In this study a mathematical model was adjusted to quantify the effect of the pump efficiency on cost variation of the pumping system in the green hourly seasonal tariff (subgroup A4 - irrigation) and the investment recovery period by a more efficient pumping station. Afterwards, the same model was applied in a pumping system supplying a center pivot irrigation machine. The hydraulics pump efficiency options were: 69.5% (pump 1), 73% (pump 2) and 78% (pump 3), with acquisition costs of R$ 6,176.00, R$ 8,479.00 and R$ 15,509.00, respectively. The results of the model applied showed that: i) the substitution of pump 1 for 2 was feasible, being the investment recovery period of 3.4 years; ii) the substitution of bomb 1 for 3 was feasible, being the investment recovery period of 9.2 years; and iii) the substitution of bomb 2 for 3 was unfeasible, being the investment recovery period of 21.1 years, therefore superior to its useful life span, considered 15 years.
mathematical model; energy; costs
