Irrigation
P. Tahmasbi; F. Dalvand; S.A. Hosseini; B. Karimi; H. Ghadrshnas
Abstract
IntroductionAgriculture plays a dual role in the energy sector meaning that it acts both as a source of raw material for bioenergy production and as a major consumer of energy, particularly in the processes of planting, cultivation and harvesting, transportation, processing, and storage of agricultural ...
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IntroductionAgriculture plays a dual role in the energy sector meaning that it acts both as a source of raw material for bioenergy production and as a major consumer of energy, particularly in the processes of planting, cultivation and harvesting, transportation, processing, and storage of agricultural products. Among the numerous challenges facing the agricultural sector, optimizing energy or input consumption is of paramount importance. These key inputs play a crucial role in ensuring food security and economic stability for the country. One of the most important agricultural development programs in the country should be to increase efficiency of energy consumption in the agricultural sector. In Iran, approximately 9.2 million hectares have been equipped with modern irrigation systems (pressure system) which has increased the water productivity index from 0.87 kg m-3 in 2014 to 0.32 kg m-3 in 2014. Accordingly, it is predicted to reach 0.60 kg m-3 hectares until 2025. The Dehgolan Plain, located in the east of Sanandaj city, has an area of 84,982 square kilometers. Groundwater is the only source of water for agriculture in the region. Due to the annual decrease in the groundwater level, energy consumption for water extraction has increased. Common irrigation systems in the region's farms include fixed-mobile sprinkler classic rain irrigation systems, center pivot, and lateral roll. Thus, it seems necessary to evaluate the energy productivity and efficiency indexes in the mentioned plain. The main objective of this study is to evaluate the energy consumption indexes of wheat in farms under fixed-mobile sprinkler classic and Willet rain irrigation systems. Materials and MethodsThis study was conducted in the farms of Dehgolan plains where the energy consumption trend of input factors in two irrigation systems was investigated. All information related to input factors and working hours of machinery, agricultural equipment, and manpower was recorded at the end of the cropping season 1400-1401 through filling out questionnaires. The studied farms in this research were all under dry wheat cultivation and equipped with two rain irrigation systems, system 1 (fixed-mobile sprinkler classic) and system 2 (Wheel move irrigation). The required input factors for wheat production in each hectare were determined. The amount of different input factors for conversion to energy standard was calculated using energy coefficients and equivalents. As a result, energy productivity, energy use efficiency, specific energy, and net energy indexes were used to investigate the energy consumption trend of wheat in the two mentioned irrigation systems. Results and DiscussionThe results of this study showed that the total input energy for wheat production in systems (1) and (2) was 85943.97 and 69189.04 MJ ha-1, respectively and energy consumption in the Willet rain irrigation system was higher than in the fixed-mobile sprinkler classic rain irrigation system due to the high consumption of electricity and irrigation water. The electricity consumption in both systems accounted for the highest energy consumption. Moreover, the energy productivity and efficiency of the two systems were almost equal as well as the net energy of irrigation system (1) and irrigation system (2) was 41510.96 and 64156.03 MJ ha-1, respectively. ConclusionIn conclusion, this study focuses on evaluating the energy trends in rain irrigation systems used in dry wheat farms in the Dehgolan plains, Kurdistan province, Iran. In this study, the energy indexes of wheat in smallholder farmers' farms in Dehgolan plain, Kurdistan province, were evaluated. The studied farms were categorized into two groups, system (1) (fixed-mobile sprinkler classic rain irrigation system) and irrigation system (2) (Willet rain irrigation system), the energy source of which was electricity for both systems. At the end of the cropping season, the total amount of input and output factors were collected by filling out questionnaires in person, and to validate the amount of electricity consumption, its amount was obtained from the Dehgolan Electricity Company. The results of the research showed that the energy consumption per unit of wheat production in the Willet irrigation system was higher than in the fixed-mobile sprinkler classic irrigation system. This difference was due to the higher consumption of electricity and irrigation water in the Willet irrigation system. The energy productivity and efficiency indexes were almost equal in both systems. Eventually, the net energy of the fixed-mobile sprinkler classic irrigation system was higher than that of the Willet irrigation system.
M. DelfanAzari; Atefeh parvaresh Rizi
Abstract
Introduction: The energy crisis has led the world toward the reduction of energy consumption. More than 70 percent of the energy in agriculture sector is used by pumps. In our country, there is no clear standard and guideline and also no adequate supervision for the design, selection, installation and ...
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Introduction: The energy crisis has led the world toward the reduction of energy consumption. More than 70 percent of the energy in agriculture sector is used by pumps. In our country, there is no clear standard and guideline and also no adequate supervision for the design, selection, installation and operation of pumping systems appropriate to the circumstances and needs. Consequently, these systems operate with low efficiency and high losses of energy. While more than 20 percent of the world's electricity is consumed by pumps, average pumping efficiency is less than 40%. So evaluation of pumping stations and providing some solutions to increase efficiency and pumping system’s life time and to reduce energy consumption can be an effective in optimization of energy consumption in the country. The main reasons for the low efficiency of pumping systems comparing to potential efficiency are using unsuitable techniques for flow control, hydraulic and physical changes of pumping system during the time, using pumps or motors with low efficiency and poor maintenance. Normally the amount of flow is not constant over the time in a pumping system and needed flow rate is changed at different times. Designing of pumping system should be responsible for peak requirements as well as it must suggest the suitable flow control method to achieve least energy losses for minimum flow requirements. Also one of the main capabilities to reduce energy consumption in pumping stations is improving the flow control method. Using the flow control valves and bypass line with high energy losses is very common. While the use of variable speed pumps (VSPs) that supply water requirement with sufficient pressure and minimum amount of energy, is limited due to lack of awareness of designers and (or) high initial costs.
Materials and Methods: In this study, the operation of the pumping stations under four scenarios (for discharge control) in a drip irrigation system was analyzed and evaluated: A) Pumping station equipped with VSPs, in this case it is possible to regulate energy consumption due to the required discharge and pressure for irrigation system , B) Pumping stations equipped with constant speed pumps (CSPs) and flow control valve maneuver in every decade of irrigation, C) Pumping stations equipped with CSPs without any flow control and D) Pumping stations equipped with CSPs and flow control valve maneuver per month of irrigation. Pumping stations equipped with CSPs was designed for a 100 hectares irrigation area for peach and apple trees in the South West of Isfahan province. The produced pressure under four types of flow control were determined. Then pump performance and energy consumption were evaluated under three operation scenarios (B, C and D) and afterward compared with the performance of VSP stations that was designed for this irrigation system.
Results and discussion: The most important point in the design of pumping stations is energy consumption, because the cost of energy supply is high and the operation should be able to save more energy. Using the output values of pressure and flow rate from developed model, the amount of energy consumption for each pump was calculated. It was observed that the energy consumed in pumping stations equipped with VSPs is significantly less than other stations. Regarding to the total energy consumption and the amount of energy that each scenario can save, the percentage of energy savings were calculated. The results show that the highest percentage of energy savings are belonging to scenario (a) (using VSPs).
Conclusion: The results of this study show that application of VSPs at pumping stations than commonly pumping stations with CPSs, depending on the type of CSP operation, saves 44 to 54 percent of energy. Using VSPs, which save a lot of energy compare to other methods, can be an important phase in optimizing energy consumption and minimizing the cost operation of the agriculture pumping station. So the type of operation that discussed in the present study and also the type of irrigation system, pump selection, cultivated area and irrigation scheduling are effective at saving energy during VSPs employment. In a recent case, reduction in energy cost should be independently calculated for each irrigation system and be considered in the lifetime costs of pumping system. Regarding the results of this research and also latest studies, it can be said that the study design and implementation of variable speed pumps in irrigation projects should be considered in national scale. Because development of pressurized irrigation schemes that inevitably need to pump, is the country's main policies for efficient use of water.
