, around the saphenous nerve. Then, the rats were subjected to skin/muscle incision and retraction (SMIR) surgery in the medial thigh. Mechanical and heat sensitivity was evaluated and morphology of the dorsal root ganglion (DRG) neurons was observed by electron microscopy. Some 62.5%, 50%, 12.5%, and 25% of rats developed mechanical hypersensitivity in Groups S, R, RD1, and RD5, respectively. The number of swollen mitochondria in DRG neurons was significantly more in Group S (257.2 ± 60.9) and Group R (291.6 ± 82.1) than in Group RD1 (97.2 ± 33.3) and Group RD5 (13.6 ± 17.9). In addition, the edema in endoplasmic reticulum and Golgi apparatus was decreased in Group RD1 and Group RD5 compared with Group S and Group R. Peripheral administration of dexmedetomidine improves mechanical and heat hyperalgesia and mitigates postoperative pain.
Abstract
Dexmedetomidine has been proposed as a novel anesthetic adjuvant. However, it remains unclear whether peripheral administration of dexmedetomidine is safe and effective to [...]
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Initial experience with application of single layer modified Kugel mesh for inguinal hernia repair: Case series of 72 consecutive patients
. Pao-Hwa Chen, . Heng-Chieh Chiang, . Yao-Li Chen, . Jesen Lin, . Bai-Fu Wang, . Meng-Yi Yan, . Chun-Chi Chen, . Hung-Jen Shih, . Jian-Ting Chen

Asian Journal of Surgery (2017). Vol. 40

Abstract
This is an initial review of the safety and efficacy of anterior preperitoneal modified Kugel (MK) mesh herniorrhaphy application without using optional onlay mesh. We retrospectively reviewed patients who underwent herniorrhaphy by a single surgeon from July 1st, 2009 to December 31st, 2010. During these 18 months, a total of 72 patients underwent single-layer MK mesh herniorrhaphy. Anterior preperitoneal approach was used to place the mesh. If the patients inguinal hernia defect did not exceed the memory ring of MK mesh, the onlay mesh was omitted. Postoperative results (wound infection, recurrence, and chronic pain/discomfort) were recorded and analyzed. A total of 72 patients underwent anterior preperitoneal single layer MK mesh herniorrhaphy. One patient had recurrent hernia after 1 year and was treated with a laparoscopic transabdominal preperitoneal operation. The most common postoperative complaint was mild soreness which was self-resolving after 1 month. Mean total operative time (skin to skin) was 73 minutes. The average hospital stay was 2 days. Most of the postoperative complications including soreness (14%), pain for > 3 months (1.4%), and scrotal hematoma (1.4%) were self-resolving. One patient experienced wound infection, which was treated with oral antibiotics. One patient had recurrence 1 year after the operation. The postoperative complication and recurrence rates of single-layer MK mesh herniorrhaphy was comparable with previously reported tension-free repair. Single-layer application is safe and feasible. A longer follow-up period and larger study group with a control group are needed to verify our method.
Abstract
This is an initial review of the safety and efficacy of anterior preperitoneal modified Kugel (MK) mesh herniorrhaphy application without using optional onlay mesh. We retrospectively [...]
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Crystallized phenol application and modified Limberg flap procedure in treatment of pilonidal sinus disease: A comparative retrospective study
. Zulfu Bayhan, . Sezgin Zeren, S. Aydin Duzgun, B. Imge Ucar, H. Yumun, . Metin Mestan

Asian Journal of Surgery (2016). Vol. 39

Abstract
Pilonidal sinus treatment includes various surgical and minimally invasive procedures, but there is still no standard treatment. Flap reconstructions and minimally invasive treatment options such as crystallized phenol application have recently been in the center of interest. The aim of this study is to compare crystallized phenol application as a minimally invasive treatment with modified Limberg flap reconstruction from many aspects. Thirty-seven patients diagnosed with pilonidal sinus and treated with modified Limberg flap reconstruction, and 44 patients treated with crystallized phenol application were evaluated retrospectively in terms of age, sex, length of stay in hospital postoperatively, wound complications, and the cause and rate of recurrence. Length of hospital stay was decreased and no postoperative incision problems were found in the group treated with crystallized phenol application (p < 0.001 and p = 0.011, respectively). The difference between the groups in terms of recurrence rate was not statistically significant (p = 0.173). Although the recurrence rate was found to be higher in the patient group treated once with crystallized phenol application, the success rate following multiple applications of crystallized phenol was found to be 94.5%. Higher body mass index (> 24.9 kg/m2) and surgical site infection were strongly correlated with recurrence rate (p < 0.001). Crystallized phenol application is a good alternative to the modified Limberg flap procedure and other surgical procedures, because it has several advantages such as being a minimally invasive procedure performed under local anesthesia with higher success rate after multiple applications, decreased length of stay in hospital, and minimal scar tissue formation.
Abstract
Pilonidal sinus treatment includes various surgical and minimally invasive procedures, but there is still no standard treatment. Flap reconstructions and minimally invasive [...]
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Outcomes of endovascular treatment for TASC C and D aorto-iliac lesions
. Sanghyun Ahn, . Keun-Myoung Park, Y. Kyun Kim, J. Il Kim, I. Sung Moon, K. Chun Hong, Y. Sun Jeon, J. Yong Kim

Asian Journal of Surgery (2017). Vol. 40

Abstract
The aim of this study was to evaluate the technical success rates, primary patency, and complications for TASC C and D aorto-iliac lesions treated by endovascular procedures. Additionally, the influence of the access site and the clinical outcomes were analyzed. Between 2008 and 2014, data from 39 patients with 45 chronic iliac artery stenosis and/or occlusion who were treated with endovascular treatment were retrospectively reviewed. The procedure time was longer for TASC D lesions than for TASC C lesions (163 ± 82 min vs. 105 ± 34 min, p = 0.002), where there was the more common use of brachial and femoral approach simultaneously. There were two perioperative deaths associated with TASC D lesions caused by one iliac artery rupture and one postoperative hospital-acquired pneumonia. The total perioperative complication rate was higher in the TASC D lesions than in TASC C lesions [five (18.5%) vs. zero, p = 0.073]. The corresponding 2-year primary patency rates were 94.9% in TASC C lesions and 88.4% in TASC D lesions. The simultaneous brachial and femoral approach took the longest procedure time (226 ± 157 min). This study demonstrated that the outcomes of endovascular treatment for TASC C and D aorto-iliac lesions were acceptable, with better technical success in TASC C lesions than in TASC D lesions. Furthermore, the 2-year patency rate for both TASC C and TASC D lesions was acceptable. Additionally, brachial access was useful for complex anatomy, but the failure rate was high.
Abstract
The aim of this study was to evaluate the technical success rates, primary patency, and complications for TASC C and D aorto-iliac lesions treated by endovascular procedures. [...]
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Meta-analysis of pancreaticogastrostomy versus pancreaticojejunostomy on occurrences of postoperative pancreatic fistula after pancreaticoduodenectomy
. Yanming Zhou, . Jianhua Yu, L. Wu, B. Li

Asian Journal of Surgery (2015). Vol. 38

Abstract
Pancreatic fistula (PF) is the most common and challenging complication after pancreaticoduodenectomy (PD). This meta-analysis aimed to evaluate the impact of pancreaticogastrostomy (PG) versus pancreaticojejunostomy (PJ) on occurrences of postoperative PF. A systematic literature search in the Medline, EMBASE, OVID, and Cochrane databases was performed to identify all eligible randomized controlled trials (RCTs). Pooled estimates were presented with 95% confidence intervals (CI). Six RCTs involving 1005 patients met the inclusion criteria. The incidence of PF [odds ratio (OR) 0.58, 95% CI, 0.42–0.81, p = 0.001], intra-abdominal abscess or collections (OR 0.43, 95% CI, 0.28–0.65, p < 0.001), and biliary fistula (OR 0.28, 95% CI, 0.11–0.74, p = 0.01) were found to be significantly lower in the PG group than in the PJ group. There was no significant difference in overall morbidity, other complications, hospital mortality, or length of hospital stay between the two groups. The meta-analysis showed that PG following PD represents a safe procedure associated with fewer PFs compared with PJ.
Abstract
Pancreatic fistula (PF) is the most common and challenging complication after pancreaticoduodenectomy (PD). This meta-analysis aimed to evaluate the impact of pancreaticogastrostomy [...]
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Survival after surgical resection of distal cholangiocarcinoma: A systematic review and meta-analysis of prognostic factors
. Yanming Zhou, . Shuncui Liu, L. Wu, T. Wan

Asian Journal of Surgery (2017). Vol. 40

Abstract
This study aimed to assess the available evidence on the survival of distal cholangiocarcinoma (DCC) patients following resection with curative intent and analyze the prognostic factors. Relevant studies published between January 2000 and January 2015 were identified by searching PubMed and Embase and reviewed systematically. Summary relative risks (RR) and 95% confidence intervals (95% CI) were estimated using random-effects models. A total of 39 observational studies involving 3258 patients were included in the review. R0 resection was achieved in 84% (range, 46–100%) of patients. The median 5-year overall survival rate after resection was 37% (range, 13–54%), with corresponding rate of 44% (range, 27–63%) in R0 resection. The meta-analysis for 25 studies showed that R1 resection (RR 2.36, 95% CI 1.89–2.93), lymph node metastasis (RR 2.35, 95% CI 1.89–2.93), perineural invasion (RR 1.96, 95% CI 1.64–2.34), lymphatic invasion (RR 1.84, 95% CI 1.47–2.31), vascular invasion (RR 1.99, 95% CI 1.40–2.82), pancreatic invasion (RR 2.13, 95% CI 1.39–3.27), and pathological tumor stage ≥ T3 (RR 1.56, 95% CI 1.25–1.93) were associated with shorter survival. In general, prognosis of DCC after resection is poor. R0 resection results in a substantially improved survival and represents one of the most important prognostic variables.
Abstract
This study aimed to assess the available evidence on the survival of distal cholangiocarcinoma (DCC) patients following resection with curative intent and analyze the prognostic [...]
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Development and evaluation of a new biodegradable vena cava filter in a canine model
. Fuxian Zhang, . Hailei Li, . Gangzhu Liang, . Huan Zhang

Asian Journal of Surgery (2017). Vol. 40

Abstract
Preliminary testing of a new biodegradable inferior vena cava filter in a canine model. The biodegradable filter consisted of two parts, a filter cone and a stent. The filter cone was constructed of six polyglycolic acid polymer strands anchored to a handmade absorbable stent. Central inferior vena cava fixation was accomplished by the absorbable stent, which was made of polycaprolactone. Device insertion was performed through a 9F sheath under ultrasound guidance on 10 adult beagles. The filters were operatively retrieved at 6 weeks after implantation. The inferior venae cavae were subsequently analyzed grossly and using light microscopy. None of the 10 beagles had abnormal vital signs. All of the 10 filters migrated cephalad approximately
Abstract
Preliminary testing of a new biodegradable inferior vena cava filter in a canine model. The biodegradable filter consisted of two parts, a filter cone and a stent. The filter [...]
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Eyedrop-shaped, modified Limberg transposition flap in the treatment of pilonidal sinus disease
M. Sabuncuoglu, . Aylin Sabuncuoglu, . Ozgur Dandin, M. Benzin, . Girayhan Celik, . Isa Sozen, . Recep Cetin

Asian Journal of Surgery (2015). Vol. 38

Abstract
Pilonidal sinus disease is an inflammatory disease seen in the intergluteal region, which is a commonly encountered problem in surgical practice that mostly affects young people. The aim of this study is to assess the effectiveness of the modified Limberg flap technique with eyedrop excision in the treatment of pilonidal sinus disease. The study population consisted of 91 patients with pilonidal disease in the sacrococcygeal region who underwent operation between June 2010 and December 2012. All cases underwent eyedrop-shaped excision and modified Limberg flap reconstruction. The mean operative time was 41.2 ± 6.7 minutes. All patients were followed up for >8 months, and the mean follow-up period was 13.1 ± 3.7 months. There were three wound dehiscences because of fecal contamination and riding cycle on postoperative Day 5. Seroma and flap echimosis were observed in two and four cases, respectively. Five patients experienced recurrence in this series (4.5%). The results of the present study suggest that use of the eyedrop-shaped modified Limberg flap is associated with a lower maceration and recurrence rate when compared with the available data on the use of the Limberg flap. Flap necrosis and wound healing was better, and the routine use of drains did not affect the wound-related complications and recurrence rates.
Abstract
Pilonidal sinus disease is an inflammatory disease seen in the intergluteal region, which is a commonly encountered problem in surgical practice that mostly affects young [...]
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Predictive factors for longer operative times for thyroidectomy
H. Yong Kwak, . Gianlorenzo Dionigi, . Xiaoli Liu, H. Sun, S. Uk Woo, G. Soo Son, J. Bok Lee, J. Won Bae, H. Yub Kim

Asian Journal of Surgery (2017). Vol. 40

Abstract
Conventional open thyroidectomy is considered as a safe surgery nowadays. However, surgeons sometimes encounter unexpected difficulty when performing thyroidectomies. The aim of this paper was to identify the predictors of a difficult thyroidectomy for the management of patients with papillary thyroid carcinoma. A database of patients who underwent open conventional thyroidectomy with cervical lymph node dissection after diagnosed papillary thyroid carcinoma between July 2008 and June 2013 was examined. In addition, the patients were subgrouped by difficult thyroidectomy (DT) and nondifficult thyroidectomy to determine the predictors of DT according to operation time. Clinicopathologic characteristics, surgical outcomes, and postoperative morbidities were investigated. No between-group differences in clinicopathologic factors and postoperative complications, except for male sex (p < 0.001) and tumor size (p = 0.039), were noted. Male sex [odds ratio (OR) 4.158, 95% confidence interval (CI) 2.020–8.559, p = 0.043] and age < 45 years (OR 2.239, 95% CI 1.304–3.843, p = 0.003) were independent factors associated with DT in a multivariate logistic regression model. Elevated antithyroglobulin antibody (OR 1.004, 95% CI 1.000–1.008, p = 0.030) was a variable which is statistically significant, but not clinically significant. Young age and male sex might be regarded as predictors of DT. Expecting DT before surgery might help surgeons, especially beginners, prevent troublesome situations.
Abstract
Conventional open thyroidectomy is considered as a safe surgery nowadays. However, surgeons sometimes encounter unexpected difficulty when performing thyroidectomies. The [...]
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Comparison between minimal right vertical infra-axillary thoracotomy and standard median sternotomy for repair of atrial septal defects
. Hafize Yaliniz, M. Sah Topcuoglu, . Ugur Gocen, . Atakan Atalay, . Vecih Keklik, . Yuksel Basturk, . Yasemin Gunes, . Mediha Turktan, O. Kemal Salih

Asian Journal of Surgery (2015). Vol. 38

Abstract
The minimal right vertical infra-axillary thoracotomy could be a safe and cosmetic alternative to standard median sternotomy. This study reviews our results and experience with a minimal right vertical infra-axillary thoracotomy technique for the repair of atrial septal defects compared with standard median sternotomy. The study was designed as a retrospective, observational, and case-controlled study. Between May 2007 and November 2012, 26 patients underwent atrial septal defect closure with standard median sternotomy (Group 1). This group was compared with 21 patients who underwent repair of atrial septal defects using minimal right vertical infra-axillary thoracotomy (Group 2). Quantitative data were given as mean ± standard deviation, and qualitative values were expressed as percentages. In the comparison of the normal variables between the two groups, we used independent sample t test, and in the comparison of categorical variables between groups, Chi-square test was used. The mean length of incision was significantly shorter in Group 2 than in Group 1 (p = 0.03). The time it took to establish cardiopulmonary bypass was longer in Group 2 (p = 0.04). There were no statistically significant differences in cardiopulmonary bypass time (p = 0.11), aortic cross-clamp time (p = 0.10), and total operation time (p = 0.10) between the two groups. Group 2 had less chest tube drainage (p = 0.04), less blood transfusion (p = 0.02), and shorter postoperative mechanical ventilation time (p = 0.09) than Group 1. Minimal right vertical infra-axillary thoracotomy can be performed with favorable cosmetic and clinical results for atrial septal defects closure. Infra-axillary thoracotomy provides a good alternative to standard median sternotomy for patients with atrial septal defects.
Abstract
The minimal right vertical infra-axillary thoracotomy could be a safe and cosmetic alternative to standard median sternotomy. This study reviews our results and experience [...]
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Should central lymph node dissection be considered for all papillary thyroid microcarcinoma?
Y. Woo Chang, H. Soo Kim, H. Yub Kim, J. Bok Lee, J. Won Bae, G. Soo Son

Asian Journal of Surgery (2016). Vol. 39

Abstract
Central lymph node dissection (CLND) in patients with papillary thyroid microcarcinoma (PTMC) is still controversial. The aim of this study was to examine the risk factors and the incidence of central lymph node metastases (CLNMs) in patients with PTMC who underwent thyroidectomy and CLND. Between 2002 and 2013, 613 patients were enrolled who underwent thyroidectomy with routine CLND for PTMC at the Korea University Medical Center, Ansan Hospital and risk factors and the incidence of CLNM were analyzed. In addition, we also evaluated the complications after thyroidectomy with CLND. Out of 613 patients, 239 (39.0%) were found to have CLNM. Male sex (p = 0.012), tumor size ≥ 0.5 cm (p = 0.001), capsular invasion or extrathyroidal extension (p = 0.029), and multifocality (p = 0.004) were independent risk factors for CLNM. Among the 69 patients who had PTMC without these risk factors, CLNM was identified in 12 (17.4%). In this study group, two (0.3%) had permanent recurrent laryngeal nerve injury, two (0.3%) had persistent hypocalcemia, and two (0.3%) developed postoperative hemorrhage. CLNM in PTMC is highly prevalent in male sex, tumor size ≥ 0.5 cm, extrathyroidal extension, and multifocality. Even in PTMC patients without these risk factors, the incidence of CLNM is rather higher than expected, and the complication rate of thyroidectomy with CLND is acceptable. Thus, CLND should be considered in all patients with PTMC.
Abstract
Central lymph node dissection (CLND) in patients with papillary thyroid microcarcinoma (PTMC) is still controversial. The aim of this study was to examine the risk factors [...]
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Application of the LMA-Supreme™ and i-gel™ laryngeal masks during pelvic operations in adults
F. Wang, . Rui Zhang

Asian Journal of Surgery (2016). Vol. 39

Abstract
The aim of this study was to evaluate the practical application and safety of the i-gel and LMA-Supreme laryngeal masks for airway management during pelvic operations in adults. Ninety patients undergoing general anesthesia for elective pelvic operations (ASA Grades I-II) were randomly divided into two groups, the i-gel group and the Supreme group. The laryngeal mask was inserted after induction, and the relevant examination grading indexes were recorded. The Supreme group required less time for laryngeal mask insertion and gastric tube indwelling time. Gastric tube indwelling was easier, compared with those in the i-gel group (p = 0.03), but the i-gel group had fewer complications (p = 0.03). There were no significant differences in the degree of difficulty in insertion, airway sealing pressure, PETCO2, Ppeak, and laryngeal mask alignment accuracy between the two groups (p > 0.05). There was no statistically significant difference in fibrobronchoscopy grading between the two groups (p > 0.05). The i-gel and LMA-Supreme laryngeal masks are safe and effective for airway management in patients during pelvic operations.
Abstract
The aim of this study was to evaluate the practical application and safety of the i-gel and LMA-Supreme laryngeal masks for airway management during pelvic operations in adults. [...]
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Short-term results of open inguinal hernia repair with self-gripping Parietex ProGrip mesh in China: A retrospective study of 90 cases
. Yinlong Wang, . Xin Zhang

Asian Journal of Surgery (2016). Vol. 39

Abstract
This study investigated short-term outcomes of Lichtenstein hernia repair using self-gripping Parietex ProGrip mesh in Chinese patients with inguinal hernias. Retrospective analysis of patients undergoing Lichtenstein hernia repair using the Parietex ProGrip mesh at a single hospital in China between July 2012 and June 2013. All patients completed the EuroQol-five dimensions (EuroQoL-5D) and short form-36 questionnaires and were followed up at 1 day, 7 days, 1 month. and 6 months, postoperatively. Ninety cases (66 males, 24 females) were studied. Mean ± standard deviation (SD) patient age was 48.7 ± 16.8 (range, 21–87) years. Most hernias were Gilberts type II (23%) or III (31%). During 6 months of follow-up, none of the patients had recurrent hernia or systemic postoperative complications. The mean ± SD pain visual analog scale score decreased from 32 ± 10.6 at postoperative Day 1 to 0.67 ± 2.5 at 6 months. From postoperative Day 1 to 6 months, there were marked improvements in health and health-related quality of life, mean ± SD visual analog scale EuroQoL score increased from 55.3 ± 8 to 95.2 ± 3 and mean ± SD HR EuroQoL score from 0.31 ± 0.07 to 0.95 ± 0.02. At 6 months, mean scores in all eight dimensions of the short form-36 questionnaires had increased from baseline. The use of self-fixating Parietex ProGrip mesh in open inguinal hernia repair is simple, rapid, effective, and safe, and is associated with low postoperative pain and improved quality life among patients.
Abstract
This study investigated short-term outcomes of Lichtenstein hernia repair using self-gripping Parietex ProGrip mesh in Chinese patients with inguinal hernias. Retrospective [...]
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Safety of clean urologic operations without prophylaxis antibiotic therapy in Cipto Mangunkusumo Hospital, Jakarta: A double-blind randomized controlled trial study
. Irfan Wahyudi, . Ponco Birowo, I. Gde Sanjaya, . Rizky Fawzi, . Nur Rasyid, C. A. Mochtar

Asian Journal of Surgery (2015). Vol. 38

Abstract
This study was conducted to identify the safety measures of performing clean urologic operations without administration of prophylaxis antibiotics. We conducted a double-blind randomized controlled trial with patients who underwent clean urologic operations in Cipto Mangunkusumo Hospital, Jakarta, Indonesia, from April 2013 to January 2014. The local and systemic infection states were compared between the prophylaxis and placebo groups. Local infection was identified as surgical site infection and systemic infection as fever and leukocytosis. A total of 42 patients participated in the study (21 patients in each group), comprising 14 (33.3%) children and 28 (66.7%) adults. The most frequently performed operation was surgical sperm retrieval. No patients in either group were found to have local or systemic infection. However, there was a statistical difference in the white blood cell counts between the two groups (p = 0.003), although there was no sign of local or systemic infection in any of the patients. Clean urologic operations without prophylaxis antibiotic therapy can be safely applied to urologic patients.
Abstract
This study was conducted to identify the safety measures of performing clean urologic operations without administration of prophylaxis antibiotics. We conducted a double-blind [...]
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Bilateral idiopathic granulomatous mastitis
. Mehmet Velidedeoglu, . Fahrettin Kilic, . Birgul Mete, . Mucahit Yemisen, . Varol Celik, . Ertugrul Gazioglu, . Mehmet Ferahman, . Resat Ozaras, M. Yilmaz, . Fatih Aydogan

Asian Journal of Surgery (2016). Vol. 39

Abstract
Idiopathic granulomatous mastitis (IGM) is a benign rare inflammatory pseudotumor. Bilateral involvement of IGM has been reported in a few cases. To our knowledge, this study is the largest series of bilateral cases to date. The goals of this study were to present clinical features of bilateral IGM and to evaluate the results of treatments. We performed a retrospective review of the idiopathic granulomatous mastitis database from 2010 to 2013. Ten female patients who met required histologic and clinical criteria of IGM in both breasts were included in study. Demographic data, clinical findings, medication history, and radiologic findings are presented. The mean age at onset of the disease was 38.4 ± 8.3 years (range: 29–52 years). Nine patients had no recurrence during a mean follow-up period of 21 months (range: 11–26 months). Additionally, the median time to second breast involvement was 15.6 months. Bilateral IGMs have a higher rate of more relapse and greater resistance to medical therapies than do unilateral IGMs. Surgical management should be avoided unless all medical treatment options have been exhausted. Nevertheless, expectant management seems a rational option for the treatment of bilateral IGM.
Abstract
Idiopathic granulomatous mastitis (IGM) is a benign rare inflammatory pseudotumor. Bilateral involvement of IGM has been reported in a few cases. To our knowledge, this study [...]
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The learning curve for laparoscopic colectomy in colorectal cancer at a new regional hospital
. Kuei-Yen Tsai, . Kee-Thai Kiu, . Ming-Te Huang, . Chih-Hsiung Wu, . Tung-Cheng Chang

Asian Journal of Surgery (2016). Vol. 39

Abstract
Laparoscopic colorectal surgery has been extensively used, although mostly performed in medical centers or university hospitals. We analyzed the learning curve of laparoscopic colectomy in a new regional hospital and determined the experience necessary to achieve proficiency. From July 2008 to December 2013, the retrospective clinical study enrolled 240 patients who underwent laparoscopic colectomy. They were sequentially divided into Group A (Patients 1–80), Group B (Patients 81–160), and Group C (Patients 161–240). Patient demographics and perioperative parameters were analyzed. Operation time, as a measure of learning time, was analyzed using the moving-average method. All patients were comparable for age, gender, body mass index, tumor location, cancer stage, length of hospital stay, intraoperative complication, morbidity, and mortality. Group A experienced more blood loss (p < 0.01) and longer operation time (p < 0.001). All laparoscopic operation time stabilized after 85 cases. Subgroup analysis showed that operation time stabilized after 15 cases for right hemicolectomy, 15 cases for sigmoidectomy, and 22 cases for low anterior resection with total mesorectal excision. Laparoscopic colectomy for colorectal cancer in a new regional hospital is feasible and safe. It does not need additional time for learning. Laparoscopic sigmoidectomy can be considered as the initial surgery for a trainee.
Abstract
Laparoscopic colorectal surgery has been extensively used, although mostly performed in medical centers or university hospitals. We analyzed the learning curve of laparoscopic [...]
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Analysis of risk factors of long-term complications in congenital diaphragmatic hernia: A single institutions experience
. Hajime Takayasu, . Kouji Masumoto, . Takahiro Jimbo, . Naoya Sakamoto, . Takato Sasaki, . Toru Uesugi, . Chikashi Gotoh, . Yasuhisa Urita, . Toko Shinkai

Asian Journal of Surgery (2017). Vol. 40

Abstract
To establish better management practices to reduce morbidities in survivors with congenital diaphragmatic hernia (CDH). Of 60 patients treated for CDH at our institution between 1991 and 2011, 49 patients without severe anomalies were retrospectively reviewed. Since 2004, gentle ventilation (GV) has been the main treatment for CDH. Patients were divided into the following two groups: the non-GV group (n = 29) who were treated before GV treatment was implemented, and the GV group (n = 20). The overall survival rate was 62.1% (18/29) and 95% (19/20) in the non-GV and GV groups, respectively (p = 0.016). Despite the high survival rate, the incidence of long-term complications in survivors was still high (14/19, 73.7%) in the GV group. In the GV group, liver-up (p = 0.106) and the need for patch repair (p = 0.257) tended to be associated with the development of long-term complications, but did not reach statistical significance. The presence of perioperative complications was associated with the development of long-term complications (p = 0.045) in the GV group. Patients who developed short-term complications seemed to be at risk of long-term complications. Therefore, to minimize long-term morbidities in CDH survivors, the prevention of short-term complications might be important.
Abstract
To establish better management practices to reduce morbidities in survivors with congenital diaphragmatic hernia (CDH). Of 60 patients treated for CDH at our institution between [...]
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