• Energy Research
• 2016-2025close
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This paper develops a dynamic general equilibrium model (DGEMI) for evaluating energy policies in Iran’s economy. DGEMI provides a detailed multisector framework for analyzing economic transition, removal of energy subsidy, and technological change policies. The results show that eliminating energy subsidies (once- for -all or gradually) in the absence of technological progress is in itself insufficient to stimulate the investment and economic growth. Although the energy intensity along with this policy declines over time, its decline can not be attributed to the energy efficiency, since the economy falls into the lower level of new steady state after removing the energy subsidies. On the other hand, the combination of eliminating energy subsidies and technological progress policies provide a strong growth stimulus accompanied by a pronounced increase in productive efficiency and a decline in intensive energy.

Abstract Background and Aim: Increasing energy consumption has created an energy crisis in the world. Fossil fuels are limited and depleting. Biogas is considered a fuel that has attracted the attention of researchers. To increase biogas production, different pretreatments have been utilized. The purpose of this study was to investigate the optimal mixing ratio of Municipal Solid Waste (MSW) and Sewage Sludge (SS), as well as the effects of various conditions of alkaline pretreatment on biodegradability of wastes and the amount of biomethane production. Materials and Methods: This study was done in a laboratory digester with 1 L volume at 37 °C with different concentrations of NaOH in a completely randomized design. Biogas volume, methane volume, and changes in pH were measured daily. Measurement parameters in the anaerobic digestion including total solids, volatile solids, and carbon and nitrogen content in the feedstock were determined according to the APHA standard methods. Results: The optimal mixing ratio of MSW to SS was 60:40 with the highest methane yield of 254.87 mL/g VS. Next, the effects of 2, 6, and 10% NaOH concentrations were evaluated on the amount of gas produced, indicating that 6% NaOH concentration significantly improved waste decomposition. Methane production, VS, and TS removal were compared to the control treatment, and there were increases of 30, 27.94, and 27.25%, respectively. Conclusion:The results showed that the mixing ratio of MSW to SS at 60:40 with 6% NaOH improves the decomposition of organic wastes and increases biomethane production. Keywords: Alkaline Pretreatment; Anaerobic Digestion; Biogas; Municipal Solid Waste; Sewage Sludge

Background and Objective: In recent years, management and disposal of municipal solid waste has become a global problem and the most important environmental concern. Anaerobic digestion is a cost-effective solution for treatment of both solid waste and wastewater. The aim of this study was to investigate the positive or negative effects of calcium chloride content in anaerobic digestion process of municipal solid waste and leachate on biogas production. Materials and Methods: Experiments with 8 levels of calcium chloride on co-digestion of municipal solid waste and leachate were investigated in 500 ml digesters under mesophilic conditions in a completely randomized design with three replications. Reactors with a ratio of substrate to inoculum of 2 (on VS basis) were operated and the volume of the biogas was measured daily. Volatile and total solids, carbon/nitrogen of waste, COD, BOD and heavy metals were measured by following APHA. Results: The results of the experiment showed that the pH was decreased with increasing calcium chloride concentration. The highest amount of cumulative biogas production was obtained in CaCl2 of 2 g/L with the highest VS and TS reduction. Higher concentrations of CaCl2 (≥3 g/L) caused a reduction in the degradability of volatile and total solids and, as a result, a decreased performance of the digester. Conclusion: The results clearly confirmed that the addition of calcium chloride was an effective solution to improve biodegradability in co-digestion of the MSW and leachate and consequently to reduce the total and volatile solids and to increase the amount of‌ biogas.

Today’s world faces two major crises including environmental pollution due to fossil fuels and the reduction of these fuels, so energy supply through renewable energies has been considered a sustainable solution. The purpose of this study was to assess factors affecting the tendency to use biofuels among villagers. Heads of households in rural areas in Chavarzagh district, Tarom township, Zanjan province formed the statistical population of the study (N=2742). The sample size was estimated using the Cochrane formula (n=161) and samples were selected using multi-stage cluster sampling method. The descriptive and correlational research method was used in this study. The validity of the questionnaire was approved by a panel of related faculty members. Cronbach's alpha coefficient was used to confirm the reliability of the questionnaire (0.70-0.83). Data was analyzed using SPSS 21. Regression analysis showed that risk, attitudes towards biofuels, self-efficacy, training, eliminating subsidies for fossil fuels and encouraging the use of biofuels, increasing public awareness about the benefits of biofuels and perceived barriers explained 40.6 percent of the variation of villagers’ tendency to use biofuels.

Abstract Background & Objective: Agriculture is one of the most important activities, whereas observing ethical dimensions (human, environment, animals, society, economy and policy) are necessary. Therefore the purpose of this study was develop strategies to apply ethics in agricultural in Sonqor County. Materials &Methods: This study is a Qual-Quan research. The study population consisted of experts and farmers producing healthy products in the city of Sonqor (n = 32) who were selected purposefully. Results: Based on results, comprehensive government attention to Agricultural ethic and financial, technical, and legal support from the farm food to the table ( ) as a first strategy and evelopment of good agricultural production for all products, regional, national, international contracts and agreements in order to meet the needs of healthy consumer markets ( ) as a second important strategy was recognized which both of them are among the aggressive strategies. Also result showed that considering ethical actions towards development of sustainable agricultural, allocation of annual budgets, leading agricultural education to ethical agriculture (WO) are the most important conservative startegies. Conclusion: in the current situation in study the, aggressive strategies should be prioritized. This means that with considering the factors affecting the non-observance of ethics in agriculture, instutational development in this area, amend the rules, guidelines and most important social institutions and ethicl norms in the community of farmers need to be addressed in this county. In this regard the approach of farmers and related organizations should be changed toward appliying manifest of ethic in agriculture.

Background and Objective: In this study, effects of residue management, irrigation methods, tillage systems and planting methods on some important aspects of common wheat-maize rotation in Khuzestan province was investigated. Materials and Methods: The experiment was conducted as strip-block split factorial on randomized complete blocks design with three replications. Residue management considered as main plots, irrigation methods as subplots and factorial combination of tillage systems and planting methods as sub subplots. Results: Retaining residue on surface in flood and drip tape irrigation systems increased maize harvested about 0.4 and 0.18 kg per each m3 of applied water, respectively. In conservation tillage practices, reduced tillage and no-tillage with residue on surface had no significant effects on wheat and maize yields compared to conventional tillage, but improved water use efficiency, energy productivity and economic indices. The highest benefit to cost ratio (BCR) was obtained as 1.72 from drip tape irrigation-with total residue-conventional tillage- ridge bed planting treatment. The lowest input energy (76635 MJ.ha-1) and the highest energy productivity (0.210 kg.MJ-1) was belonged to drip tape irrigation-with total residue-no tillage- ridge bed planting treatment, Also BCR in this conservation system was obtained 1.62. Conclusion: Moving towards adoption of agricultural conservation techniques such as retain residue, reduce tillage, planting on permanent ridge bed and use high efficiency irrigation methods would result in a sustainable production. According to the results of this research, the use of conservation tillage systems are recommended.

One of the main sources of greenhouse gas (GHG) emissions is the use of energy for groundwater pumping. Reducing energy consumption is very important to achieve the environmental sustainability and decrease the climate change impacts. In this paper, the amount of greenhouse gas emissions from groundwater pumping in the Guilan’s aquifers was investigated. Firstly, groundwater depletion and the types of pumps for water pumping were examined in the current condition; then, the values of consumed energy, GHG emissions and climate change indicator of the current condition were estimated. The primary investigations showed that 55 percent of wells in the studied region had a diesel engine pump, while 51.3 percent of the required energy for groundwater pumping was supplied by electric pump. Calculated total GHG emissions and the value of climate change indicator in the current condition were equal to 8.98 and 7.59 Milion kg CO2 eq , respectively. In order to achieve environmental sustainability and energy security, scenarios of replacing electric pumps and applying solar energy were examined. The results of the scenarios showed that diesel fuel wells had no significant effect on the reduction of greenhouse gas emissions, but the use of solar energy reduced them. GHG emissions, in comparison with the base scenarios, were decreased by 44.4% in June, July and August, respectively, by applying the scenario of using the solar pump in agricultural section. Therefore, it is preferred to apply policies in future planning to use renewable energies such as solar energy instead of diesel and electricity energy.

Importance of renewable-energy resources because of scarcity, greenhouse-gas emissions, and their fundamental roles in production and sustainable development, has made governments to reduce energy consumption and improving energy efficiency. In this regard, targeting subsidies rule was running in Iran since 2010. Since energy additionaly to labor and capital is one of the important inputs in production, running this rule with increasing energy price, affects manufacturing industries due to the type of energy and industry. In this research, the impacts of price liberalization on electricity efficiency have evaluated. Partial adjustment model, generalized method of moment and energy intensity measure are applied to this purpose. Data are collected from Statistical Center of Iran during 1995-2013. The research innovations are: using a partial adjustment model in evaluating efficiency, assessment whole industrial groups, and the period of research. The results show that in 95 percent level of confidence, the Iranian manufacturing industries are significantly flexible for changing the use of electricity. But the electricity efficiency has gotten worse after running the rule. In general, apposite of expectations, targeting subsidies rule has failed to improve electricity efficiency at least in short run.

According to the importance of expanding the use of clean energy, especially solar energy, in this study a solar cooker was designed, built and its performance in terms of the angle of the side mirrors at the same time and working time on the amount of energy absorbed was investigated by response surface methodology (RSM). The total amount of solar radiation as a measure of energy intake and increased water temperature inside the container was taken as an indicator of the amount of energy absorbed. The model on the basis of response surface methodology was used to validate the test and had a good validation (R2=0.89, R2adjusted=0.74 and lack of fit: no significant). Analyzing the results of a mathematical model was obtained for investigation of the effect of the side mirrors angle and time on the performance of the system. The amount of absorbed energy by theory and laboratory has been also compared and the average of error at all tests was 2.75%. Based on this model in the optimal condition, energy absorption was increased by 22.56%. This study was done at Institute of Food Science and Technology located in Mashhad with latitude 54 and 36 degrees and a height of 985 meters above sea level.

Abstract: Fuzzy DEA methods have been introduced to deal with the fuzziness of variables. Although, some of these variables are affected by uncertainty and also information granularity, the membership function of fuzzy set is certain and this contrasts with the fuzzy concept as a whole. Type-2 fuzzy sets are introduced because of this and their membership functions have the nature of fuzzy type-1. The calculations of type-2 fuzzy sets are very complicated. However, interval type-2 fuzzy sets which have the characteristics of type-2 fuzzy sets and do not add any complexity to the calculation process can be applied to deal with such a problem. That is why in this paper, it is explored that how an extension of interval type-2 fuzzy dynamic network DEA approach helps to measure airports’ sustainability. Sustainable airports play an irrefutable role in making transportation systems sustainable. Such an integrative approach in DEA models is unprecedented. So, this extension of DEA is valuable from both technical and conceptual aspects. Introduction: Airports are an essential component of aviation (Knudsen, 2004). The importance of airports becomes clearer when it comes to the fact that aviation traffic is more than before and, therefore, sustainability becomes difficult. While, various studies have suggested that the sustainability of airports is essential to improve the performance of these systems, improve the living conditions of the public and increase the airport's credit (Brian, 2005; ICAO, 2012; SAGA, 2015). Paying attention to the concept of sustainability in managing airports has various benefits, such as increased competitiveness by purifying activities, reducing operating costs, and reducing costs for life cycle of materials and equipment, better use of assets, utilization newer and better technologies, reducing asset development costs, getting more support from the community, improving working conditions and, as a result, improving employee productivity, reducing environmental risks, health, safety and promotion (SAGA, 2015; Bretzke, 2013; TRB, 2012; ACARE, 2011; Too, Earl, 2010). For the reasons mentioned, it can be said that it is necessary to pay attention to the sustainability of the passenger airports of the country. Certainly, before adopting any approach, the current situation must be assessed correctly. Various methods have been used to evaluate performance, but Data Envelopment Analysis (DEA) is one of the most widely used methods (Azizi et al., 2004). Data envelopment analysis is a functional and nonparametric method that allows consideration of various components as input and output or intermediate activities (Bray et al., 2015). However, no research has been found to determine the performance of airports in accordance with the principles of sustainability in Iran. Materials and Methods: Type-2 fuzzy Dynamic Data Envelopment Analysis (DEA) is used to assess the performance of Iran’s passenger airports based on sustainability development. By use of Dynamic Network Data Envelopment Analysis, one can see how the different parts of a decision unit can be linked. It also shows how the past performance of a decision-making unit can affect its current performance. In this type of data envelopment analysis, the function of the decision-making unit is transmitted through time-based intermediaries to the next period. Thus via using dynamic data envelopment analysis method, it is possible to consider the activities of different parts of a decision unit and also the efficiency with respect to time periods. However, the point is that in the real world, due to the increasing socioeconomic complexity and the inherent ambiguity of human thinking, there is no possibility of precise determination of many of the components. For this reason, type-2 fuzzy theory is employed that its membership function is the fuzzy of the first type. Since the complexity of calculations while using type-2 fuzzy set is high, interval type-2 fuzzy is applied. The 20 most popular passenger airports in Iran are selected to evaluate their performance in accordance with the principles of sustainability principles and via the help of the developed DEA model. Results and Discussion: Results of investigation show that Larestan Airport is the most efficient one among all and the last rank is allocated to the Isfahan airport considering fixed return to scale while in variable return to scale, Shiraz airport gets the last rank. The efficiency intervals of airports such as Larestan, Gorgan, Rasht and Yazd have little difference in two modes of return to scale. For this reason, we can say that there is no significant function inefficiency about these airports. But this difference is more evident in the efficiency of airports such as Mashhad. Airports, whose performance is generally low or are inefficient, are able to provide a groundbreaking improvement with appropriate benchmarking. Since airports operate in different conditions, difference in climatic conditions and the in workforce etc. should be considered while benchmarking. References ACARE (Advisory Council for Aeronautics Research in Europe) (2011). "Flight path 2050 Europe’s Vision for Aviation". Luxembourg: Publications Office of the European Union. Azizi, H., Kordrostami, S., & Amirteimoori, A. (2015). "Slacks-based measures of efficiency in imprecise data envelopment analysis: An approach based on data envelopment analysis with double frontiers". Computers & Industrial Engineering, 79, 42-51. Azizi, H., Jafari Shaerlar, A., & Farzipoor Saen, R. (2014). "A new Approach for Considering a Dual-Role Factor in Supplier Selection Problem: DEA with efficient and inefficient frontiers". Journal of production and operation management. 6(2), 129-144. Bray, S., Caggiani, l., & Ottomanelli, M. (2015). "Measuring transport systems efficiency under uncertainty by fuzzy sets theory based Data Envelopment Analysis: theoretical and practical comparison with traditional DEA model". Transportation Research Procedia, 5, 186 – 200. Bretzke, W.R. (2013). "Service Quality Versus Sustainability: A New Conflict of Objectives". Information Technology in Environmental Engineering Part of the series Environmental Science and Engineering, Springer, 179-190. Brian, E. (2005). "The Modern Airport Terminal: New Approaches to Airport Architecture". 2nd Edition, Taylor & Francis. ICAO (International Civil Aviation Organization) (2012). "Sustainable Future for Aviation: ICAO Rio+20 Global Initiative". http://climate-l.iisd.org/news/icao-publishes-booklet-for-rio20-decision makers (accessed 14.09.2015). Knudsen, F.B. (2004). "Defining Sustainability in the Aviation Sector". Brussell: Eurocontrol Experimental Centre. SAGA (Sustainable Aviation Guidance Alliance) (2015). "Learn". http://www.airportsustainability.org/learn, (accessed 16.12.2015). Transport Research Board (TRB) (2011). "Critical Issues in Aviation and the Environment 2011". Washington, DC: TRB. Too, L., & Earl, L. (2010). "Public transport service quality and sustainable development: a community stakeholder perspective". 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