It's nothing new to most folks. The price of diesel is at or near an all-time high and has also been very unstable. Almost 80 percent of the irrigation systems in Georgia (1970s era) were initially installed with diesel operated pumps. This was due in part to the low cost of diesel fuel at that time and also due to the unavailability of three phase electricity in rural areas.
The availability of three phase electricity is constantly changing. Your local power supplier can answer the availability question for your specific location. What you want to know is “Will electricity save me enough in operating cost to justify the change?” Or “How long will it take to pay for the change with energy savings?”
Perhaps the easiest and quickest way to answer the “payback” question is to look at some numbers. Let's take a 100 horsepower load (not necessarily a 100 hp engine or motor). Regardless of the energy source, the actual horsepower load will remain the same. Yes, it takes a larger horsepower engine than this, but the amount of energy that is used will be based on the load.
With diesel at $4 per gallon; the cost to operate the pump will be about $25.16 per hour. With electricity costs of 8 cents per kw-hr, the cost to operate that same 100 hp pump load is $6.78 per hour. This is a savings of $18.38 per hour.
Now you need to find out the cost to convert energy sources. This could be a combination of input from the power company, irrigation dealer and/or well driller.
For this example, let's use $30,000 ($15,000 for the electric motor and controls and $15,000 for line extension charges from the power company). You can now figure out how many hours of operating time it will take for the cost to convert energy sources to pay for itself.
In this example, it will take about 1,630 hours of operating time for the energy savings to pay for the $30,000 in changes. For most irrigation systems, with average usage, that is about three years for simple payback (no interest, etc.).
While this example shows a savings of more than 75 percent with a three-year simple “pay back,” that may or may not hold true for other situations. It all depends on several individual factors: The horsepower, the energy costs, and the cost to convert from one energy source to another.
Of course, there will always be other questions to answer and other considerations that factor into the decision to change energy sources. Some of the most common questions are:
Will there be any electrical operating restrictions?
Depending on the power company, you could have a monthly demand or standby charge. You could also have to sign an agreement to be on an interruptible power arrangement. You could also have to pay a higher price for electricity used during certain hours of the day. It is extremely important to discuss this with your power supplier so that if design changes are necessary they can be included up front. Note that the example above used a single price for electricity and did not include any demand or standby charges.
What about the need/possibility to upgrade the existing sprinkler package or pump?
If you are talking about a center pivot, the design change mentioned above might fit right into this category. This would be the perfect time to upgrade the sprinkler package or increase pumping capacity.
What is the condition of the existing diesel engine? If the diesel engine is due to be replaced anyway, use that money to go towards the power company or electric motor replacement. The engine might have some use as a “backup” in some other function on the farm.
What about using some of the EQIP funds I've heard about?
Check with your local NRCS office to determine what is available in your area/district. You could potentially get funding for a new sprinkler package and the electric motor conversion.
Finally, it is not an easy task or decision to make. You might have to talk to the power company, an electrician, the well driller, and the irrigation dealer multiple times before finally getting all of the information you need to make your decision.
Give yourself plenty of time. New electric motors, installing power lines or getting a new pump will take time to get in place.