Setting efficiency indicators for center pivots

Abstract

ABSTRACT:In this study, it was discussed the efficiency criteria in each of the elements that compose a central pivot, and this analysis was applied to two sets of systems located in regions of Cruz Alta and Santo Augusto, state of Rio Grande do Sul, Brazil. The methodology used combines water and energy assessment through an indicator called Normalized Specific Consumption in Irrigation (C ENI ), allowing thus a comparison between equipment and projects. The C ENI in Cruz Alta region showed 72% of the equipment above the standard (8.68 kWh mm -1 ha -1 100m -1 ), and in Santo Augusto region 64.28% with consumption above the standard. The mean irrigation efficiency for Cruz Alta region was 29.85%, with standard deviation of 5.41%, and for Santo Augusto region, it was 29.02%, with standard deviation of 5.15%.

Energy Efficiency of a Center Pivot Irrigation System

“…The average values of Es it was considerate statistically equal for the angular positions in uphill and downhill. This observation differs fro m that made by Schons et al (2012) where these authors relate values of Es only in function of the topography. Thus, the Es values may be more related to other factors, and according to Luc et al (2006) who analyzed a group of 115 pump ing units with a capacity greater than 80 m³.h -1 , and found that there is a linear relat ion with determination index (R²) equal to 0.98 of the Es values with the TDH values.…”

“…Co mparing the positions of the lateral line in area irrigated by center pivot, we can see higher values of Es for areas of higher elevation in the last tower (maximu m value equal 0.43 kWh m -3 for the 336° position) and smaller Es values for lower altitude area (0.416 kWh m -3 referring to the 96° position). Schons et al (2012) find an estimated value of 0.41 kWh m -3 for a center pivot in the state of Rio Grande do Sul. These authors also report that Es can be used to compare projects within the same irrigation system, and to evaluate the efficiency and depreciation of equip ment.…”

“…For the specific case of center pivot irrigation systems in Brazil, Cezar-de-Lima et al (2008) and Schons et al (2012) used a specific normalized energy consumption index that is expressed in kWh.mm −1 .ha −1 .100m −1 . Th is index represents the amount of active electrical energy (kWh) that is required in order to pump a normalized volu me o f water (mm.ha = 10m…”