# 10.3: Calculating Power Costs

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It is important for water managers to determine the potential costs in electricity for pumping water. Units used for measuring electrical usage are typically in kilowatt-hours (kW-Hr). In order to convert horsepower to kilowatts of power, the following conversion factor is used.

1 horsepower = 0.746 kilowatts of power

Once you know the hp that is needed you can then determine the amount of kW-Hr needed. Then, costs can be determined depending on what the local electric company charges per kW-Hr. Water utilities will calculate estimated budgets for pumping costs since these are typically the largest operating costs.

## Exercises

Solve the following problems.

Pump

Flow Rate

Hp

Efficiency

Run Time

Total Cost

1

500 gpm

50

2

1,000 gpm

75

4

2,000 gpm

250

Well

Flow (gpm)

Run Time (Hr/Day)

Wire-to-Water Eff

hp

Cost/Year ($) @$0.135/kW-Hr

A

750

18

68%

110

B

1,800

13

61%

85

C

2,750

12

57%

95

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