Journal of Energy http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Study of Light Harvesting Properties of Different Classes of Metal-Free Organic Dyes in TiO2 Based Dye-Sensitized Solar Cells Mon, 18 Aug 2014 07:07:11 +0000 http://www.hindawi.com/journals/jen/2014/517574/ In dye-sensitized solar cells, the photosensitization of TiO2 thin film semiconductor was accomplished by using different classes of metal-free (fluorone, triarymethane, azo and thiazine based) organic dyes as photosensitizer. The broad electronic absorption spectra of these dyes have been obtained in the visible region due to the presence of chromophoric groups in these dyes. The contribution of these dyes as light harvesting species is seen from the photocurrent action spectrum of the cell. Here, we report the sensitization activity of these dyes in terms of current-potential curve, open-circuit potential, fill factor, IPCE, and overall solar energy conversion efficiency which have been evaluated under 100 mW/cm2 light intensity. The results suggest that dyes based on fluorone and azo groups are promising candidates for high performance, dye-sensitized solar cells because of better anchoring groups (–COOH, –OH, and –) present in these dyes. Better anchorage of dyes to the surface of TiO2 semiconductor helps in charge transfer phenomenon. Ratna Chauhan, Reena Kushwaha, and Lal Bahadur Copyright © 2014 Ratna Chauhan et al. All rights reserved. Analysis of Si/SiGe Heterostructure Solar Cell Wed, 23 Jul 2014 06:38:39 +0000 http://www.hindawi.com/journals/jen/2014/946406/ Sunlight is the largest source of carbon-neutral energy. Large amount of energy, about 4.3 × 1020 J/hr (Lewis, 2005), is radiated because of nuclear fusion reaction by sun, but it is unfortunate that it is not exploited to its maximum level. Various photovoltaic researches are ongoing to find low cost, and highly efficient solar cell to fulfil looming energy crisis around the globe. Thin film solar cell along with enhanced absorption property will be the best, so combination of SiGe alloy is considered. The paper presented here consists of a numerical model of heterostructure solar cell. The research has investigated characteristics such as short circuit current density (), generation rate (), absorption coefficient (α), and open circuit voltage () with optimal Ge concentration. The addition of Ge content to Si layer will affect the property of material and can be calculated with the use of Vegard’s law. Due to this, short circuit current density increases. Ashish Kumar Singh, Jahnvi Tiwari, Ashish Yadav, and Rakesh Kumar Jha Copyright © 2014 Ashish Kumar Singh et al. All rights reserved. Hydropower Production Profiles: Impacts on Capacity Structure, Emissions, and Windfall Profits Mon, 14 Apr 2014 12:30:15 +0000 http://www.hindawi.com/journals/jen/2014/710414/ Production structure in markets with a significant role of hydropower is sensitive to the production profile of hydropower. In this paper we utilize a long-run oriented real-time price based simulation model to analyze through scenarios the impact of different hydropower production profiles on the total annual energy consumed, prices, and capacity structure. We also show the relation between different hydropower production profiles and emissions, costs, and windfall profits. There seems to be no superior scenario under which all socially desirable goals are achieved as there is a clear tradeoff between allowing high windfall profits with highest cost efficiency and achieving the target for lower emissions. Maria Kopsakangas-Savolainen and Rauli Svento Copyright © 2014 Maria Kopsakangas-Savolainen and Rauli Svento. All rights reserved. Microwave Assisted Alkali Pretreatment of Rice Straw for Enhancing Enzymatic Digestibility Tue, 25 Mar 2014 12:09:41 +0000 http://www.hindawi.com/journals/jen/2014/483813/ Rapid industrialization, increasing energy demand, and climate change are the conditions that forced the researchers to develop a clean, efficient, renewable, and sustainable source of energy which has a potential to replace fossil fuels. Ethanol is one of the attractive and suitable renewable energy resources. In present study, effectiveness of microwave pretreatment in combination with sodium hydroxide (NaOH) for increasing enzymatic hydrolysis of rice straw has been investigated and under optimum conditions obtained a maximum reducing sugar (1334.79 µg/mL) through microwave assisted NaOH pretreatment. Chemical composition analysis and scanning electron microscope (SEM) images showed that the removal of lignin, hemicellulose, and silicon content is more in microwave assisted NaOH pretreatment than the blank sample. X-ray diffraction (XRD) analysis revealed that the crystallinity index of rice straw treated with microwave assisted alkali (54.55%) is significantly high as compared to the blank (49.07%). Hence, the present study proves that microwave assisted alkali pretreatment can effectively enhance enzymatic digestibility of rice straw and it is feasible to convert rice straw for bioethanol production. Renu Singh, Sapna Tiwari, Monika Srivastava, and Ashish Shukla Copyright © 2014 Renu Singh et al. All rights reserved. Computer Simulation of the Mass and Energy Balance during Gasification of Sugarcane Bagasse Sun, 16 Mar 2014 11:53:17 +0000 http://www.hindawi.com/journals/jen/2014/713054/ This paper investigated the mass and energy balance of the gasification of sugarcane bagasse using computer simulation. The key parameters and gasifier operating conditions were investigated in order to establish their impact on gas volume and conversion efficiency of the gasification process. The heating value of sugarcane bagasse was measured and found to be 17.8 MJ/kg which was used during calculation of the conversion efficiency of the gasification process. Fuel properties and gasifier design parameters were found to have an impact on conversion efficiency of the gasification process of sugarcane bagasse. The moisture content of sugarcane bagasse was varied by 1.14%, 15%, and 25%, respectively. Optimum conversion efficiency was achieved at low moisture content (1.14%) after computer simulation of the gasification process. The volume of carbon monoxide increased at low moisture content. It was also found that maximum conversion efficiency was achieved at reduced particle diameter (6 cm) and at reduced throat diameter (10 cm) and throat angle (25°), respectively, after these parameters were varied. Temperature of input air was also found to have an impact on the conversion efficiency of the gasification process as conversion efficiency increased slightly with increasing temperature of input air. Anthony Anukam, Sampson Mamphweli, Edson Meyer, and Omobola Okoh Copyright © 2014 Anthony Anukam et al. All rights reserved. Effect of Glass Thickness on Performance of Flat Plate Solar Collectors for Fruits Drying Wed, 12 Mar 2014 06:50:19 +0000 http://www.hindawi.com/journals/jen/2014/247287/ This study aimed at investigating the effect of thickness of glazing material on the performance of flat plate solar collectors. Performance of solar collector is affected by glaze transmittance, absorptance, and reflectance which results into major heat losses in the system. Four solar collector models with different glass thicknesses were designed, constructed, and experimentally tested for their performances. Collectors were both oriented to northsouth direction and tilted to an angle of 10° with the ground toward north direction. The area of each collector model was 0.72 m2 with a depth of 0.15 m. Low iron (extra clear) glass of thicknesses 3 mm, 4 mm, 5 mm, and 6 mm was used as glazing materials. As a control, all collector performances were analysed and compared using a glass of 5 mm thickness and then with glass of different thickness. The results showed that change in glass thickness results into variation in collector efficiency. Collector with 4 mm glass thick gave the best efficiency of 35.4% compared to 27.8% for 6 mm glass thick. However, the use of glass of 4 mm thick needs precautions in handling and during placement to the collector to avoid extra costs due to breakage. Ramadhani Bakari, Rwaichi J. A. Minja, and Karoli N. Njau Copyright © 2014 Ramadhani Bakari et al. All rights reserved. Minimizing Energy Cost in Electric Arc Furnace Steel Making by Optimal Control Designs Thu, 20 Feb 2014 16:28:11 +0000 http://www.hindawi.com/journals/jen/2014/620695/ Production cost in steel industry is a challenge issue and energy optimization is an important part. This paper proposes an optimal control design aiming at minimizing the production cost of the electric arc furnace steel making. In particular, it is shown that with the structure of an electric arc furnace, the production cost which is a linear programming problem can be solved by the tools of linear quadratic regulation control design that not only provides an optimal solution but also is in a feedback form. Modeling and control designs are validated by the actual production data sets. Er-wei Bai Copyright © 2014 Er-wei Bai. All rights reserved. Determining Infiltration Rates and Predicting Building Occupancy Using CO2 Concentration Curves Thu, 06 Feb 2014 13:34:28 +0000 http://www.hindawi.com/journals/jen/2014/670236/ Demand controlled ventilation (DCV) reduces energy loss by reducing the air exchange flow rate to the minimum required to maintain acceptable indoor air quality (IAQ). DCV commonly uses carbon dioxide (CO2) as a proxy for human activity and increases the ventilation rate once a preset CO2 threshold is exceeded. Significant improvements over threshold based ODV strategies are possible if the natural infiltration rate of the building is measured and the occupancy schedule determined by analysing the CO2 concentration continuously. These calculated parameters allow mathematical modeling of the ventilated space and the determination of future CO2 concentrations and allow prediction of future ventilation demands. The natural infiltration rate and the onset and duration of vacancy periods in a residential dwelling were determined by analysing CO2 concentration data. Concentration declines which fit an exponential decay curve with a correlation coefficient >0.90 identified all vacancy periods. The measured natural infiltration rate was found statistically correlated with average wind speed. A dynamic predicted occupancy map was constructed that has the potential to facilitate significant energy savings via deferred ventilation and intelligent cooling and heating strategies. P. Parsons Copyright © 2014 P. Parsons. All rights reserved. Numerical Prediction of Heat Transfer Characteristics of Nanofluids in a Minichannel Flow Tue, 04 Feb 2014 08:29:57 +0000 http://www.hindawi.com/journals/jen/2014/307520/ CFD simulation of the heat transfer and pressure drop characteristics of different nanofluids in a minichannel flow has been explained using FLUENT version 6.3.26. Different nanofluids with nanoparticles of Al2O3, CuO, SiO2, and TiO2 have been used in the simulation process. A comparison of the experimental and computational results has been made for the heat transfer and pressure drop characteristics for the case of Al2O3-water nanofluid for the laminar flow. Also, computations have been made by considering Brownian motion as well as without considering Brownian motion of the nanoparticles. After verification of the computational model with the experimental results for Al2O3-water nanofluid, the simulations were performed for the same experimental readings for different nanofluids in the laminar flow regime to find out the heat transfer and pressure drop characteristics. Arjumand Adil, Sonam Gupta, and Pradyumna Ghosh Copyright © 2014 Arjumand Adil et al. All rights reserved. Chemical Looping Combustion of Methane: A Technology Development View Thu, 28 Nov 2013 17:55:13 +0000 http://www.hindawi.com/journals/jen/2013/949408/ Methane is a reliable and an abundantly available energy source occurring in nature as natural gas, biogas, landfill gas, and so forth. Clean energy generation using methane can be accomplished by using chemical looping combustion. This theoretical study for chemical looping combustion of methane was done to consider some key technology development points to help the process engineer choose the right oxygen carrier and process conditions. Combined maximum product (H2O + CO2) generation, weight of the oxygen carrier, net enthalpy of CLC process, byproduct formation, CO2 emission from the air reactor, and net energy obtainable per unit weight (gram) of oxygen carrier in chemical looping combustion can be important parameters for CLC operation. Carbon formed in the fuel reactor was oxidised in the air reactor and that increased the net energy obtainable from the CLC process but resulted in CO2 emission from the air reactor. Use of CaSO4 as oxygen carrier generated maximum energy (−5.3657 kJ, 800°C) per gram of oxygen carrier used in the CLC process and was found to be the best oxygen carrier for methane CLC. Such a model study can be useful to identify the potential oxygen carriers for different fuel CLC systems. Rutuja Bhoje, Ganesh R. Kale, Nitin Labhsetwar, and Sonali Borkhade Copyright © 2013 Rutuja Bhoje et al. All rights reserved. Empirical Study of Decomposition of Emission Factors in China Thu, 21 Nov 2013 08:04:46 +0000 http://www.hindawi.com/journals/jen/2013/747516/ China’s CO2 emissions increase has attracted world’s attention. It is of great importance to analyze China’s CO2 emission factors to restrain the CO2 rapid growing. The CO2 emissions of industrial and residential consumption sectors in China during 1980–2010 were calculated in this paper. The expanded decomposition model of CO2 emissions was set up by adopting factor-separating method based on the basic principle of the Kaya identities. The results showed that CO2 emissions of industrial and residential consumption sectors increase year after year, and the scale effect of GDP is the most important factor affecting CO2 emissions of industrial sector. Decreasing the specific gravity of secondary industry and energy intensity is more effective than decreasing the primary industry and tertiary industry. The emissions reduction effect of structure factor is better than the efficiency factor. For residential consumption sector, CO2 emissions increase rapidly year after year, and the economy factor (the increase of wealthy degree or income) is the most important factor. In order to slow down the growth of CO2 emissions, it is an important way to change the economic growth mode, and the structure factor will become a crucial factor. Yadong Ning, Yonghong Zhang, Tao Ding, and Yutaka Tonooka Copyright © 2013 Yadong Ning et al. All rights reserved. Review of the Wall Temperature Prediction Capability of Available Correlations for Heat Transfer at Supercritical Conditions of Water Wed, 13 Nov 2013 15:06:41 +0000 http://www.hindawi.com/journals/jen/2013/159098/ The validity of the wall temperature predictions by 18 correlations available in the literature for supercritical heat-transfer regimes of water was verified for 12 experimental datasets consisting of 355 data points available in the literature. The correlations were ranked based on criteria like % data with <5% error, % data with <10°C error and minimum error band in temperature prediction. Details of the best fitting correlations were tabulated. The analysis indicated that for normal heat-transfer conditions, most of the correlations give close predictions. However, at deteriorated heat transfer regimes, only very few prediction points are closer to experimental value. Also, in the ranking process, the first position keeps varying, and no one correlation shall be said as the best for all experiments. Evaluation of the applicability of heat flux to mass-flux-ratio-based prediction of heat-transfer deterioration indicated 75% agreement. The empirical formulae linking mass flux for the prediction of the starting heat flux for heat-transfer deterioration indicated 58.33% of agreement. This review indicated that continued precise experimentation covering wide range of parameter conditions near pseudocritical regime and development of correlations is felt necessary for the accurate prediction of supercritical fluid heat transfer. Dhanuskodi Ramasamy, Arunagiri Appusamy, and Anantharaman Narayanan Copyright © 2013 Dhanuskodi Ramasamy et al. All rights reserved. Natural Pigments from Plants Used as Sensitizers for TiO2 Based Dye-Sensitized Solar Cells Mon, 04 Nov 2013 18:36:42 +0000 http://www.hindawi.com/journals/jen/2013/654953/ Four natural pigments, extracted from the leaves of teak (Tectona grandis), tamarind (Tamarindus indica), eucalyptus (Eucalyptus globulus), and the flower of crimson bottle brush (Callistemon citrinus), were used as sensitizers for TiO2 based dye-sensitized solar cells (DSSCs). The dyes have shown absorption in broad range of the visible region (400–700 nm) of the solar spectrum and appreciable adsorption onto the semiconductor (TiO2) surface. The DSSCs made using the extracted dyes have shown that the open circuit voltages () varied from 0.430 to 0.610 V and the short circuit photocurrent densities () ranged from 0.11 to 0.29 mA cm−2. The incident photon-to-current conversion efficiencies (IPCE) varied from 12–37%. Among the four dyes studied, the extract obtained from teak has shown the best photosensitization effects in terms of the cell output. Reena Kushwaha, Pankaj Srivastava, and Lal Bahadur Copyright © 2013 Reena Kushwaha et al. All rights reserved. Sustaining Biodiesel Production via Value-Added Applications of Glycerol Thu, 10 Oct 2013 13:45:07 +0000 http://www.hindawi.com/journals/jen/2013/178356/ The production of biofuels worldwide has been significant lately due to the shift from obtaining energy from nonrenewable energy (fossil fuels) to renewable sources (biofuels). This energy shift arose as a result of the disturbing crude petroleum price fluctuations, uncertainties about fossil fuel reserves, and greenhouse gas (GHG) concerns. With the production of biofuels increasing considerably and the current global biodiesel production from different feedstock, reaching about 6 billion liters per year, biodiesel production costs have been highly dependent on feedstock prices, ranging from 70 to 25; of total production costs, and in comparison with the conventional diesel fuel, the biodiesel is currently noncompetitive. An efficient production process is, therefore, crucial to lowering biodiesel production costs. The question of sustainability, however, arises, taking into account the African diverse conditions and how vital concerns need to be addressed. The major concern about biodiesel production costs can be reduced by finding value-added applications for its glycerol byproduct. This paper, thus, provides an overview of current research trends that could overcome the major hurdles towards profitable commercialization of biodiesel and also proposes areas of opportunity probable to capitalize the surplus glycerol obtained, for numerous applications. Omotola Babajide Copyright © 2013 Omotola Babajide. All rights reserved. Review on the HVAC System Modeling Types and the Shortcomings of Their Application Thu, 22 Aug 2013 12:00:06 +0000 http://www.hindawi.com/journals/jen/2013/768632/ The modeling of the heating, ventilation, and air conditioning (HVAC) system is a prominent topic because of its relationship with energy savings and environmental, economical, and technological issues. The modeling of the HVAC system is concerned with the indoor thermal sensation, which is related to the modeling of building, air handling unit (AHU) equipments, and indoor thermal processes. Until now, many HVAC system modeling approaches are made available, and the techniques have become quite mature. But there are some shortcomings in application and integration methods for the different types of the HVAC model. The application and integration processes will act to accumulate the defective characteristics for both AHU equipments and building models such as nonlinear, pure lag time, high thermal inertia, uncertain disturbance factors, large-scale systems, and constraints. This paper shows types of the HVAC model and the advantages and disadvantages for each application of them, and it finds out that the gray-box type is the best one to represent the indoor thermal comfort. But its application fails at the integration method where its response deviated to unreal behavior. Raad Z. Homod Copyright © 2013 Raad Z. Homod. All rights reserved. Synthesis of Petroleum-Based Fuel from Waste Plastics and Performance Analysis in a CI Engine Mon, 19 Aug 2013 11:53:22 +0000 http://www.hindawi.com/journals/jen/2013/608797/ The present work involves the synthesis of a petroleum-based fuel by the catalytic pyrolysis of waste plastics. Catalytic pyrolysis involves the degradation of the polymeric materials by heating them in the absence of oxygen and in the presence of a catalyst. In the present study different oil samples are produced using different catalysts under different reaction conditions from waste plastics. The synthesized oil samples are subjected to a parametric study based on the oil yield, selectivity of the oil, fuel properties, and reaction temperature. Depending on the results from the above study, an optimization of the catalyst and reaction conditions was done. Gas chromatography-mass spectrometry of the selected optimized sample was done to find out its chemical composition. Finally, performance analysis of the selected oil sample was carried out on a compression ignition (CI) engine. Polythene bags are selected as the source of waste plastics. The catalysts used for the study include silica, alumina, Y zeolite, barium carbonate, zeolite, and their combinations. The pyrolysis reaction was carried at polymer to catalyst ratio of 10 : 1. The reaction temperature ranges between 400°C and 550°C. The inert atmosphere for the pyrolysis was provided by using nitrogen as a carrier gas. Christine Cleetus, Shijo Thomas, and Soney Varghese Copyright © 2013 Christine Cleetus et al. All rights reserved. Mitigating Climate Change by the Development and Deployment of Solar Water Heating Systems Tue, 06 Aug 2013 08:49:43 +0000 http://www.hindawi.com/journals/jen/2013/679035/ Solar energy is becoming an alternative for the limited fossil fuel resources. One of the simplest and most direct applications of this energy is the conversion of solar radiation into heat, which can be used in Water Heating Systems. Ogun State in Nigeria was used as a case study. The solar radiation for the state was explored with an annual average of 4.775 kWh/m2 recorded. The designed system comprised storage tanks and the collector unit which comprises wooden casing, copper tube, and aluminium foil. Test results for the unlagged and lagged storage tanks for water temperature at various angles of inclination (2.500°–20.000°) were on the average 27.800°C and 28.300°C, respectively, for the inlet temperature and 60.100°C and 63.000°C for the outlet temperature, respectively. The efficiency of the Solar Water Heating System was 72.500% and the power saved 2.798 kW. The cost of the unit is put at 1121,400 ($145) as at August 2012. The unit developed can be applied for the purpose of reducing the cost of energy, dealing with environmental challenges, and improving the use of energy, hence serving as a climate mitigation process as this can be extended for water heating for domestic and other industrial purposes. S. T. Wara and S. E. Abe Copyright © 2013 S. T. Wara and S. E. Abe. All rights reserved. Extraction of Transmission Parameters for Siting and Sizing of Distributed Energy Sources in Distribution Network Thu, 25 Jul 2013 15:49:52 +0000 http://www.hindawi.com/journals/jen/2013/938958/ This paper introduces a novel method for sitting and sizing the grid connected distributed generator (DG) for installation in distribution system at any input load condition, which is based on two port transmission equations, named as modified transmission parameters (MTP) method by considering the loss minimization as a constraint. If properly organized, with the help of various transmission parameters optimal DG allocation with minimum transmission losses, contribution of DG as well as the main supply source to each load, type of DG required to handle the existing power flow scenario, and operating power factor at which DG should operate can be easily investigated. Apart from this the author has also investigated the worst location for DG installation and referred to it as Consecutive Bus. The method has been tested on two test distribution systems with varying sizes and intricacy and the results have been compared with the two established methods reported earlier. Relative study presented has shown that the proposed method leads existing methods in terms of its simplicity, computational time, and handling less number of variables. Shilpa Kalambe and Ganga Agnihotri Copyright © 2013 Shilpa Kalambe and Ganga Agnihotri. All rights reserved. Practical Coupled Resonators in Domino Arrangements for Power Transmission and Distribution: Replacing Step-Down Power Transformers and Their Branches across the Power Grid Thu, 18 Jul 2013 13:32:38 +0000 http://www.hindawi.com/journals/jen/2013/795835/ This paper considers the potential of replacing step-down power transformers of the entire power grid as well as part of their transmission line branches with wireless power transfer (WPT) technology components. Exploiting the state-of-the-art evolutions in the fields of WPT technology, coupled resonators in domino arrangements—domino coupled resonator (DCR) configurations—are proposed as suitable technological substitute for step-down power transformers and are investigated in terms of performance metrics such as power transfer efficiency (PTE) and transformation ratio (TR). The contribution of this paper is fivefold. First, an analytical theoretical analysis appropriate to the study of practical DCR configurations is demonstrated. In order to support the DCR configuration replacement venture, a detailed set of assumptions regarding efficient mid- and long-range high-power WPTs as well as related technical issues is first presented. The validity of the theoretical analysis is verified through experimental measurements. Second, applying the proposed theoretical analysis, a wealth of system parameters that mainly influences the PTE and TR of DCR configurations is identified. Their quantitative effect as well as corresponding DCR configuration adjustments are first presented. Third, an approximate method, denoted as approximate chain scattering matrix (CSM) method, is first introduced. Based on the scattering matrix theory formalism, the approximate CSM method is suitable for mid- and long-range DCR configurations when the theoretical analysis becomes computationally slow. The numerical results of approximate CSM method are compared with the respective ones of theoretical analysis validating the extent and the accuracy of approximate CSM method. Fourth, the potential of power transformer replacement with practical DCR configurations is thoroughly investigated in terms of their TRs. A plethora of high-voltage/medium-voltage (HV/MV), MV/low-voltage (MV/LV), and HV/LV power transformers used across the world is investigated verifying their replacement potential with practical DCR configurations in all the cases examined. Fifth, based on a detailed collection of dimensions concerning power transformers and transmission line branches, it is first verified that practical DCR configurations cannot only substitute all step-down power transformers of the today's power grid but also replace entire transmission line branches too. Finally, it is obvious that there is a long journey ahead for WPT technology and its ultramodern DCR configurations to be affordably, widely, reliably, sustainably, and safely adopted in the human society. During these first steps of WPT development for power transmission and distribution, theoretical analyses and visions are necessary. The last cable problem, that is, the seamless power delivery as easily as information is now transmitted through the air, is one of the major technological challenges of the 21st century, and, thus, WPT technology will certainly play key role. Athanasios G. Lazaropoulos Copyright © 2013 Athanasios G. Lazaropoulos. All rights reserved. Comparison of Technological Options for Distributed Generation-Combined Heat and Power in Rajasthan State of India Tue, 18 Jun 2013 10:24:54 +0000 http://www.hindawi.com/journals/jen/2013/712319/ Distributed generation (DG) of electricity is expected to become more important in the future electricity generation system. This paper reviews the different technological options available for DG. DG offers a number of potential benefits. The ability to use the waste heat from fuel-operated DG, known as combined heat and power (CHP), offers both reduced costs and significant reductions of CO2 emissions. The overall efficiency of DG-CHP system can approach 90 percent, a significant improvement over the 30 to 35 percent electric grid efficiency and 50 to 90 percent industrial boiler efficiency when separate production is used. The costs of generation of electricity from six key DG-CHP technologies; gas engines, diesel engines, biodiesel CI engines, microturbines, gas turbines, and fuel cells, are calculated. The cost of generation is dependent on the load factor and the discount rate. It is found that annualized life cycle cost (ALCC) of the DG-CHP technologies is approximately half that of the DG technologies without CHP. Considering the ALCC of different DG-CHP technologies, the gas I.C. engine CHP is the most effective for most of the cases but biodiesel CI engine CHP seems to be a promising DG-CHP technology in near future for Rajasthan state due to renewable nature of the fuel. Ram Kumar Agrawal and Kamal Kishore Khatri Copyright © 2013 Ram Kumar Agrawal and Kamal Kishore Khatri. All rights reserved. A Low-Cost Polytetrafluoroethylene-Framed TiO2 Electrode Decorated with Oleic Acid-Capped CdSe Quantum Dots for Solar Cell Sat, 15 Jun 2013 17:36:04 +0000 http://www.hindawi.com/journals/jen/2013/394512/ Colloidal CdSe QDs have been assembled, as quantum dot-sensitized solar cells (QDSSCs), on a novel architecture comprising a polytetrafluoroethylene- (PTFE-) framed TiO2 electrode for the first time. CdSe QDs are anchored on the surface of the film using a linker molecule (3-mercaptopropionic acid, MPA). The resulting photoelectrode comprises a TiO2 compact layer and a PTFE-framed structural layer with average respective thicknesses of 2 μm for the compact layer and either 23 μm or 28 μm for the PTFE-framed structural layer. UV-vis absorption spectra show that more CdSe quantum dots are anchored on the surface of the modified with MPA TiO2 film compared to direct absorption onto an unmodified film. Energy conversion efficiencies of up to 0.18% can be achieved with cells prepared from a TiO2 (25 μm)/MPA/CdSe QD electrode. Electrochemical impedance measurements show that the recombination resistance is relatively higher for a cell assembled with TiO2 (25 μm)/MPA/CdSe QD photoanode than with TiO2 (25 μm)/CdSe QD resulting in an increase of cell efficiency. The PTFE-framed structure along with the compact layer is a new approach to QDSSC application that provides a tunable film thickness and a cost-effective preparation technique for the large-scale production of the photoanode. Delele Worku Ayele, Wein-Nien Su, and Bing-Joe Hwang Copyright © 2013 Delele Worku Ayele et al. All rights reserved. Comparison of Power Plants Efficiency among 73 Countries Mon, 10 Jun 2013 10:55:52 +0000 http://www.hindawi.com/journals/jen/2013/916413/ Effective and efficient production of electricity is promised to be one of the critical factors to utilize energy for sustainable development. We employ data envelopment analysis (DEA), including undesirable CO2 emissions outputs, to evaluate power plants resource utilization efficiency within 73 countries in order to incorporate the global warming effect. We find that Asia enjoys the highest technical efficiency and European countries suffer from the lowest technical efficiency among Europe, Asia, and America continents. Besides, we compare models with and without CO2 emissions and find that they have significant differences among technical and pure technical efficiencies. We also set up three hypotheses to examine gross national product (GNP), urbanization, and electricity import level factors that potentially influence power plants efficiency by Tobit regression analysis. Results show that GNP and urbanization have significant effects on power plants efficiency except electricity import level. Tser-Yieth Chen, Tsai-Lien Yeh, and Yi-Ting Lee Copyright © 2013 Tser-Yieth Chen et al. All rights reserved. Influences of Contact Pressure on the Performances of Polymer Electrolyte Fuel Cells Sun, 09 Jun 2013 10:26:20 +0000 http://www.hindawi.com/journals/jen/2013/571389/ Fuel cells face major challenges in sustaining the laboratory-scale performance during the scale up. The contact resistance mainly arises from the dimensional mismatch between gasket and gas diffusion layer during scale up, which may cause diminution in performance. In the present work, experiment as well as modelling is carried out for different combinations of clamping force and gasket thickness. The polarisation behaviours of PEFCs configured under different clamping torques and gasket thicknesses are analysed. The combination of 0.3 mm gasket and 0.3 mm GDL under 3 Nm and 5 Nm clamping forces offers 480 mΩ cm2 and 148 mΩ cm2 contact resistances, respectively. The configurations under 3 Nm and 5 Nm clamping torques with 0.2 mm thick gasket offer contact resistances as low as 23 mΩ cm2 and 11 mΩ cm2, respectively. The polarisation behaviour obtained from the experiment of such configurations is found to be in good agreement with the modelling results. Prakash C. Ghosh Copyright © 2013 Prakash C. Ghosh. All rights reserved. A New Strategy for Accurately Predicting Electrical Characteristics of PV Modules Using a Nonlinear Five-Point Model Thu, 06 Jun 2013 09:33:53 +0000 http://www.hindawi.com/journals/jen/2013/321694/ This paper presents the modelling of electrical response of illuminated photovoltaic crystalline modules. As an alternative method to the linear five-parameter model, our strategy uses advantages of a nonlinear analytical five-point model to take into account the effects of nonlinear variations of current with respect to solar irradiance and of voltage with respect to cells temperature. We succeeded in this work to predict with great accuracy the characteristics of monocrystalline shell SP75 and polycrystalline GESOLAR GE-P70 photovoltaic modules. The good comparison of our calculated results to experimental data provided by the modules manufacturers makes it possible to appreciate the contribution of taking into account the nonlinear effect of operating conditions data on characteristics of photovoltaic modules. Sakaros Bogning Dongue, Donatien Njomo, and Lessly Ebengai Copyright © 2013 Sakaros Bogning Dongue et al. All rights reserved. Biochemical Methane Potential of Agro Wastes Wed, 05 Jun 2013 19:05:56 +0000 http://www.hindawi.com/journals/jen/2013/350731/ The focus of our work is on anaerobic digestion of locally available agro wastes like coconut oil cake, cashew apple waste, and grass from lawn cuttings. The most productive agro waste, in terms of methane yield, was coconut oil cake and grass. The results showed that the initial volatile solids concentration significantly affected the biogas production. The methane yield from coconut oil cake was found to be 383 ml CH4/g VS and 277 ml CH4/g VS added at 4 and 4.5 g VS/l. In case of grass the biogas production increased with increasing VS concentrations with methane yield of 199, 250, 256, 284, and 332 ml CH4/g VS at 3, 3.5, 4, 4.5, and 5.0 g VS/l. For cashew apple waste single-stage fermentation inhibited biogas production. However, phase separation showed methane yield of 60.7 ml CH4/g VS and 64.6 ml CH4/g VS at 3.5 and 4.0 g VS/l, respectively. The anaerobic biodegradability of coconut oil cake was evaluated in fed batch mode in a 5 L anaerobic reactor at 4 g VS/L per batch, and the maximum methane yield was found to be 320 ml CH4/g VS. Vidhya Prabhudessai, Anasuya Ganguly, and Srikanth Mutnuri Copyright © 2013 Vidhya Prabhudessai et al. All rights reserved. Preparation and Characterization of Malaysian Dolomites as a Tar Cracking Catalyst in Biomass Gasification Process Wed, 29 May 2013 16:39:45 +0000 http://www.hindawi.com/journals/jen/2013/791582/ Three types of local Malaysian dolomites were characterized to investigate their suitability for use as tar-cracking catalysts in the biomass gasification process. The dolomites were calcined to examine the effect of the calcination process on dolomite’s catalytic activity and properties. The modifications undergone by dolomites consequent to thermal treatment were investigated using various analytical methods. Thermogravimetric and differential thermal analyses indicated that the dolomites underwent two stages of decomposition during the calcination process. The X-ray diffraction and Fourier-transform infrared spectra analyses showed that thermal treatment of dolomite played a significant role in the disappearance of the CaMg(CO3)2 phase, producing the MgO-CaO form of dolomite. The scanning electron microscopy microphotographs of dolomite indicated that the morphological properties were profoundly affected by the calcination process, which led to the formation of a highly porous surface with small spherical particles. In addition, the calcination of dolomite led to the elimination of carbon dioxide and increases in the values of the specific surface area and average pore diameter, as indicated by surface area analysis. The results showed that calcined Malaysian dolomites have great potential to be applied as tar-cracking catalysts in the biomass gasification process based on their favorable physical properties. M. A. A. Mohammed, A. Salmiaton, W. A. K. G. Wan Azlina, M. S. Mohamad Amran, and Y. H. Taufiq-Yap Copyright © 2013 M. A. A. Mohammed et al. All rights reserved. An Integrated Decentralized Energy Planning Model considering Demand-Side Management and Environmental Measures Tue, 28 May 2013 17:47:49 +0000 http://www.hindawi.com/journals/jen/2013/602393/ Decentralized energy planning (DEP) is looked upon as an indisputable opportunity for energy planning of villages, isolated islands, and far spots. Nonetheless, at this decentralized planning level, the value of demand-side resources is not fairly examined, despite enjoying great advantages. Therefore, the core task of this study is to integrate demand-side resources, as a competing solution against supply-side alternatives, with decentralized energy planning decisions and demonstrate the rewarding role it plays. Moreover, sustainability indicators (SIs) are incorporated into DEP attempts in order to attain sustainable development. It is emphasized that unless these indicators are considered at lower energy planning levels, they will be ignored at higher planning levels as well. Hence, to the best knowledge of the authors, this study for the first time takes into account greenhouse gas (GHG) emissions produced by utilization of renewable energies in DEP optimization models. To address the issues mentioned previously, multiobjective linear programming model along with a min-max goal programming approach is employed. Finally, using data taken from the literature, the model is solved, and the obtained results are discussed. The results show that DSM policies have remarkably contributed to significant improvements especially in terms of environmental indicators. Seyed Mahmood Kazemi and Masoud Rabbani Copyright © 2013 Seyed Mahmood Kazemi and Masoud Rabbani. All rights reserved. Recent Strategy of Biodiesel Production from Waste Cooking Oil and Process Influencing Parameters: A Review Wed, 22 May 2013 11:16:05 +0000 http://www.hindawi.com/journals/jen/2013/926392/ Cost of biodiesel produced from virgin vegetable oil through transesterification is higher than that of fossil fuel, because of high raw material cost. To minimize the biofuel cost, in recent days waste cooking oil was used as feedstock. Catalysts used in this process are usually acids, base, and lipase. Since lipase catalysts are much expensive, the usage of lipase in biodiesel production is limited. In most cases, NaOH is used as alkaline catalyst, because of its low cost and higher reaction rate. In the case of waste cooking oil containing high percentage of free fatty acid, alkaline catalyst reacts with free fatty acid and forms soap by saponification reaction. Also, it reduces the biodiesel conversions. In order to reduce the level of fatty acid content, waste cooking oil is pretreated with acid catalyst to undergo esterification reaction, which also requires high operating conditions. In this review paper, various parameters influencing the process of biofuel production such as reaction rate, catalyst concentration, temperature, stirrer speed, catalyst type, alcohol used, alcohol to oil ratio, free fatty acid content, and water content have been summarized. A. Gnanaprakasam, V. M. Sivakumar, A. Surendhar, M. Thirumarimurugan, and T. Kannadasan Copyright © 2013 A. Gnanaprakasam et al. All rights reserved. Life-Cycle Analyses of Energy Consumption and GHG Emissions of Natural Gas-Based Alternative Vehicle Fuels in China Thu, 16 May 2013 09:45:42 +0000 http://www.hindawi.com/journals/jen/2013/268263/ Tsinghua life-cycle analysis model (TLCAM) has been used to examine the primary fossil energy consumption and greenhouse gas (GHG) emissions for natural gas- (NG-) based alternative vehicle fuels in China. The results show that (1) compress NG- and liquid NG-powered vehicles have similar well-to-wheels (WTW) fossil energy uses to conventional gasoline- and diesel-fueled vehicles, but differences emerge with the distance of NG transportation. Additionally, thanks to NG having a lower carbon content than petroleum, CNG- and LNG-powered vehicles emit 10–20% and 5–10% less GHGs than gasoline- and diesel-fueled vehicles, respectively; (2) gas-to-liquid- (GTL-) powered vehicles involve approximately 50% more WTW fossil energy uses than conventional gasoline- and diesel-fueled vehicles, primarily because of the low efficiency of GTL production. Nevertheless, since NG has a lower carbon content than petroleum, GTL-powered vehicles emit approximately 30% more GHGs than conventional-fuel vehicles; (3) The carbon emission intensity of the LNG energy chain is highly sensitive to the efficiency of NG liquefaction and the form of energy used in that process. Xunmin Ou and Xiliang Zhang Copyright © 2013 Xunmin Ou and Xiliang Zhang. All rights reserved. Experimental Evaluation of Supercapacitor-Fuel Cell Hybrid Power Source for HY-IEL Scooter Thu, 16 May 2013 09:36:30 +0000 http://www.hindawi.com/journals/jen/2013/162457/ This paper presents the results of development of a hybrid fuel cell supercapacitor power system for vehicular applications that was developed and investigated at the Energy Sources Research Section of the Wroclaw Division of Electrotechnical Institute (IEL/OW). The hybrid power source consists of a polymer exchange membrane fuel cell (PEMFC) stack and an energy-type supercapacitor that supports the system in time of peak power demands. The developed system was installed in the HY-IEL electric scooter. The vehicle was equipped with auxiliary components (e.g., air compressor, hydrogen tank, and electromagnetic valves) needed for proper operation of the fuel cell stack, as well as electronic control circuits and a data storage unit that enabled on-line recording of system and vehicle operation parameters. Attention is focused on the system energy flow monitoring. The experimental part includes field test results of a vehicle powered with the fuel cell-supercapacitor system. Values of currents and voltages recorded for the system, as well as the vehicle’s velocity and hydrogen consumption rate, are presented versus time of the experiment. Operation of the hybrid power system is discussed and analysed based on the results of measurements obtained. Piotr Bujlo, Grzegorz Pasciak, Jacek Chmielowiec, and Andrzej Sikora Copyright © 2013 Piotr Bujlo et al. All rights reserved.