Showing papers in "international journal of energy and environmental engineering in 2014"
TL;DR: In this article, the experimental data were fitted with isotherm models like Langmuir and Freunlich isotherms, and the thermodynamics parameters were calculated and found to be exothermic in natures for all three adsorbents.
Abstract: Combustion of fossil fuels is one of the major sources of greenhouse gas (GHG) CO2, it is therefore necessary to develop technologies that will allow us to utilize the fossil fuels while reducing the emissions of GHG. Removal of CO2 from flue gasses has become an effective way to mitigate the GHG and adsorption is considered to be one of the methods. Adsorption of CO2 on zeolite 13X, zeolite 4A and activated carbon (AC) have been investigated at a temperature ranging from 25 to 60 °C and pressure up to 1 bar. The experimental data were fitted with isotherm models like Langmuir and Freunlich isotherm model. The Langmuir model fit well with the two zeolites and Freunlich model fit well with AC. The thermodynamics parameters were calculated and found to be exothermic in natures for all three adsorbents. Moreover, regeneration studies have been conducted in order to verify the possibility of activated carbon reutilization, to determine its CO2 adsorption capacity within consecutive cycles of adsorption–desorption. Temperature swing adsorption was employed as the regeneration method through heating up to a temperature of approximately 100 °C. There is no full reversibility for zeolites while AC can achieve complete regenerations.
165 citations
TL;DR: In this paper, the link between the aspect ratio of a vertical-axis straight-bladed (H-Rotor) wind turbine and its performance (power coefficient) was analyzed.
Abstract: This work analyses the link between the aspect ratio of a vertical-axis straight-bladed (H-Rotor) wind turbine and its performance (power coefficient). The aspect ratio of this particular wind turbine is defined as the ratio between blade length and rotor radius. Since the aspect ratio variations of a vertical-axis wind turbine cause Reynolds number variations, any changes in the power coefficient can also be studied to derive how aspect ratio variations affect turbine performance. Using a calculation code based on the Multiple Stream Tube Model, symmetrical straight-bladed wind turbine performance was evaluated as aspect ratio varied. This numerical analysis highlighted how turbine performance is strongly influenced by the Reynolds number of the rotor blade. From a geometrical point of view, as aspect ratio falls, the Reynolds number rises which improves wind turbine performance.
143 citations
TL;DR: This present study concludes that N. oculata is feasible as biomass fuel feedstock, either to direct or co-combustion mode by giving special attention to high ash content.
Abstract: Microalgal biomass is the most promising and attractive alternative to replace the terrestrial crop utilization for renewable biomass fuel feedstock. The potential for biomass fuel is due to its fast growth rate and high ability for CO2 fixation as compared to terrestrial vegetation. There are many species in the globe, growing both in marine and freshwater. In this work, the marine microalgae Nannochloropsis oculata (N. oculata) had been investigated in terms of potential abundance and physicochemical properties, which determine its feasibility as biomass fuel feedstock. The chemical composition was evaluated by energy-dispersive X-ray spectrometry, and the proximate analysis was done by performing experiments in the thermal gravimetric analyzer. During 7 days of cultivation, the average rate of increase in algal biomass was about 1.5 × 106 cells/ml/day. The proximate analysis of N. oculata indicated that it had compositions of low moisture content and fixed carbon, whereas high volatile matter and ash content, i.e., 3.99, 8.08, 67.45, and 24.47 %, respectively. The energy content, which was calculated through the proximate analysis results, was 16.80 MJ/kg. The algal biomass and its residue after 1,200 °C were characterized by Fourier transform infrared spectroscopy to investigate their chemical macromolecular compounds. This present study concludes that N. oculata is feasible as biomass fuel feedstock, either to direct or co-combustion mode by giving special attention to high ash content.
90 citations
TL;DR: In this article, the authors looked into possibilities of hydrogen production on an offshore platform in Norway, to capitalize Norway's offshore wind potential matching political goals to reduce emissions and make Norway's transportation sector cleaner.
Abstract: This study looks into possibilities of hydrogen production on an offshore platform in Norway, to capitalize Norway’s offshore wind potential matching political goals to reduce emissions and make Norway’s transportation sector cleaner The potential power output of a hypothetical offshore wind farm has been assessed using real operating data of other wind farms The usable electricity was between and segmented into three scenarios Solid oxide electrolysis cell and proton exchange membrane electrolysis are compared Their function and the necessary technologies to operate them are described in detail Based on these scenarios the annual hydrogen production was calculated with values between 1530 and 8020 tons per year The second part of the study estimates the investment to find the production cost per kilogram hydrogen, which was compared to recent fuel prices in Norway to see whether the production of hydrogen was profitable Prices vary between 520 € and 10610 € per kg hydrogen
79 citations
TL;DR: In this article, the authors used an energy model of food waste digestion to provide a usable source of information regarding energy potential of the food waste generated from urban areas in Vietnam in forms of electricity, heat, and upgraded biogas under two different scenarios.
Abstract: Anaerobic digestion (AD) was introduced in Vietnam more than 10 years ago, but at a small scale to deal with agricultural wastes, manure, etc. Despite its many advantages, AD does not yet make a significant contribution to resolving Vietnams urban waste issues due to a lack of information, data and experience. This paper, using an energy model of food waste digestion, provides a usable source of information regarding energy potential of food waste generated from urban areas in Vietnam in forms of electricity, heat, and upgraded biogas under two different scenarios. Results show that if food waste is separated from the municipal solid waste (MSW) stream and sent to AD plants, total available energy equivalent each day is about 19, 20 and 45 GWh in 2015, 2020, and 2025, respectively. This could contribute between 2.4 and 4.1 % of the electricity demand of Vietnam, as well as double this amount of energy in the form of heat. Alternatively, upgraded biogas could contribute approximately 2.2–4.7 % of fuel consumption for transportation. This suggests AD is a promising method to treat MSW in cities, especially when considering the problematic aspects of other current waste disposal methods such as: landfilling, composting and, incineration.
62 citations
TL;DR: An effective method and a new optimization algorithm using ‘improved binary PSO’ is presented and discussed to minimize power losses in distribution network by simultaneous network reconfiguration and capacitor placement.
Abstract: Optimal reconfiguration and capacitor placement are used to reduce power losses and keep the voltage within its allowable interval in power distribution systems considering voltage, current, and radial condition constraints. It is needed to solve two nonlinear discrete optimization problems simultaneously, so an intelligent algorithm is used to reach an optimum solution for network power losses. An effective method and a new optimization algorithm using ‘improved binary PSO’ is presented and discussed to minimize power losses in distribution network by simultaneous network reconfiguration and capacitor placement. The proposed model uses binary strings which represent the state of the network switches and capacitors. The algorithm is applied and tested on 16- and 33-bus IEEE test systems to find the optimum configuration of the network with regard to power losses. Five different cases are considered, and the effectiveness of the proposed technique is also demonstrated with improvements in power loss reduction compared to other previously researched methods, through MATLAB under steady-state conditions.
57 citations
TL;DR: In this paper, the authors investigated the techno-economic and environmental effect of applying demand side management (DSM) activities to rural loads before design and sizing of hybrid energy systems for such community.
Abstract: According to the United Nation Development Programme, access to modern low-cost energy systems in developing countries is important in the realization of the globally agreed developmental goals, as well as the Millennium Development Goals, and sustainable development, which would assist in the reduction of poverty and to improve the conditions and quality of life for the greater part of the world’s population. Planners have suggested hybrid energy system for the electrification of rural areas worldwide. This study investigates the techno-economic and environmental effect of applying demand side management (DSM) activities to rural loads before design and sizing of hybrid energy systems for such community. Iporin a rural area in Ibadan, Nigeria which is endowed with an average daily solar radiation of 3.84 kWh/m2/day was taken as a case study. The total daily consumption which was initially estimated as 297 kWh/day after the application of DSM techniques dropped to 130 kWh/day representing a decrease of 56.80 %. Hybrid Optimization Model for Electric Renewables software was used for simulation and optimization purpose. Parameters such as DSM index, net present cost, and emission level were used in determining the effect of the DSM technique. Overall, the DSM activities proved to be more economical and environmental friendly.
51 citations
TL;DR: In this paper, a linear frequency domain model is created to predict the behavior of the heaving point absorber wave energy converter (WEC) system, and a time domain analysis was also conducted to derive the responses of the WEC in the hydrodynamic time response domain.
Abstract: This paper presents, assesses, and optimizes a point absorber wave energy converter (WEC) through numerical modeling, simulation, and analysis in both frequency and time domain. Wave energy conversion is a technology especially suited for assisting in power generation in the offshore oil and gas platforms. A linear frequency domain model is created to predict the behavior of the heaving point absorber WEC system. The hydrodynamic parameters are obtained with AQWA, a software package based on boundary element methods. A linear external damping coefficient is applied to enable power absorption, and an external spring force is introduced to tune the point absorber to the incoming wave conditions. The external damping coefficient and external spring forces are the control parameters, which need to be optimized to maximize the power absorption. Two buoy shapes are tested and a variety of diameters and drafts are compared. Optimal shape, draft, and diameter of the model are then determined to maximize its power absorption capacity. Based on the results generated from the frequency domain analysis, a time domain analysis was also conducted to derive the responses of the WEC in the hydrodynamic time response domain. The time domain analysis results allowed us to estimate the power output of this WEC system.
48 citations
TL;DR: In this article, the calculative accuracy of TRNSYS, Archelios, Polysun, PVSyst, PV*SOL and PVGIS is examined in comparison to the real electrical energy generated by a grid-connected 19.8kWp photovoltaic installation.
Abstract: As the use of photovoltaics expands, with more and more commercial and residential users investing on solar energy systems around the globe, there is substantial demand for relatively simple, easy-to-use software packages for the planning and performance estimation of photovoltaic installations by installers and architects. In this paper, the calculative accuracy of TRNSYS, Archelios, Polysun, PVSyst, PV*SOL and PVGIS is being examined in comparison to the real electrical energy generated by a grid-connected 19.8kWp photovoltaic installation. The assessment has been performed by using the climatic data which have been recorded at the site of the real photovoltaics (PV) park over the same calendar year. Our results displayed that the software packages tend to overestimate the global irradiation received by the PV modules but still significantly underestimate the electrical energy generated by the installation.
47 citations
TL;DR: In this article, the authors employ and compare the potential of various artificial neural net-work structures of multi-layer perceptron (MLP) and radial basis function for prediction of the wind velocity time series in Tehran, Iran.
Abstract: The uncertainty caused by the discontinuous nature of wind energy affects the power grid. Hence, forecasting the behavior of this renewable resource is important for energy managers and electricity traders to overcome the risk of unpredictability and to provide reli- ability for the grid. The objective of this paper is to employ and compare the potential of various artificial neural net- work structures of multi-layer perceptron (MLP) and radial basis function for prediction of the wind velocity time series in Tehran, Iran. Structure analysis and performance evaluations of the established networks indicate that the MLP network with a 4-7-13-1 architecture is superior to others. The best networks were deployed to unseen data and were capable of predicting the velocity time series via using the sliding window technique successfully. Applying the statistical indices with the predicted and the actual test data resulted in acceptable RMSE, MSE and R 2 values with 1.19, 1.43 and 0.85, respectively, for the best network.
47 citations
TL;DR: In this paper, the authors optimized pH (4.5 to 7.0), mesophilic condition (35°C ± 2°C), and thermophilic conditions (50°C −2°C) for dark-fermentative hydrogen production.
Abstract: Biohydrogen production could be generated from organic wastes - food and beverage processing wastewater, restaurant food waste, and raw starch waste. Fermentative hydrogen production from food and beverage processing wastewater by sewage microflora was optimized in terms of pH (4.5 to 7.0), mesophilic condition (35°C ±2°C), and thermophilic condition (50°C ±2°C). Low initial pH (6.5) and mesophilic condition favored hydrogen production (0.28 L/L) indicating that such parameters along with the wastewater characteristics were crucial to dark-fermentative hydrogen production. Pretreatment methods (methanogenic inhibitor, sterilization, sonication, and acidification) on restaurant food waste and raw starch waste to enhance biohydrogen production were also investigated in this study. Maximum hydrogen yields of 3.48 ml H2/g COD and 2.18 ml H2/g COD were observed in sterilization of pretreated restaurant food and raw starch wastes, respectively.
TL;DR: In this article, a life cycle analysis for pyrolysis biochar systems was carried out to determine greenhouse gas balance, carbon cycling, and the economics of biochar production from different agricultural residues and wastes.
Abstract: A life cycle analysis (LCA) for pyrolysis biochar systems was carried out to determine greenhouse gas balance, carbon cycling, and the economics of biochar production from different agricultural residues and wastes. Investigating a range of feedstocks (forest residues, corn stover, etc.) provided insight into the use of biomass residues rather than bioenergy crops as biochar production substrates and the resulting energy and climate change impacts. The analyses were conducted based on various optimized pyrolysis parameters for corn fodder and forest residue. The observed reductions of greenhouse gas (GHG) emissions (CO2 equivalent per Mg dry feedstock) for both corn fodder and forest residue were mainly contributed by the stable carbon in the biochar. Corn fodder showed a greater reduction in emissions than forest residue, indicating the corn fodder’s greater economic potential for soil sequestration of stable carbon. The relative GHG emission analysis found that the optimization of a biomass pyrolysis system for biochar production is better suited for soil sequestration of stable carbon than as a fuel source. The economic viability of the pyrolysis-biochar system is largely dependent on the costs of feedstock production, pyrolysis, and the value of C offsets. The LCA reported in this study can be instrumental in assessing the environmental potential of biochar production and its application in the region.
TL;DR: In this paper, the solar radiation on diversely oriented surfaces and optimum tilts for solar absorbers were assessed using MATLAB-based environment to compute the monthly solar radiation values.
Abstract: In this paper, the solar radiation on diversely oriented surfaces and optimum tilts for solar absorbers were assessed. The KT solar radiation model was coded in the MATLAB-based environment to compute the monthly solar radiation values. Seven years data of monthly average daily solar radiation on a horizontal surface in Bangi, Malaysia (latitude = 3° N) was adopted as input in the simulation programme, and the results were compared with the local optimum tilt angle at solar noon and other solar radiation model. The contour mappings of solar irradiation at various orientations in 12 months were presented. Results showed that the surface tilted at ≤20° could intercept a relatively high solar intensity, which was less sensitive to the variation of azimuths with average insolation deviation of 11.82%. The monthly optimum tilt angle altered throughout the year, ranging from -24° (in equator direction) to +22° (in north direction). The estimated annual optimum slope, 1.4° facing to the equator, was close to local latitude. Based on the seasonal analysis, the north-facing surface was able to intercept higher daily average solar radiation energy compared to south-facing plane. The optimum angles for seasonal south- and north-facing surfaces were found to be 14.4° and 14.8°, respectively, with a tolerable slope deviation of ±5° from the optimal values in the present work.
TL;DR: In this paper, a comprehensive computational modeling of a membraneless single-chamber MFC, in which bacteria consumed molasses as a substrate, is reported, where the simulated cathode had a layer of polytetrafluoroethylene, which allowed oxygen molecules to diffuse through to take part in the reduction reaction.
Abstract: Microbial fuel cell (MFC) is a novel bio-electrochemical system that can use various organic substances as energy source. Computational models of MFC are needed for prediction and optimization of the MFC performance. A comprehensive computational modeling of a membraneless single-chamber MFC, in which bacteria consumed molasses as a substrate, is reported here. The simulated cathode had a layer of polytetrafluoroethylene, which allowed oxygen molecules to diffuse through to take part in the reduction reaction. The substrate molecules diffused through the biofilm, which deposited on the anode surface, and were oxidized by the bacteria localized within the film. The simulation program accepted inputs such as the initial amount of molasses, thickness of the biofilm layer, and dimensions of the MFC chamber. Some outputs of the program include concentration profiles of molasses and oxygen as functions of time and location, and the open-circuit voltage of the MFC as a function of time. As the cathode thickness decreased or the biofilm increased, the voltage increased. To obtain a higher voltage, increasing the biofilm thickness was more effective than decreasing the cathode thickness when the initial COD levels were >5,000 mg/L.
TL;DR: In this paper, various white-rot fungi were used for the pretreatment of oil palm empty fruit bunch (EFB) using solid-state cultivation, and the results showed that Trametes versicolor TISTR 3224 gave the highest selectivity value (the ratio of lignin degradation to cellulose degradation) of 1.57.
Abstract: In the present study, various white-rot fungi were used for the pretreatment of oil palm empty fruit bunch (EFB) using solid-state cultivation. The results showed that Trametes versicolor TISTR 3224 gave the highest selectivity value (the ratio of lignin degradation to cellulose degradation) of 1.57. In comparison, Trametes sp. BCC 8729, Phanerochaete chrysosporium ATCC 24725, Marasmius sp. BCC 9542 and Xylaria sp. BCC 7749 gave selectivity of 0.60, 0.59, 0.30 and 0.06, respectively. Screening parameters for the fungal pretreatment of EFB using T. versicolor TISTR 3224 was studied by Plackett–Burman design (PBD). It indicated that the moisture content and co-substrate gave a positive effect on the lignin degradation, while EFB concentration had a negative effect on cellulose degradation. The optimum conditions for lignin degradation obtained from Box–Behnken statistical experimental design (BBD) were 80 % moisture content, 2.29 % wheat flour and 23.3 % EFB. Under this condition, 15.6 % of delignification was obtained. After an enzymatic hydrolysis, the digestibility of fungal treated EFB under the optimum condition achieved 1.34-fold compared with untreated EFB.
TL;DR: In this article, a factorial central composite orthogonal and rotatable design (FCCORD) was used to optimize the removal of parabens from waters through the Fenton process, and the experimental procedure plan- ned according to the FCCORD makes it possible to opti- mize the removal.
Abstract: Degradation rates and removal efficiencies of different parabens, namely, methylparaben, ethylparaben, propylparaben, and butylparaben using H2O2/Fe 2þ advanced oxidation process are studied in this work. With the aim of optimizing the removal of parabens from waters through the Fenton process, a factorial central composite orthogonal and rotatable design (FCCORD) was used. H2O2 and Fe 2þ ion initial concentrations were selected as independent variables. The experimental procedure plan- ned according to the FCCORD makes it possible to opti- mize the removal. The occurrence of interactions between these two variables can also be analyzed with the aid of the experimental design. Fenton process provides conversion efficiencies comprising between 85 and 94 % after a reaction time of 48 h, which reveals the appropriateness of this procedure for the removal of parabens from aqueous matrices.
TL;DR: Nigeria is rich in both conventional and renewable energy resources that empower the country with a large capacity to develop an effective national energy policy as discussed by the authors The study aims at reviewing the current energy resource structure of Nigeria in terms of production and utilization, comparing sectoral performance and reviewing issues confronting energy growth, sustainability, policies and frameworks towards the actualization of energy effiency.
Abstract: Nigeria is rich in both conventional and renewable energy resources that empower the country with a large capacity to develop an effective national energy policy The study aims at reviewing the current energy resource structure of Nigeria in terms of production and utilization, comparing sectoral performance and reviewing issues confronting energy growth, sustainability, policies and frameworks towards the actualization of energy effi- ciency The total energy consumption in 2011 was 288 million tons of oil equivalent about 54 % of the world value in 2010 Nigeria share of world CO2 emissions in 2011 was 032 % and a drop of 002 % in 2010 In addressing the country's challenges of energy demand, production, consumption and related environmental prob- lems, the government has initiated sustainable and effec- tive energy conservation strategies to improve efficiency These include: reduction of energy consumption at the household sector, reduction of gas flaring, adoption and maximum renewable energy technologies, reduction of energy intensity in industries by appropriate energy con- servation and management system In addition, the policies also include the development and integration of alternative energy resources such as nuclear, biomass, wind and solar into the total energy mix structure For all these to be accomplished, the energy development strategy must fol- low a sustainable framework to balance economic growth, social expansion and eco-friendly protection
TL;DR: The effect of Al(OH)3 on the hydrogen generation from Al/water system is evaluated in this paper, where four synthesized and one commercial Al(NO)3 powders are employed to investigate their assistance to the hydrogen generator.
Abstract: The effect of Al(OH)3 on the hydrogen generation from Al/water system is evaluated. Four synthesized and one commercial Al(OH)3 powders are employed to investigate their assistance to the hydrogen generation from Al/water system at room temperature. It was found that the Al(OH)3 product derived from Al(NO)3 precursor exhibits the best catalytic effect and exerts the highest hydrogen generation rate. 100 % yield of hydrogen (1,360 ml/g Al at 25 °C) can be achieved within 6 min at a proper Al:Al(OH)3:H2O weight ratio (3:15:50). That is, by adjusting Al:Al(OH)3:H2O ratio, the highest hydrogen generation rate ever reported so far, without using any alloying elements or corrosive additives, can be achieved.
TL;DR: In this article, the effect of solar chimney parameters on wind tower parameters was numerically investigated as a second phase of the new integrated model and the results showed that the system achieves nearly at least close to 80% acceptable comfort range according to Adaptive Comfort Standard of American Society of Heating, Refrigerating and Air-Conditioning Engineers with optimum ventilation rate 414m3/h for the hottest day.
Abstract: Houses in Egypt are often designed without taking the climate into account sufficiently. Consequently, new houses often have a poor indoor climate, which affects comfort, health and building efficiency. In hot and arid climates, passive cooling system employs non-mechanical procedures to maintain suitable indoor temperature. Thus, they have been increasing the influence of the traditional cooling concepts but with new technology. Therefore, these conditions encourage such a concept to enhance natural ventilation with evaporative cooling and save energy in the New Assiut city. In the present study, the effect of solar chimney parameters on wind tower parameters was numerically investigated as a second phase of the new integrated model. All the detailed mathematical equations and system description are presented in phase one. A numerical simulation is implemented in Transient systems simulation program-Conjunction of multizone infiltration specialists program softwares. The parametric studies of the integrated system in phase two were studied to achieve high performance with new compact small design especially for the hottest days in the summer season. The temperature and airflow rates are predicted iteratively taking into account the zone pressure and the pressure drop in the evaporative cooler component. The result shows that the system achieves nearly at least close to 80 % acceptable comfort range according to Adaptive Comfort Standard of American Society of Heating, Refrigerating and Air-Conditioning Engineers with optimum ventilation rate 414 m3/h for the hottest day. The findings show that the system achieves high performance in the hottest day with small solar chimney dimension and is easy to integrate in the building envelope than the proposed system before parametric studies in phase one.
TL;DR: In this paper, the authors describe the design and analysis of several buoy geometries that may be applied to a near-shore floating point-absorber wave energy converter, and a numerical model and a simulator in the time domain are developed and the structural performance of the wave energy converters evaluated for three different buoy geometry.
Abstract: This paper describes the design and analysis of several buoy geometries that may be applied to a near-shore floating point-absorber wave energy converter. After the characterisation of the device, a numerical model and a simulator in the time domain were developed and the structural performance of the wave energy converter evaluated for three different buoy geometries. The influence of the buoy dimensions, different submerged conditions and position of hydraulic cylinder piston rod, on the structural performance of the wave energy converter is also analysed. The numerical study was conducted using a commercial finite element code. This software needs, among other parameters, the magnitude of the forces acting upon each buoy. A dynamic model was, therefore, developed assuming that the buoy heave motion is excited by the sea waves. The finite element analysis revealed that a load with a higher magnitude than those computed from the simulator was required. It was shown that, even considering the partially submerged condition, the spherical buoy geometry leads to best structural behaviour.
TL;DR: In this paper, the authors investigated the suitability and the accuracy of a methodology aimed at estimating the time profile of the cell temperature of a photovoltaic system on the basis of only the monthly mean values of the daily global irradiation on a horizontal surface.
Abstract: Instantaneous solar irradiance profiles or solar irradiation data collected with small time intervals (e.g., minutes) are usually required for the energy simulation of photovoltaic systems, especially as concerns the estimation of the cell temperature. However, meteorological stations and technical standards often provide just monthly average values of the horizontal daily solar irradiation; extensive climate databases that make available up to date hourly observation data or satellite-derived data are seldom available. The goal of the present paper is to investigate the suitability and the accuracy of a methodology aimed at estimating the time profile of the cell temperature of a photovoltaic system on the basis of only the monthly mean values of the daily global irradiation on a horizontal surface. The methodology consists of a chain of well-established models that are applied one after another, in a step-by-step procedure, in order to derive the cell temperatures from the solar radiation data. In particular, we selected different models as possible candidates for each step of the methodology and compared their predictions with measured data to identify the most suitable ones. In addition, we tried several combinations of models in order to identify the most accurate combination. Comparisons with data measured in Rome confirm the suitability of the proposed approach and give information about its accuracy.
TL;DR: In this paper, the integration of both hybridization and thermal storage in an isolated unit of 10kWe dish-Stirling was investigated. And the results showed that hybridization has an advantage that depends on the nature of fuel used, being of 20% for natural gas and 112% for biogas.
Abstract: A high potential of thermosolar power generation systems is the use of thermal storage and/or hybridization to overcome dependability of solar resource availability. The incorporation of these technologies can be of special interest for isolated units intended for distributed generation systems. Among the thermosolar systems, dish–Stirling technology is the one with more possibilities to be used as a system to feed power independently, i.e., due to the modularity of the units that range between 3 and 25 kWe, depending on the supplier. Thus, the present analysis is focused on studying integration of both hybridization and thermal storage in an isolated unit of 10 kWe dish–Stirling. In particular, hybridization will enable a more continuous operation of the system. Hybridization is analyzed both for a conventional fuel, such as natural gas, and for a renewable energy source, biogas. Analysis of performance of the dish–Stirling system enables to determine the interest of introducing the complementary technologies referred above. Regarding the specific case evaluated in this paper, analyzed data show that hybridization has an advantage that depends on the nature of fuel used, being of 20 % for natural gas and 112 % for biogas in relation to output power of solar-only operation. Thermal energy storage system shows no significant benefits when implemented to a variable power system.
TL;DR: This article investigated the economic value of biodiversity attributes that could provide policy makers reliable information to estimate welfare losses due to biodiversity reductions and analyzed the trade-off between biodiversity and economics to obtain the nonmarket benefits of biodiversity conservation, an indirect utility function and willingness to pay for biodiversity attributes were applied using the approach of choice modeling with the analysis of multinomial logit model.
Abstract: The study investigated the economic value of biodiversity attributes that could provide policy makers reliable information to estimate welfare losses due to biodiversity reductions and analyze the trade-off between biodiversity and economics To obtain the non-market benefits of biodiversity conservation, an indirect utility function and willingness to pay for biodiversity attributes were applied using the approach of choice modeling with the analysis of multinomial logit model The study found that Mekong Delta residents accepted their willingness to pay of VND 913 monthly for a 1 % increase in healthy vegetation, VND 360 for an additional mammal species and VND 2,440 to avoid the welfare losses of 100 local farmers
TL;DR: In this paper, the authors assess the environmental impacts of eucalyptus RFB chips production chain in Portugal and present an economic and environmental impact comparison of the processes included in the production chain.
Abstract: The residual forest biomass (RFB) sector has been experiencing strong development at European level and particularly in Portugal mainly due to the increase of energy production from renewable sources. The aim of this study is to assess the environmental impacts of eucalyptus RFB chips production chain in Portugal. The environmental and economic impact comparison of the processes included in the production chain is presented as well. The environmental impacts were calculated by the life cycle assessment approach described in the ISO 14040 series of standards. The production chain assessed included all processes from eucalyptus forest until the delivery of RFB chips at the power plant. The main conclusion of this study is that eucalyptus wood production is the process that presents the greatest environmental impact through the product life cycle. Considering only emissions and depletion of energy resources, RFB chipping is the process that presents the higher environmental impact followed by transport of RFB by truck and trailer and transport of RFB by forwarder. These operations are responsible for approximately 81 % on “Respiratory inorganic” and 87 % on “Fossil fuels” which are the two most significant normalized impact categories. In economic terms, the transport of RFB by truck and trailer presents the highest cost followed by chipping and processing of trees. These three operations are responsible for approximately 80 % of total costs. A sensitivity analysis showed that a 32 % increase in the transport distance from the forest to the power plant would cause an 8 % increase in “Climate change”.
TL;DR: In this article, an attempt was made to combine the pre-treatment and dyeing processes with optimal quantities of textile auxiliaries in single bath without the usual intermediate washings.
Abstract: Nowadays, all research efforts in the field of wet processing of textiles are directed towards shortening and simplification of the processing sequence. To minimise water and energy consumption, it has become necessary to combine several textile processing stages to reduce the number of operations or shorten the process time. An attempt was made to combine the pre-treatment and dyeing processes with optimal quantities of textile auxiliaries in single bath. In this process, individual stages of pre-treatment like desizing, scouring and bleaching followed by dyeing using direct dyes were carried out in a single bath without the usual intermediate washings. This process was carried out without replacing the liquor bath until the end of dyeing. An attempt was also made to dye a woven fabric at different stages, viz., grey, desizing and scouring. These efforts were made to conserve water and energy required for that particular pre-treatment process. The depth of dyeing and the colour fastness properties of all these dyed fabrics were then compared with a bleached fabric which was dyed with conventional method. The properties were at par with the conventional method. Moreover, the combined process saved 83.1 % water, 88.6 % energy (thermal) and 79.3 % time than the conventional processes. Thus, the process has been shown to be ecological, economical and energy conserving.
TL;DR: In this article, a methodology for simulation and optimization of energy consumption in cold chambers by improving both constructive and operating parameters (external temperature, enclosure insulation, door opening time, etc.), which contribute to the infiltration of heat energy.
Abstract: The use of industrial cooling for food preservation has been revealed to be an efficient and widely employed technique, from harvest time to final consumption by the customer. However, the most used method to generate that cold (based on the compression refrigeration cycle) requires a considerable amount of electric energy, especially if no appropriate energy efficiency measures are implemented in cold storage chambers. This fact contributes to the increased costs in electricity bills, reduction of competitiveness among companies and also to a negative impact in terms of global warming. To help companies define and implement the right efficiency measures for cold production, this work aims to develop a methodology for simulation and optimization of energy consumption in cold chambers by improving both constructive and operating parameters (external temperature, enclosure insulation, door opening time, etc.), which contribute to the infiltration of heat energy. It is also intended that this methodology determines which of those parameters have greater influence in energy consumptions, as well as to estimate possible savings resulting from the optimization process. Results obtained in a garlic cold chamber showed that it is possible to achieve energy savings of up to 40 % for an initial investment around 1,500 € in efficiency measures and a payback time among 2 and 5 years. On the other hand, parameters that had the greatest influence in energy consumptions were those directly related with thermal insulation of enclosures and entry of warm air within. Total contribution of these two parameters in the global consumption was about 95 %.
TL;DR: In this paper, a building environmental assessment system oriented to energy performance and the significance weight determination was presented, based on available information analysis from particular fields of building environmental assessments and also on the basis of our experimental experiences.
Abstract: The sustainability assessment methods used over the world were the basis of new system development for Slovak conditions. The proposed fields are site selection and project planning; building construction; indoor environmental quality; energy performance; water and waste management. The evaluated indicators were proposed on the basis of available information analysis from particular fields of building environmental assessment and also on the basis of our experimental experiences. The aim of this paper is to present developed building environmental assessment system oriented to energy performance and the significance weight determination. Percentage weight of fields and indicators was determined on the basis of their significance, according to mathematical method.
TL;DR: In this paper, the authors evaluate the possibility of using more than one kind of phase change materials (PCM) in plastering mortars, termed as hybrid PCMs, to achieve adequately advantageous performance in all seasons of the year.
Abstract: The use of phase change materials (PCMs) for the building sector is increasingly attracting attention from researchers and practitioners. Several research studies forwarded the possibility of incorporating microencapsu- lated PCM in plastering mortars for building facades, in pursuit of increased energy efficiency associated with the heat storage capacity of PCM. However, most of these studies are centred in the use of a single type of PCM, which is bound to be more adequate for a given season of the year (e.g. winter or summer) than for all the seasons. The study proposed in this work regards the evaluation of the possibility of using more than one kind of PCM, with distinct melting ranges, here termed as hybrid PCMs, in plastering mortars, to achieve adequately advantageous performance in all seasons of the year. To characterize the PCM, the specific enthalpy and phase change temperature should be adequately measured. The main purpose of this study was to show the conceptual feasibility of combining PCMs in mortars and to evaluate the behaviour of the resulting mortars with differential scanning calorimeter. The results showed that the behaviour of the mortar that contains more than one type of PCM can be predicted through the superposition of effects of the independent PCMs and no interaction occurs between them. The knowledge obtained from the experimental testing estab- lished bases for a framework of numerical simulation of real-scale applications, which can be used to ascertain the feasibility of the hybrid PCM concept for decreases in energy consumption of heating/cooling demands in the buildings.
TL;DR: In this paper, the optimum thickness of the building envelope insulation materials depends on a large number of parameters, including economic, energetic, and environmental costs, and the authors show that the biggest differences in optimum thicknesses between two different insulation materials correspond to the highest differences in the unitary costs, for all the optimization points of views.
Abstract: The optimum thickness of the building envelope insulation materials depends on a large number of parameters. But the optimum thickness is calculated considering only economic arguments. In this paper, life-cycle assessment of the materials used in the building, and specifically the insulation ones, are included in the process to calculate the optimum insulation thickness from both environmental and energetic points of views. Within this frame, the large influence of the parameters associated with the manufacturing of the materials on the determination of the optimum thickness has been demonstrated: For all the studied cases, the insulation thickness depends in a large way on the unitary economic, energetic and environmental costs. The biggest differences in optimum thicknesses between two different insulation materials correspond to the highest differences in the unitary costs, for all the optimization points of views. The study also demonstrates that increasing values of the characteristic parameters of the manufacturing phase, which depend on the nature of the insulation materials, imply a decrease of the impact of the calculation settings, associated with the use phase of the building.
TL;DR: In this article, a review of the potential of lignocellulosic biomass, the largest renewable natural resource for bio-fuel generation has been discussed in reference to economical consideration.
Abstract: Climatic vicissitudes have laid further stress on already dwindling fossil fuels. In response to the emerging energy needs, biofuels can be considered as the safest and sustainable energy resources. At present, ethanol fermentations have been successful in fueling motor vehicles in some countries. However, with the existing population dynamic, obtaining ethanol from food competing resources/commodities might not be a desirable option. Therefore, non-food competing second-generation biofuels are the right choice to accommodate the increasing energy demand. Regarding the production of biohydrogen, shifting from food competing substrates to non-food competing natural resources would be geared at dawn of biohydrogen productions. In this review potential of lignocellulosic biomass, the largest renewable natural resource for biofuels’ generation has been discussed in reference to economical consideration. The strategies will likely involve thermophilic microbes possessing cellulolytic as well as ethanologenic potential. The process economics might be supported to some extent by procuring byproducts of some value from the bioenergy fermentations. Nutritional evaluation of the fermentation residues for animal feed may improve the biofuel economics. The proposed strategies appear promising more specifically in reference to climatic conditions of Pakistan.