Energy and Renewable Energies
Behnam Mohammadi; Majid Namdari; Alireza Yousefi; Moslem Heydari
Abstract
Introduction: The generation of waste and the emission of pollutants are significant challenges in production processes, leading to increased economic costs and environmental degradation. Addressing these challenges has become a priority, as unsustainable production practices not only harm the environment ...
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Introduction: The generation of waste and the emission of pollutants are significant challenges in production processes, leading to increased economic costs and environmental degradation. Addressing these challenges has become a priority, as unsustainable production practices not only harm the environment but also hinder long-term economic development. Sustainable production and environmental efficiency are critical goals for manufacturing units aiming to achieve sustainable development. Achieving these goals requires innovative tools and methodologies that can assess and optimize resource use across various production systems. Cleaner production approaches, which focus on optimizing production processes and reducing negative environmental impacts, have emerged as key strategies in this context. One such tool is Material Flow Cost Accounting (MFCA), developed under ISO 14051:2011. MFCA has proven to be a powerful tool for simultaneously improving environmental and financial performance by quantifying material flows and associated costs within production systems. This study applies MFCA to analyze the energy and economic performance of olive production in Tarom County, Iran, a region known for its significant olive cultivation. The research seeks to identify inefficiencies, reduce resource waste, and promote sustainable agricultural practices through an integrated assessment of energy and economic parameters.
Materials and Methods: This study was conducted in olive orchards in Tarom County during the 2022 agricultural year, using an approach grounded in both scientific rigor and practical applicability. Data were collected through comprehensive questionnaires covering all major agricultural activities such as plowing, pruning, irrigation, fertilization, pest control, labor, and fuel and electricity consumption. A statistically reliable sample of 50 orchards was selected using Cochran's formula to ensure adequate representation of the region’s olive production practices. MFCA was employed to quantify material and energy flows, focusing on input resources (e.g., water, fertilizers, electricity) and output products (e.g., olives, waste, and emissions). The methodology strictly adhered to ISO 14051 guidelines, which define four cost categories for each quantity center (QC): system costs, material costs, energy costs, and waste management costs. Energy equivalents for inputs and outputs were calculated using standard conversion factors. Additionally, energy indices such as energy efficiency, energy productivity, and net energy were evaluated to provide a comprehensive understanding of the system’s energy dynamics. The economic analysis encompassed parameters such as gross production value, net income, benefit-to-cost ratio, and economic productivity, offering insights into the financial implications of production practices.
Results and Discussion: The total energy input for olive production was calculated at 77,417.56 MJ/ha, with electricity (59%), urea fertilizer (15%), and fossil fuels (14%) identified as the primary contributors. Positive energy outputs totaled 40,221.48 MJ/ha, while negative energy outputs, which included product loss and fertilizer waste, amounted to 6,853.04 MJ/ha. Among negative outputs, product loss (71%) and nitrate leaching (21%) represented the largest shares. The energy efficiency ratio was 0.52 using conventional methods but dropped to 0.43 when analyzed with MFCA, underscoring the hidden costs of waste and inefficiencies that traditional accounting methods fail to capture. These findings highlight the need for improved management practices to enhance both energy efficiency and economic viability. Economic analysis revealed that labor costs constituted 67% of variable production costs, whereas electricity, despite its high contribution to energy inputs, accounted for a mere 0.28% of financial costs. This discrepancy points to the critical need for better energy management strategies, including the adoption of renewable energy sources to reduce dependency on fossil fuels. Several inefficiencies were identified, particularly excessive water use during irrigation and significant product loss during harvesting, which adversely affect both energy and economic performance. To address these issues, implementing precision irrigation systems, mechanizing harvesting processes, and integrating renewable energy sources for pumping were proposed as effective strategies to reduce resource waste and improve sustainability. These findings align with those of previous studies on other crops, underscoring the universal applicability of MFCA in identifying inefficiencies and fostering sustainable agricultural practices. Furthermore, the study emphasizes that adopting cleaner production methods not only enhances resource efficiency but also supports broader sustainable development goals. This dual benefit makes MFCA a valuable tool for promoting both environmental stewardship and economic competitiveness in agriculture.
Conclusion: This study demonstrates the effectiveness of MFCA in providing a comprehensive analysis of energy and economic performance in olive production systems. By quantifying material and energy flows, MFCA revealed significant inefficiencies in critical areas such as water use and product loss, which are often overlooked in conventional accounting methods. The results emphasize the importance of adopting cleaner production practices, including precision irrigation, mechanized harvesting, and renewable energy integration, to improve both sustainability and economic viability. The application of MFCA not only enhances resource efficiency but also contributes to achieving sustainable development goals by reducing environmental impacts and lowering production costs. Future research should focus on the practical implementation of the proposed strategies and assess their long-term effects on carbon footprint reduction, resource optimization, and market competitiveness. This study underscores the transformative potential of MFCA as a tool for advancing sustainable agriculture, offering valuable insights for policymakers, farmers, and researchers aiming to optimize resource use and promote environmental stewardship in olive production and beyond.
Energy and Renewable Energies
Davood Mohammadzamani; Mahdi Jafari; Mohammad Rasooli
Abstract
Introduction: The yield of methane production in the anaerobic digestion processes of municipal organic solid waste alone is low. Adding animal waste or other additives to municipal solid waste as feed for anaerobic digestion system not only increases the relative composition of methane, but also increases ...
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Introduction: The yield of methane production in the anaerobic digestion processes of municipal organic solid waste alone is low. Adding animal waste or other additives to municipal solid waste as feed for anaerobic digestion system not only increases the relative composition of methane, but also increases the rate of biogas production (Rivas-García, 2020). Carbon and nitrogen are essential elements for the growth and reproduction of aerobic microorganisms. The balanced ratio for C/N in the process is between 20-30. Simultaneous digestion is used to balance the C/N ratio (Yousefi & Bahri. 2021). This process has many advantages, including the synergistic effect of microorganisms, increasing the stability of the process, increasing the efficiency of biogas, increasing the recycling of nutrients and reducing odor.Materials and Methods: This research was carried out with the aim of increasing the rate of biogas production, reducing the feed retention time in the digester and increasing the amount of biogas production, by investigating the effect of co-digestion of urban solid organic waste with cow excrement using anaerobic digestion method. For this purpose, 52 samples of mixed urban waste (during the year 1400, once a week and one sample each time) were prepared from the waste transfer station of Qazvin city, and in order to investigate the effect of animal manure on the studied variables, from a cattle farm located in 50 kg of fresh manure was collected in the region. After preparing the samples, a laboratory bioreactor was used to perform the experiments. The biogas production process was carried out in two stages. In the first stage, urban waste materials were used, and in the second stage, a combination of urban waste materials and animal manure was used.Results and Discussion: The ratio of carbon to nitrogen (C/N) in the primary feed and residual materials was obtained in the first and second stages. In this way, this ratio was estimated as 19.39 and 27.64 for the primary feed and the remaining materials in the first stage and 18.60 and 28.23 respectively for the second stage. In this study, the amount of ash decreased during the process, which indicated the participation of this substance in improving the activity of microorganisms. In both stages of the experiments, the organic matter of the primary feed decreased during the digestion process, which indicates the decomposition of these materials during the process. Also, the conversion percentage of dry material from primary feed to secondary material in stage 1 and 2 was 8.2% and 10.5%, respectively, which shows that in the second stage, in which the combination of animal manure was used, the percentage of conversion The dry matter is more and the process has progressed towards the production of biogas. The changes in the pressure of biogas inside the tank in the experiment related to stage 1 reached its maximum value (0.19 bar/kg) within 23 days after the start of the process, and then stabilized at 0.14 bar/kg of solid material in the last seven days. Is. Since the criterion for the completion of the digestion process was pressure stabilization in seven consecutive days, therefore, after 38 days, the first stage process was completed and the biogas and residual (secondary) materials were discharged. The maximum biogas pressure in the second stage test was 0.28 bar/kg of solid material, which was achieved on the 15th day, and finally, after 26 days, the pressure reached 0.16 and stabilized at this pressure for seven days. Therefore, the digestion process in the second stage lasted for 32 days. Therefore, it can be seen that by using animal manure in the primary feed and keeping other variables constant, the retention time has decreased by 6 days compared to the first stage. The maximum amount of biogas produced in stage 1 was equal to 6.27 liters/kg of solid matter and in stage 2 it was equal to 10.3 liters/kg of solid matter. As can be seen, by using animal manure in combination with urban organic waste, the volume of biogas production has increased under the same conditions. Taking into account the cumulative amount of biogas production, it was found that in stage 1 and 2, 140.89 and 230 liters/kg of solid biogas were produced during the digestion period, respectively. Therefore, the efficiency of biogas production has increased by 38%. Although the total amount of biogas produced in both stages of the experiments compared to the theoretical values obtained in this study (at the rate of 370 liters/kg of solid matter) and also reported by other researchers (Salehoun, et.al, 2020 and Kozminesky , 1995) has been less.Conclusion: According to the results of this study, it was found that in the second stage compared to the first stage, the role of the two elements carbon and nitrogen in the biogas production process became more effective and one should expect more biogas production in the process, because the increase in the conversion of organic matter and nitrogen is The more effective decomposition of these materials by microorganisms has been achieved by adding animal manure to the primary feed. According to the results obtained from this study, it can be concluded that in the process of biogas production, the combination of animal manure with urban organic waste, in addition to reducing the retention time, can help to increase the efficiency of biogas production, which in this study A 38% increase in biogas production was observed in the case of using a combination of animal manure with urban organic waste compared to using only urban organic waste. Although the role of other variables such as temperature, type and amount of stirring, type of initial preparation of materials in terms of size, humidity, pH, addition of yeast and bacteria, degree of impurity and toxicity of materials, ratio of carbon to nitrogen, type and size of reactor and other examined the variables.
Energy and Renewable Energies
Abbas Shekofte del; Abbas Asakereh; Mohsen Soleymani; Seyed Mohammad Safieddin Ardebili
Abstract
Introduction: Anaerobic digestion, in addition to producing biogas, can minimize the environmental problems of animal manure and produce high-quality fertilizer. Finding suitable places for the construction of anaerobic digestion reactors is essential for the sustainable development of these types of ...
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Introduction: Anaerobic digestion, in addition to producing biogas, can minimize the environmental problems of animal manure and produce high-quality fertilizer. Finding suitable places for the construction of anaerobic digestion reactors is essential for the sustainable development of these types of power plants. Locating the biogas production site is a complex process with different and sometimes contradictory criteria including environmental, economic and technical criteria from which the location-related factors play the main role. The integration of geographic information systems (GIS) with multi-criteria decision making (MCDM) provides a powerful tool that can be useful in locating biogas power plants.Materials and Methods: In this study, spatial and non-spatial data were integrated with geographic information system in order to determine the optimal places for installing anaerobic digesters of livestock and poultry waste in the southeast of Khuzestan province. Data related to the type and number of livestock and poultry were collected separately from the Ministry of Agriculture. The location of livestock farms and chicken farms was determined using the GPS system. Livestock and poultry raised in the traditional way in the villages were not taking into account due to the problems of collecting manure and lack of economic justification. In order to determine the evaluation criteria and score them, similar studies, rules and guidelines, as well as the Delphi technique were used. 14 sub-criteria were evaluated in three main environmental, social-safety and topographical groups. Land suitability layers for the construction of anaerobic digestion reactors were prepared from the perspective of all sub-criteria in the GIS environment. In order to simplify calculations and easier weighting of criteria and sub-criteria to obtain the final result, some layers of criteria were combined. In this way, 14 layers were combined and overlapped until 7 layers of final criteria were formed. Since the spatial potential layer of biogas production is the main criterion and has the main effect on the suitability of land for the construction of a power plant, and on the other hand, it has no essential relationship with other criteria, it was valued separately. Roads and residential areas were also valued separately due to the greater importance of lower transport costs, accessibility, reducing transport time and losses, as well as environmental, health and safety impacts. The overall layer of surface water was obtained by multiplying the four layers of land suitability considering the sea, river, wetland and flood prone areas. Sensitive areas including forest, agriculture and protected areas were also considered in an exclusive layer. The other two layers were the combination layer of slope, height and fault, and the combination of railway lines and high voltage power lines. These layers were weighted using pairwise comparisons and hierarchical analysis method. The final layer of land suitability for the construction of anaerobic digesters and power plant was created by overlapping all the criteria layers based on the obtained weight.Results and Discussion: The findings showed that anaerobic digestion of livestock and poultry wastes in the region has a potential to produce 7.25 million m3/year of biogas. Cow and chicken excrement have the largest share with 51.32 and 29.34 percent, respectively. The restriction layer showed that 73.28% of the area is unusable due to one or more restrictions. The results also showed that "regional biogas production potential" and "access to roads and energy consumption centers" are respectively the most effective factors in determining the appropriate location for the power plant. Finally, using spatial analysis in ArcGIS environment, the studied area was classified into five suitability levels: "unsuitable", "weak", "moderate", "suitable" and "very suitable". Based on this, 73.28% of the studied area was completely unsuitable and only 1.68% of the studied area was very suitable for the construction of a power plant. But in almost all the studied areas, there was enough land with suitable or very suitable conditions to build a biogas plant.Conclusion: In the studied area, lands with suitable conditions for the construction of a power plant from animal waste using anaerobic digestion technology were identified. There is a suitable distribution of "suitable" or "very suitable" levels in the study area for the construction of a biogas power plant. The findings of this study can be a guide for those in charge to make a decision for the construction of a power plant.
Energy and Renewable Energies
Mahmoud Karimi; Reza Mohammadigol; roohollah rahimi
Abstract
Introduction: Biodiesel is viewed as a promising alternative to fossil fuels due to its favorable chemical properties and environmental benefits. Research has shifted towards producing biodiesel from non-edible oils and waste cooking oils to avoid food scarcity issues. The high cost of production is ...
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Introduction: Biodiesel is viewed as a promising alternative to fossil fuels due to its favorable chemical properties and environmental benefits. Research has shifted towards producing biodiesel from non-edible oils and waste cooking oils to avoid food scarcity issues. The high cost of production is a major challenge, with raw materials accounting for 75% of the total cost. Sustainability depends on low-cost feedstocks like waste cooking oil. Exergy analysis is a useful tool for optimizing biodiesel production by reducing energy and resource consumption and increasing production yield. The study focuses on the exergy flow of transesterification of waste cooking canola oil, with parameters like methanol:oil ratio, catalyst concentration, and temperature being evaluated.Materials and Methods: Waste cooking oil (WCO) was used in the present study, with physicochemical properties including density, viscosity, free fatty acid content, and acid value measured. Biodiesel production using a two-step catalyzed method was carried out, with the first step being esterification to remove high water and FFA content in the waste cooking oil. The second step involved transesterification using different methanol:oil ratios, catalyst concentrations, and reaction temperatures. The FAME content of the samples was analyzed using gas chromatography and an equation was provided to calculate the FAME content of the biodiesel samples. In the process of transesterification of WCO, four balance equations were used to analyze exergy. Mass, energy, and entropy input and output must be balanced, with a portion of exergy input being destroyed. The mass exergy component is divided into physical, chemical, potential, and kinetic exergy. The overall exergy of a mixture of substances was calculated by considering physical and chemical exergy. Mixing in the transesterification process is irreversible, with potential work being wasted. Exergy transfer by heat flow and workflow was calculated using specific equations. An exergy conversion coefficient was used to estimate the chemical exergy content of fuels. Dead state conditions were considered for calculating exergy efficiency in the transesterification process.Results and Discussion: The GC analysis of transesterification conversion products from a standard sample showed that the main components in WCO-derived biodiesel were methyl salicylate, methyl palmitate, methyl stearate, methyl oleate, methyl linoleate, and methyl oleate. The efficiency of the transesterification process under specific conditions was determined to be 90.23% with an exergy efficiency of 91.73%. Exergy analysis revealed that the exergy embodied in biodiesel was higher than that in WCO, but a portion of WCO's exergy was consumed in the production of biodiesel. The study also highlighted ways to reduce energy loss and material waste in the transesterification process, emphasizing the importance of recycling and reusing waste materials to improve overall resource efficiency. The experiment variables of methanol:oil molar ratio, KOH concentration, and reaction temperature were investigated in the transesterification process for biodiesel production. A higher methanol:oil molar ratio of 6:1 was recommended for maximum yield when using pure oil with low FFA and water content. Increasing the ratio from 4:1 to 8:1 resulted in higher biodiesel yield and exergy efficiency. However, further increasing the ratio to 12:1 led to decreased efficiency. The KOH concentration and reaction temperature also had significant impacts on biodiesel yield and exergy efficiency. Higher catalyst concentration and reaction temperature increased exergy destruction, while a temperature increase from 45℃ to 55℃ improved efficiency and yield. The study suggested that careful optimization of these variables is essential for maximizing biodiesel production and minimizing exergy losses.Conclusion: Exergy analysis is a valuable tool for assessing the environmental impacts of products, processes, or activities by quantifying energy and material usage and waste generation within a comprehensive framework. It also allows for estimating the resource requirements for processes such as transesterification in the production of renewable resources like biodiesel. In this study, the exergy flow in the transesterification of waste cooking oil was evaluated, with a focus on the impact of variables such as methanol:oil ratio, potassium hydroxide concentration, and reaction temperature on biodiesel yield, exergy efficiency, and exergy destruction. Experimental data was collected and used for exergy calculations, revealing that maximum biodiesel yield and exergy efficiency were achieved at specific conditions. Excess methanol or potassium hydroxide led to decreased efficiency and increased exergy loss in the process. Lower temperatures also resulted in higher exergy loss due to reduced conversion efficiency. Understanding the effects of these variables can help improve exergy efficiency and economic performance in commercial biodiesel production. Exergy analysis can also be used to evaluate environmental performance and aid in the development of environmental policies and resource management strategies.
Energy and Renewable Energies
Abolfazl Hedayatipour; Mohsen Soleymani; Mostafa Kiani Deh Kiani
Abstract
Introduction: In recent years, due to its availability and low environmental pollution, the use of Earth-Air Heat Exchanger (EAHE) has been developed as an efficient energy system in heating and cooling residential buildings and agricultural greenhouses. In this system, air is circulated by a fan through ...
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Introduction: In recent years, due to its availability and low environmental pollution, the use of Earth-Air Heat Exchanger (EAHE) has been developed as an efficient energy system in heating and cooling residential buildings and agricultural greenhouses. In this system, air is circulated by a fan through a pipe buried deep in the ground. Depending on the geographical location and soil type, the soil temperature at a depth of 2-3 meters remains unchanged throughout the season. Of course, this depth varies throughout the year and according to climatic changes. The heat exchange between the soil and the air inside the pipe depends on the type of soil and its moisture content, the length and diameter of the air transmission pipe, the depth of burial and the velocity of the air flow (air velocity). Air circulation can be done in an open-loop or closed-loop circuit.Materials and Methods: A factorial experiment was conducted in the form of a completely randomized block design with two factors (pipe length at three levels (34, 17 and 52 meters) and air velocity at two levels (5 and 10 m/s)) in three replications, to investigate the effect of these factors on the coefficient of performance (COP), system efficiency and outlet air temperature. The experiment was conducted in a greenhouse in Arak city, Iran, in Joune 2022. This 150 square meter greenhouse was equipped with geothermal equipment. Air was circulated through a 200 mm diameter PVC pipe buried three meters deep in the ground. Air was circulating through an open loop circuit. Dependent variables were measured during the hot hours of the day (from 12:00 to 18:00) for one week at the end of July. The air temperature at the fan inlet and at 17, 34 and 52 meters along the pipe was measured by a single-channel data logger. Hourly changes in outlet air temperature, COP and efficiency were measured in a 24-hour period and plotted using Excel software.Results and Discussion: The outlet air temperature for the pipe length of 34 and 52 m did not change when the air velocity decreased from 10 m/s to 5 m/s. But for the pipe length of 17 m, the maximum temperature, COP and efficiency were observed at an air velocity of 5 m/s. Regardless the air velocity, the average temperature of the outlet air for the three levels of the pipe length was 28.5, 25.5 and 25.3°C, respectively. The outlet air temperature was almost the same for the 34 and 52 m pipe lengths. In other words, the optimal length of the pipe is about 34 meters. The mean efficiencies for these two pipe length levels were 0.69 and 0.66, but the COP depended on the air velocity. The average COP for air velocity of 5 and 10 m/s was obtained 1.4 and 2.5, respectively. Based on these results, the best performance of the system in terms of output temperature reduction, cooling efficiency and COP is obtained in situation that the length of the pipe is 34 m and the air velocity is 10 m/s. when the length of the pipe is 17 meters, the temperature of the air outlet at two velocities of 10 and 5 m/s was 29.9 and 27 °C, respectively. The cooling efficiency and COP at two velocity of 10 and 5 m/s, were 0.34, 0.54; and 2.1, 1.7 respectively. If the desired temperature is 28-30 °C, pipe length of 17 m and the air velocity of 5 m/s is recommended. The results of hourly performance analysis showed that the highest difference between inlet and outlet air temperatures, is obtained at middle hours of the day. The higher the ambient temperature, the higher the efficiency of the EAHE system. Conclusion: This system successfully met the cooling needs of a model greenhouse in the weather conditions of Markazi Province in June. Based on the results, the optimal pipe length and air velocity were obtained as 34 m and 10 m/s, respectively. The average air outlet temperature and cooling efficiency were 25.5, 0.66 and 2.5 respectively. The higher the ambient temperature, the higher the EAHE efficiency. This is mainly due to the higher temperature difference between the outgoing and incoming air during the hottest hours of the day. As a result, system efficiency and COP increase at the hottest hours of the day.
Energy and Renewable Energies
Ahmadreza Abdollahpour; Reza Tabatabaee; Jafar Hashemi
Abstract
Introduction: Agricultural residues and wastes are the main source of biomass for use in bioenergy production and animal and poultry feed production industries. These biomasses in their original form have a large volume and low energy (per unit volume) and require a lot of space and extensive movement. ...
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Introduction: Agricultural residues and wastes are the main source of biomass for use in bioenergy production and animal and poultry feed production industries. These biomasses in their original form have a large volume and low energy (per unit volume) and require a lot of space and extensive movement. Therefore, one of the methods of optimal use of these biomasses is to transform them into pellets, which have more mass and energy per unit volume and enable their easier use and transportation. Currently, biomass has the fourth place in energy supply after oil, natural gas and coal and provides approximately 14% of the world's energy needs. The use of biomass, especially in European Union countries, as an attractive source for replacing fossil fuels is developing and expanding. The use of biomass as fuel has significantly reduced the amount of environmental pollutants, so that the amount of CO2 absorbed from the atmosphere during biomass growth is similar to the amount produced during combustion, followed by a net cycle of production. Materials and Methods: The raw materials for making pellets were prepared from spruce wood sawdust (collected from a sawmill in Sari) as well as corn stalk and soybean residues in the fields of Dasht Naz in Sari. The desired materials were transferred to the laboratory in the necessary amount and kept at ambient temperature until the experiments. The samples were first crushed into 20 mm sizes and then powdered using a grain mill (Mehr Tehiz company, Iran) and passed through 18 mesh sieves in the range of 1 mm to make pellets. A palletization mechanism was used to compress the pellet. This system was designed and built in biosystem mechanics of Sari University of Agricultural Sciences and Natural Resources. The material was placed inside a steel mold with a cylinder inner diameter of 8.05 mm and a height of 150 mm with a blocked end. A piston with a diameter of 8 mm connected to the driving arm of the tension-compression test machine was used to compress the material. Loading by a piston with a quasi-static speed of 5 mm per minute is compressed to a pressure of 1300 N.Results and Discussion: In this research, the mechanical and thermal properties of pellets made from the combination of spruce sawdust and corn and soybean residues were evaluated. In the present study, the effect of four combinations of agricultural and forest materials at two moisture levels (12% and 18% based on fresh weight) on the indices of density, compressibility, Hausner ratio, strength and calorific value of the produced pellets were investigated and evaluated. it placed. The results showed that the pellet density at 18% humidity was lower than the density at 12% humidity. The highest density related to the combination of 60% spruce wood sawdust-40% corn stalks was obtained with a value of about 149 kg/m3 and the lowest value related to 100% soybean stalks was about 110 kg/m3. Also, the ratio of Hanser and CI in the combined pellets that have a higher percentage of sawdust and also in the combination of sawdust with corn stalks are within the permissible range. The highest pellet strength was 23.8 N/cm corresponding to 100% sawdust at 18% humidity and the lowest was 15.4 N/cm corresponding to 100% soybean stalk at 12% humidity. The calorific value of the pellets is in the range of 14.37 to 18.52 MJ/kg, which is the minimum value for the pellet made from 100% soybean stalk at 18% humidity and the maximum value for the pellet made from 100% fir wood sawdust and It was obtained at a humidity of 12%. Therefore, the use of agricultural wastes and their proper combination is a good option for the production of biofuels due to their density and strength.Conclusion: The type of biological waste and moisture percentage affect the physical and mechanical properties of the produced pellets. In general, the combination of spruce wood sawdust with corn stalks and soybean improved the mechanical and thermal properties of the pellet. Hanser's ratio and compressibility in the combined pellets that have a higher percentage of sawdust and also in the combination of sawdust with corn stalks are within the standard range. Also, in the compositions that have a higher proportion of spruce wood sawdust and lower moisture, the density and strength factors of the pellet increase. The highest and lowest calorific values were obtained in a higher ratio of sawdust and a higher ratio of corn, respectively. Therefore, it is possible to make pellets from the waste of garden and agricultural products that have good density and strength and high calorific value.
Energy and Renewable Energies
M. Soleymani; Alireza Keyhani; Mahmood Omid
Abstract
Introduction Replacing fossil fuels with renewable and environmentally friendly fuels is so essential, due to issues such as climate change, increasing fossil fuels prices, energy security and limitations of fossil fuels resources. Alternatives are wind energy, solar energy, geothermal energy, hydropower, ...
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Introduction Replacing fossil fuels with renewable and environmentally friendly fuels is so essential, due to issues such as climate change, increasing fossil fuels prices, energy security and limitations of fossil fuels resources. Alternatives are wind energy, solar energy, geothermal energy, hydropower, biomass and biofuel. Currently, ethanol produced from sugarcane in Brazil or from corn in USA is the most dominant bioufuel in the world. However there is no comprehensive agreement on the environmental benefits of alternative fuels including ethanol. The aim of this study was to conduct a LCA (Life Cycle Assessment) on ethanol produced from sugarcane molasses in Iran and also to compare its environmental impacts with a conventional fossil fuel. Materials and Methods All required data was obtained from Sugarcane Agro-industry and ancillary Industry Development, Karoon Agro-Industry and also from recorded databases. Economic allocation was chosen to allocate emissions between the main product and the byproducts. Also, Simapro software was applied to model and evaluate the life cycle environmental effects in the life cycle of sugarcane molasses based ethanol (from cultivating sugarcane to burn ethanol into the engine). Two different scenarios of ethanol production (existing system and modified system) were considered and the environmental impacts of these two systems were compared with each other. Finally the environmental impacts of whole life cycle of molasses based ethanol were compared to that’s of diesel as a conventional fossil fuel. Results and Discussion Life cycle inventory results showed that electricity, P2O5 and urea respectively had the most negative environmental impacts through the life cycle of molasses based ethanol. Replacing the fossil fuel originated electricity with electricity from renewable resources can have a significant effect on reducing the amount of these negative impacts. Also, producing electricity in the nearest location to the consumption sites will reduce the power transmission losses and consequently reduce these impacts. Since the major share of electricity is used for pumping water to the field, better management of water consumption is so essential. According to the results, in case of emissions, there was significant difference between diesel fuel and sugarcane molasses ethanol in the base scenario. But by modifying the production system and using bagass to produce biogas or electricity (scenario 2), the environmental impacts of life cycle of sugarcane molasses based ethanol would reduce by 10%. Even now, the amount of greenhouse gas (GHG) emission of ethanol is 60% lower than these emissions of diesel fuel. This reduction will reach 70% if wasted bagass in ordinary production system is used to produce biogas and electricity. Comparing with diesel fuel, Molasses based ethanol had less negative impacts on impact categories such as Respiration Inorganics, Climate Change, Acidification/Eutrofication, and fossil fuels and more negative impacts on categories such as Land Use and Carcinogens, only because of using land and also using herbicides and pesticides to cultivate sugarcane. Greenhouse gas emission in the life cycle of one mega joule molasses based ethanol, estimated by Biograce model, is respectively 69, 70 and 60 percent lower than that of gasoline, diesel and natural gas. Due to undeveloped industries to process sugarcane and its byproducts in Iran, studies on the production of ethanol from molasses or electricity from bagass are in the area of waste management. Therefore, in these cases, even if it there was suitable energy or environmental indicato, continuing the production of these products is justified according to other side issues including environmental benefits and employment. Conclusion In terms of environmental aspects, in the current situation there are no significant differences between ethanol and diesel. But if bagass is used to generate electricity, the environmental impact of ethanol production will reach reduced by 10%. Greenhouse gas emissions of ethanol is 60% lower than that of from diesel and this amount will be 70%, if wasted bagass is used to produce biogas or electricity. It is possible to obtain more environmental benefits by applying appropriate management strategies in ethanol production system (such as producing value added products from bagass or other waste materials). Since sugar is the main product in sugarcane industry in Iran and approximately all other byproducts are wasted, to prevent the loss of this valuable byproduct, producing ethanol from molasses, even if in current situation and with current production system is acceptable.
Energy and Renewable Energies
M Rekabi; M. H Abbaspour Fard; H Mortezapour
Energy and Renewable Energies
M Mozafari; A Ghazanfari Moghadam; H Hashemipour Rafsenjani; A Atae
