After conducting a Michigan Farm Energy Audit, Grand Valley Farm, the host site for the Aug. 17 agricultural energy efficiency tour, found it could cut energy expenses by more than 50 percent by replacing two traveling guns with a more energy-efficient center pivot system. The two installed center pivots use a Berkley Model, 75-horsepower irrigation pump with a flow of 1,200 gallons per minute. This pump replaced the 125-horsepower pump from the previous system and included a variable frequency drive to accommodate flow and pressure variations.
Table 1 documents the electricity of the two traveling guns used before the new system. Assuming a $0.14-per-kilowatt-hour rate, the total yearly operating expense for the two traveling guns was $58,220.
In Table 2, the electricity usage for the installed center pivot system is shown. The total electricity used is less than one-third of the consumed electricity of the old system. This led to a total expense of $25,343, less than half the original expense. Overall, Grand Valley Farm achieved a 56 percent energy reduction.
Table 1 – Traveler Rigs Electricity Usages
|
Irrigation System
|
Pumping Rate (gpm)
|
Total
Dynamic Head
|
Water
Horsepower
(WHP)
|
Electricity Rate
(kWh/hr)
|
Operating (hours)
|
Electricity Usage
(kWh/yr)
|
Cost @ $0.14/kWh
|
|
Traveler 1
|
650
|
383
|
62.8
|
71.0
|
2,841
|
201,554
|
$28,218
|
|
Traveler 2
|
650
|
407
|
66.8
|
75.4
|
2,841
|
214,305
|
$30,003
|
|
|
|
Totals
|
|
|
5,681
|
415,859
|
$58,220
|
Table 2 – Center Pivot Electricity Usages
|
Center Pivot
|
Pumping Rate (gpm)
|
Total
Dynamic Head
|
Water
Horsepower
(WHP)
|
Electricity Rate
(kWh/hr)
|
Operating (hours)
|
Electricity Usage
(kWh/yr)
|
Cost @ $0.14/kWh
|
|
Full Circle
|
1,200
|
247
|
74.7
|
84.4
|
771
|
65,099
|
$9,114
|
|
1,050
|
268
|
71.1
|
80.4
|
456
|
36,631
|
$5,128
|
|
3/4 Circle
|
1,200
|
264
|
80.0
|
90.4
|
453
|
40,990
|
$5,739
|
|
1,050
|
282
|
74.8
|
84.5
|
453
|
38,297
|
$5,362
|
|
|
|
Totals
|
|
|
2,134
|
181,018
|
$25,343
|
Not only did the farm reduce its energy expenses with the center pivot system, the system also reduced water loss from evaporation and wind using low-elevation spray application (LESA). The entire system is low-pressure, with the center pivot operating at 50 psi and the end gun at 30 psi. The higher efficiency allowed by this application system has allowed Grand Valley Farm to see a 30-bushel-per-year increase in its corn yields. It is estimated that the new system is allowing 99 percent of the pumped water to reach the crops. Achieving the proper hydration for the crops led to higher yields within the first years of operating the new system.
Grand Valley Farm applied for and received USDA Rural Education Achievement Program grant that covered 25 percent of the total cost of the irrigation system. The farm also received an energy savings rebate from Consumers Energy. These funding opportunities are still available.
Data in this article comes from a publication entitled “Farming for Efficiency: A Case Study—Grand Valley Farms” by Kara Dean, Breanna Earls and Aluel Go with the Michigan Farm Energy Program.
Source: Michigan State University Extension