Thursday, November 7, 2013

Three Phase Power: The First Choice for Irrigation Energy if it is Available | by Dr. Lyndon Kelley

Electric power is the least expensive source of energy for irrigation, when it is readily available. A comparison of several energy sources discussed in “Comparable Costs of Various Energy Sources for Irrigation Pumping” by Purdue University finds that to match the common electric rate of 10.4 cents per kilowatt hour, you would need to be able to buy diesel fuel for $1.31 per gallon.

Electric power provides many advantages for irrigation. Liquid fuel storage located near wells and surface water pose potential environmental risks that electric use avoids. Electric driven pumping plants are easier to control remotely, a bonus for the tech savvy irrigation manager. The higher initial investment in pumping equipment and higher annual maintenance cost of combustion engines pushes more irrigation toward the use of electric power. The question for most irrigators is, “how much will it cost to bring electric service to the irrigation system?” The answer depends on your location, service provider, and what is currently available for electric power.

Almost all farms have single phase electric power available. Electrical motors and controls for field-scale irrigation systems are designed for three phase power. Farm-supplied electric phase converters or variable frequency drives systems can be used to create three phase electric power from a single phase line, but will often be limited to small motors to reduce brownout problems on the service line. To further reduce brownout problems, electrical service providers may also require farms to buy and maintain soft start pump motors or variable frequency drives systems to reduce the start-up load of the larger horsepower pump motors.

Having three phase electric power provided at the location of the pump by your electric service provider is the simplest and safest energy source. It requires the least amount of farm owned/maintained equipment to run irrigation systems. Electric service providers can often generate a cost estimate for adding three phase electric power service to you location. In some situations, estimates may be free with a commitment to use a quantity of power in the future. More likely, a simple line drop from a new set of transformers on an existing three phase line maybe $500 to $2,000. If three phase power is not near the location, costs to install the service are estimated to be between $10,000 and $30,000 a mile. These costs are to be paid by the potential irrigator to upgrade service in the area.

Irrigators will often calculate the savings in initial equipment and annual maintenance and energy costs for electric power versus combustion engine over a five to 10-year period. The 10-year savings on a typical 160-acre irrigated field may be in the $25,000 range or higher, which could be applied to improving the electric power infrastructure in the neighborhood. Some power companies have programs to reimburse a portion of the cost for the original investor if other users hook on to the new three phase line in the next few years.

With the fast pace of growth of irrigation and other agricultural-related expansions, the demand for three phase electrical power in intensive agricultural areas is high. 

This piece was written for and published by Michigan State University Extension News

Dr. Lyndon Kelley
Michigan State University Extension and Purdue Extension

Lyndon is a guest writer for the Growing the Conversation blog by Valley. He has been an irrigation educator for MSU and Purdue Extension for the past three years, working in the areas of irrigation management and water policy. Lyndon is a 23 year member of MSU extension staff.  Based in St. Joseph County, MI., his workshops, presentations, and publications focus on irrigation scheduling, costs, system uniformity, and water rights rules.