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3^UniversityofIdaho ^^ College of Agriculture Current Information Series No. 572 Cooperative Extension Service August 1981 Agricultural Experiment Station •a IV JUN17H983 Hill Buying a Low Energy Irrigation System T. S. Longley, J. F. Guenthner and J. L. Boesel Increasing power costs for irrigation pumping (and limited availability of electrical energy in some cases) have created much interest in lower pressure sprinkler systems. Nearly every manufacturer of center pivot or linear irrigation systems has available a low energy nozzling package. Reduced pressure nozzles are also available for wheelline and handline systems. While these low energy packages tend to reduce power costs, other factors may make this type of system less than an ideal choice. Four considerations are important in the choice of a low pressure system (whether a new system or a conversion of an existing system): (1) economics, (2) the infiltration and runoff potential, (3) weather con siderations and (4) the manufacturer or dealer guarantee. In general, the selection of a low pressure irrigation system seems an economically sound investment because of its energy saving potential. However, each grower needs to make an economic analysis of the financial feasibility of such a system for his own operation. A low pressure irrigation system will decrease a grower's energy costs each year it is used. A dollar in some future year, though, will probably be worth less than a dollar today. Present value analysis is a financial tool that uses interest rates and mathematical formulas to convert the value of all future dollars to present dollars. The financial feasibility of a low pressure irrigation system can be determined by comparing the present value of the expected cost savings to the initial investment cost. If the cost savings are greater, the investment is feasible. Economic Feasibility Many factors influence the economic feasibility of a low pressure irrigation system.* These include: • Area power cost and power cost inflation. • Expected future inflation. • Pressure reduction. • Efficiency of the overall system. • Life expectancy of the system. • Interest rates on capital investment. • Hardware options used with the system. Many calculations can be made using different values for one or more of the factors listed. Most dealers have techniques and devices that will simplify these calculations. Table 1 represents an example of the economic analysis process that most dealers will go through in helping a grower select a new pivot system. The analysis is similar for reduced pressure wheel and handline systems. Power cost and annual power inflation rate are assumed to be 2 cents perKWH and 20 percent respectively. Gross seasonal water application is assumed to be 22 inches, a sufficient amount for most crops. Most conventional systems are designed with an 80 to 100 psi pressure at the pivot (to operate an endgun). Most low pressure systems will operate at 50 psi at the pivot (allowing for some elevation changes because of hilly terrain); the pressure reduction with this low energy example is thus assumed to be 50 psi. The pumping plant efficiency is assumed to be 70 *Note that well depth does not influence this analysis because the static lift (well depth) does not change as the operating pressure is lowered. A Reference to trade names is made with the understanding that neither discrimination is intended nor endorsement implied.
Object Description
Title  Buying a low energy irrigation system 
Creator  Longley, T. S.; Guenthner, Joseph F. (Joseph Frank), 1951; Boesel, J. L. 
Date  19810801 
Description  1 sheet; 28 cm. 
Subject (NALT)  irrigation systems 
Subject (LCSH)  Irrigation pumpsEnergy conservation 
Publisher  Idaho Agricultural Extension Service 
Identifier  uica_cis0572 
Disclosure Statement  Documents are preserved for archival purposes. The information may be out of date. For more recent editions check the University of Idaho Library catalog or University of Idaho Extension Publication website, http://www.cals.uidaho.edu/edComm/catalog.asp 
Rights  Digital image copyright 2011, the University of Idaho. All rights reserved. For more information contact Special Collections and Archives, University of Idaho Library, Moscow, ID 838442350; http://www.lib.uidaho.edu/specialcollections/. 
Source  Special Collections Idaho S 53 (Between E3  E415) 
Digitization Specifications  150 dpi jpg converted to pdf. Master file is a 400800 dpi TIFF. 
Contributing Institution  University of Idaho Library 
Extent  1 sheet; 28 cm. 
Format  application/pdf 
Type  Text 
DateCreated  2013 
Language  eng 
RelationIs Format Of  Current Information Series (University of Idaho. College of Agriculture) 
Number  572 
Place of Publication  Idaho 
Original OCLC number  26281256 
Description
Title  Page 1 
Type  Text 
Full text  3^UniversityofIdaho ^^ College of Agriculture Current Information Series No. 572 Cooperative Extension Service August 1981 Agricultural Experiment Station •a IV JUN17H983 Hill Buying a Low Energy Irrigation System T. S. Longley, J. F. Guenthner and J. L. Boesel Increasing power costs for irrigation pumping (and limited availability of electrical energy in some cases) have created much interest in lower pressure sprinkler systems. Nearly every manufacturer of center pivot or linear irrigation systems has available a low energy nozzling package. Reduced pressure nozzles are also available for wheelline and handline systems. While these low energy packages tend to reduce power costs, other factors may make this type of system less than an ideal choice. Four considerations are important in the choice of a low pressure system (whether a new system or a conversion of an existing system): (1) economics, (2) the infiltration and runoff potential, (3) weather con siderations and (4) the manufacturer or dealer guarantee. In general, the selection of a low pressure irrigation system seems an economically sound investment because of its energy saving potential. However, each grower needs to make an economic analysis of the financial feasibility of such a system for his own operation. A low pressure irrigation system will decrease a grower's energy costs each year it is used. A dollar in some future year, though, will probably be worth less than a dollar today. Present value analysis is a financial tool that uses interest rates and mathematical formulas to convert the value of all future dollars to present dollars. The financial feasibility of a low pressure irrigation system can be determined by comparing the present value of the expected cost savings to the initial investment cost. If the cost savings are greater, the investment is feasible. Economic Feasibility Many factors influence the economic feasibility of a low pressure irrigation system.* These include: • Area power cost and power cost inflation. • Expected future inflation. • Pressure reduction. • Efficiency of the overall system. • Life expectancy of the system. • Interest rates on capital investment. • Hardware options used with the system. Many calculations can be made using different values for one or more of the factors listed. Most dealers have techniques and devices that will simplify these calculations. Table 1 represents an example of the economic analysis process that most dealers will go through in helping a grower select a new pivot system. The analysis is similar for reduced pressure wheel and handline systems. Power cost and annual power inflation rate are assumed to be 2 cents perKWH and 20 percent respectively. Gross seasonal water application is assumed to be 22 inches, a sufficient amount for most crops. Most conventional systems are designed with an 80 to 100 psi pressure at the pivot (to operate an endgun). Most low pressure systems will operate at 50 psi at the pivot (allowing for some elevation changes because of hilly terrain); the pressure reduction with this low energy example is thus assumed to be 50 psi. The pumping plant efficiency is assumed to be 70 *Note that well depth does not influence this analysis because the static lift (well depth) does not change as the operating pressure is lowered. A Reference to trade names is made with the understanding that neither discrimination is intended nor endorsement implied. 