http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2013 , Hindawi Publishing Corporation . All rights reserved. Mon, 20 May 2013 13:17:59 +0000 http://www.hindawi.com/isrn/re/2013/902053/ The present rate of economic growth is unsustainable without saving of fossil energy like crude oil, natural gas, or coal. There are many alternatives to fossil energy such as biomass, hydropower, and wind energy. Also, suitable waste management strategy is another important aspect. Development and modernization have brought about a huge increase in the production of all kinds of commodities, which indirectly generate waste. Plastics have been one of the materials because of their wide range of applications due to versatility and relatively low cost. The paper presents the current scenario of the plastic consumption. The aim is to provide the reader with an in depth analysis regarding the recycling techniques of plastic solid waste (PSW). Recycling can be divided into four categories: primary, secondary, tertiary, and quaternary. As calorific value of the plastics is comparable to that of fuel, so production of fuel would be a better alternative. So the methods of converting plastic into fuel, specially pyrolysis and catalytic degradation, are discussed in detail and a brief idea about the gasification is also included. Thus, we attempt to address the problem of plastic waste disposal and shortage of conventional fuel and thereby help in promotion of sustainable environment. Neha Patni, Pallav Shah, Shruti Agarwal, and Piyush Singhal Copyright © 2013 Neha Patni et al. All rights reserved. Mon, 13 May 2013 11:04:49 +0000 http://www.hindawi.com/isrn/re/2013/107851/ Bioethanol as a fossil fuel additive to decrease environmental pollution and reduce the stress of the decline in crude oil availability is becoming increasingly popular. This study aimed to evaluate the concentration of bioethanol obtainable from fermenting cashew apple juice by the microorganism Saccharomyces cerevisiae Y2084 and Vin13. The fermentation conditions were as follows: initial sugar = 100 g/L, pH = 4.50, agitation = 150 rpm, temperatures = 30°C (Y2084) and 20°C (Vin13), oxygen saturation = 0% or 50%, and yeast inoculum concentration = ~8.00 Log CFU/mL. The maximum ethanol concentration achieved by Y2084 was 65.00 g/L. At 50% oxygen the fermentation time was 5 days, whilst at 0% oxygen the fermentation time was 11 days for Y2084. The maximum ethanol concentration achieved by Vin13 was 68.00 g/L. This concentration was obtained at 50% oxygen, and the fermentation time was 2 days. At 0% oxygen, Vin13 produced 31.00 g/L of ethanol within 2 days. Both yeast strains produced a higher glycerol concentration at 0% oxygen. Yeast viability counts showed a decrease at 0% oxygen and an increase at 50% oxygen of both yeast stains. Other analyses included measurement of carbon dioxide and oxygen gases, process monitoring of the fermentation conditions, and total organic carbon. Gas analysis showed that carbon dioxide increased in conjunction with ethanol production and oxygen decreased. Process monitoring depicted changes and stability of fermentation parameters during the process. Total organic carbon analysis revealed that aerobic fermentation (50% oxygen) was a more efficient process as a higher carbon recovery (95%) was achieved. Evanie Devi Deenanath, Karl Rumbold, and Sunny Iyuke Copyright © 2013 Evanie Devi Deenanath et al. All rights reserved. Mon, 04 Mar 2013 13:24:33 +0000 http://www.hindawi.com/isrn/re/2013/827681/ A recyclable energy cycle using a pulsed laser and base-metal nanoparticles is proposed. In this energy cycle, iron nanoparticles reduced from iron oxides by laser ablation in liquid are used for hydrogen generation. The laser energy can be stored in the base-metal nanoparticles as the difference between the chemical energies of iron oxide and iron. According to the results of an experiment on hydrogen production using the reduced iron nanoparticles, the reaction efficiency of the hydrogen generation at a temperature of 673 K was more than 94% for the ideal amount of generated hydrogen. Takehiro Okada, Taku Saiki, Seiji Taniguchi, Tsuyoshi Ueda, Kazuhiro Nakamura, Yusuke Nishikawa, and Yukio Iida Copyright © 2013 Takehiro Okada et al. All rights reserved. Thu, 28 Feb 2013 13:19:58 +0000 http://www.hindawi.com/isrn/re/2013/738326/ We present 11.7% efficient p-type crystalline silicon solar cells with a nanoscale textured surface and no dielectric antireflection coating. We propose nanocrystalline-like textured surface consisting of nanocrystalline columnar structures of diameters from 50 to 100 nm and depth of about 500 nm formed by reactive-ion etching (RIE) in multihollow cathode system. This novel nano textured surface acts as an antireflective absorbing surface of c-Si abbreviate as ARNAB (antireflective nanoabsorber). Light shining on the surface of RIE-etched silicon bounces back and forth between the spikes in such a way that most of it never comes back. Radio frequency (RF) hollow cathode discharge allows an improvement of plasma density by an order of magnitude in comparison to standard RF parallel-plate discharge. Desirable black silicon layer has been achieved when RF power of about 20 Watt per one hollow cathode glow is applied for our multihollow cathode system. The RF power frequency was 13.56 MHz. The antireflection property of ARNAB textured surface has been investigated and compared with wet-textured and PECVD coated silicon samples. Solar cell using low-cost spin-on coating technique has been demonstrated in this paper. We have successfully achieved 11.7% efficient large area (98 cm2) ARNAB textured crystalline silicon solar cell using low-cost spin-on coating (SOD) doping. Utpal Gangopadhyay, Sukhendu Jana, and Sayan Das Copyright © 2013 Utpal Gangopadhyay et al. All rights reserved. Thu, 31 Jan 2013 08:24:27 +0000 http://www.hindawi.com/isrn/re/2013/406312/ This paper presents a grid-connected PV system in a centralized configuration constructed through a three-phase dual-stage inverter. For the DC-DC stage the three-phase series resonant converter is chosen thanks to the advantages that it exhibits. However, it is inadequate for the accomplishment of MPPT, due to its efficiency strongly depending on the implemented deadtime and switching frequency. Then, this paper proposes a conceptual modification, that is, a modified dual-stage inverter in which the inverter stage is responsible for both the MPPT and the grid-current control. In addition, the DC-DC converter operates with constant duty cycle and frequency. Such configuration requires a new concept, introduced as Behavior Matching. It serves as a fundamental feature for the DC-DC converter to reproduce the PV array I–V characteristic when they are connected, without control action. The maximum power operating point is found by maximizing the direct axis current, obtained by Park's transformation from the inverter, through the perturbation and observation algorithm. Any specific measurement to realize the MPPT is needed. The galvanic isolation is achieved by using a high-frequency transformer. The structure is appropriate for high power applications, above 10 kW. Denizar Cruz Martins Copyright © 2013 Denizar Cruz Martins. All rights reserved. Mon, 31 Dec 2012 17:12:58 +0000 http://www.hindawi.com/isrn/re/2012/631574/ Global energy use has reached unprecedented levels and increasing human population, technological integration, and improving lifestyle will further fuel this demand. Fossil fuel based energy is our primary source of energy and it will remain to be in the near future. The effects from the use of this finite resource on the fate of our planet are only now being understood and recognised in the form of climate change. Renewable energy systems may offer a credible alternative to help maintain our lifestyle sustainably and there are a range of options that can be pursued. Biofuels, especially algae based, have gained significant publicity recently. The concept of making biofuels, biochemicals, and by-products works well theoretically and at small scale, but when considering scaleup, many solutions can be dismissed on either economical or ecological grounds. Even if an (cost-) effective method for algae cultivation is developed, other input parameters, namely, fixed nitrogen and fresh water, remain to be addressed. Furthermore, current processing routes for harvesting, drying, and extraction for conversion to subsequent products are economically unattractive. The strategies employed for various algae-based fuels are identified and it is suggested that ultimately only an integrated algal biorefinery concept may be the way forward. Bhavish Patel, Bojan Tamburic, Fessehaye W. Zemichael, Pongsathorn Dechatiwongse, and Klaus Hellgardt Copyright © 2012 Bhavish Patel et al. All rights reserved. Thu, 27 Dec 2012 09:41:53 +0000 http://www.hindawi.com/isrn/re/2012/730631/ Hydropower is an important renewable energy resource worldwide. However, its development is accompanied with environmental and social drawbacks. Issues of degradation of the environment and climate change can negatively impact hydropower generation. A sustainable hydropower project is possible, but needs proper planning and careful system design to manage the challenges. Well-planned hydropower projects can contribute to supply sustainable energy. An up-to-date knowledge is necessary for energy planners, investors, and other stakeholders to make informed decisions concerning hydropower projects. This is basically a review paper. Apart from using expert knowledge, the authors have also consulted extensively from journals, conference papers, reports, and some documents to get secondary information on the subject. The paper has reviewed the world energy scenario and how hydropower fits in as the solution to the global sustainable energy challenge. Issues of hydropower resource availability, technology, environment and climate change have been also discussed. Hydropower is sensitive to the state of environment, and climate change. With global climate change, though globally the potential is stated to slightly increase, some countries will experience a decrease in potential with increased risks. Adaptation measures are required to sustainably generate hydropower. These are also discussed in the paper. Chiyembekezo S. Kaunda, Cuthbert Z. Kimambo, and Torbjorn K. Nielsen Copyright © 2012 Chiyembekezo S. Kaunda et al. All rights reserved. Mon, 24 Dec 2012 12:36:08 +0000 http://www.hindawi.com/isrn/re/2012/954180/ A key objective of this paper is to provide an assessment of the current and future situation on the “food versus fuel” debate and to contribute to possible alternatives to minimise or avoid future conflict. The debate has centred on three main areas: (i) food versus biofuel production, (ii) their positive and negative effects (i.e., GHG, climate change, and the broader environment), and (iii) a socioeconomic impact. The debate has been controversial because it has largely been driven by politics, ethical/moral considerations, and vested interests rather than by science. The paper focuses on food prices, land competition, GHG, energy balance, and energy subsidies and concerns with the rapid expansion of bioenergy for electricity and heat, climatic changes, the role of agriculture as a key factor, the potential of biomass energy resources, and the various alternatives to minimize or avoid conflict between food and fuel production. Biomass for energy is both “part of the problem and part of the solution.” It proposes a holistic approach: a new paradigm that takes full account of the diverse and complex nature of biomass energy sources and states that the fundamental underlying causes are social injustice, inequality, waste, and so forth, rather than land competition for food and fuel. Frank Rosillo-Calle Copyright © 2012 Frank Rosillo-Calle. All rights reserved. Thu, 20 Dec 2012 18:18:42 +0000 http://www.hindawi.com/isrn/re/2012/987904/ Oscillating water column plants are one of the most popular wave energy device types. Prototype OWC units have been operating in various parts of the world since the mid-1980s and such developers have more field experience of this technology than any other relevant plant. The most common turbine used is the self-rectifying Well's turbine which has a rather low peak efficiency if compared to other designs but was preferred in terms of its simplicity and cycle performance. The present study exploits the merits of a new concept for the power extraction process, that of an encaged turbine for OWC plants, which allows conventional high-efficiency turbines to be employed in such plants. This is achieved by guiding the pressurized air into a sequence of three chambers, creating a unidirectional closed air circuit through the turbine. A theoretical model is deployed simulating the operation of the plant and a sensitivity analysis is carried out for the design and working parameters. Results indicate that the power extraction efficiency may exceed the 50% level in a real plant. Demos P. Georgiou, Kypros F. Milidonis, and Eleutherios N. Georgiou Copyright © 2012 Demos P. Georgiou et al. All rights reserved. Wed, 19 Dec 2012 15:03:13 +0000 http://www.hindawi.com/isrn/re/2012/167629/ Pine wood samples were used as model feedstock to study the properties of catalytic fast pyrolysis oils. The influence of two commercial zeolite catalysts (BASF and SudChem) and pretreatment of the pine wood with sodium hydroxide on pyrolysis products were investigated. The pyrolysis oils were first fractionated using column chromatography and characterized using GC-MS. Long chain aliphatic hydrocarbons, levoglucosan, aldehydes and ketones, guaiacols/syringols, and benzenediols were the major compounds identified in the pyrolysis oils. The catalytic pyrolysis increased the polycyclic hydrocarbons fraction. Significant decreases in phthalate derivatives using SudChem and long chain aliphatics using BASF catalyst were observed. Significant amounts of aromatic heterocyclic hydrocarbons and benzene derivatives were formed, respectively, using BASF and SudChem catalysts. Guaiacyl/syringyl and benzenediols derivatives were partly suppressed by the zeolite catalysts, while the sodium hydroxide treatment enriched phenolic derivatives. Zeolite catalyst and sodium hydroxide were employed together; they showed different results for each catalyst. J. Pereira, F. A. Agblevor, and S. H. Beis Copyright © 2012 J. Pereira et al. All rights reserved. Mon, 03 Dec 2012 09:32:20 +0000 http://www.hindawi.com/isrn/re/2012/148563/ This paper presents the basis for the development of an intelligent and autonomous energy management strategy for hybrid power system (HPS). Two hierarchical levels are proposed to control and manage the HPS. The low level is performed by a local control unit (DC-DC converters controller) of the different power sources. Dynamic equations describing the coupling of converters are derived, and a robust sliding mode dynamic controller is designed. The high level is performed by the online supervisor unit. This unit is designed by applying on-line Takagi-Sugeno fuzzy logic principles. As a result the robust control system gets rid of the limits of the HPS, which has the imprecision, uncertainty, strong coupling, and nonlinearity, to achieve its tractability, robustness, and low solution cost. Under the operation constraints related to each type of sources, the simulation results show that the optimal operation objective of HPS has been achieved. Salem Zerkaoui Copyright © 2012 Salem Zerkaoui. All rights reserved. Wed, 21 Nov 2012 11:22:11 +0000 http://www.hindawi.com/isrn/re/2012/142857/ The recent increase in the world biofuels demand, along with the need to reduce costs while improving the environmental sustainability of the biodiesel production, have led to the search for catalysts that should be economically viable, efficient, and environmentally friendly. This paper reviews recent research and development of organic and inorganic tin catalysts; focusing on kinetic properties and catalytic activity in two key reactions for biodiesel production: free fatty acids (FFA) esterification and triglycerides (TG) transesterification. First the basic knowledge of homogeneous tin catalysts in esterification reactions of different carboxylic acids is provided. Second, main advances obtained in the study of FFA esterification reactions catalyzed by tin chloride are covered. The effect of the principal parameters of reaction on the yield and rate of alkyl esters production is described. Kinetic measurements allowed the determination of the activation energy (46.79 kJ mol−1) and a first-order dependence in relation to both FFA and tin chloride catalyst concentration. Aspects related to recycling of the tin chloride catalyst in phase homogeneous are discussed. Third the advances obtained in the development of homogeneous catalysts based on tin complexes in transesterification reactions are summarized. Finally, results obtained from the use of tin organometallics compounds in reactions of vegetable oils transesterification reactions are concisely presented. The optimization of processes catalytic homogeneous utilized in the transesterification reactions can contribute to the improvement of the technology biodiesel production. Arthur Batista Ferreira, Abiney Lemos Cardoso, and Márcio José da Silva Copyright © 2012 Arthur Batista Ferreira et al. All rights reserved. Wed, 14 Nov 2012 11:35:02 +0000 http://www.hindawi.com/isrn/re/2012/613642/ Stirling cycle and Rankine cycle heat engines are used to transform the heat energy of solar concentrators to mechanical and electrical energy. The Rankine cycle is used for large-scale solar power plants. The Stirling cycle can be used for small-scale solar power plants. The Stirling cycle heat engine has many advantages such as high efficiencyand long service life. However, the Stirling cycle is good for high-temperature difference. It demands the use of expensive materials. Its efficiency depends on the efficiency of the heat regenerator. The design and manufacture of a heat regenerator are not a trivial problem because the regenerator has to be placed in the internal space of the engine. It is possible to avoid this problem if we place the regenerator out of the internal engine space. To realize this idea it is necessary to develop the Ericsson cycle heat engine. We propose theoretical model and design of this engine. Ernst Kussul, Oleksandr Makeyev, Tatiana Baidyk, and Omar Olvera Copyright © 2012 Ernst Kussul et al. All rights reserved. Wed, 14 Nov 2012 10:23:10 +0000 http://www.hindawi.com/isrn/re/2012/904269/ Strategies for parking a vertical axis wind turbine at storm load are considered. It is proposed that if a directly driven permanent magnet synchronous generator is used, an elegant choice is to short-circuit the generator at storm, since this makes the turbine efficiently damped. Nondamped braking is found to be especially problematic for the case of two blades where torsional oscillations may imply thrust force oscillations within a range of frequencies. F. Ottermo, S. Eriksson, and H. Bernhoff Copyright © 2012 F. Ottermo et al. All rights reserved. Wed, 14 Nov 2012 09:56:03 +0000 http://www.hindawi.com/isrn/re/2012/476702/ The steaming of raw cashew seeds prior to shelling is adopted widely in small-scale cashew nut processing mills with the help of baby boiler. The wide variations in energy intensity of these mills reveal the scope for energy conservation. The baby boiler coupled with cooker commonly used for steaming of raw seeds was evaluated. The variation in steam pressure, temperature and operating time with respect to fuel was observed along with thermal efficiency of a boiler. The energy intensity to produce the steam using different fuel sources determined. The study revealed that the thermal efficiency of boiler using electricity as a fuel was higher (69.31%) as compared to 4.66% (Wood) and 4.47% (Cashew nut shell). It was observed that, the energy consumed per kg of cashew nut steaming using electricity (248.99 kJ/kg) was minimum followed by wood (3829.96 kJ/kg) and cashew nut shell (3835.64 kJ/kg). The variation of energy consumption for cashew nut steaming revealed the scope for energy conservation in biomass combustion system. The improvement in the biomass combustion efficiency for steam generation could results in less fuel consumption and shorter period. Atul Mohod, Y. P. Khandetod, S. H. Sengar, and H. Y. Shrirame Copyright © 2012 Atul Mohod et al. All rights reserved. Mon, 05 Nov 2012 18:43:00 +0000 http://www.hindawi.com/isrn/re/2012/194359/ The paper describes the performance of a direct-mode solar crop dryer with a solar chimney. Tests were performed for three differently inclined drying-chamber roofs, each with three inlet areas for a given exit area. Cassava was used as the test crop. The results show that the increase in the inlet area for a given exit area can improve the ventilation in the dryer. However, this does not necessarily improve the drying performance of the direct-mode dryer. A wide inlet area for a given exit area can only improve the drying performance of the direct-mode dryer in a geographical location of low relative humidity. It is therefore not advisable to just copy the design of a direct-mode dryer from one location to another without regard to the ambient relative humidity. The designer and builder of the dryer must consider the relative humidity as a prime factor in the design and construction of direct-mode dryers, which are highly sensitive to the ambient relative humidity. J. K. Afriyie and A. Bart-Plange Copyright © 2012 J. K. Afriyie and A. Bart-Plange. All rights reserved. Wed, 24 Oct 2012 15:36:15 +0000 http://www.hindawi.com/isrn/re/2012/130782/ This study examines the composition and combustion performance of biodiesel produced from waste cooking oil. Six fuel batches produced from waste oil used in dining-hall fryers were examined to determine their physical and chemical properties, including their elemental and fatty acid methyl ester composition. Oleic and linoleic methyl esters accounted for more than 70% of the fuel composition, while the oxygen content averaged 10.2% by weight. Exhaust emissions were monitored for 5–100% biodiesel blends using two off-road engines: a 2007 Yanmar diesel generator and a 1993 John Deere front mower. Increasing biodiesel content resulted in reduced emissions of partial combustion products from the diesel generator but a rise in NOx, with the greatest changes occurring between 5 and 20% biodiesel content. For the riding mower, biodiesel content up to 50% had little effect on emissions, while NOx and total hydrocarbon emissions decreased with 100% biodiesel. The difference in NOx emissions is attributed to the two different fuel injection control designs used in the two engines. These results indicate that the effects of biodiesel use on nonroad engine exhaust emissions may be substantially lower in older engines optimized for performance over emissions control. Jing Guo, Edward Peltier, Ray E. Carter, Alex J. Krejci, Susan M. Stagg-Williams, and Christopher Depcik Copyright © 2012 Jing Guo et al. All rights reserved. Tue, 16 Oct 2012 15:38:59 +0000 http://www.hindawi.com/isrn/re/2012/847356/ This work aims to describe the wind power density in five sites in the State of Paraiba, as well as to access the ability of the mesoscale atmospheric model Brazilian developments on the regional atmospheric modeling system (BRAMS) in describing the intensity of wind in São Gonçalo Monteiro, Patos, Campina Grande, and João Pessoa. Observational data are wind speed and direction at 10 m high, provided by the National Institute of Meteorology (INMET). We used the numerical model BRAMS in simulations for two different months. We ran the model for rainy months: March and April. It was concluded that the BRAMS model is able to satisfactorily reproduce the monthly cycle of the wind regime considered, as well as the main direction. However the model tends to underestimate the wind speed. Francisco José Lopes de Lima, Enilson Palmeira Cavalcanti, Enio Pereira de Souza, and Emerson Mariano da Silva Copyright © 2012 Francisco José Lopes de Lima et al. All rights reserved. Mon, 15 Oct 2012 11:46:33 +0000 http://www.hindawi.com/isrn/re/2012/261325/ This paper deals with the assessment of DC components generated by renewable energy resources with inverter-based interconnection system to the electric grid. DC injection is a critical issue related to power quality of distribution network systems with high penetration of inverter-based interconnection systems. This type of interface systems may improve the performance of the electric generation unit and affect positively or negatively the power quality of the distribution network depending on the proper or improper designation. The investigation of the various causes of DC components and the analytical assessment of their maximum levels are crucial for the proper operation of inverter-based interface systems and the limitation of DC injection. A method based on analytical calculations using a computer software has been implemented for the assessment of DC components contained on an inverter's output voltage when even harmonics are present on the network voltage. Moreover, a simulation package was used to demonstrate the existence of DC components under various conditions. It was proved by the current analysis that the amounts of DC components generated when even harmonics are present on the network voltage can be high under abnormalities on the power grid but they are not considerable under normal operating conditions. Marios N. Moschakis, Vasilis V. Dafopoulos, Emmanuel S. Karapidakis, and Antonis G. Tsikalakis Copyright © 2012 Marios N. Moschakis et al. All rights reserved. Sun, 23 Sep 2012 08:49:04 +0000 http://www.hindawi.com/isrn/re/2012/219703/ The use of bioethanol in the transport sector can contribute to mitigate the greenhouse gas emissions of the vehicles. To achieve this goal, together with a positive energy balance in global productive process of ethanol (well to tank), it is important that adding ethanol to gasoline does not cause a worsening of the efficiency of the internal combustion engine (tank to wheel). In this paper, a research activity on a commercial spark-ignition light-duty engine at the test bench is reported. The aim of the work was to characterize the effect of different bioethanol/gasoline blends on engine behaviour. Blends until 85% of ethanol were tested. Comparative studies of combustion development of gasoline and gasoline/ethanol blends at different concentrations have been made through the analysis of pressure cycles in combustion chamber. Moreover, emissions were collected and analyzed. Emissions downstream of the catalyst, measured with the blends, resulted quite similarly to the gasoline case. Instead, upstream the catalyst a reduction of emissions, proportional to oxygenated content was noted. Moreover, a general carbon dioxide reduction with ethanol blends was achieved due in particular to better engine thermal efficiency. Luigi De Simio, Michele Gambino, and Sabato Iannaccone Copyright © 2012 Luigi De Simio et al. All rights reserved. Thu, 20 Sep 2012 09:59:47 +0000 http://www.hindawi.com/isrn/re/2012/167192/ The purpose of this paper is to reinforce with theoretical and experimental evaluation the effectiveness of employing an induction generator to enhance the performance of a small wind energy converter (SWEC). With this generator, the SWEC works more efficiently and therefore can produce more energy in a unit turbine area. To verify the SWEC performance, a model has been proposed, simulated, built, and experimentally tested over a range of operating conditions. The results demonstrate a significant increase in output power with an induction generator that employs an auxiliary winding, which is only magnetically coupled to the stator main winding. It is also shown that the operating performance of the induction machine with the novel proposed technique is significantly enhanced in terms of suppressed signal distortion and harmonics, severity of resistive losses and overheating, power factor, and preventing high inrush current at starting. Riadh W. Y. Habash, Qianjun Tang, Pierre Guillemette, and Nazish Irfan Copyright © 2012 Riadh W. Y. Habash et al. All rights reserved. Sun, 16 Sep 2012 11:03:52 +0000 http://www.hindawi.com/isrn/re/2012/541596/ Biomass is one of the most promising renewable energy sources. Abundantly, the potential as an alternative source to meet the world energy demand has been widely acknowledged. Gasification is one of the most efficient processes concerning thermochemical conversion, having as objective the production of a gas with useful energy power, known as producer gas. In order to optimize thermochemical processes such as the combustion of gases and subsequent gas mixture, computer modeling is becoming an important tool. Aiming to improve the performance of a combustion chamber, previously coupled to a downdraft gasifier, a thermofluidynamic model was elaborated and validated, using the concepts of computational fluid dynamics (CFD). It was reported that temperature, pressure, and velocity distributions of the computational model showed good consistency with experimental data, which allows using this model to predict the performance of this type of combustion chambers. Jofran Luiz de Oliveira, Márcio Arêdes Martins, Jadir Nogueira da Silva, Michel de Oliveira dos Santos, and William Rosário dos Santos Copyright © 2012 Jofran Luiz de Oliveira et al. All rights reserved. Thu, 06 Sep 2012 14:27:23 +0000 http://www.hindawi.com/isrn/re/2012/890820/ This paper deals with the critical design specifications and field performance of walk in type hemicylindrical solar tunnel dryer for drying 1500vkg industrial product (dibasic calcium phosphate) in actual use. A tunnel like framed structural covered with UV-stabilized polythene sheet walk-in type solar tunnel dryer was designed, developed, and commissioned at Udaipur (27∘42N, 75∘33E), Rajasthan, India with a solar collector area of 134.74 m2 for drying di-basic calcium phosphate, having an initial moisture content of 62.87% dry basis and to get a desired moisture content of 10.62% dry basis within two days. The performance of solar tunnel dryer for drying di-basic calcium phosphate was evaluated through no-load and full-load conditions tests in the summer and winter months. The results were shown in terms of the variation of air temperature, solar radiation, relative humidity, air flow rate, moisture content, drying rate, and so forth. M. S. Seveda Copyright © 2012 M. S. Seveda. All rights reserved. Tue, 04 Sep 2012 13:19:45 +0000 http://www.hindawi.com/isrn/re/2012/365469/ This paper presents the maps of solar radiation on the surface of south-east region of Spain named Región de Murcia. These maps are the result of treatment, study, and correlations obtained by data of 35 weather stations distributed throughout the region. These stations have collected data for 6 to more than 25 years. The paper presents the work performed for the treatment of collected data, the correlations used for the adjustment of the data, and the parameters obtained as a result of this adjustment. The weather stations are equipped with various sensors to collect several parameters, the measures covered and used for the study were global and diffuse radiation (in case that the station has pyranometer diffuse) and ambient temperature. The results were used to produce maps of horizontal radiation (global and diffuse) and ambient temperature at the surface of the region studied. To achieve the irradiation maps for this extended region has been used “r.sun” program, technical program that with the help of GRASS program uses geographic information systems (GISs) to evaluate the influence of geographical variables captured on horizontal plane at the surface. Using the results of the program for theoretical data and/or generic, and with the feedback obtained by the correlations of measures covered from weather stations, we have studied the incident radiation on the region. The main result of this study was to produce maps of irradiation on horizontal plane, correction for inclined surfaces, and also maps of temperature of the studied region. On this basis, results have been produced maps and tables of monthly solar radiation (mean maximum and minimum) for each of the 45 municipalities of the Region of Murcia. Thus, was obtained a useful tool for the calculation of available energy and thermal needs at the design process of plants using solar thermal and photovoltaic. F. Vera-García, J. R. García-Cascales, Z. Hernández-Guillén, and J. P. Delgado-Marín Copyright © 2012 F. Vera-García et al. All rights reserved. Wed, 29 Aug 2012 17:43:04 +0000 http://www.hindawi.com/isrn/re/2012/327296/ This paper provides a new approach to maximize the amount of power generated by the switched reluctance generator (SRG) in the low and medium speed operations. There are many control variables which affect the power generated such as: firing angles, reference current, speed and voltage. It will incur high costs and time consuming to modify the variables using experimental set up. Hence, to minimize time, cost and aid in the manufacturing industry, a simulation model of the overall SRG drive is developed. The objective of the work is to identify the optimal parameters and characterize them under closed loop control. The study indicates that there is an optimal voltage, firing angles and reference current at each speed range. Also, the percentage of the power generated can be categorized as a function of dwell angle and speed at optimal voltage level. The optimal dwell angle is determined using the least square method. Within the closed loop system, the high percentage of power generated can be maintained by adjusting the voltage level. It allows operation in single pulse mode as opposed to the conventional current chopping during the low and medium speed. A. Arifin, I. H. Al-Bahadly, and S. C. Mukhopadhyay Copyright © 2012 A. Arifin et al. All rights reserved. Tue, 28 Aug 2012 16:11:41 +0000 http://www.hindawi.com/isrn/re/2012/132606/ The importance of renewable energy such as small hydropower for sustainable power generation in relation to its capacity to contribute towards alleviating acute shortage of rural electricity supply in the sub-Saharan African region has been discussed. A relatively comprehensive small hydropower technology review has been presented. Rural electricity supply scenario in the region has been presented and, in general, the region has very low electricity access levels coupled with various challenges. Small hydropower technology has been discussed as one of the promising decentralised power generation system for rural electricity supply in the region. Despite challenges in data acquisition, this paper has shown that the SSA has significant hydropower resources, but the level of installation is very low. Challenges hampering SHP technology development in the region have been identified and discussed, such as those concerning technology, climate change, finance, and policy. This is basically a paper where the authors consulted a wide range of literature including journals, conference proceedings, and reports as well as expert knowledge in the area. It is hoped that this paper contributes to the information base on SHP technology which is quite lacking in the region. Chiyembekezo S. Kaunda, Cuthbert Z. Kimambo, and Torbjorn K. Nielsen Copyright © 2012 Chiyembekezo S. Kaunda et al. All rights reserved. Mon, 27 Aug 2012 08:45:49 +0000 http://www.hindawi.com/isrn/re/2012/107397/ Supply chain optimization for biomass-based power plants is an important research area due to greater emphasis on green energy sources. This paper develops and applies two optimization models to analyze the impacts of biomass competition on cost structures and gross margins for four competing biomass-based power plants in northwestern Ontario. Model scenarios are run to study the impacts of changes in parameters relevant to biomass type and processing technology, and prices of inputs and outputs on procurement costs. Cost minimization model shows that per unit procurement costs are directly proportional to the size of the power plants in all scenarios. Profit maximization model, on the other hand, shows that FMUs that are closer to the power plants make higher gross margins. However, the margins significantly increase for FMUs that are close to the power plants potentially offering higher prices. The variations in costs and gross margin structures under various model scenarios are explained by location of depletion cells relative to power plants, availability of each type of biomass in depletion cells, biomass demands, and differential processing costs for two types of biomass. These results can aid decision makers to make improved decisions related to biomass supply chains for bioenergy production. Md. Bedarul Alam, Reino Pulkki, Chander Shahi, and Thakur Prasad Upadhyay Copyright © 2012 Md. Bedarul Alam et al. All rights reserved. Sun, 26 Aug 2012 18:52:19 +0000 http://www.hindawi.com/isrn/re/2012/536417/ In many developing countries, biomass use as a means of generating energy is still relevant with the developed countries also gradually increasing this source of energy in their energy-mix. Furthermore, increased research and developmental efforts concerning bioenergy are more in these developed countries compared to many of the developing ones. This might have contributed to the present level of biomass conversion technologies, most of which are observed to be outdated, in developing countries such as those in sub-Sahara Africa. Improving on the available old bioenergy conversion technologies may not only be adequate for sustainable utilisation of renewable natural resources; there may be the need for adoption/adaptation of other recent research outputs geared toward optimal resource utilisation in this regard. Contributing to and application of improvements in biomass conversion technologies, such as gasification techniques, might assist in achieving this aim. This article was therefore conceived at highlighting information concerning biomass gasification in such a way as to sensitise the different stakeholders in research and developmental issues in developing countries where there are still challenges facing this sector. The language and presentation of the article was aimed at specifics avoiding too many technical details for the benefit of experts and non-experts alike. Andrew Agbontalor Erakhrumen Copyright © 2012 Andrew Agbontalor Erakhrumen. All rights reserved. Thu, 16 Aug 2012 13:33:54 +0000 http://www.hindawi.com/isrn/re/2012/385415/ We have fabricated bulk heterojunction organic solar cells using coumarin 6 (C6) as a small organic dye, for light harvesting and electron donating, with fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester (PCBM), acting as an electron acceptor, by spin-coating technique of the blend solutions. We have studied effect of PCBM concentration on photocurrent and performance parameters of the solar cells. We found that the optical absorption of the dye increased with increasing its concentration in the active layer blends. The higher concentrations of PCBM in active layer enhanced the photocurrent of the solar cells, as a result of improving charge carrier separation and electron transport in solar cell active layer. The improved charge carrier separation between C6, as a donor, and PCBM, as an acceptor, was indicated through the formation of bulk heterojunction by blending C6 with PCBM. The formation of C6:PCBM bulk heterojunction blend was confirmed through the symbatic behavior of the corresponding solar cell and, also, through the homogeneity and smoothing in the atomic force microscopy images of the C6:PCBM blend films. For the same reasons, the performance parameters of the C6:PCBM solar cell improved by modification of the PCBM concentration in the solar cell active layer. Yasser A. M. Ismail, T. Soga, and T. Jimbo Copyright © 2012 Yasser A. M. Ismail et al. All rights reserved. Thu, 16 Aug 2012 12:45:48 +0000 http://www.hindawi.com/isrn/re/2012/282538/ Applying solar collectors is a popular tool for harnessing solar energy. In this work, a flat plate solar air collector was investigated under direct solar radiation in an endeavor to enhance the thermal efficiency of solar air collector with a slatted glass cover, perforated absorber aluminum sheets (porosity 0.0177, 0.0314 and absorber thickness of 1.25, 2.5 mm) which is the most suitable for a solar dryer. The effects of porosity and thickness on absorber performance of collector were evaluated. Six levels of air mass flow rates (0.0056 to 0.0385 kg m−2 s−1) were adopted. The tests were conducted in three replications on very clear sky days in September and October. The experimental results showed that thermal efficiency of collector was increased by an increase in the porosity of the absorber. The absorber with lower porosity showed a better thermal efficiency at lower air mass flux. In the minimum air flow rate, absorber efficiency with porosity 0.0177 and 0.0314 was 0.31 and 0.29, respectively, whereas at the maximum flow, efficiency showed an enormous change of 0.83 and 0.88, respectively. This solar air heater can be used for drying agricultural products, heating the space of greenhouse, and so forth. Ali Zomorodian and Maryam Zamanian Copyright © 2012 Ali Zomorodian and Maryam Zamanian. All rights reserved.