Showing papers in "International Journal of Energy Research in 2014"

Study on using hydrogen and ammonia as fuels: Combustion characteristics and NOx formation

Abstract: This paper evaluates the potential of hydrogen (H-2) and ammonia (NH3) as carbon-free fuels The combustion characteristics and NOx formation in the combustion of H-2 and NH3 at different air-fuel equivalence ratios and initial H-2 concentrations in the fuel gas were experimentally studied NH3 burning velocity improved because of increased amounts of H-2 atom in flame with the addition of H-2 NH3 burning velocity could be moderately improved and could be applied to the commercial gas engine together with H-2 as fuels H-2 has an accelerant role in H-2-NH3-air combustion, whereas NH3 has a major effect on the maximum burning velocity of H-2-NH3-air In addition, fuel-NOx has a dominant role and thermal-NOx has a negligible role in H-2-NH3-air combustion Thermal-NOx decreases in H-2-NH3-air combustion compared with pure H-2-air combustion NOx concentration reaches its maximum at stoichiometric combustion Furthermore, H-2 is detected at an air-fuel equivalence ratio of 100 for the decomposition of NH3 in flame Hence, the stoichiometric combustion of H-2 and NH3 should be carefully considered in the practical utilization of H-2 and NH3 as fuels H-2 as fuel for improving burning performance with moderate burning velocity and NOx emission enables the utilization of H-2 and NH3 as promising fuels Copyright (C) 2014 John Wiley & Sons, Ltd

A review on selected heterogeneous photocatalysts for hydrogen production

Abstract: SUMMARY In this study, visible light-driven heterogeneous photocatalysts for hydrogen production are comparatively assessed based on technical, environmental, and cost criteria. The photocatalysis systems are compared with respect to their (i) rate of hydrogen generation per gram; (ii) rate of hydrogen generation per m2 of the specific surface area; and (iii) the band gap energy. The photocatalysis systems are also compared and discussed in terms of flammability, reactivity, and their impact on living systems' health. Furthermore, the costs of the required components of the photocatalysis systems are ranked. In addition to individual photocatalyst comparison, seven photocatalyst groups are ranked and compared. The results show that TiO2-C-362 and Ag0.03Mn0.40Cd0.60S show the highest in terms of µmol/h-gcat and µmol/h-m2cat, respectively, and TiO2-C-362 has the highest overall rankings. The Zn/In/S-based photocatalyst groups show the highest hydrogen production rate in terms of µmol/h-gcat and µmol/h-m2cat. Overall, Cd/S/Zn has the highest rankings when cost and health and environmental impact criteria are taken into account. Copyright © 2014 John Wiley & Sons, Ltd.

A review on PEDOT-based counter electrodes for dye-sensitized solar cells

Abstract: SUMMARY The dye-sensitized solar cell (DSSC) is a promising alternative for the Si solar cell due to its low-cost and easy fabrication. As a novel conductive polymer, poly(3,4-ethylenedioxythiophene) (PEDOT) has attracted much attention for DSSCs. In this review article, the progress of PEDOT-based counter electrodes for DSSCs is presented. First, the properties and structure of PEDOT are briefly described, and its feasibility as a DSSC counter electrode is demonstrated. Then, the effect of various treatments on the electrical conductivity and catalytic activity of PEDOT as well as its stability is examined. Furthermore, efficient and low-cost composite counter electrodes consisting of PEDOT and other materials are deeply discussed. Finally, an outlook for PEDOT counter electrodes is provided. Copyright © 2014 John Wiley & Sons, Ltd.

An overview of algae bioethanol production

Abstract: SUMMARY Because of rapid growth in population and industrialization, worldwide ethanol demand is increasing continuously. The first-generation and second-generation biofuels are unable to meet the global demand of bioethanol production because of their primary value of food and feed. Therefore, algae are among the most potentially significant sources of sustainable biofuels in the future of renewable energy because of the accumulating high starch/cellulose and because they are widely distributed in nature. The focus of this paper is to review the production and recent advances in research and development in the algae bioethanol, including pretreatment, hydrolysis, and fermentation of algae biomass. Despite the many developments made in the recent years, commercialization of algal bioethanol remains challenging chiefly because of the techno-economic constraints. Technological breakthroughs in all major aspects must be overcome before it can be a successfully large-scale and commercialized product. Copyright © 2014 John Wiley & Sons, Ltd.

Energy and exergy analyses of five conventional liquefied natural gas processes

Abstract: SUMMARY In this paper, five conventional LNG processes were investigated by energy and exergy analysis methods. On the basis of the energy analysis, three-stage process of Linde AG and Stat oil (mixed fluid cascade [MFC]) has less energy consumption than the other ones (0.254 kWh/kg liquefied natural gas). Also, coefficient of performance of the cycles of this process is higher compared with the other ones. Exergy analysis results showed that the maximum exergy efficiency is related to the MFC process (51.82%). However, performance of the MFC process in terms of quality and quantity of energy consumption is considerable. But using three cycles in this process needs more components and consequently more fixed costs. In this study, sensitivity of coefficient of performance, specific energy consumption, and indexes of exergy analysis were also analyzed versus important operating variables for all cases. Copyright © 2014 John Wiley & Sons, Ltd.

An overview of unsolved deficiencies of direct methanol fuel cell technology: factors and parameters affecting its widespread use

Abstract: SUMMARY Direct methanol fuel cells (DMFCs) have evolved over the years as a potential candidate for application as a power source in portable electronic devices and in transportation sectors They have certain associated advantages, including high energy and power densities, ease of fuel storage and handling, ability to be fabricated with small size, minimum emission of pollutants, low cost, ready availability of fuel and solubility of fuel in aqueous electrolytes However, in spite of several years of active research involved in the development of DMFC technology, their chemical-to-electrical energy conversion efficiencies are still lower compared with other alternative power sources traditionally used This review paper will focus on the existing issues associated with DMFC technology and will also suggest on the possible developmental necessities required for this technology to realize its practical potentials Copyright © 2014 John Wiley & Sons, Ltd

Nanofluids with encapsulated tin nanoparticles for advanced heat transfer and thermal energy storage

Abstract: SUMMARY Novel high-temperature heat transfer fluids (HTFs) with incorporated phase change nanomaterials were synthesized and tested for heat transfer and thermal energy storage. The advanced thermal properties were achieved by preparing a nanofluid consisting of core/shell silica encapsulated tin (Sn/SiO2) nanoparticles dispersed in a synthetic HTF Therminol 66 (TH66) at loadings up to 5 vol%. Tin nanoparticles were synthesized by modified polyole reduction method followed by sol–gel silica encapsulation process. The measured increase in thermal conductivity of the nanofluid (~13% at 5 vol%) was in agreement with Maxwell's effective medium theory. Latent heat of phase change during melting of Sn core added ~11% increase to the volumetric thermal energy storage of the nanofluid when cycled in between 100°C and 270°C. The value could be further improved if thermal cycling is conducted in a narrower temperature range. The experimental results demonstrated dual functionality of the engineered nanofluids as desired for Concentrated Solar Power systems. Viscosity and stability of the nanofluids as well as thermal stability of core/shell nanomaterials) were investigated in a wide temperature range to obtain a perspective on any additional pumping power requirements for the nanofluid over the base fluid. Copyright © 2013 John Wiley & Sons, Ltd.

Heat generation in high power prismatic Li-ion battery cell with LiMnNiCoO2 cathode material

Abstract: SUMMARY While in use, battery modules and battery packs generate large amounts of heat, which needs to be accounted for. The main challenge in battery thermal management is the correct estimation of heat generation in the battery cell during charging/discharging. In this paper, a method to calculate accurate heat generation in one individual cell is provided. The heat generation is calculated by measuring the overpotential resistances with four different methods and entropic heat generation in the cell. The effect and contribution of entropic heat generation towards the total heat generation in the cell are also calculated and measured. Finally, calorimeter tests are carried out to compare the calculated and measured heat generation. The results indicate that except for direct current resistance measured by impedance spectroscopy, all the overpotential resistances are very close to each other. Copyright © 2014 John Wiley & Sons, Ltd.

Application of extreme learning machine for estimating solar radiation from satellite data

Abstract: SUMMARY In this paper, a simple and fast method based on extreme learning machine (ELM) for the estimation of solar radiation in Turkey was presented. To design the ELM model, satellite data of the National Oceanic and Atmospheric Administration advanced very high-resolution radiometer from 20 locations spread over Turkey were used. The satellite-based land surface temperature, altitude, latitude, longitude, month, and city were applied as input to the ELM, and the output variable is the solar radiation. To show the applicability of the ELM model, a performance comparison in terms of the estimation capability and the learning speed was made between the ELM model and conventional artificial neural network (ANN) model with backpropagation. The comparison results showed that the ELM model gave better estimation than the ANN model for the overall test locations. Moreover, the ELM model was about 23.5 times faster than the ANN model. The method could be used by researchers or scientists to design high-efficiency solar devices such as solar power plant and photovoltaic cell. Copyright © 2013 John Wiley & Sons, Ltd.

A review on carbon nanotube/polymer composites for organic solar cells

Abstract: SUMMARY Carbon nanotubes (CNTs) have unique properties, such as their electrical conductivity, that enable them to be combined with conducting polymers to form composites for use in organic solar cells (OSCs). It is envisaged that the improved composite has a higher efficiency of green energy and will reduce the cost of these cells. The use of such alternative energy sources also drastically reduces overuse of fossil fuels and consequently limits environmental degradation. This review compares research and performance between conventional silicon solar cells and OSCs. It also discusses OSC photoexcitation and charge carrier generation with the incorporation of CNTs, physicochemical properties of the composites and other factors that affect the efficiencies of OSCs. In addition, properties of CNTs that favour their dispersion in polymer matrices as acceptors and charge carriers to the electrodes are covered. The effects of CNTs containing dopants, such as nitrogen and boron, on charge transfer are discussed. Also, the fabrication techniques of OSCs that include CNT/polymer composite processing and the methods of film deposition on the substrate are described. Finally, the case studies of OSCs containing polymers with single-walled CNTs, double-walled CNTs or multi-walled CNTs are evaluated. Copyright © 2014 John Wiley & Sons, Ltd.

Thermal analysis of high-power lithium-ion battery packs using flow network approach

Abstract: SUMMARY High-power applications of lithium-ion batteries require efficient thermal management systems. In this work, a lumped capacitance heat transfer model is developed in conjunction with a flow network approach to study performance of a commercial-size lithium-ion battery pack, under various design and operating conditions of a thermal management system. In order to assess the battery thermal management system, capabilities of air, silicone oil, and water are examined as three potential coolant fluids. Different flow configurations are considered, and temperature dispersions, cell-averaged voltage distributions, and parasitic losses due to the fan/pump power demand are calculated. It is found that application of a coolant with an appropriate viscosity and heat capacity, such as water, in conjunction with a flow configuration with more than one inlet will result in uniform temperature and voltage distributions in the battery pack while keeping the power requirement at low, acceptable levels. Simulation results are presented and compared with literature for model validation and to show the superior capability of the proposed battery pack design methodology. Copyright © 2014 John Wiley & Sons, Ltd.

Development and application of vanadium oxide/polyaniline composite as a novel cathode catalyst in microbial fuel cell

Abstract: SUMMARY Polyaniline (Pani), vanadium oxide (V2O5), and Pani/V2O5 nanocomposite were fabricated and applied as a cathode catalyst in Microbial Fuel Cell (MFC) as an alternative to Pt (Platinum), which is a commonly used expensive cathode catalyst. The cathode catalysts were characterized using Cyclic Voltammetry and Linear Sweep Voltammetry to determine their oxygen reduction activity; furthermore, their structures were observed by X-ray Diffraction, X-ray Photoelectron Spectroscopy, Brunauer–Emmett–Teller, and Field-Emission Scanning Electron Microscopy. The results showed that Pani/V2O5 produced a power density of 79.26 mW/m2, which is higher than V2O5 by 65.31 mW/m2 and Pani by 42.4 mW/m2. Furthermore, the Coulombic Efficiency of the system using Pani/V2O5 (16%) was higher than V2O5 and Pani by 9.2 and 5.5%, respectively. Pani–V2O5 also produced approximately 10% more power than Pt, the best and most common cathode catalyst. It declares that Pani–V2O5 can be a suitable alternative for application in a MFC system. Copyright © 2013 John Wiley & Sons, Ltd.

Impact of choice of CO2 separation technology on thermo-economic performance of Bio-SNG production processes

Abstract: Three different CO2 separation technologies for production of synthetic natural gas (SNG) from biomass gasification – amine-based absorption, membrane-based separation and pressure swing adsorption – are investigated for their thermo-economic performance against the background of different possible future energy market scenarios. The studied scale of the SNG plant is a thermal input of 100 MWth,LHV to the gasifier at a moisture content of 20 wt-% with a preceding drying step reducing the biomass' natural moisture content of 50 wt-%. Preparation of the CO2-rich stream for carbon capture and storage is investigated for the amine-based absorption and the membrane-based separation technology alternatives. The resulting cold gas efficiency ηcg for the investigated process alternatives ranges between 0.65 and 0.695. The overall system efficiency ηsys ranges from 0.744 to 0.793, depending on both the separation technology and the background energy system. Amine-based absorption gives the highest cold gas efficiency whereas the potential for cogeneration of electricity from the process' excess heat is higher for membrane-based separation and pressure swing adsorption. The estimated specific production costs for SNG cSNG for a process input of 90.3 MWth,LHV at 50 wt-% moisture vary between 103–127 €2010/MWhSNG. The corresponding production subsidy level csubsidy needed to achieve end-user purchase price-parity with fossil natural gas is in the range of 56–78 €2010/MWhSNG depending on both the energy market scenario and the CO2 separation technology. Sensitivity analysis on the influence of changes in the total capital cost for the SNG plant on the production cost indicates a decrease of about 12% assuming a 30% reduction in total capital investment. Capture and storage of biogenic CO2 – if included in the emission trading system – only becomes an option at higher CO2 charges. This is due to increased investment costs but, in particular, due to the rather high costs for CO2 transport and storage that have been assumed in this study.

Energy harvesting system using reverse electrodialysis with nanoporous polycarbonate track-etch membranes

Abstract: SUMMARY Energy harvesting technology has recently gained attraction as it enables the utilization of diverse ambient energy sources. Reverse electrodialysis (RED) is such a technique that converts electrical energy from the concentration gradient between a concentrated solution (e.g., seawater) and a diluted solution (e.g., fresh water). We experimentally investigated a RED device using nanoporous polycarbonate track-etch membranes. We performed the parametric study by varying the concentration differences, the pore size, and the electrolyte types. We characterized the RED performance in terms of maximum voltage, maximum current, and maximum power. The experimental results showed that the maximum voltage has a nonlinear dependency on the concentration difference with the highest value around the 100:1 concentration ratio. The maximum current and maximum power, on the other hand, monotonically increase as the concentration difference increases. We also found that the performance of the RED cell is enhanced with the decreased pore size in the experiments for the nominal diameter ranging from 15 to 100 nm. The results with different cations show that the electricity generation of the RED cell increases as the ion mobility increases or the valence number decreases. Copyright © 2013 John Wiley & Sons, Ltd.

Vacuum insulated panels for sustainable buildings: a review of research and applications

Abstract: New research has identified vacuum insulation panels (VIPs) as highly efficient insulators for use in building construction. They are reported to be several times more effective than conventional materials of a similar thickness in terms of thermal conductivity. Because of their smaller space requirement, VIPs maximize the internal usage area of buildings and so reduce the cost of construction. There are however some obstacles that have hindered the application of VIPs, notably their high cost, susceptibility to perforation and the long-term water and gas effects that worsen their performance. This paper reviews the contemporary research on VIP as a state-of-the-art material for building insulation. The main components and physical principles of VIP performance are discussed. Finally, the review of VIPs available on the market and their performance is provided.

Forecasting electricity price and demand using a hybrid approach based on wavelet transform, ARIMA and neural networks

Abstract: SUMMARY Demand and price forecasting are extremely important for participants in energy markets. Most research work in the area predicts demand and price signals separately. In this paper, a model is presented which predicts electricity demand and price simultaneously. The model combines wavelet transforms, ARIMA models and neural networks. Both time domain and wavelet domain variables are considered in the feature set for price and demand forecasting. The best input set is selected by two-step correlation analysis. The proposed model is better adapted to real conditions of an energy market since the forecast features for price and demand are not assumed as known values but are predicted by the model, thus accounting for the interactions of the demand and price forecast processes. The forecast accuracy of the proposed method is evaluated using data from the Finnish energy market, which is part of the Nordic Power Pool. The results show that the proposed model provides significant improvement in both demand and price prediction accuracy compared with models using a separate frameworks approach. Copyright © 2013 John Wiley & Sons, Ltd.

Latent heat energy storage characteristics of building composites of bentonite clay and pumice sand with different organic PCMs

Abstract: SUMMARY In the present work, six new kinds of building composite PCMs (BCPCMs), PS/octadecane, BC/octadecane, PS/CA–MA, BC/CA–MA, PS/PEG1000, and BC/PEG1000 composites, were prepared by using vacuum impregnation method. The maximum percent of PCM in the composites was assigned to be 12, 13, 18, 23, 30, and 42 wt%, respectively. The form-stable BCPCMs were characterized using SEM, FT-IR, DSC, and TG analysis techniques. The characterization results showed the existence of homogenous dispersion of the PCM into the PBM matrixes. The DSC measurements indicated that the melting temperatures of the form-stable BCPCMs are in the range of 20–33°C while they have latent heats of melting in the range of about 28–55 J/g. These results make them promising BCPCMs for low temperature-passive TES applications in buildings. Thermal cycling test indicated that the prepared BCPCMs have good thermal reliability and chemical stability. TG analysis proved that the prepared BCPCMs have good thermal durability. In addition, the thermal conductivity of BCPCMs was enhanced considerably by addition of expanded graphite (EG). The improvement in thermal conductivity of the BCPCMs caused appreciably reduction in their melting times. Copyright © 2014 John Wiley & Sons, Ltd.

Comparison of oil extraction methods, energy analysis and biodiesel production from flax seeds

Abstract: In recent years, the commercial potential of oil extraction and biodiesel production derived from vegetable seed is being realized. The process energy input requirements are important factors in oil extraction and biodiesel production. This research work investigated oil extraction from flax seeds and compared extraction yield with the energy load. The effect of moisture content on the oil yield was compared between a mechanical oil expeller, organic solvent extraction, organic solvent and microwave assisted, organic solvent and ultrasonic assisted, and combined microwave and ultrasonic with organic solvent. The maximum oil yields % wt/wt from these techniques was 22.6%, 36.3%, 10.0%, 42.0% and 27.8%, respectively. The moisture content had a significant effect on oil yield with the mechanical oil expeller, organic solvent method and ultrasonic assisted extraction, whereas no or little effect was found on microwave-assisted extraction. The microwave-assisted extraction showed better results compared with the ultrasonic-assisted and combined treatment methods. The relative energy consumption of these processes was experimentally investigated; energy ratios were calculated based on the amount of energy recovered to the amount of energy supplied to the flax seed for oil extraction. The net energy ratios showed that microwave-assisted extraction had the highest (25.21%), followed by organic solvent method (14.04%), ultrasonic method (6.33%) and lowest was with combined ultrasonic and microwave assisted treatment (5.73%). These results showed that flax seed oil can be extracted using microwave-assisted methods efficiently and in an energy feasible manner. In situ ultrasonic transesterification was applied to powdered samples with 4%, 8% and 12% moisture content (on % dry basis) within an ultrasonic bath having an intensity of 0.124 W/cm2. The flax seed biodiesel produced showed a highest conversion yield of 93%, and the effect of different moisture content on the yield showed that 4% moisture content sample produced the greatest biodiesel yield.

Design of an energy hub based on natural gas and renewable energy sources

Abstract: SUMMARY This paper presents a simulation model for an energy hub consisting of natural gas (NG) turbines as the main sources of energy (including both electricity and heat) and two renewable energy sources—wind turbines (WTs) and photovoltaic (PV) solar cells The hub also includes water electrolyzers for hydrogen production The hydrogen serves as an energy storage medium that can be used in some transportation applications, or it can be mixed with the NG feed stream to improve the emission profile of the gas-turbine unit The capacity of the designed hub is meant to simulate and replace the coal-fired Nanticoke Generating Station with a NG-fired power plant Therefore, the aim of this work is to develop a simulated model that combines different energy generation technologies, which are evaluated in terms of the total energy produced, the cost per kWh of energy generated, and the amount of emissions produced The proposed model investigates the benefits, both economic and environmental, the technological barriers, and the challenges of energy hubs by developing several scenarios The simulation of these scenarios was done using General Algebraic Modeling System (GAMS®) Although the software is strongly known for its optimization capability, the mixed complementary problems solver makes it a strong tool for solving equilibrium problems Excess energy produced during off-peak demand by WTs and PV solar cells was used to feed the electrolyzer to produce H2 and O2 The proposed approach shows that a significant reduction in energy cost and greenhouse gas emissions were achieved, in addition to the increased overall efficiency of the energy hub Out of the examined three scenarios, Scenario C appeared to be the most feasible option for a combination of renewable and non-renewable technologies as it did not only produce hydrogen, but also provided electricity at relatively lower prices Copyright © 2013 John Wiley & Sons, Ltd

Forecasting aggregated wind power production of multiple wind farms using hybrid wavelet-PSO-NNs

Abstract: SUMMARY This paper describes the problem of short-term wind power production forecasting based on meteorological information. Aggregated wind power forecasts are produced for multiple wind farms using a hybrid intelligent algorithm that uses a data filtering technique based on wavelet transform (WT) and a soft computing model (SCM) based on neural network (NN), which is optimized by using particle swarm optimization (PSO) algorithm. To demonstrate the effectiveness of the proposed hybrid intelligent WT + NNPSO model, which takes into account the interactions of wind power, wind speed, wind direction, and temperature in the forecast process, the real data of wind farms located in the southern Alberta, Canada, are used to train and test the proposed model. The test results produced by the proposed hybrid WT + NNPSO model are compared with other SCMs as well as the benchmark persistence method. Simulation results demonstrate that the proposed technique is capable of performing effectively with the variability and intermittency of wind power generation series in order to produce accurate wind power forecasts. Copyright © 2014 John Wiley & Sons, Ltd.

Enhanced performance of direct methanol fuel cells: a study on the combined effect of various supporting electrolytes, flow channel designs and operating temperatures

Abstract: SUMMARY Establishing a better coordination between operating parameters and flow channel design is one of the most critical factors in achieving an optimum final performance of a fuel cell, since even a marginal change in any of the parameters can sharply affect the cell's performance. In this study, we report the use of three different acids, viz. sulphuric acid (H2SO4), formic acid (HCOOH) and phosphoric acid (H3PO4) as supporting electrolytes in combination with 2 M methanol fuel, wherein we demonstrated the effects of different combinations of acidic fuels and channel designs on the final cell performance. For this purpose, we made use of four different types of serpentine flow design. In the process, it was observed that an addition of 2 M concentrations of H2SO4 and H3PO4 enhanced the cell performance sharply in terms of current density, reaching values of 210 mAcm−2 and 180 mAcm−2, respectively, when analyzed at 0.2 V potential. This result was a considerable improvement over the current density value of 90 mAcm−2 achieved while using only 2 M methanol analyzed at the same potential. Moreover, the open-circuit voltage showed a value of greater than 0.6 V for both fuel samples. With a flow channel length of 650 mm (A5SF2) and at an open ratio of 52%, we obtained maximum power values of 42 mWcm−2 and 36 mWcm−2 for fuels containing 2 M H2SO4 (M2S2) and 2 M H3PO4 (M2P2), respectively, when analyzed at 70°C. Copyright © 2013 John Wiley & Sons, Ltd.

An investigation of thermal behaviour of biomass and coal during copyrolysis using thermogravimetric analysis

Abstract: SUMMARY The biomass, coal and their blends at blending ratios (biomass : coal) of 95:5, 90:10, 85:15 and 80:20 were pyrolysed under a nitrogen environment at four different heating rates comprising 5°C, 10°C, 15°C and 20°C per minute to investigate their pyrolytic behaviour and to determine kinetic parameters of thermal decomposition through Kissinger's corrected kinetic equation using the thermogravimetric analysis results. In the kinetic analysis, the activation energy of both types of biomass was less than that of coal, being 168.7 kJ/mol (cypress wood chips), 164.6 kJ/mol (macadamia nut shells) and 199.6 kJ/mol (Australian bituminous coal). The activation energy of the blends of biomass and coal followed that of the weighted average of the individual samples in the blends. Char production of the samples and the blends was also analysed to observe any synergetic effects and thermal interaction between biomass and coal. The char production of the blends corresponded to the sum of the results for the individual samples with the coefficient of determination of 0.999. Thermal decomposition of biomass and coal appeared to take place independently, and thus, the activation energy of the blends can be calculated from that of the two components. There was no evidence for any significant synergetic effects and thermal interaction between either type of biomass and coal during copyrolysis. Copyright © 2013 John Wiley & Sons, Ltd.

Oxy–steam gasification of biomass for hydrogen rich syngas production using downdraft reactor configuration

Abstract: SUMMARY The paper focuses on the use of oxygen and steam as the gasification agents in the thermochemical conversion of biomass to produce hydrogen rich syngas, using a downdraft reactor configuration. Performance of the reactor is evaluated for different equivalence ratios (ER), steam to biomass ratios (SBR) and moisture content in the fuel. The results are compared and evaluated with chemical equilibrium analysis and reaction kinetics along with the results available in the literature. Parametric study suggests that, with increase in SBR, hydrogen fraction in the syngas increases but necessitates an increase in the ER to maintain reactor temperature toward stable operating conditions. SBR is varied from 0.75 to 2.7 and ER from 0.18 to 0.3. The peak hydrogen yield is found to be 104 g/kg of biomass at SBR of 2.7. Further, significant enhancement in H2 yield and H2 to CO ratio is observed at higher SBR (SBR = 1.5–2.7) compared with lower range SBR (SBR = 0.75–1.5). Experiments were conducted using wet wood chips to induce moisture into the reacting system and compare the performance with dry wood with steam. The results clearly indicate the both hydrogen generation and the gasification efficiency (ηg) are better in the latter case. With the increase in SBR, gasification efficiency (ηg) and lower heating value (LHV) tend to reduce. Gasification efficiency of 85.8% is reported with LHV of 8.9 MJ Nm−3 at SBR of 0.75 compared with 69.5% efficiency at SBR of 2.5 and lower LHV of 7.4 at MJ Nm−3 at SBR of 2.7. These are argued on the basis of the energy required for steam generation and the extent of steam consumption during the reaction, which translates subsequently in the LHV of syngas. From the analysis of the results, it is evident that reaction kinetics plays a crucial role in the conversion process. The study also presents the importance of reaction kinetics, which controls the overall performance related to efficiency, H2 yield, H2 to CO fraction and LHV of syngas, and their dependence on the process parameters SBR and ER. Copyright © 2013 John Wiley & Sons, Ltd.

Identification of reservation capacity in critical peak pricing electricity demand response program for sustainable manufacturing systems

Abstract: SUMMARY Electricity demand response is considered an effective approach to balance the electricity demand and supply with existing infrastructure of generation, transmission, and distribution. A majority of existing literature on the electricity demand response has mainly centered on the commercial and residential building sectors while the application for the industrial sector is largely neglected. This paper presents a methodology for the application of a typical demand response program, Critical Peak Pricing (CPP) program, for the manufacturing enterprises. The configuration of the reservation capacity (in kilowatt, kW) in the CPP program, which plays a critical role in the cost of the final bill charge, will be identified by optimal production scheduling for the typical manufacturing systems with multiple machines and buffers. Mixed Integer Nonlinear Programming formulation is used to establish the mathematical model with the objective to minimize the electricity bill cost as well as the potential penalty cost due to the non-fulfillment of the target production. An approximate technique is introduced to find a near optimal solution, and a numerical case study is used to illustrate the effectiveness of the proposed method. Copyright © 2013 John Wiley & Sons, Ltd.

Production characterization and efficiency of biodiesel: a review

Abstract: Vegetable oil is one of the main first generation liquid biofuels. The fuel characteristics of vegetable oil such as viscosity and atomization cannot be accommodated by existing diesel engines. An alternate process has been developed to improve the fuel characteristics of vegetable oils through the process of alcoholysis to produce a fuel called biodiesel. It can be used in engines as substitute for fossil fuel. This paper reviews the characteristics of different oils available for biodiesel production and the production technologies, engine performance using vegetable oil and biodiesel, and emission studies. Copyright (C) 2014 John Wiley a Sons, Ltd.

The role of renewable and sustainable energy in the energy mix of Malaysia: a review

Abstract: Energy consumption has risen in Malaysia because of developing strategies and increasing rate of population. Depletion of fossil fuel resources, fluctuation in the crude oil prices, and emersion of new environmental problems due to greenhouse gasses effects of fossil fuel combustion have convinced governments to invest in development of power generation based on renewable and sustainable energy (RSE) resources. Recently, power generation from RSE resources has been taken into account in the energy mix of every country to supply the annual electricity demand. In this paper, the scenario of the energy mix of Malaysia and the role of RSE resources in power generation are studied. Major RSE sources, namely biomass and biogas, hydro-electricity, solar energy, and wind energy, are discussed, focusing more toward the electrical energy demand for electrification. It is found that power generation based on biomass and biogas utilization, solar power generation, and hydropower has enough spaces for more development in Malaysia. Moreover, mini hydropower and wind power generation could be effective for rural regions of Malaysia.

Techno-economic optimization of hybrid power system using genetic algorithm

Abstract: SUMMARY This paper presents an optimum sizing methodology to optimize the hybrid energy system (HES) configuration based on genetic algorithm. The proposed optimization model has been applied to evaluate the techno-economic prospective of the HES to meet the load demand of a remote village in the northern part of Saudi Arabia. The optimum configuration is not achieved only by selecting the combination with the lowest cost but also by finding a suitable renewable energy fraction that satisfies load demand requirements with zero rejected loads. Moreover, the economic, technical and environmental characteristics of nine different HES configurations were investigated and weighed against their performance. The simulation results indicated that the optimum wind turbine (WT) selection is not affected only by the WT speed parameters or by the WT rated power but also by the desired renewable energy fraction. It was found that the rated speed of the WT has a significant effect on optimum WT selection, whereas the WT rated power has no consistent effect on optimal WT selection. Moreover, the results clearly indicated that the HES consisting of photovoltaics (PV), WT, battery bank (Batt) and diesel generator (DG) has superiority over all the nine systems studied here in terms of economical and environmental performance. The PV/Batt/DG hybrid system is only feasible when wind resource is very limited and solar energy density is high. On the other hand, the WT/Batt/DG hybrid system is only feasible at high wind speed and low solar energy density. It was also found that the inclusion of batteries reduced the required DG and hence reduced fuel consumption and operating and maintenance cost. Copyright © 2014 John Wiley & Sons, Ltd.

Short-term load forecasting based on support vector regression and load profiling

Abstract: SUMMARY The article proposes a methodology to forecast the electric load for the 24 h of the following day based on support vector regression. The study considers 24 distinct models, one for each predicted hour, where each individual model is treated independently. Its objective is to find the optimal combination of support vector machine parameters that could generalize low forecasting errors, using simulated annealing as a metaheuristic. The adopted methodology is compared to concurrent methods based on neural networks when applied to a simulated load diagram (to illustrate a distribution feeder supplying a sample of 740 consumers). The results have proven its effectiveness with mean absolute percentage errors being less than 5% for testing samples. The study also focuses on evaluating the potential benefits of adopting load profiling information as input in support vector regression, giving a consistent proof of its importance. Copyright © 2013 John Wiley & Sons, Ltd.

Effects of magnetic field and pulse potential on hydrogen production via water electrolysis

Abstract: This experiment uses nickel electrodes and adds pulse potential and magnetic force when producing hydrogen via water electrolysis and explores how related parameters are affected by magnetohydrodynamics and pulse potential. Experiments showed that the Lorentz force of the magnetic field changes the direction of convective flow of the electrolyte, which affects the flow of bubbles during electrolysis. Adding a magnetic field increases the rate of current density by roughly 15% under a normal temperature, a distance of 2mm between electrodes and a potential of 4V. Pulse potential instantaneously increases current and accelerates both the movement of bubbles from the electrode surface and the mass transfer rate in the electrolyte, which lowers electrochemical polarization in the diffussion layer and further increases hydrogen production efficiency. When the duty cycle is 10% and the pulse on-time is 10ms, almost 88% of overall power is converted, and current density increases by 680mA/cm, which is an increase of roughly 38%. Generally, pulse potential and magnetic field effects enhance each other when added under suitable pulse potential and basic potential. Copyright © 2013 John Wiley & Sons, Ltd.