Comparable Costs of Various Energy sources for Irrigation Pumping
Rolland Z. Wheaton and Edwin J. Monke Department of Agricultural Engineering, Purdue University
Because of continued rising prices of petroleum products, many irrigators are looking more closely at the comparative costs of various energy sources for irrigation pumping. The purpose of this publication is not only to provide such a comparison, but also to alert you to other factors that must be considered in selecting a particular energy source.
Performance Standards for Various Energy Forms
From Nebraska Test data, standards have been developed for the horsepower-hours that engines or motors should produce using four different energy forms--gasoline, diesel fuel, propane gas and electricity. (A horsepower-hour is 1 horsepower' produced continuously for 1 hour.) The results are shown in Table 1.
These standards are the best that can be expected for engines operating at 85 percent and electric motors operating at 100 percent of their horsepower ratings. If loadings are reduced below these percentages, the standards must also be reduced. For continuous opera-
tion, recommended loadings are 80 percent of maximum horsepower ratings for water-cooled engines, 65 percent for small air-cooled engines and 100 percent for electric motors.
Determining Comparable Costs
The above standards were used to calculate the amount that can be paid for each of the energy sources to obtain an equal number of horsepower-hours per dollar spent. The price figures are presented in Table 2. However, they are only for the energy purchased, and do not take into account such factors as initial cost, maintenance requirements, convenience, energy availability and dependability of service.
COOPERATIVE EXTENSION SERVICE • PURDUE UNIVERSITY • WEST LAFAYETTE, INDIANA