Papers by Alireza Keyhani
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Fuel and Energy Abstracts, 2011
This paper examines the energy use patterns and relationship between energy input and yield for g... more This paper examines the energy use patterns and relationship between energy input and yield for grape production in Malayer region of Hamadan Province. Data from 50 farmers were collected using a face-to-face questionnaire method. In the surveyed vineyards, average yield and energy consumption were calculated as 18,530 kgha−1 and 45,213.66 MJha−1, respectively. Among input energy sources, fertilizers, electricity and farmyard manure contained highest energy shares with 37.25%, 19%, and 17.84%, respectively. The energy ratio and energy productivity were found to be 4.95 and 0.42 kgMJ−1.Three econometric models were developed to estimate the impact of energy inputs on yield. The results revealed that impact of chemical, fertilizer and water on yield were significant at 1% probability level. Also, indirect and non-renewable energies were found to be rather high. Sensitivity analysis indicated that among the inputs, chemical has the highest MPP value of energy inputs. RTS (returns to scale) values for grape yield was found to be 2.15; thus, there prevailed an IRS of grape for estimated model. The net return was found to be positive as 2810.56 $ha−1 for grape. The benefit-cost ratio was calculated as 2.08.► The total energy consumption in grape production was 45,213.66 MJ and share of non-renewable energy for grape production was 61%. ► Chemical fertilizers and electricity were found the most energy consumer among all energy sources. ► Energy ratio was calculated as 4.95, indicated efficiency use of energy in the grape production. ► The impact of chemicals, water for irrigation and chemical fertilizer energy were significantly positive on yield (p < 1%). ► Among energy sources, chemicals and human labor had the highest MPP values.
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Energy for Sustainable Development
The aims of this study were to investigate influences of energy inputs and energy forms on output... more The aims of this study were to investigate influences of energy inputs and energy forms on output levels and evaluation of inputs sensitivity for alfalfa production in Hamedan province, Iran. The sensitivity of energy inputs was estimated using the marginal physical productivity (MPP) method and partial regression coefficients on alfalfa yield. Data were collected from 80 alfalfa farms in August and September 2009. The sample volume was determined by random sampling method. The total energy of 810.57 GJ ha− 1 was calculated for establishment and 7 years production life. The electricity used in pumping system was the highest energy inputs for alfalfa production (75.79%). Econometric model evaluation showed that the machinery energy was the most significant input affecting the output level. Sensitivity analysis results indicate that with an additional use of 1 MJ of each machinery and seeds energy, would lead to an additional increase in yield by 5.094 and 4.986 kg, respectively. The MPP of human labor, farmyard manure and biocides was negative. It can be because of applying the inputs more than required or improperly applying.► We investigated energy use and inputs–output relationship of alfalfa production. ► Total energy input was 810.57 GJha–1 and electricity has the highest energy inputs. ► The machinery energy was the most significant input affecting the output level. ► The MPP of human labor, farmyard manure and biocides was negative.
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Pakistan Journal of Nutrition, 2009
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Energy Conversion and Management, 2011
The most well-known reason of global warming is equivalent carbon dioxide (CO2equ) emitted from f... more The most well-known reason of global warming is equivalent carbon dioxide (CO2equ) emitted from fossil fuels combustion in on-road and off-road vehicles. An appreciable portion of off-road pollution is allocated to farm implements. All cited studies have shown that renewable based electric vehicles (EVs) decrease petroleum consumption and consequently reduce criteria emissions under nearly all circumstances. Considering this, a Solar Assist Plug-in Hybrid electric Tractor (SAPHT) was designed, constructed and evaluated. This research evaluated the life cycle analysis of SAPHT project and compared the results with that of an internal combustion engine tractor (ICET). The life cycle was analyzed based on economical cost and environmental emissions. The externality of environmental pollutions was calculated to derive the life-cycle costs (LCC). The results showed that substituting each ICET by SAPHT can prevent 14 ton CO2equ emission to atmosphere annually. Also it prevents a high volume of other emissions such as CO, NOx and PM10 entering the atmosphere. LCC assessment emphasizes on economical effectiveness of SAPHT rather than ICET at any diesel fuel price, therefore, increasing fuel unit prices leads to more effectiveness. It is concluded that levelized cost of energy (LCE) in €/kW h for ICET is almost twice as that of SAPHT. Some of these advantages for SAPHT are offset in part by high purchase costs, heavy and massive batteries and low operating range.
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International Journal of Green Energy, 2012
Prediction of daily global solar radiation (GSR) plays an important role in design of renewable e... more Prediction of daily global solar radiation (GSR) plays an important role in design of renewable energy systems. Artificial Neural Networks (ANNs) are powerful tools for modeling and estimating GSR even though using few inputs. In order to train the networks, a dataset of meteorological daily time series for 15 years (1993–2008) collected in Tehran by Iran Meteorological Office were used. The meteorological parameters used to estimate GSR were daily values of maximum, minimum, and mean temperatures; relative humidity; sunshine duration; and precipitation as inputs and the daily GSR in MJ m−2 day−1 as output. Various ANN models were designed and implemented by combining different meteorological data. The optimum model for estimating GSR had one hidden layer multilayer perceptron (MLP) with 37 neurons in it when the inputs were number of the maximum and minimum temperature, sunshine duration, daylight hours, extraterrestrial radiation, and number of day in the year. The empirical Hargreaves and Samani equation (HS) was also considered for the comparison. To estimate the difference between measured and estimated values of ANN and empirical models, mean absolute error (MAE), root mean square error (RMSE), and correlation coefficient (r) were determined. For 6-37-1 topology, r, RMSE, and MAE values were found to be 0.968, 3.09, and 2.57, respectively. Obtained results showed that ANN model outperformed HS model and can be successfully used for estimating the daily GSR for Tehran province and any other location.
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Sustainability, 2009
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Transportation Research Part D-transport and Environment, 2010
This paper looks at the various battery technologies available for use in solar assist plug-in hy... more This paper looks at the various battery technologies available for use in solar assist plug-in hybrid electric tractors In this context, solar assist plug-in hybrid electric tractors are those that may be used in light-duty agricultural operations. To determine the most suitable battery, four common technologies are analyzed looking at the environmental life-cycle effects and costs.
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International Journal of Food Properties, 2008
Drying conditions can greatly affect the physical and mechanical properties of grains. The drying... more Drying conditions can greatly affect the physical and mechanical properties of grains. The drying process must be controlled to reduce or minimize drying damage. In this paper the thin layer drying behavior of wheat (Tajan) in a convective dryer is experimentally investi-gated. ...
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Pakistan Journal of Nutrition, 2009
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International Journal of Food Properties, 2010
The present study was conducted to compute effective moisture diffusivity and activation energy o... more The present study was conducted to compute effective moisture diffusivity and activation energy of orange slices during convection drying. The thin-layer drying experiments were carried out at five air temperatures of 40, 50, 60, 70, and 80ºC, three air velocities of 0.5, 1.0, and 2.0 ...
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Renewable & Sustainable Energy Reviews, 2010
In this study data from 17 years (1990–2006) were collected to determine energy intensive areas a... more In this study data from 17 years (1990–2006) were collected to determine energy intensive areas and evaluate energy parameters of Iran's agronomy sector. All the direct and indirect inputs of energy for the production of 19 agricultural commodities were evaluated. The inputs and outputs were calculated by multiplying the amounts of inputs and outputs by their energy equivalents. The results indicated that total energy input increased from 32.40 GJ ha−1 in 1990 to 37.20 GJ ha−1 in 2006. At the same period, total output energy increased from 30.85 to 43.68 GJ ha−1. The results show that irrigation with 40.0% and fertilizer (28.4%) had the highest share in energy consumption. The average net energy gain was a positive value; however, about 87% of the input energy emanates from non-renewable sources of energy. The mean energy ratio was estimated to be 1.07 and showed an increasing trend during the period rising from 0.95 in 1990 to 1.17 in 2006. This indicates that increased use of inputs ha−1 in production was accompanied by a larger increase in the output levels. It can be inferred from the results that improvements in irrigation and fertilizer application can significantly affect the energy efficiency of Iranian agriculture.
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Agriculture Ecosystems & Environment, 2010
The objectives of this study were to determine the energy consumption and evaluation of inputs se... more The objectives of this study were to determine the energy consumption and evaluation of inputs sensitivity for barley production in Hamedan Province, Iran. The sensitivity of energy inputs was estimated using the marginal physical productivity (MPP) method and partial regression coefficients on barley yield. The results revealed that total energy input for barley production was ∼25,027 MJ ha−1; the non-renewable energy shared about 66% while the renewable energy did 34%. Energy use efficiency, energy productivity, and net energy were 2.86, 0.19 kg MJ−1, and ∼46,498 MJ ha−1, respectively. Econometric model evaluation showed that machinery energy was the most significant input which affects the output level. Sensitivity analysis indicates that with an additional use of 1 MJ of each of the human labour, machinery and electricity energy would lead to an increase in yield by 7.37, 1.66 and 0.33 kg, respectively. Also, the MPP of biocides energy was calculated to be −1.97 implying that the use of biocides energy is in excess for barley production, causing an environmental risk problem in the region.
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Journal of Cleaner Production, 2009
The RAMseS project, financed by the European Commission under the 6th framework Program, has the ... more The RAMseS project, financed by the European Commission under the 6th framework Program, has the purpose of developing a solar powered agricultural vehicle in order to replace the conventional vehicles based on internal combustion engines (ICE). In the present study, we report a comparison of life-cycle emission between two systems; a conventional ICE vehicle (ICEV) and the RAMseS electrical vehicle (EV). The study has been conducted by designing a specific model and using the SimaPro software. The results show that the RAMseS system is considerably more environmentally friendly than conventional ICE based system and that, specifically, it can avoid the emission of about 23 ton of CO2equ per year. Regarding all other pollutants, we found that the RAMseS system is 2.6 times more efficient than the ICEV. The main contribution to emissions of the RAMseS system is due to the batteries which contribute for a 73% of the total. Therefore, further improvement can be obtained with the use of more advanced battery systems, not based on lead.
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Journal of Cleaner Production, 2009
The RAMseS project, under the European Commission's 6th Framework Program, is dedicated to the co... more The RAMseS project, under the European Commission's 6th Framework Program, is dedicated to the construction and test of low-power operations based on photovoltaic power and a multipurpose electric vehicle. In the present study, the life-cycle costs and economical indices for the vehicle during its life span were assessed, compared to those of a standard internal combustion engine vehicle (ICEV). The results indicated that the life-cycle costs for the RAMseS vehicle and the ICEV are the same for a fuel unit price of 1.8 €/L. Also, the levelized cost of energy (LCE) for the RAMseS vehicle, was found to be 2.13 €/kWh, while RAMseS LCE, without EV taken into account, was shown to be 0.62 €/kWh. The RAMseS payback period (PBP) without EV taken into account was calculated to be 9 years if the value of the produced energy becomes at least 0.35 €/kWh. Vehicles that use PV systems as their power source, such as RAMseS, will be economically effective for fuel costs higher than 1.8 €/L, but considering the environmental benefits that are provided in terms of external costs, they can be considered profitable even at lower fuel costs.
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Renewable & Sustainable Energy Reviews, 2009
Finding energy sources to satisfy the world's growing demand is one of society's foremost challen... more Finding energy sources to satisfy the world's growing demand is one of society's foremost challenges for the next half-century. The challenge in converting sunlight to electricity via photovoltaic solar cells is dramatically reducing $/watt of delivered solar electricity. In this context the sun trackers are such devices for efficiency improvement.The diurnal and seasonal movement of earth affects the radiation intensity on the solar systems. Sun-trackers move the solar systems to compensate for these motions, keeping the best orientation relative to the sun. Although using sun-tracker is not essential, its use can boost the collected energy 10–100% in different periods of time and geographical conditions. However, it is not recommended to use tracking system for small solar panels because of high energy losses in the driving systems. It is found that the power consumption by tracking device is 2–3% of the increased energy.In this paper different types of sun-tracking systems are reviewed and their cons and pros are discussed. The most efficient and popular sun-tracking device was found to be in the form of polar-axis and azimuth/elevation types.
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Papers by Alireza Keyhani