Hardware-in-the-Loop Test for Automatic Voltage Regulator of Synchronous Condenser
Automatic voltage regulator (AVR) plays an important role in volt/var control of synchronous condenser (SC) in power systems. Test AVR performance in steady-state and dynamic conditions in real grid is expensive, low efficiency, and hard to achieve. To address this issue, we implement hardware-in-the-loop (HiL) test for the AVR of SC to test the steady-state and dynamic performances of AVR in different operating conditions. Startup procedure of the system and voltage set point changes are studied to evaluate the AVR hardware response. Overexcitation, underexcitation, and AVR set point loss are tested to compare the performance of SC with the AVR hardware and that of simulation. The comparative results demonstrate how AVR will work in a real system. The results show HiL test is an effective approach for testing devices before deployment and is able to parameterize the controller with lower cost, higher efficiency, and more flexibility.
Brushless DC Motor Driven for Solar Photo Voltaic Powered Air Cooling System
Solar photovoltaic (SPV) power systems can be employed as electrical power sources to meet the daily residential energy needs of rural areas that have no access to grid systems. In view of this, a standalone SPV powered air cooling system is proposed in this paper, which constitutes a DC-DC boost converter, two voltage source inverters (VSI) connected to two brushless DC (BLDC) motors which are coupled to a centrifugal water pump and a fan blower. A simple and efficient Maximum Power Point Tracking (MPPT) technique based on Silver Mean Method (SMM) is utilized in this paper. The air cooling system is developed and simulated using the MATLAB/Simulink environment considering the dynamic and steady state variation in the solar irradiance.
Aquifer Monitoring Technology for Safe Shale Oil, Gas Exploration and Extraction
The hydrocarbons extracted within shale formations present different technical and environmental challenges when compared to conventional hydrocarbons formations. The key issue causing concern is related to the use of hydraulic fracturing process. One of the main environmental impacts is the underground water supplies held in aquifers which can become contaminated by chemicals used in fracking as well as methane gas released from the rock itself. The oil and gas industry must demonstrate and guarantee safe exploration and exploitation by meeting monitoring requirements set by environmental regulators. Existing methods for monitoring the quality of groundwater rely on manual methods which involve taking samples at hydrological boreholes and analyzing them in a remote laboratory. However, the process of collecting, preparing and transporting the samples is manpower intensive and prone to errors. Moreover, analyzing the samples can take several weeks, allowing pollution to go undetected for some time. As natural fluctuations occur in the aquifers, the low sampling frequency of the current monitoring methods makes it difficult to capture small changes in the occurrence of methane in particular, which could arise from pollution from fracking. Therefore, there is a clear need to develop and implement a new in-situ technology that can continuously and reliably monitor the aquifer quality specific to the shale oil and gas industry. In this work, we have developed an instrumentation system which allows multiple sensor probes to be deployed in hydrological monitoring wells around the wellsite to provide automated continuous in-situ monitoring of a broad range of targeted contaminants. These probes transmit the data to the outside world via a central remote server. This paper focuses on the performance and validation of the gas sensors incorporated in each probe. These are a Non-Dispersive Infrared (NDIR) sensor to detect methane, and a Photo-Ionisation Detection (PID) sensor for detection of volatile organic compounds (VOCs). The VOCs cover a broad range of chemicals including the biocide additives acrylamide and glutaraldehyde used in fracking. The two complementary gas sensor technologies are highly sensitive and robust. Each probe is also equipped with an electrical conductivity sensor that allows direct monitoring of the water salinity which is also affected by potential contaminants. The equipment developed to measure the concentrations of dissolved methane and VOCs follows the general approach of extracting the dissolved gases into their gas phase prior to transduction. This is done by using a membrane with hydrophobic properties and high permeability to methane and VOCs. We present the results obtained for the measurement of concentrations of dissolved gases in the laboratory by submerging both gas sensors in water containing known concentrations of methane, hexane and toluene. The validity and response time of each sensor are evaluated and optimized. Moreover, testing the complete system including the sensors performance and data transfer indicates promising results in terms of accuracy, repeatability, and stability. The increased frequency of readings over manual methods will undoubtedly improve data quality, allowing more accurate trending to be obtained and dramatically decrease the response time in case of contamination.
Effect of External Radiative Heat Flux on Combustion Characteristics of Rigid Polyurethane Foam under Piloted-Ignition and Radiative Auto-Ignition Modes
Rigid polyurethane foam (RPU) has been extensively applied in building insulation system, yet with high flammability for being easily ignited by high temperature spark or radiative heat flux from other flaming materials or surrounding building facade. Using a cone calorimeter by Fire Testing Technology and thermal couple tree, this study systematically investigated the effect of radiative heat flux on the ignition time and characteristic temperature distribution during RPU combustion under different heat fluxes gradient (12, 15, 20, 25, 30, 35, 40, 45, and 50 kW/m²) with spark ignition/ignition by radiation. The ignition time decreases proportionally with increase of external heat flux, meanwhile increasing the external heat flux raises the peak heat release rate and impresses on the vertical temperature distribution greatly. The critical ignition heat flux is found to be 15 and 25 kW/m² for spark ignition and radiative ignition, respectively. Based on previous experienced ignition formula, a methodology to predict ignition times in both modes has been developed theoretically. By analyzing the heat transfer mechanism around the sample surroundings, both radiation from cone calorimeter and convection flow are considered and calculated theoretically. The experimental ignition times agree well with the theoretical ones in both radiative and convective conditions; however, the observed critical ignition heat flux is higher than the calculated one under piloted-ignition mode because the heat loss process, especially in lower heat flux radiation, is not considered in this developed methodology.
Successful Optimization of a Shallow Marginal Offshore Field and Its Applications
This note discusses the feasibility of field development of a challenging shallow offshore field in South East Asia and how its learnings can be applied to marginal field development across the world especially developing marginal fields in this low oil price world. The field was found to be economically challenging even during high oil prices and the project was put on hold. Shell started development study with the aim to significantly reduce cost through competitively scoping and revive stranded projects. The proposed strategy to achieve this involved Improve Per platform recovery and Reduction in CAPEX. Methodology: Based on various Benchmarking Tool such as Woodmac for similar projects in the region and economic affordability, a challenging target of 50% reduction in unit development cost (UDC) was set for the project. Technical scope was defined to the minimum as to be a wellhead platform with minimum functionality to ensure production. The evaluation of key project decisions like Well location and number, well design, Artificial lift methods and wellhead platform type under different development concept was carried out through integrated multi-discipline approach. Key elements influencing per platform recovery were Wellhead Platform (WHP) location, Well count, well reach and well productivity. Major Findings: Reservoir being shallow posed challenges in well design (dog-leg severity, casing size and the achievable step-out), choice of artificial lift and sand-control method. Integrated approach amongst relevant disciplines with challenging mind-set enabled to achieve optimized set of development decisions. This led to significant improvement in per platform recovery. It was concluded that platform recovery largely depended on the reach of the well. Choice of slim well design enabled designing of high inclination and better productivity wells. However, there is trade-off between high inclination Gas Lift (GL) wells and low inclination wells in terms of long term value, operational complexity, well reach, recovery and uptime. Well design element like casing size, well completion, artificial lift and sand control were added successively over the minimum technical scope design leading to a value and risk staircase. Logical combinations of options (slim well, GL) were competitively screened to achieve 25% reduction in well cost. Facility cost reduction was achieved through sourcing standardized Low Cost Facilities platform in combination with portfolio execution to maximizing execution efficiency; this approach is expected to reduce facilities cost by ~23% with respect to the development costs. Further cost reductions were achieved by maximizing use of existing facilities nearby; changing reliance on existing water injection wells and utilizing existing water injector (W.I.) platform for new injectors. Conclusion: The study provides a spectrum of technically feasible options. It also made clear that different drivers lead to different development concepts and the cost value trade off staircase made this very visible. Scoping of the project through competitive way has proven to be valuable for decision makers by creating a transparent view of value and associated risks/uncertainty/trade-offs for difficult choices: elements of the projects can be competitive, whilst other parts will struggle, even though contributing to significant volumes. Reduction in UDC through proper scoping of present projects and its benchmarking paves as a learning for the development of marginal fields across the world, especially in this low oil price scenario. This way of developing a field has on average a reduction of 40% of cost for the Shell projects.
Regeneration of Geological Models Using Support Vector Machine Assisted by Principal Component Analysis
History matching is a crucial procedure for predicting reservoir performances and making future decisions. However, it is difficult due to uncertainties of initial reservoir models. Therefore, it is important to have reliable initial models for successful history matching of highly heterogeneous reservoirs such as channel reservoirs. In this paper, we proposed a novel scheme for regenerating geological models using support vector machine (SVM) and principal component analysis (PCA). First, we perform PCA for figuring out main geological characteristics of models. Through the procedure, permeability values of each model are transformed to new parameters by principal components, which have eigenvalues of large magnitude. Secondly, the parameters are projected into two-dimensional plane by multi-dimensional scaling (MDS) based on Euclidean distances. Finally, we train an SVM classifier using 20% models which show the most similar or dissimilar well oil production rates (WOPR) with the true values (10% for each). Then, the other 80% models are classified by trained SVM. We select models on side of low WOPR errors. One hundred channel reservoir models are initially generated by single normal equation simulation. By repeating the classification process, we can select models which have similar geological trend with the true reservoir model. The average field of the selected models is utilized as a probability map for regeneration. Newly generated models can preserve correct channel features and exclude wrong geological properties maintaining suitable uncertainty ranges.
History matching with the initial models cannot provide trustworthy results. It fails to find out correct geological features of the true model. However, history matching with the regenerated ensemble offers reliable characterization results by figuring out proper channel trend. Furthermore, it gives dependable prediction of future performances with reduced uncertainties. We propose a novel classification scheme which integrates PCA, MDS, and SVM for regenerating reservoir models. The scheme can easily sort out reliable models which have similar channel trend with the reference in lowered dimension space.
Effective Scheduling of Hybrid Reconfigurable Microgrids Considering High Penetration of Renewable Sources
This paper addresses the optimal scheduling of hybrid reconfigurable microgrids considering hybrid electric vehicle charging demands. A stochastic framework based on unscented transform to model the high uncertainties of renewable energy sources including wind turbine and photovoltaic panels, as well as the hybrid electric vehicles’ charging demand. In order to get to the optimal scheduling, the network reconfiguration is employed as an effective tool for changing the power supply path and avoiding possible congestions. The simulation results are analyzed and discussed in three different scenarios including coordinated, uncoordinated and smart charging demand of hybrid electric vehicles. A typical grid-connected microgrid is employed to show the satisfying performance of the proposed method.
Production Optimization under Geological Uncertainty Using Distance-Based Clustering
It is important to figure out reservoir properties for better production management. Due to the limited information, there are geological uncertainties on very heterogeneous or channel reservoir. One of the solutions is to generate multiple equi-probable realizations using geostatistical methods. However, some models have wrong properties, which need to be excluded for simulation efficiency and reliability. We propose a novel method of model selection scheme, based on distance-based clustering for reliable application of production optimization algorithm. Distance is defined as a degree of dissimilarity between the data. We calculate Hausdorff distance to classify the models based on their similarity. Hausdorff distance is useful for shape matching of the reservoir models. We use multi-dimensional scaling (MDS) to describe the models on two dimensional space and group them by K-means clustering. Rather than simulating all models, we choose one representative model from each cluster and find out the best model, which has the similar production rates with the true values. From the process, we can select good reservoir models near the best model with high confidence. We make 100 channel reservoir models using single normal equation simulation (SNESIM). Since oil and gas prefer to flow through the sand facies, it is critical to characterize pattern and connectivity of the channels in the reservoir. After calculating Hausdorff distances and projecting the models by MDS, we can see that the models assemble depending on their channel patterns. These channel distributions affect operation controls of each production well so that the model selection scheme improves management optimization process. We use one of useful global search algorithms, particle swarm optimization (PSO), for our production optimization. PSO is good to find global optimum of objective function, but it takes too much time due to its usage of many particles and iterations. In addition, if we use multiple reservoir models, the simulation time for PSO will be soared. By using the proposed method, we can select good and reliable models that already matches production data. Considering geological uncertainty of the reservoir, we can get well-optimized production controls for maximum net present value. The proposed method shows one of novel solutions to select good cases among the various probabilities. The model selection schemes can be applied to not only production optimization but also history matching or other ensemble-based methods for efficient simulations.
A Comprehensive Review on Health Hazards and Challenges for Microbial Remediation of Persistent Organic Pollutants
Persistent organic pollutants (POPs) have become a great concern due to their toxicity, transformation and bioaccumulation property. Therefore, this review highlights the types, sources, classification health hazards and mobility of organochlorine pesticides, industrial chemicals and their by-products. Moreover, with the signing of Aarhus and Stockholm convention on POPs there is an increased demand to identify and characterise such chemicals from industries and environment which are toxic in nature or to existing biota. Due to long life, persistent nature they enter into body through food and transfer to all tropic levels of ecological unit. In addition, POPs are lipophilic in nature and accumulate in lipid-containing tissues and organs which further indicates the adverse symptoms after the threshold limit. Though, several potential enzymes are reported from various categories of microorganism and their interaction with POPs may break down the complex compounds either through biodegradation, biostimulation or bioaugmentation process, however technological advancement and human activities have also indicated to explore the possibilities for the role of genetically modified organisms and metagenomics and metabolomics. Though many studies have been done to develop low cost, effective and reliable method for detection, determination and removal of ultra-trace concentration of persistent organic pollutants (POPs) but due to insufficient knowledge and non-feasibility of technique, the safe management of POPs is still a global challenge.
A Co-Creation Methodology for Smart Cities: Insights from Multiple Case Studies
Today, as city governments struggle to meet the demands for improvement in public service delivery and the quality of urban life - while facing ever-diminishing resources – an examination is warranted of how we understand current dynamics between smart city (governance) and citizens in public service delivery. This paper seeks to yield insight into how products and services can be co-created between city and citizens, to benefit both the city and everyday urban life. The concept of co-creation - associated with a participatory turn in digital development practices reflected in the claimed democratization of digital technologies - may, arguably, offer a solution towards delivering sustainable long-term benefits for public service providers and users. It highlights what has been termed the smart city’ as an opportunity for promoting citizen participation and bottom-up innovation approaches. This is also reflected in the concept of ‘Smart Citizenship’ as defined in the literature, where citizens are co-creators of urban design and technology. The underlying, fundamental shift in relationships between public administrations, citizens and stakeholders is, however, easier said than done. Value co-creation has been applied in marketing as a way to strengthen the relationship between company and customers. Also in the public sector, particularly within the Smart City one, the relevance of value co-creation has become increasingly clear in theory and practice. Less clear is how cities can collaborate with citizens in co-creating services and products. Even public administrations that are keen to apply this approach often struggle in identifying the best way to approach it in a sustainable fashion. This is due to changes in practices that are required to integrate the complex co-creation process in organizational design, as well as diffuse understandings of co-creation as a means. This paper realizes and addresses the evident need for a systematic framework that supports Smart Cities and their administrations in understanding how to develop and implement co-creation to ultimately become more participatory. It aims to support cities in applying a clear-cut user-driven approach to co-creation. This paper is therefore designed to enhance our understanding and offer a systematic approach by deploying the results of several case studies, for which a co-creation methodology for Smart Cities has been defined and tried. By drawing upon European projects the reasoning behind the methodology and its implementation can be illustrated. The methodology rests on three pillars; First, it guides the reader through the overall co-creation process including problem analysis via stakeholder identification to evaluation; Second, it helps to identify specific and appropriate means to achieve the set objectives, i.e. co-creation methods and tools to implement; Third, it provides guidelines to put them into action. In addition to the presentation of the methodology, the paper discusses feedback from users, how the guidance and structure it provides, helps to co-create services and products, to demonstrate the value and feasibility of co-creation, and to promote and strengthen the participatory Smart City.
Promotion of Renewable Marines Energies in Morocco: Perspectives and Strategies
The current energy policy recommends the subject of energy efficiency and to phase out fossil energy as a master question for the prospective years. The kingdom requires restructuring its power equipment by improving the percentage of renewable energy supply and optimizing power systems and storage. Developing energy efficiency, therefore, obliges as a consubstantial objection to reducing energy consumption. The objective of this work is to show the energy transition in Morocco towards renewable energies, in particular, to show the great potential of renewable marine energies in Morocco, This goes back to the advantages of cost and non-pollution in addition to that of the independence of fossil energies. Bearing in mind the necessity of the balance of the Moroccan energy mix, hydraulic and thermal power plants have also been installed which will be added to the power stations already established as a prospect for a balanced network that is flexible to fluctuate demand.
Mathematical Modelling for Diesel Consumption of Articulated Vehicle Used in Oyo State, Nigeria
Since the usefulness of articulated vehicles is becoming more apparent and the diesel consumption of these vehicles constitutes a major portion of operating costs, development of mathematical model for their diesel consumption is of a great importance. Therefore, the present work developed a quantitative relationship between diesel consumption and vehicle age, annual use and cost of maintenance of the different makes of articulated vehicles. The vehicles selected for the study were FIAT 682 T3, IVECO 19036 and M.A.N. Diesel 19.240. The operating parameters for 90 vehicles of different age groups were recorded. Multiple regression models for diesel consumption of articulated vehicles of different makes were developed. From the analysis of results, it can be concluded that as the age of the vehicles increases, the diesel consumption increases. Also, as the diesel consumption increases, the cost of maintenance increases and there is a subsequent decrease in annual use. Moreover, FIAT 682 T3 and IVECO 19036 should be replaced at 7 years of age while M.A.N diesel should be replaced at 8 years of age. These are the ages where the diesel consumption becomes abnormal and uneconomical and they are points of optimal overhaul.
The Analysis of Exhaust Emission from Single Cylinder Non-Mobile Spark Ignition Engine Using Ethanol-Gasoline Blend as Fuel
In view of the prevailing pollution problems and its consequences on the environment, efforts are being made to lower the concentration of toxic components in combustion products and decreasing fossil fuel consumption by using renewable alternative fuels. In this work, the impact of ethanol-gasoline blend on the exhaust emission of a single cylinder non-mobile spark ignition engine was investigated. Gasoline was blended with 5 – 20% of ethanol sourced from the open market (bought off the shelf) in an interval of 5%. The results of the emission characteristics of the exhaust gas from the combustion of the ethanol-gasoline blends showed that increasing the percentage of ethanol in the blend decreased CO emission by between 2.12% and 52.29% and HC emissions by between12.14% and 53.24%, but increased CO2 and NOx emissions by between 25% to 56% and 59% to 60% respectively. E15 blend is preferred above other blends at no-load and across all the load variations. However its NOx emission was the highest when compared with other samples. This will negatively affect human health and the environment but this drawback can be remedied by adequate treatment with appropriate additives.
Distributed Generation Connection to the Network: Obtaining Stability Using Transient Behavior
The growing use of DGs in distribution networks provide many advantages and also cause new problems which should be anticipated and be solved with appropriate solutions. One of the problems is transient voltage drop and short circuit in the electrical network, in the presence of distributed generation - which can lead to instability. The appearance of the short circuit will cause loss of generator synchronism, even though if it would be able to recover synchronizing mode after removing faulty generator, it will be stable. In order to increase system reliability and generator lifetime, some strategies should be planned to apply even in some situations which a fault prevent generators from separation. In this paper, one fault current limiter is installed due to prevent DGs separation from the grid when fault occurs. Furthermore, an innovative objective function is applied to determine the impedance optimal amount of fault current limiter in order to improve transient stability of distributed generation. Fault current limiter can prevent generator rotor's sudden acceleration after fault occurrence and thereby improve the network transient stability by reducing the current flow in a fast and effective manner. In fact, by applying created impedance by fault current limiter when a short circuit happens on the path of current injection DG to the fault location, the critical fault clearing time improve remarkably. Therefore, protective relay has more time to clear fault and isolate the fault zone without any instability. Finally, different transient scenarios of connection plan sustainability of small scale synchronous generators to the distribution network are presented.
The SynchroniCity Methodological Framework for Smart Cities in the European Union to Implement Co-Creation
Co-creation is an effective process to generate ideas by sharing knowledge and experiences, connecting products and services to the real users. In Smart Cities projects, citizens should be engaged since the beginning, in a continuous process to effectively transform ideas into action and contribute to the co-creation activities. The analysis of co-creation strategies in Smart Cities is still scarce in the literature, and a common methodological approach for supporting the implementation of real use cases is needed. The purpose of this paper is to establish first a solid framework on co-creation approaches within the Smart Cities environment; secondly, to provide guidance to the SynchroniCity project, to concretely identify which methodologies should be implemented by the cities; thirdly, to validate the results achieved in terms of citizens’ engagement in co-creation activities. The background of the study is based on literature review on the topic, and the framework is validated through an online questionnaire and in-depth interviews with the Smart Cities part of the project. The research found that co-creation is required to improve innovation capabilities and the sustainability of new and already existing products, especially during the co-design phase, by increasing the number of people, not only citizens but also industries and actors from the utility sector, participating in this process. Co-creation is also necessary in Smart Cities to improve the governance framework within their municipalities.
Photovoltaic System: An Alternative to Energy Efficiency in a Residence
The concern to carry out a study related to Energy Efficiency arose based on the various debates in international television networks and not only, but also in several forums of national debates. The concept of Energy Efficiency is not yet widely disseminated and /or taken into account in terms of energy consumption, not only at the domestic level but also at the industrial level in Mozambique. In the context of the energy audit, the time during which each of the appliances is connected to the voltage source, the time during which they are in standby mode was recorded on a spreadsheet basis. Based on these data, daily and monthly consumption was calculated. In order to have more accurate information on the daily levels of daily consumption, the electricity consumption was read every hour of the day (from 5:00 am to 11:00 pm), since after 23:00 the energy consumption remains constant. For ten days. Based on the daily energy consumption and the maximum consumption power, the design of the photovoltaic system for the residence was made. With the implementation of the photovoltaic system in order to guarantee energy efficiency, there was a significant reduction in the use of electricity from the public grid, increasing from approximately 17 kwh per day to around 11 kwh, thus achieving an energy efficiency of 67.4 %. That is to say, there was a reduction not only in terms of the amount of energy consumed but also of the monthly expenses with electricity, having increased from around 2,500,00Mt (2,500 meticais) to around 800Mt per month.
Efficiency of Pre-Treatment Methods for Biodiesel Production from Mixed Culture of Microalgae
The rapid depletion of fossil fuel supplies and the emission of carbon dioxide by their continued combustion have paved the way for increased production of carbon-neutral biodiesel from naturally occurring oil sources. The high biomass growth rate and lipid production of microalgae make it a viable source for biodiesel production compared to conventional feedstock. In Sri Lanka, the production of biodiesel by employing indigenous microalgae species is at its emerging stage. This work was an attempt to compare the various pre-treatment methods before extracting lipids such as autoclaving, microwaving and sonication. A mixed culture of microalgae predominantly consisting of Chlorella sp. was obtained from Beire Lake which is an algae rich, organically polluted water body located in Colombo, Sri Lanka. After each pre-treatment method, a standard solvent extraction using Bligh and Dyer’s method was used to compare the total lipid content in percentage dry weight (% dwt). The fatty acid profiles of the oils extracted with each pretreatment method were analyzed using gas chromatography-mass spectrometry (GC-MS). The properties of the biodiesels were predicted by Biodiesel Analyzer© Version 1.1, in order to compare with ASTM 6751-08 biodiesel standard.
CFD Modelling and Thermal Performance Analysis of Ventilated Double Skin Roof Structure
In hot countries, the major challenge is the air conditioning. The increase in energy consumption by air conditioning stems from the need to live in more comfortable buildings, which is understandable. But in Djibouti, one of the countries with the most expensive electricity in the world, this need is exacerbated by an architecture that is inappropriate and unsuitable for climatic conditions. This paper discusses the design of the roof which is the surface receiving the most solar radiation. The roof determines the general behavior of the building. The study presents Computational Fluid Dynamics (CFD) modeling and analysis of the energy performance of a double skin ventilated roof. The particularity of this study is that it considers the climate of Djibouti characterized by hot and humid conditions in winter and very hot and humid in summer. Roof simulations are carried out using the Ansys Fluent software to characterize the flow and the heat transfer induced in the ventilated roof in steady state. This modeling is carried out by comparing the influence of several parameters such as the internal emissivity of the upper surface, the thickness of the insulation of the roof and the thickness of the ventilated channel on heat gain through the roof. The energy saving potential compared to the current construction in Djibouti is also presented.
Paraffin/Expanded Perlite Composite as a Novel Form-Stable Phase Change Material for Latent Heat Energy Storage
Latent heat storage using Phase Change Materials (PCMs) has attracted growing attention recently in the renewable energy utilization and building energy efficiency. Paraffin (PA) of low melting temperature, which is close to human comfort temperature in the range of 24-28 °C has been considered to be used in building applications. A form-stable composite Paraffin/Expanded perlite (PA-EP) has been prepared by retaining PA into porous particles of EP. DSC (Differential scanning calorimeter) is used to measure the thermal properties of PA in the form-stable composite with/without building materials. TGA (Thermal gravimetric analysis) shows that the composite is thermally stable. SEM (Scanning electron microscope) demonstrates that the layer structure of the EP particles is uniformly absorbed by PA. The mechanical properties in flexural mode have been discussed. The thermal energy storage performance has been evaluated using a small test room (100 mm ×100 mm ×100 mm) with thickness 10 mm. The flammability test of modified sample has been discussed using a cone calorimeter. The results confirm that the form-stable composite PA has the function of reducing building energy consumption.
Electrochemical/Electro-Catalytic Applications of Novel Alcohol Substituted Metallophthalocyanines
Phthalocyanines with macrocyclic ring containing at least three heteroatoms have nine or more membered structures. Metal-free phthalocyanines react with metal salts to obtain chelate complexes. This is one of the most important features of metal-free phthalocyanine as ligand structure. Although phthalocyanines have very similar properties with porphyrins, they have some advantages such as lower cost, easy to prepare, and chemical and thermal stability. It’s known that Pc compounds have shown one-electron metal-and/or ligand-based reversible or quasi-reversible reduction and oxidation processes. The redox properties of phthalocyanines are critically related to the desirable properties of these compounds in their technological applications. Thus, Pc complexes have also been receiving increasing interest in the area of fuel cells due to their high electrocatalytic activity in dioxygen reduction and fuel cell applications. In this study, novel phthalocyanine complexes coordinated with Fe(II) and Co (II) to be used as catalyst were synthesized. Aiming this goal, a new nitrile ligand was synthesized starting from 4-hydroxy-3,5-dimethoxy benzyl alcohol and 4-nitrophthalonitrile in the presence of K2CO3 as catalyst. After the isolation of the new type of nitrile and metal complexes, the characterization of mentioned compounds was achieved by IR, H-NMR and UV-vis methods. In addition, the electrochemical behaviour of Pc complexes was identified by cyclic voltammetry, square wave voltammetry and in situ spectroelectrochemical measurements. Furthermore, the catalytic performances of Pc complexes for oxygen reduction were tested by dynamic voltammetry measurements, carried out by the combined system of rotating ring-disk electrode and potentiostat, in a medium similar to fuel-cell working conditions.
CO₂/O₂ Based Underground Coal Gasification Integrated with Conventional and Advanced Power Generation System in Context of Clean Coal Technology
Coal is the largest fossil fuel, which is available in abundance. In India, more than 70% of electricity production depends on coal. In India, around 37 % of coal resources found at a depth of more than 300 meters. Coal on combustion produces greenhouse and pollutant gases such as CO₂, SOₓ, NOₓ, and H₂S etc. Underground coal gasification (UCG) technology is an efficient and an economic in-situ clean coal technology, which converts unmineable coals into calorific valuable gases. The UCG syngas (mainly H₂, CO, CH₄, and some lighter hydrocarbons) which can be utilized for the production of electricity and manufacturing of various useful chemical feedstocks. It is an inherent clean coal technology as it avoids ash disposal, mining, transportation, and storage problems. Gasification of underground coal using steam as a gasifying medium is not an easy process because sending superheated steam to deep underground coal leads to major transportation difficulties and cost effective. Transportation of preheated CO₂ is more economical than sending superheated steam to the underground coal seam. Therefore, for reducing this problem, we have used CO₂ as a gasifying medium, which is a major greenhouse gas. The current study focuses on CO₂/O₂ based UCG laboratory scale experimental data for Indian Coal integrated with conventional and advanced power generating system. A borehole combustion and gasification experiment carried out by two-stage gasification methodology on two types of Indian coal at different flow rate. By reaction of dry reforming process of CO₂ and tar cracking, we observed an average percentage composition of H₂, CO and CH₄ are 25%, 8%, and 20% respectively in case of low ash coal and 20%, 11% and 15 % in case of high ash coal. Therefore, we have integrated these experimental data of UCG with conventional power generating system (steam turbine) and advanced power-generating system (Proton Exchange Membrane Fuel Cell). Excel sheet and Matlab programming used for calculation of mass and energy balance for the entire power plant system. The net thermal efficiency with conventional power generating system (steam turbine) and advanced power generating system (CLR based PEM Fuel cell) are approx. 28% and 46 % with CCS respectively.
Active Solar Chimney (ASC): An Experimental Analysis of the Implementation of Phase-Changing Materials for Energy Storage in Solar Chimneys
Natural ventilation systems have increasingly been the subject of research due to rising energetic consumption within the building sector and increased environmental awareness. In the last two decades, the mounting concern of greenhouse gas emissions and the need for an efficient passive ventilation system have driven the development of new alternative passive technologies such as ventilated facades, trombe walls or solar chimneys. A solar chimney (SC) is a technology that has existed for centuries, particularly useful in hot climates. In its simplest form, it is an air channel evacuating hot air to the exterior through the buoyancy effect. The materials employed for its construction can vary depending on the design. Most modern studies of solar chimneys analyse variables such as aspect ratio between inlet and outlet, height, inclination or construction materials; however, few focus prolonging air circulation in the absence of a heat source through energy storage. An Active Solar Chimney (ASC) employs energy storage devices to improve the performance of the current SC. The main objective of the article is to compare how the implementation of energy storage devices - mainly paraffinic RT44 phase changing material (PCM) panels - assessed under laboratory conditions compare against experimental in situ measurements obtained under environmental conditions. A preliminary study on an individual panel is performed to characterise the behaviour of the paraffinic material, macroencapsulated in the aluminium panels. The feasibility of RT44 panels is compared through laboratory and in situ experiments, analysed through an experimental protocol recording temperature and airflow evolution across the SC prototype. Surface temperatures are recorded at different heights during the study to observe the temperature evolution between inlet and outlet. Tests are carried out with and without RT44 panels to evidence the difference between a classic SC and the ASC. Preliminary results produced by the individual panel display the behaviour of the material and exhibit the capacity for energy storage along with the change of phase. Initial results show a clear temperature difference for three different heights across the laboratory SC prototype (1m, 2.5m, and 4m). Indeed, the results for the prototype without PCM register an important temperature difference (approximately 15°C) between the lower and the higher surface temperature sensors. Furthermore, ASC results demonstrate a more even temperature distribution across the different heights. Moreover, outlet airflow results reveal the impact of PCM panels for a prolonged use. Comparative results between laboratory and in situ experiments will be published in the full paper. PCM panels are implemented because of their capacity to release stored energy and create thermal inertia. The performance of these materials is highly dependent on the incoming energy. Therefore further studies are required to ensure the complete change of state. Initial tests show an increase in the outlet air flow of the prototype in the absence of a heating source. These findings must be compared to the in situ experiment to observe the influence of external factors (e.g. wind speed, humidity) on the performance of the system.
The Need for Institutional Capacity Building in Solar Power Projects for Rural Electrification: A Case Study in East Timor
Developing countries still face vast challenges in providing cost-effective, reliable, and sufficient energy supply choices to the societies. Even though the past few years have seen marked progress in overall electrification rates in developing countries, the underserved rural areas in these countries remain impoverished; not to mention the gap between the national and rural electrification rates is very apparent. One of the greatest challenges in the rural regions is the energy access to generate electricity as most parts of these regions are not connected to the main grid. Furthermore, this paper believes the initiative to conduct community renewable energy projects is very important to overcome uneven electrification rates in developing countries as well as to empower the local community socioeconomically.The emphasis of this paper is the importance of institutional capacity building for both the implementing agencies, who conduct the solar power projects, and the government. To facilitate a better understanding of this concept, a case study in East Timor will be used in this paper. East Timor is amongst the least developed countries in the world whose geographical position is blessed with a constant amount of sunlight all year long that makes it ideal for solar power generating systems.Since the general aim of community renewable energy is not only to solely generate the electricity, but also to empower the community itself, implementing solar power projects in rural areas means dealing with people from diverse backgrounds where cross-cultural challenges are inevitable. In the context of East Timor, the difficulty of local partners to conduct regular reports to the implementing agency due to a language barrier appears as one of the significant constraints in executing solar power projects, besides the fact that the weak government capacity is also present in the country in which the government of East Timor keeps on changing the master plan for community renewable energy initiatives. The concept of institutional capacity building targets both the government and the implementing agency, from top-down and bottom-up perspectives to tackle the challenges by providing strategies to maximize their capacities in solar power projects and scale up the impact.
Li-Ion Batteries vs. Synthetic Natural Gas: A Life Cycle Analysis Study on Sustainable Mobility
The growth of non-dispatchable renewable energy sources in the European electricity generation mix is promoting the research of technically feasible and cost-effective solutions to make use of the excess energy, produced when the demand is low. The increasing intermittent renewable capacity is becoming a challenge to face especially in Europe, where some countries have shares of wind and solar on the total electricity produced in 2015 higher than 20%, with Denmark around 40%. However, other consumption sectors (mainly transportation) are still considerably relying on fossil fuels, with a slow transition to other forms of energy. Among the opportunities for different mobility concepts, electric (EV) and biofuel-powered vehicles (BPV) are the options that currently appear more promising. The EVs are targeting mainly the light duty users because of their zero (Full electric) or reduced (Hybrid) local emissions, while the BPVs encourage the use of alternative resources with the same technologies (thermal engines) used so far. The batteries which are applied to EVs are based on ions of Lithium because of their overall good performance in energy density, safety, cost and temperature performance. Biofuels, instead, can be various and the major difference is in their physical state (liquid or gaseous). In this study gaseous biofuels are considered and, more specifically, Synthetic Natural Gas (SNG) produced through a process of Power-to-Gas consisting in an electrochemical upgrade (with Solid Oxide Electrolyzers) of biogas with CO2 recycling. The latter process combines a first stage of electrolysis, where syngas is produced, and a second stage of methanation in which the product gas is turned into methane and then made available for consumption. A techno-economic comparison between the two alternatives is possible, but it does not capture all the different aspects involved in the two routes for the promotion of a more sustainable mobility. For this reason, a more comprehensive methodology, i.e. Life Cycle Assessment, is adopted to describe the environmental implications of using excess electricity (directly or indirectly) for new vehicle fleets. The functional unit of the study is 1 km and the two options are compared in terms of overall CO2 emissions, both considering Cradle to Gate and Cradle to Grave boundaries. Showing how production and disposal of materials affect the environmental performance of the analyzed routes is useful to broaden the perspective on the impacts that different technologies produce, in addition to what is emitted during the operational life. In particular, this applies to batteries for which the decommissioning phase has a larger impact on the environmental balance compared to electrolyzers. The lower (more than one order of magnitude) energy density of Li-ion batteries compared to SNG implies that for the same amount of energy used, more material resources are needed to obtain the same effect. The comparison is performed in an energy system that simulates the Western European one, in order to assess which of the two solutions is more suitable to lead the de-fossilization of the transport sector with the least resource depletion and the mildest consequences for the ecosystem.
Absorption Control of Organic Solar Cells under LED Light for High Efficiency Indoor Power System
Organic solar cells have high potential which enables these to absorb much weaker light than 1-sun in indoor environment. They also have several practical advantages, such as flexibility, cost-advantage, and semi-transparency that can have superiority in indoor solar energy harvesting. We investigate organic solar cells based on poly(3-hexylthiophene) (P3HT) and indene-C60 bisadduct (ICBA) for indoor application while Finite Difference Time Domain (FDTD) simulations were run to find the optimized structure. This may provide the highest short-circuit current density to acquire high efficiency under indoor illumination.
Techno-Economic and Life Cycle Assessments of Selected Sugarcane-Based Biorefineries Producing Bioenergy and Chemicals in South Africa
There is still significant commercial interest in the use of sugarcane as feedstock for expanded ethanol production in South Africa (SA), primarily for use as biofuel. Limitation in expansions possible in sugarcane production implies whole crop utilisation required. Second generation is not taken seriously from a commercial perspective, not because of technology maturity, but rather cost considerations.
The main aim of this work is to develop biorefinery scenarios using fibrous sugarcane material as feedstock for the co-production of bio-ethanol and valuable chemicals. These biorefineries were designed in a way to provide both economic and environmental benefits, to stimulate interest in the policy and commercial spheres in their commercial implementation. Key questions in the development of such biorefineries were the mix of products to be included, and the optimal sizing and locations of such biorefineries in the context of South Africa. It has been assumed that such biorefineries were integrated to existing sugar mills and 1st generation bioethanol plants, which benefits both conversion efficiencies and reduction of costs. Both sugarcane harvesting residues and surplus bagasse from sugar mills or first generation bio-ethanol plants serve as feedstock to these lignocellulose biorefineries. The following lignocellulose biorefineries were selected based on a thorough review of literature, and potential of chemicals co-production to significantly improve the economic viability of second generation ethanol production from available lignocellulose. 1. Co-production of bioethanol (from cellulose) with lactic acid (from hemicellulose) and surplus power for export (from lignin). This biorefinery relies on a dilute acid pretreatment of lignocellulose, to liberate chemical constituents for further conversion into lactic acid. 2. Co-production of bioethanol (from cellulose) with furfural (from hemicellulose) and surplus power for export (from lignin). This biorefinery relies on a dilute acid fractionation of lignocellulose, to liberate chemical constituents for further conversion into furfural. 3. Integrated production of bio-ethanol (from cellulose and hemicellulose) and surplus power for export (from lignin) where there is no co-production of chemicals.
Electrochemical Synthesis of ZnTe and Cu-ZnTe Thin Films for Low Resistive Ohmic Back Contact for CdS/CdTe Solar Cells
ZnTe is direct band gap, the P-type semiconductor with the high absorption coefficient of the order of 104cm-1 is suitable for solar cell development. It can be used as a low resistive ohmic contact to CdS/CdTe or tandem solar cell application. ZnTe and Cu-ZnTe thin film have been electrochemically synthesized on to fluorine-doped tin oxide coated glass substrates using three electrode systems containing Ag/AgCl, graphite and FTO as reference, counter and working electrode respectively were used to deposit the thin films. The aqueous electrolytic solution consist of 0.5M TeO2, 0.2M ZnSO4, and 0.1M Na3C6H5O7:2H2O, 0.1MC6H8O7:H2O and 0.1mMCuSO4 with PH 2.5 at room temperature was used. The reaction mechanism is studied in the cyclic voltammetry to identify the deposition potentials of ZnTe and Cu-ZnTe.The potential was optimized in the range -0,9 to -1,1 V. Vs Ag/AgCl reference electrode. The effect of deposition potential on the structural properties was studied by using X-ray diffraction. The X-ray diffraction result reveled cubic crystal structure of ZnTe with preferential (111) orientation with cubic structure. The surface morphology and film composition were analyzed by means of Scanning electron microscopy (SEM) and Energy Dispersive Analysis of X- Rays (EDAX). The optical absorption measurement has been analyzed for the band gap determination of deposited layers about 2.26 eV by UV-Visible spectroscopy. The drastic change in resistivity has been observed due to incorporation of copper probably due to the diffusion of Cu into grain boundaries.
Investigation of Doping of CdSe QDs in Organic Semiconductor for Solar Cell Applications
Cadmium selenide (CdSe) quantum dots (QDs) were prepared by solvothermal route. Subsequently a inorganic QDs-organic semiconductor (copper phthalocyanine) nanocomposite (i.e CuPc:CdSe nanocomposites) were produced by different concentration of QDs varied in CuPc. The nanocomposite thin films have been prepared by means of spin coating technique. The optical, structural and morphological properties of nanocomposite films have been investigated. The transmission electron microscopy (TEM) confirmed the formation of QDs having average size of 4 nm. The X-ray diffraction pattern exhibits cubic crystal structure of CdSe with reflection to (111), (220) and (311) at 25.4ᵒ, 42.2ᵒ and 49.6ᵒ respectively. The additional peak observed at lower angle at 6.9ᵒ in nanocomposite thin films are associated to CuPc. The field emission scanning electron microscopy (FESEM) observed that surface morphology varied in increasing concentration of CdSe QDs. The obtained nanocomposite show significant improvement in the thermal stability as compared to the pure CuPc indicated by thermo-gravimetric analysis (TGA) in thermograph. The effect in the Raman spectra of composites samples gives a confirm evidence of homogenous dispersion of CdSe in the CuPc matrix and their strong interaction between them to promotes charge transfer property. The success of reaction between composite was confirmed by Fourier transform infrared spectroscopy (FTIR). The photo physical properties were studied using UV - visible spectroscopy. The enhancement of the optical absorption in visible region for nanocomposite layer was observed with increasing the concentration of CdSe in CuPc. This composite may obtain the maximized interface between QDs and polymer for efficient charge separation and enhance the charge transport. Such nanocomposite films for potential application in fabrication of hybrid solar cell with improved power conversion efficiency.
Impact of Saturation Hysteresis on Wells Planning
Saturation hysteresis commonly exhibits in relative permeability curves whenever a cyclic process is undergone in the oil field development. In order to describe hysteresis impact on reservoir production, scanning curves are normally generated in numerical simulation models. According to hysteresis models, scanning curves and trapped oil saturation are dependent on the initial oil saturation. Carbonate reservoirs have a thick transition zone, in which different initial oil saturations are distributed as per saturation-height functions. Therefore the trapped oil saturations vary. In the field development plan during water flooding process, traditional wells planning is mainly based on oil-in-place or single residual oil saturation, while hysteresis-model derived recoverable oil is calculated from history-matched model and employed to execute more-reliable wells planning. An automated infill-drilling program has been coded by considering hysteresis effect. First, extract initial and current oil saturation, and identify end-point saturation of saturation-function tables from the model. Second, calculate the trapped and up-to-date remaining recoverable oil using Killough hysteresis model. Then, identify the optimum infill locations contacting maximum mobile oil volume, select perforation intervals, and generate completion data. After that, run simulations to iterate wells planning optimization. This proposed wells planning approach has been implemented in simulation and achieved the recovery target. The classical practice of chasing remaining oil may not identify the best wells locations in the brown field. This approach is validated by suggesting less and optimum number of wells while bringing significantly higher and maximized secondary recovery according to simulation performances. Potential of Enhanced Oil Recovery (EOR) can be further evaluated with the quantified remaining oil and trapped oil saturation after water flood. In transition zones, larger pores are filled with oil and the trapped oil saturation is lower compared to dry oil intervals, so it could be economical to perforate wells in the transition zone. Unlike most other approaches, this improved wells planning approach takes into account hysteresis-led trapped oil saturation for the preliminary automatic wells optimization before verifying their production performances through reservoir simulation. This process is repeatable and adjustable frequently based on the development guidelines. For the giant and mature oil field, it demonstrates a reliable, efficient and economical mode for field development plan.
Electric Arc Furnaces as a Source of Voltage Fluctuations in the Power System
The paper presents the impact of work on the electric arc furnace power grid. The arc furnace operating will be modeled at different power conditions of steelworks. The paper will describe how to determine the increase in voltage fluctuations caused by working in parallel arc furnaces. The analysis of indicators characterizing the quality of electricity recorded during several cycles of measurement made at the same time at three points grid, with different power and different short-circuit rated voltage, will be carried out. The measurements analysis presented in this paper were conducted in the mains of one of the Polish steel. The indicators characterizing the quality of electricity was recorded during several cycles of measurement while making measurements at three points of different power network short-circuit power and various voltage ratings. Measurements of power quality indices included the one-week measurement cycles in accordance with the EN-50160. Data analysis will include the results obtained during the simultaneous measurement of three-point grid. This will determine the actual propagation of interference generated by the device. Based on the model studies and measurements of quality indices of electricity we will establish the effect of a specific arc on the mains. The short-circuit power network’s minimum value will also be estimated, this is necessary to limit the voltage fluctuations generated by arc furnaces.