• Energy Research
• 2016-2025close
• 13. Climate action close
• 7. Clean energy close
• 6. Clean water close
• 11. Sustainability close
• Persian close

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

Introduction: Evapotranspiration (ET) is an important component of the hydrological cycle, energy equations at the surface and water balance. ET estimation is needed in various fields of science, such as hydrology, agriculture, forestry and pasture, and water resources management. Conventional methods used to estimate evapotranspiration from point measurements. Remote sensing models have the capability to estimate ET using surface albedo, surface temperature and vegetation indices in larger scales. Surface Energy Balance Algorithm for Land (SEBAL) estimate ET at the moment of satellite path as a residual of energy balance equation for each pixel. In this study Hargreaves-Samani (HS) and SEBAL models ET compared to an alfalfa lysimeter data’s, located in Shahrekord plain within the Karun basin. Satellite imageries were based on Landsat 7 ETM+ sensor data’s in seven satellite passes for path 164 and row 38 in the World Reference System, similar to lysimeter sampling data period, from April to October 2011. SEBAL uses the energy balance equation to estimate evapotranspiration. Equation No. 1 shows the energy balance equation for an evaporative surface: λET=Rn–G–H [1] In this equation Rn, H, G and λET represent the net radiation flux input to the surface (W/m2), Sensible heat flux (W/m2), soil heat flux (W/m2), and latent heat of vaporization (W/m2), respectively. In this equation the vertical flux considered and the horizontal fluxes of energy are neglected. The above equation must be used for large surfaces and uniformly full cover plant area. SEBAL is provided for estimating ET, using the minimum data measured by ground equipment. This model is applied and tested in more than 30 countries with an accuracy of about 85% at field scale, and 95 percent in the daily and seasonal scales. In Borkhar watershed (East of Isfahan, IRAN) ASTER and MODIS satellite imageries were used for SEBAL to compare Penman-Monteith model. Results showed that estimated ET of SEBAL were about 20% less than sugar beet ET and about 15% more for maize ET by Penman-Monteith. He concluded the differences may be due to the limited number of satellite imageries which extrapolated ET through the entire growth period and the data obtained from the weather station far from 24 km in the studied area. In another study at Zayanderud Basin, the different irrigation networks were examined using Landsat 7 imageries to increase the spatial resolution of NOAA satellite to determine the energy balance components and actual evapotranspiration. In this study, data from a lysimeter to a depth of 2.5 m and a diameter of 3 meters planted with alfalfa in the Chahar-Takhteh agricultural research station (Agricultural and natural resources research center of Shahrekord, IRAN) was used. The lysimeter (LYS_REF) located in the in the middle of 25 × 40 m (1000 square meter) alfalfa cultivated farm, surrounded by other planted area. The lysimeter used to measure the reference evapotranspiration (ETr) and around alfalfa was used as cold pixels. Materials and Methods: This study was conducted to evaluate SEBAL and Hargreaves-Samani estimated ET models against evapotranspiration measured by lysimeter within the Shahrekord plain. Meteorological data required for a period of 185 days (according to the lysimeter data period) includes minimum and maximum relative humidity (RHmax and RHmin), maximum and minimum air temperature (Tmax and Tmin), wind speed at two meters (U2), precipitation, evaporation rate, sunshine hours, air pressure and dew point temperature obtained from a weather station nearby lysimeter. In order to assess reference evapotranspiration (ETr) models, statistical indices such as the coefficient of determination (R2), mean absolute error (MAE), mean bias error (MBE), root mean square error (RMSE) and index of agreement (d) were used. Results and Discussion: The results showed that RMSE, MAE and MBE for SEBAL model over the lysimeter data were 1.782, 1.275 and -0.272 mm/day and 0.700 for the d index, respectively. Similar indices for the Hargreaves-Samani model were 1.003, 0.580 and 0.290 mm/day and 0.917 for the d index. For HS model results show that RMSE, MAE and MBE values were 0.813, 0.477 and 0.206 mm/day, and 0.930 for the index of d, during the entire growing period (185 days). Conclusion: However, results showed that the efficiency and reliability of the SEBAL model by processing satellite visible, near infrared and thermal infrared bands. The need for irrigation water requirements and ET estimation are noteworthy, during the growth of various plants, which vary and thus the complete time series of satellite imageries is required to estimate the total and annual evapotranspiration.

A study on the impacts of soil humidity and artificial shading on growth, biomass production and its allocation to different organs of wild pistachio (Pistacia atlantica Desf.)saplings was carried out in Alborz research station complex (Karaj, Iran). One year seedlings were treated by soil humidity (20, 50 and 100 percent of field capacity) and shading (100, 70 and 50 percent of full sunlight) factors in a split plot experiment based on a randomized complete block design from June to December 2014. Results showed significant impact of oil humidity on height, collar diameter, fresh and dry biomass of leaves and stem as well as on total fresh biomass. Shade significantly decreased height, root and total dry biomass and root to shoot fresh biomass ratio. Moreover, wild pistachio saplings with different soil humidity treatments show different responses to shade. In particular, shade significantly decreases height, fresh leaves biomass and R/S fresh biomass ratio for well-irrigated saplings and increases these parameters for saplings under drought stress. Response trends of different parameters under humidity × shade treatments showed that shade can reduce undesirable effects of drought stress on wild pistachio saplings.

In this study, the effect of some soil parameters on the life forms and total aboveground net primary production (ANPP) in meadow rangelands in Fandoghlou region of Namin county in Ardabil Province were investigated. ANPP in 180 plots of 12 by harvesting and weighting method were measured. Eighteen soil samples were collected along transects. Some physical and chemical attributes of the soil were measured by standard methods. The relationship between these parameters and ANPP was performed using multivariate regression (enter) method. To determine the effects of important soil parameters on ANPP variation, principal component analysis (PCA) was used. The results of regression analysis showed that electrical conductivity (EC), magnesium (Mg), spreadable clay (WDC), volumetric moisture content (VM), organic carbon (OC), soluble potassium (KS), exchangeable potassium (Kexch), sodium (Na) and phosphorus (P) were the effective parameters on the life forms and total ANPP (p<0.01). The accuracy of obtained equations for grasses, forbs and total ANPP were calculated 79, 76 and 70%, respectively. Moreover, results of PCA showed that soil parameters justify 84.52 percent of total ANPP variation and in comparison, with regression results with 28% it provides better results.

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.

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.

Introduction:Vinasse is a byproduct of the sugar industry. Sugarcane or Sugarbeet is processed to produce crystallinesugar, pulp and molasses. The latter isfurther processed by fermentation to ethanol, ascorbicacid or other products. After the removal of the desired product (alcohol, ascorbicacid, etc.) the remaining material is called vinasse. Vinasse is sold after a partial dehydration and usually has a viscositycomparable to molasses. Commercially offered vinasse comes either from sugarcaneand is called cane-vinasse or from sugarbeet and is called beet-vinasse. On average, for each liter of vinasse, 12 liters alcohol produced. Vinasse is a material with dark brown color and the smell of burned sugar, which is rich in potassium, calcium, magnesium, phosphorus and nitrogen. Materials and Methods:To determine the effect of vinasse and additive nitrogen and phosphorus on growth and yield of tomato, a factorial pot experiment was conducted at ZanjanUniversity in 2008. Two different plant nutrient including N and P and their combination (N+P) were added to vinasse with three different concentrations to form experimental treatments. In addition to these treatments, three control treatments with vinasse of different concentrations, but with no additive were also included in the experiment. Each treatment used with two different application methods (soil application and soil + foliar application).The experiment had 24 treatments, a complete randomized design and three replications. The vinasse used in this experiment was diluted with water 10, 20 and 40 times to make a nutrient solution of three different concentrations of tomato plant. The amounts of nitrogen and phosphorus that were added to vinasse were 224 and 62 mg/l, respectively. Phosphorus and nitrogen were applied to as super-phosphate triple and calcium nitrate and ammonium nitrate respectively. After being deployed to ensure complete installation of tomatoes in pots containing perlite (about 2 weeks after the transfer of seedlings tothe pots) treatments wereapplied to the pots. It should be noted that initially, three tomato seedlingswere planted in each pot at later stage after the plants were thinned to one plant per pot.Five months later after planting seedlings, fruits were picked and measured separately. At the end of the growth period, fruit yield, leaf and some quality characteristicsof fruit were measured. Results Discussion: The results showed that the effects of vinasse concentrations on fruit yield, dry matter content of fruit, dry weight of root and plant height were significant at p