Vasundhara Sen
Abstract
India seeks to achieve 175 Giga-Watt (GW) of Renewable power by 2022. As of December 2017, out of 333 GW of total installed capacity of electricity, close to 62GW come from renewable sources. Meeting the set targets calls for augmentation of renewable energy based capacities as expeditiously as possible. ...
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India seeks to achieve 175 Giga-Watt (GW) of Renewable power by 2022. As of December 2017, out of 333 GW of total installed capacity of electricity, close to 62GW come from renewable sources. Meeting the set targets calls for augmentation of renewable energy based capacities as expeditiously as possible. However, the sick financial health of the distribution companies/utilities, who act as the primary purchasing authorities of such power, is posing as a threat to the success of the renewable industry. This paper highlights that while the cost of procurement of renewable power, to the utilities, has gone down significantly in the recent past; the worsening financial health of utilities remains a key concern. Data is presented to substantiate that the said distribution companies/utilities are saddled by high gaps between Average Cost of Supply (ACS) and Average Revenue Requirement (ARR). Revenues to the power supplying utilities are under-recovered due to the long standing practice of cross- subsidization in the Indian power sector – agricultural and residential consumers of electricity consume power at lower tariffs, than commercial and industrial consumers. A case is therefore suggested for implementing evidence based tariff setting by the utilities. Under the suggested framework, electricity tariffs for different consumer categories can be charged with a premium for green power, based on their willingness to pay for such power. Collected funds, then can be used towards purchase of green power, by the said utilities, and consequently help foster the development of green energy in the country. This study also presents limited empirical evidence, recording the willingness to pay for such premiums, across different categories of “paying” consumers.
Renewable Energy Resources and Technologies
Hediyeh Safari; Fateme Ahmadi Boyaghchi
Abstract
This research is concerned with the design and analysis of a geothermal based multi-generation system by applying both conventional and advanced exergy and exergoeconomic concepts. The proposed energy system consists of a dual-organic Rankine cycle (ORC) to vaporize liquefied natural gas (LNG) and produce ...
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This research is concerned with the design and analysis of a geothermal based multi-generation system by applying both conventional and advanced exergy and exergoeconomic concepts. The proposed energy system consists of a dual-organic Rankine cycle (ORC) to vaporize liquefied natural gas (LNG) and produce electricity. A proton exchange membrane(PEM) electrolyzer is employed to produce hydrogen by receiving the power and coolant heat waste of dual ORC. Moreover, cooling effect is produced during LNG regasification by utilizing the cryogenic energy of LNG. Parametric studies are conducted to assess the effects of substantial input parameters, namely turbine 1 inlet pressure, mass rate of upper cycle, geothermal mass flow rate, on the various parts of exergy destruction and cost rates within the major components.
Gholam Reza Arab Markadeh; Nasrin Banimehdi
Abstract
This paper proposes an improved direct active and reactive power control (DPC) strategy for a grid-connected doubly fed induction generator (DFIG) based wind-turbine system under unbalanced grid voltage condition. The method produces required rotor voltage references based on the sliding mode control ...
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This paper proposes an improved direct active and reactive power control (DPC) strategy for a grid-connected doubly fed induction generator (DFIG) based wind-turbine system under unbalanced grid voltage condition. The method produces required rotor voltage references based on the sliding mode control (SMC) approach in stationary reference frame, without the requirement of synchronous coordinate transformation, and therefore causes a simpler design for power control system. Under unbalanced grid voltage condition, two control targets obtained simultaneously, i.e., removing stator active and reactive power oscillations. Moreover this method reduces the THD of stator current. Also it is shown that the proposed control method not only has a high-speed dynamic response but is stable during wind speed and system parameters variations. Simulation results for a 2kw DFIG confirm prominence of proposed control strategy.
Renewable Energy Economics, Policies and Planning
Masoud Rezaei; Alireza Boushehri; Naser Bagheri Moghaddam
Abstract
Using a variety of solar power plants is one of the solutions governments use to respond to energy and sustainable development needs. While Iran has a strong potential for using solar energy, the application of solar energy, especially through PV technology, has been limited due to the country’s ...
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Using a variety of solar power plants is one of the solutions governments use to respond to energy and sustainable development needs. While Iran has a strong potential for using solar energy, the application of solar energy, especially through PV technology, has been limited due to the country’s richness of fossil fuels and their low prices. Therefore, it is important to adopt effective strategies and policies to promote the development and application of this technology. The purpose of this study is to identify factors affecting the use of photovoltaic technology in Iran. To this end, 142 factors were first identified through a comprehensive review of the literature. Then, all of these factors were prioritized and categorized by “semi-structured interview” with 15 energy policy experts. The “content analysis” of the experts’ opinions showed that only 59 of these factors were considered important at the sectorial level for Iran. Based on the same content analysis, a conceptual framework for the application of decentralized photovoltaic power plants in Iran was developed. The framework shows that 10 generic categories of factors should be considered by policy-makers at the solar energy sector to promote PV technology application in Iran. They include policy factors, institutional factors, finance and budgeting factors, system economy factors, macroeconomic factors, socio-cultural factors, human resource factors, factors influencing capabilities of industries, technological and related infrastructural factors, geographical, climatic and environmental factors, and foreign political factors. It is also emphasized that all these categories should be considered at three levels: industry (electricity industry) level, national level, and international level. Thus, renewable energy policy-makers in Iran should take into account all means that influence these factors in order to improve the conditions for decentralized photovoltaic technology application.
Advanced Energy Technologies
Maryam Rahmani; Faramarz Faghihi; Hassan Moradi CheshmehBeigi; Seyed Mehdi Hosseini
Abstract
In this paper, the effect of a static synchronous compensator (STATCOM) influence on the frequency of islanded microgrids based on frequency control using fuzzy cooperative control is investigated. To achieve fast frequency control, instantaneous power balance between generation and consumption is inevitable, ...
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In this paper, the effect of a static synchronous compensator (STATCOM) influence on the frequency of islanded microgrids based on frequency control using fuzzy cooperative control is investigated. To achieve fast frequency control, instantaneous power balance between generation and consumption is inevitable, and it can be supplied through energy storage systems such as battery with a proper frequency control method. Besides, the frequency control of islanded microgrids could be studied under different circumstances, where one aspect analyzed is added to a flexible AC transmission system (FACTS) device, such as STATCOM, in the microgrids. Although STATCOM is charged with improving the voltage profile, it can affect frequency stability by adjusting the voltage very quickly. Due to the importance of refining frequency stability, two controller methods are compared: a classic PI controller and a fuzzy PID controller. Accordingly, the performance of STATCOM is evaluated via two scenarios. Based on simulation results, by applying the fuzzy PID controller to the microgrid, STATCOM can reach the nominal frequency. Moreover, with greater validation and investigation of this topic, this device could be an agreeable alternative to the battery energy storage system (BESS).
Renewable Energy Resources and Technologies
Payam Ghorbannezhad; Behnam Dehbandi; Imtiaz Ali
Abstract
Furandicarboxylic acid (FDCA) is recognized as a valuable product of hydroxymethylfurfural (HMF) derived from cellulosic materials as an abundant renewable source. It could find future bioplastic application if a feasible separation process is developed. To find a commercially available solvent, FDCA ...
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Furandicarboxylic acid (FDCA) is recognized as a valuable product of hydroxymethylfurfural (HMF) derived from cellulosic materials as an abundant renewable source. It could find future bioplastic application if a feasible separation process is developed. To find a commercially available solvent, FDCA should be selectively separated from HMF and the downstream process be supported by pyrolysis-gas chromatography-mass spectrometry experiments in line with density functional theory (DFT). Evaluation of the sigma potential and sigma surface analysis demonstrated that benzene and ethyl acetate enjoyed better extraction and HMF selectivity, whereas FDCA exhibited ideal behavior in the presence of DMF and DMSO solvents. It was proved that the hydrophobicity could be changed by improving the hydrogen-bonding interaction between them. Moreover, the up-down selection of classes of solvents based on the experimental data found by GC-MS revealed that polar molecular solvents (ethanol-water) were more compatible with carboxylic acids and alcohol compounds, while n-hexane was a desirable solvent for phenolic compounds. It was found that levoglucosan retained a significant fraction of water compared to other solvents, which need to be considered for further economic and environmental analysis under the multifaceted framework of biomass-derived products.
Environmental Impacts and Sustainability
Laleh R. Kalankesh; Mohammad Ali Zazouli; Ahmad Mansouri
Abstract
Water scarcity is a critical issue in Caspian Sea regions of Iran. Thus, people may use polluted water or saline brackish groundwater, estuarine water or seawater. This paper deals with the application of Low-Pressure reverse osmosis (RO) for removing salt and Total Organic Carbon (TOC) in synthetic ...
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Water scarcity is a critical issue in Caspian Sea regions of Iran. Thus, people may use polluted water or saline brackish groundwater, estuarine water or seawater. This paper deals with the application of Low-Pressure reverse osmosis (RO) for removing salt and Total Organic Carbon (TOC) in synthetic and Caspian Sea waters. The study aims to achieve optimization at different pressures (30, 50, 70, and 90 PSI) with synthetic seawater at initial salt concentrations (5, 25, and 35 g/L TDS) at various retention time intervals (15, 30, 60, 90, and 120 minutes). The results showed that the low-pressure RO system was able to reject 95 %, 57 %, and 46 % of 5, 25, and 35 g/L of TDS from synthetic seawater. In addition, rejection efficiency was achieved at 86 % and 78 % for Caspian seawater and Tajan River, respectively. In addition, optimal conditions (pressure: 70 PSI, time: 120 min) for salt rejection included 16-23 %, 93-94, 52-56 %, 88-90, and 22 % for 35g/L TDS, Tajan River, 5g/L TDS, 25g/L TDS, and Caspian seawater, respectively. Moreover, TOC rejection was achieved at >95 % and >97 % of Tajan River and Caspian seawater, respectively, at an overall 120-minute interval. In the case of growing environmental pollution that is discharged into Caspian sea including industrial and agricultural effluents from rivers, this study proposed the suggested pilot as a simple design that will significantly reduce salt, TOC, and TDS.
Renewable Energy Resources and Technologies
Saeed Hosseinpour; Seyed Alireza Haji Seyed Mirza Hosseini; Ramin Mehdipour; Amir Hooman Hemmasi; Hassan Ali Ozgoli
Abstract
In this study, an advanced combined power generation cycle was evaluated to obtain sustainable energy with high power and efficiency. This combined cycle includes biomass gasification, the Cascaded Humidified Advanced Turbine (CHAT), and the steam turbine. The fuel consumed by the system is derived from ...
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In this study, an advanced combined power generation cycle was evaluated to obtain sustainable energy with high power and efficiency. This combined cycle includes biomass gasification, the Cascaded Humidified Advanced Turbine (CHAT), and the steam turbine. The fuel consumed by the system is derived from the gas produced in the biomass gasification process. The biomass consumed in this study is wood because of its reasonable supply and availability. The economic analysis conducted in the present research has produced significant gains. The proposed cycle with current prices intended to sell electricity in Iran has a positive Net Present Value (NPV). Therefore, the presented cycle in terms of energy supply has good economic value. Due to the significantly higher purchase/sale price of electricity from renewable power plants in developed countries in Europe or the United States, the power generation cycle proposed in this study may be more economically feasible in other regions than Iran. Of course, with a slight price increase in electricity sales in Iran (3 US₵ kWh-1), the proposed system will have acceptable NPV. Because of the complicated equipment used in high-pressure and low-pressure turbines and compressors sets, the equipment used in this cycle requires a higher initial investment cost than conventional power generation systems. The results showed that the investment cost per unit of energy was approximately 909 USD kW-1.
Advanced Energy Technologies
Shima Sharifi; Rahbar Rahimi; Davod Mohebbi-Kalhori; Can Ozgur Colpan
Abstract
The power density of a direct methanol fuel cell (DMFC) stack as a function of temperature, methanol concentration, oxygen flow rate, and methanol flow rate was studied using a response surface methodology (RSM) to maximize the power density. The operating variables investigated experimentally include ...
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The power density of a direct methanol fuel cell (DMFC) stack as a function of temperature, methanol concentration, oxygen flow rate, and methanol flow rate was studied using a response surface methodology (RSM) to maximize the power density. The operating variables investigated experimentally include temperature (50-75 °C), methanol concentration (0.5-2 M), methanol flow rate (15-30 ml min-1), and oxygen flow rate (900-1800 ml min-1). A new design of the central composite design (CCD) for a wide range of operating variables that optimize the power density was obtained using a quadratic model. The optimum conditions that yield the highest maximum power density of 86.45 mW cm-2 were provided using 3-cell stack at a fuel cell temperature of 75 °C with a methanol flow rate of 30 ml min-1, a methanol concentration of 0.5 M, and an oxygen flow rate of 1800 ml min-1. Results showed that the power density of DMFC increased with an increase in the temperature and methanol flow rate. The experimental data were in good agreement with the model predictions, demonstrating that the regression model was useful in optimizing maximum power density from the independent operating variables of the fuel cell stack.
Abdolreza Esmaeli
Abstract
a new intelligent photovoltaic (PV) panel structure to extract the maximum power in mismatch irradiance is proposed. In conventional structures, difference of irradiance between series panels can cause the deviation of maximum power point. In this condition tracking MPP becomes difficult and reduces ...
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a new intelligent photovoltaic (PV) panel structure to extract the maximum power in mismatch irradiance is proposed. In conventional structures, difference of irradiance between series panels can cause the deviation of maximum power point. In this condition tracking MPP becomes difficult and reduces efficiency. Improvements in power electronics and its effects in PV industrial technology, developed many new PV structure in recent years. This paper proposes a new intelligent structure with module integrated converter for increasing energy capture in the PV series string. The advantage of new structure is that the MPP region extends from single panel MPP to a much wider range, causing the panels to operate independent of each other in mismatch condition. To study and show advantage of intelligent structure, a real simple model is selected and verified. For operating in MPP region, P&O algorithm is selected. Despite conventional structures, voltage is not appropriately varied for P&O algorithm used in intelligent structure and system experiences instability. To solve this instability problem, resistance is proposed as variable.MATLAB/Simulink is used for simulation and demonstration of expression. The results of this work have shown that using intelligent structure improves the energy harvesting up to 14 percent, and resistance is the best variable in tracking speed and accuracy.
Mohammad Ameri; Mojtaba Yoosefi
Abstract
This paper presents sizing, energy management strategy, and cost analysis for a configuration consisting of solar photovoltaic (PV) panels, fuel cell (FC) storage system, and reverse osmosis (RO) desalination technology for combined power and fresh water production. In this system, PV is the main power ...
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This paper presents sizing, energy management strategy, and cost analysis for a configuration consisting of solar photovoltaic (PV) panels, fuel cell (FC) storage system, and reverse osmosis (RO) desalination technology for combined power and fresh water production. In this system, PV is the main power supply source; fuel cell is a storage system accompanied by Hydrogen production and storage devices; and for fresh water production, RO technology is considered as desalination unit. Energy production strategy, developed on the basis of solar irradiance, hourly electricity consumption, and daily fresh water demand to minimize the capacity of components. To this goal, a flowchart diagram is designed, and sizing method is modeled using MATLAB software based on this flowchart. Finally, economic analysis for co-production of fresh water and electricity is discussed, and results of sensitivity analysis for variations of net present value (NPV) cost in terms of different fuel cell storage system prices and different interest rates are presented. Results show that described energy management strategy causes the configuration to follow hourly electrical demand and daily fresh water requirement precisely, so that the total surplus energy production during a day is very little and negligible. Moreover, calculations show that the largest part of costs is due to the energy storage system. So, while the solar PV is the main energy source and solar irradiance in Khark Island more than Astara, the overall configuration cost is greater in Khark Island just because of greater energy storage system costs, nevertheless, using such energy storage systems is necessary due to intermittent inherent of solar energy.
Renewable Energy Resources and Technologies
Toyese Friday Oyewusi; Gabriel Alebiowu; Elizabeth Funmilayo Aransiola; Ayowumi Rita Soji-Adekunle; Busayo Sunday Adeboye
Abstract
Briquettes from agro-residues have been promoted as a better alternative to firewood and charcoals for heating and cooking in the rural communities. In this light, a study was carried out to investigate the effect of pretreatment methods on physical properties and heating values of briquettes produced ...
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Briquettes from agro-residues have been promoted as a better alternative to firewood and charcoals for heating and cooking in the rural communities. In this light, a study was carried out to investigate the effect of pretreatment methods on physical properties and heating values of briquettes produced from corncob. To accomplish this work, an experiment was designed as a 2 × 3 × 3 × 3 completely randomized with three replicates. The parameters are pretreatment methods (carbonized and uncarbonized), binder types (cassava, corn, and gelatin), binder concentrations (10, 20, 30 %), and compacting pressures (50, 100, and 150 kPa). A charcoal kiln was fabricated to obtain the pretreatment through pyrolysis and a punch and die was also fabricated to facilitate briquette densification. The physical properties tested were limited to moisture content (MC), density and compressive strength and were determined using a conventional method. The heating value of the briquettes produced was determined using bomb calorimeter. The results demonstrated that averagemoisture content ranged between 5.29-6.58 % and 12.75-13.72 %, mean relaxed density varied from 813-925kgm-3 and 963-1166 kgm-3, compressive strength ranged between 2.27-5.07 MPa and 5.97-10.12 MPa, andheating value ranged between 28.85-32.36 MJkg-1 and 27.58-28.80 MJkg-1 for carbonized and uncarbonizedbriquettes, respectively. Briquettes produced from carbonized corncob had a better moisture content and heating value, while briquettes produced from uncarbonized corncob had higher density and compressive strength. The study shows that pretreatment methods under different binder types and concentrations and the compacting pressure significantly affected the briquettes physical properties and heating values. Therefore, this technology can be successfully applied in rural off-grid areas by the government and other stakeholders in the energy sector as part of renewable energy technologies.
Olatunde A. Oyelaran; Yau Y. Tudunwada; James K. Abidoye; Olawale M. Sanusi
Abstract
Biogas production from co-digestion of local brewery waste (BW) and cow dung (CD) was study for value added to this solid waste. The objective of this research was to fine the optimum condition for maximum biogas production and also examined the effectiveness of the biogas residue (liquor from anaerobic ...
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Biogas production from co-digestion of local brewery waste (BW) and cow dung (CD) was study for value added to this solid waste. The objective of this research was to fine the optimum condition for maximum biogas production and also examined the effectiveness of the biogas residue (liquor from anaerobic digestion process) as a nitrogen source for the production of okro. The experiments were performed in a laboratory scale of 1.5 liters plastic bottles were used as digesters operated in batch mode and mesophilic conditions [35°C±0.5]. The feedstock were test in the following ratios CD:BW, 90:10, 80:20. 70:30, 60:40, 50:50, 40:60, 30:70. 20:80 and 10:90. The maximum biogas yield was attained with mixtures in the proportions of 70:30 CD:BW. At these proportions, there was a biogas yield increase as compared to other ratios. The addition of BW increased the biogas yield from 0.40t/lt.day to 0.92lt/lt.day. It was found that CD: BW of 70:30 is the optimum ratio from batch process. The gradual reduction of the VFA concentration clearly indicated the stability of the process. A micro (pot) experiment was conducted to study the comparative effects of biogas residues, and NPK fertilizers on growth and yield using okro as the test crop. Twelve experimental soil filled pot in a complete randomized block design was used comprising of three each for Control T1 (no NPK and no BR), T2 100% NPK fertilizer, T3 50% BR plus 50% NPK fertilizers and T4 biogas residues (BR 100). The parameters studied showed that plant height, root length, number of fruits per plant and fruit weight was affected by the addition of biogas residue. A maximum 20.2% plant height increase over control T1 was observed in T3, 100% NPK has 10% while T4 has 8%. A maximum increase of 28.57% number of fruits was recorded in treatment T2 and T3, while 14.29% increased was recorded in T4 compared with control. The 50% BR applied in combination with 50% NPK (T3) resulted in 25.42% increase in fruit weight over control, T4 has 20.34% and 16.95% was observed in T2. Based on these results, it may be concluded that the application of approximately 50% of biogas residue and 50% inorganic fertilizer improves the production of okro.
Advanced Energy Technologies
Azin Hasanvand; Mehdi Pourabdoli; Ahmad Ghaderi Hamidi
Abstract
The effect of Al2O3 (1-10 wt %) and Y2O3 (1-10 wt %) additions on thermochemical heat storage properties of Co3O4/CoO system was investigated by thermogravimetry, XRD, and SEM analyses. Results showed that the addition of Al2O3 to Co3O4 at constant 8 h mechanical activation improved the redox cycle stability ...
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The effect of Al2O3 (1-10 wt %) and Y2O3 (1-10 wt %) additions on thermochemical heat storage properties of Co3O4/CoO system was investigated by thermogravimetry, XRD, and SEM analyses. Results showed that the addition of Al2O3 to Co3O4 at constant 8 h mechanical activation improved the redox cycle stability and increased oxygen sorption value and rate. It was found that oxygen sorption and their rate decreased with increasing the alumina content to more than 8 wt %. The formation of the spinel phase and an increase in its amount by increasing the alumina content led to a decrease in the oxygen sorption capacity. SEM studies showed that Al2O3 prevented the sintering and particle growth of cobalt oxide particles during reduction and re-oxidation processes. In addition, results showed that the addition of Y2O3 in all ranges to Co3O4 improved the redox cycle stability of cobalt oxide; however, it significantly decreased the oxygen sorption in the Co3O4/CoO system. XRD patterns of a sample containing 10 wt % yttria before the redox process indicated the presence of only Co3O4 phase; however, after three redox cycles, other phases including CoO and Y2O3 appeared.
Renewable Energy Resources and Technologies
Hadi Farzan
Abstract
Recently, novel techniques have been developed in building industries to use solar heating and cooling systems. The current study develops a Solar-powered Heating and Cooling (SHC) system for an office building in Kerman and assesses the transient dynamics of this system and office indoor temperature. ...
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Recently, novel techniques have been developed in building industries to use solar heating and cooling systems. The current study develops a Solar-powered Heating and Cooling (SHC) system for an office building in Kerman and assesses the transient dynamics of this system and office indoor temperature. To this end, TRNSYS simulation software is utilized to simulate system dynamics. The developed system comprises Evacuated-Tube solar Collectors (ETCs), heat storage tank, heat exchanger, circulating pumps, axillary furnace, cooling tower, single-effect absorption chiller, and air handling unit. The office indoor temperature is assessed in two scenarios, including commonly-insulated and well-insulated envelopes, while window awnings are used to prevent the sun from shining directly through the windows. The results illustrate that the SHC system can meet the thermal loads and provide thermal comfort in line with ASHRAE standards. The indoor temperature reaches 21 °C and 24 °C on cold winter and hot summer days by using the SHC system; however, without the SHC system, the indoor temperature experiences 15 °C and 34 °C on cold and hot days, respectively. The SHC system provides 45 °C and 15 °C supply air on cold and hot days to keep the indoor temperature in the desired range. A thermostat monitors the indoor temperature and saves energy by turning off the system when no heating or cooling is required. Furthermore, the ETCs can run the SHC system for a long time during daytime hours, but the axillary heater is still essential to work at the beginning of the morning.
Advanced Energy Technologies
Zeinab Sabzian-Molaee; Esmaeel Rokrok; Meysam Doostizadeh
Abstract
In this study, a novel stochastic planning method is proposed for AC-DC hybrid distribution networks. The proposed approach is based on the graph theory, and the optimal AC-DC structure of the network is selected among the system spanning trees. The presented method is a Mixed Integer Nonlinear Programming ...
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In this study, a novel stochastic planning method is proposed for AC-DC hybrid distribution networks. The proposed approach is based on the graph theory, and the optimal AC-DC structure of the network is selected among the system spanning trees. The presented method is a Mixed Integer Nonlinear Programming (MINLP) problem, which is solved using genetic algorithm. The buses and lines of the network can be either AC or DC to minimize the system investment costs in the master optimization problem. The location and capacity of the Distributed Energy Resources (DERs) as well as the site and size of the Electric Vehicle (EV) charging stations are optimized in the slave problem to minimize the network losses and system costs. The proposed model utilizes Monte Carlo simulation to deal with the stochastic variations of the renewable energy resources power and load demands. Besides, the converter efficiency curve in the proposed planning problem is modeled based on a function of its input current using PLECS software. The proposed approach for network design can be applied to different DG resources and AC-DC loads. The comparison between the simulation results of the proposed approach and the conventional AC planning method demonstrates the efficiency of the proposed model in reducing network losses and system costs
Masood Mehrabian; Sonya Aslyousefzadeh
Abstract
Zinc oxide nanorod arrays (ZnO NRs) were grown on the ZnO seed layers via an aqueous solution using hydrothermal method and their photovoltaic properties were investigated. It was found that the growth period of 20 minutes is the optimum condition for ZnO nanorods growth, the cell containing these nanorods ...
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Zinc oxide nanorod arrays (ZnO NRs) were grown on the ZnO seed layers via an aqueous solution using hydrothermal method and their photovoltaic properties were investigated. It was found that the growth period of 20 minutes is the optimum condition for ZnO nanorods growth, the cell containing these nanorods was considered as a reference cell. In order to further increase the cell performance, ZnS quantum dots (QDs) were fabricated on the ZnO NRs (reference cell) by SILAR technique with different number of cycles. The effect of the number of SILAR cycle (n) on structural and photovoltaic properties was studied. The optimum number of SILAR cycles for ZnS QDs was obtained (n=4). Experimental results showed that using ZnS QDs as light absorber material is an effective way to improve device performance. Morphology, crystalline structure and optical absorption of layers were analyzed by a scanning electron microscope (SEM), X-ray diffraction (XRD) and UV-Visible absorption spectra, respectively. The maximum power conversion efficiency of 3.59% in the inverted configuration of ITO/ZnO film/ZnO NR(20)/ZnS(n) QDs/P3HT/PCBM/Ag hybrid solar cell was achieved for a device based on ZnS(4) under an illumination of one Sun (AM 1.5G, 100 mW/cm2)
Sajad Alah Rezazadeh; Iraj Mirzaie; Nader Pourmahmoud; Nima Ahmadi
Abstract
A full three-dimensional, single phase computational fluid dynamics model of a proton exchange membrane fuel cell (PEMFC) with both the gas distribution flow channels and the Membrane Electrode Assembly (MEA) has been developed. A single set of conservation equations which are valid for the flow channels, ...
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A full three-dimensional, single phase computational fluid dynamics model of a proton exchange membrane fuel cell (PEMFC) with both the gas distribution flow channels and the Membrane Electrode Assembly (MEA) has been developed. A single set of conservation equations which are valid for the flow channels, gas-diffusion electrodes, catalyst layers, and the membrane region are developed and numerically solved using a finite volume based computational fluid dynamics technique. In this research some parameters such as oxygen consumption, water production, temperature distribution, ohmic losses, anode water activity, cathode over potential and the fuel cell performance for straight single cell were investigated in more details. The numerical simulations reveal that these important operating parameters are highly dependent to each other and the fuel cell efficiency is affected by the kind of species distribution. So for especial uses in desirable voltages, for preventing from the unwilling losses, these numerical results can be useful. Finally the numerical results of proposed CFD model have been compared with the published experimental data that represent good agreement.
Mehdi Jamali Ghahderijani; Fathollah Ommi
Abstract
In this paper, a solar based hydrogen production in the city of Tehran, the capital of Iran is simulated and the cost of produced hydrogen is evaluated. Local solar power profile is obtained using TRNSYS software for a typical parking station in Tehran. The generated electricity is used to supply power ...
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In this paper, a solar based hydrogen production in the city of Tehran, the capital of Iran is simulated and the cost of produced hydrogen is evaluated. Local solar power profile is obtained using TRNSYS software for a typical parking station in Tehran. The generated electricity is used to supply power to a Proton Exchange Membrane (PEM) electrolyzer for hydrogen production. Dynamic nature of solar power and necessity of reasonable accuracy for estimating of amount of hydrogen production leads to propose a new 1D dynamic fluid flow model for PEM electrolyzer cell simulation. The hydrogen price in this system is estimated using Equivalent Annual Worth (EAW) analysis. Although it is convenient to select a yearly useful lifetime for electrolyzer as well as solar cells in this paper an hourly lifetime is considered which allows finding the hydrogen cost based on electrolyzer operating time. Also, electrolyzer sizing is done by selecting various number of cells for each stack and alternatives are compared from performance and economic point of view. In this regards 4 cases consist of 2, 3, 4 and 5 electrolyzer cell are compared. Hydrogen price at each case is evaluated and sensitivity analysis is performed. The results represent that the system with higher efficiency is not always an economical choice. As an alternative, the electrolyzer turning off at some conditions is also investigated for possibility of extending lifetime and reducing the hydrogen price. It is found that turning off the electrolyzer under specified minimum current density (2000 A/m2) in all cases reduce the final produced hydrogen price however this price and electrolyzer size is still strongly dependent to the electrolyzer capital cost.
Advanced Energy Technologies
Neda Azizi; Hassan Moradi CheshmehBeigi
Abstract
This paper focuses on improving the active and reactive power control of Wind Energy Conversion System (WECS) by employing the Battery Energy Storage System (BESS) and controlling the frequency and voltage regulation instantaneously. The proposed power control scheme is composed of two control loops ...
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This paper focuses on improving the active and reactive power control of Wind Energy Conversion System (WECS) by employing the Battery Energy Storage System (BESS) and controlling the frequency and voltage regulation instantaneously. The proposed power control scheme is composed of two control loops so that they are implemented and designed for active power control and controlling the reactive power, respectively, which both are equipped with PI type controllers. In addition, two control loops were utilized to control the frequency and voltage on the rotor side converter under balance and unbalance grid conditions. In this paper, the presented control strategy optimally tuned all the parameters of controllers at the same time by utilizing a mixed integer nonlinear optimization programming and solved by the ICA algorithm. Moreover, in order to demonstrate the effectiveness of the proposed strategy, non-linear time domain simulations were carried out in MATLAB software. The obtained simulation results verified that the proposed control scheme efficiently utilize BESS to control the active and reactive power control and confirm the effectiveness of the proposed strategy under the balanced and unbalanced grid conditions.
Advanced Energy Technologies
Shokoofeh Bagheri; Hassan Moradi CheshmehBeigi
Abstract
Today, the presence of energy storage systems along with the alternative nature of renewable energy sources has become undeniable and one of these types of systems is battery energy storage systems. The most important factor in studying the stability of DC microgrids (DCMGs) is the stabilization of the ...
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Today, the presence of energy storage systems along with the alternative nature of renewable energy sources has become undeniable and one of these types of systems is battery energy storage systems. The most important factor in studying the stability of DC microgrids (DCMGs) is the stabilization of the DC bus voltage when an error occurs on its reference value. Therefore, batteries along with power electronic converters play an important role in maintaining DCMG stability. In this paper, the use of Cascaded Buck-Boost Converter (CBBC) can be considered as a suitable alternative to bidirectional buck-boost converter due to such advantages as high power density, 98 % efficiency, and higher operating temperature in battery. The control strategy is applied in the microgrid implemented in the converter system set with storage, and Virtual DC Machine (VDCM) is based on charging and discharging battery through CBBC. In the studied control method, the theoretical properties of the DC machine, which is responsible for amplifying the virtual inertia in the system, are directed to the CBBC for correct switching. VDCM can be changed from motoring to generating mode or vice versa, regardless of mechanical machinery. Therefore, the proposed control system is simulated in an islanded DCMG in Matlab/Simulink and the stability of the studied system is analyzed according to the small-signal model of the proposed control and converter units. According to the simulation results and small-signal model analysis, the stability of the proposed idea under different scenarios is confirmed.
Hiroshi Yukimoto; Ebe Shohei; Tatsuya Ohike; Masahiro Okanami; Takashi Ano
Abstract
Soil microbial fuel cells (SMFCs) are expected as an application to produce sustainable energy. Here, we focused on soil ecosystems, specifically the earthworms which are known to improve soil-fertility by degrading fallen leaves or plant litter. The aim of this study was to investigate the effect of ...
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Soil microbial fuel cells (SMFCs) are expected as an application to produce sustainable energy. Here, we focused on soil ecosystems, specifically the earthworms which are known to improve soil-fertility by degrading fallen leaves or plant litter. The aim of this study was to investigate the effect of earthworm on power generation of the SMFC. The maximum power density and the internal resistance were compared to the SMFC with and without earthworms. The power density increased by about 800% and the internal resistance decreased by about 90%. The soil structure of each SMFC was different and the clear soil aggregate structure was found in the SMFC with earthworms, which had been made with the passage of soil through the earthworm gut. The results indicated that adding earthworms had a significant effect on the SMFC performance, especially the power and soil structure. It is considered that the soil environments were changed biologically and physicochemically by adding earthworms into SMFC and these changes had a positive influence on SMFC. There is no report of hybrid type SMFC combined with earthworm. This is a very novel approach to use earthworms as enhanced power generation through the SMFC.
Renewable Energy Resources and Technologies
Alireza Shirneshan; Mohammad Mostofi
Abstract
The determination of the optimum engine working conditions plays an important role in increasing engine performance and reducing exhaust emissions. The main objective of this study is to optimize the performance and emission characteristics of a CI engine fueled with aviation fuel-biodiesel-diesel blends ...
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The determination of the optimum engine working conditions plays an important role in increasing engine performance and reducing exhaust emissions. The main objective of this study is to optimize the performance and emission characteristics of a CI engine fueled with aviation fuel-biodiesel-diesel blends at various engine speeds and loads using Mixture-RSM. According to the experimental tests carried on a 4-cylinder engine, the mathematical models were developed. Then, the optimization processes were defined as the six scenarios containing the consideration of performance or emission parameters or both of them. Scenario 1 shows that the higher percentage of diesel and jet fuel can improve the performance parameters of the engine; however, Scenario 2 shows that only higher percentage of diesel can improve the engine emission due to negative effect of biodiesel on the NOx emissions and negative impact of aviation fuel on the CO and HC emissions that limit the amount of biodiesel and aviation fuel in the fuel mixture. The results also show that Scenario 3 does not vary compared to Scenario 2. The optimized point for both of engine performance and emission parameters presented in Scenario 6 was calculated as D48.9B32.7J18.4 at 2526 RPM and full engine load to obtain 88.4 (kW), 337 (N.m), 255 (gr/Kw.hr), 0.0268 (%), 469 (ppm), 7.7 (%) brake power, torque, BSFC, CO, NOx, and HC emission, respectively.
Advanced Energy Technologies
Moslem Geravandi; Hassan Moradi CheshmehBeigi
Abstract
The ability of power systems against severe events shows their increased resilience, which in turn reduces the operation costs and recovery time of the system. This study presents a new resilient stochastic unit commitment model using the frequency change rate as a new index of system resilience. Furthermore, ...
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The ability of power systems against severe events shows their increased resilience, which in turn reduces the operation costs and recovery time of the system. This study presents a new resilient stochastic unit commitment model using the frequency change rate as a new index of system resilience. Furthermore, uncertainties of wind and solar power plants and demanded load are considered simultaneously. In the proposed method that considers the occurrence of a destructive incident in important production units in the worst-case scenarios and by using the generation capacity, adaptive frequency load shedding, and interrupting contracts, an effective strategy was provided to solve the unit commitment problem of thermal units to prevent instability in system frequency and to minimize unwanted load shedding. The proposed model was tested and evaluated on the IEEE 39-bus system with a wind power plant and a solar power plant. Moreover, the results obtained from simulation were reported. The effectiveness of this innovative approach in increasing the resilience of the power system against different degrees of uncertainty was confirmed based on the results.
Roonak Daghigh; Abdellah Shafieian
Abstract
This study analyzes the thermal performance of solar thermal energy using double-pass absorber plate in Sanandaj, Iran. To this end, a mathematical model was encoded according to the energy and exergy balance equations and solved by MATLAB software. Given the environmental conditions and radiation intensity ...
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This study analyzes the thermal performance of solar thermal energy using double-pass absorber plate in Sanandaj, Iran. To this end, a mathematical model was encoded according to the energy and exergy balance equations and solved by MATLAB software. Given the environmental conditions and radiation intensity of a winter day in Sanandaj, the effects of external parameters such as radiation intensity and internal parameters such as canal’s height, inlet mass flow rate, absorber length as well as some physical parameters on the efficiency of the system were analyzed and the energy and exergy output of the system was studied. To validate the proposed model, the results obtained from numerical simulation were compared with experimental data, which showed an acceptable compatibility. Finally, the ability of the system to supply the thermal load of the building in the given day was examined and the roles of various factors in the area under thermal coverage of this system were analyzed. The obtained findings indicated that a system with an area of 3 m2 and mass rate of 250 kg/hr in radiation intensity of 619 W/m2 and temperature of 3.45° is capable of supplying the thermal load of a space with an approximate area of 14 m2.
