|
Energy Estimator for Irrigation is the third of several tools from Natural
Resources Conservation Service (NRCS) developed to increase energy awareness in
agriculture. This NRCS energy consumption tool enables you to estimate energy
cost of pumping water in the irrigation operations on your farm or ranch. NRCS
technical specialists have developed these cost estimates based on irrigation
methods for predominant crops in your state. This tool does not provide
field-specific recommendations. It evaluates options based on user input.
Steps to use the Energy Estimator: Irrigation Tool
Step 1: Zip Code
To use this tool, begin by
entering your zip code, then click Continue:
Step 2: Hydraulic Setting and Irrigation System
There are several factors that
affect the energy consumption and cost of irrigating your crops. The vertical
elevation difference between water surface being pumped and pumping plant
discharge point during pumping operations (i.e., for vertical turbine pump
static water level plus draw down) referred to as lift, and system water
pressure at pumping plant discharge point in pounds per square inch (psi) are
critical factors in determining energy consumption and operation cost. There
are system modifications that you can perform that will improve the efficiency
of your system that will lead to energy consumption and cost savings.
Enter the lift in feet, system water pressure in psi, and price per unit of
fuel/energy you use to power your irrigation system. Select ‘Yes or No’ to the
questions regarding the system modifications you have completed.
Step 3: Crops and Irrigation Rate
The listed crops are the most commonly irrigated crops in the state that was
identified by the zip code you entered. These crops may not be the most common
crops in your immediate neighborhood, but they are significant crops in your
state.
Instructions:
-
Select a crop from the drop-down list.
-
Enter the number of acres you irrigate for one crop with the irrigation system
you selected on the previous page. You may run this tool again to examine
additional crops and/or systems.
-
The default value for each crop is the average gross seasonal water application
depth (ac-in/ac) for that crop in your selected state based on the irrigation
system you selected. If you know your gross seasonal application depth, you can
enter that value and all computations will be based on the value you enter.
Step 4: Irrigation System Analysis
The table below indicates your
irrigation system water use and cost estimates for your selected crop and
compares it with our projected use and costs for your system after irrigation
system modifications have been implemented to improve efficiency. The table
also shows estimates of energy cost and potential cost savings if you were to
implement recommendations of a pumping plant evaluation with the corresponding
irrigation system modifications. Factors considered in the analysis include
adding a flow meter, implementing irrigation scheduling and conducting system
maintenance & upgrades. This tool does not provide field-specific
recommendations. It evaluates alternatives based on your input. Changes in
energy use and costs are reported as differences from your current system
configuration based on your responses on the previous pages.
Assumptions
What is Well Lift?
The vertical distance, in feet, of the distance between the level of water in the well and the pump. If surface water is used, it is the vertical distance between the average level of the surface water and the pump. For the purpose of this program, the frictional loss of head due to the well drop pipe is assumed to be negligible.
Based on:
Static Suction Lift: The vertical distance in feet, when the source of supply is below the pump, from the surface of the liquid to the pump centerline. (Source: Cornell Pump)
Total Static Head: The potential energy due to the vertical distance between the pumping water level and the entrance to the distribution system. (Source MWPS-30)
What is system operating pressure?
The measured water pressure of the irrigation system. The iPAT tool will give the most accurate results if the water pressure is known close to the outlet of the pump.
Based on:
Pressure Head: The pressure energy necessary at the distribution system entrance to overcome losses and operate sprinklers at the design pressure. (Source MWPS-30)
Pressure ranges
Operating pressure will vary for each individual system based on initial conditions but a general range follows. The range includes friction loss from the pump to the point of application.
| Low pressure | 0 – 25 psi | most surface and some drip/micro systems | | Medium pressure | 26 – 59 psi | some drip/micro and some sprinkler systems | | High pressure | 60 + - psi | some sprinkler systems |
What are Energy Units?
The energy units are as follows:
- Electric - dollars / kilowatt-hours $/kwh (The minimum is $0.001 and the maximum is $0.50.)
- Diesel - dollars / gallon $/gallon (The minimum is $1.00 and maximum is $9.99)
- Natural Gas - dollars / one thousand cubic feet $/MCF (The minimum is $1.00 and the maximum is $50.00)
- Propane - dollars / gallon $/gallon (The minimum is $1.00 and the maximum is $9.99)
- Gasoline - dollars / gallon $/gallon (The minimum is $1.00 and the maximum is $9.99)
Why These Crops?
These crops are the most commonly irrigated crops by acre in the state that was identified by the zip code you entered. They may not be the most common crops in your immediate neighborhood but are significant crops in your state.
How were the average gross seasonal water application values determined?
How were estimates made?
The Energy Estimator uses national averages to estimate the energy savings for a particular farm.
A pumping efficiency is assumed for each different type of irrigation system.
The use of a flow meter, irrigation scheduling, and/or regular maintenance & upgrades typically reduces the amount of water pumped over the course of a growing season.
Pumping less water will result in some measurable energy savings.
In addition, conducting a pumping plant evaluation and acting on the resulting recommendations has been shown to increase the efficiency of the pumping plant by 15%.
All of these figures are based on averages. Your own energy savings may vary from the estimate given.
What are the assumptions?
Estimated cost if a flow meter is used. Irrigation water must be measured if it is to be used efficiently. Measurement often results in a decision to use less water. Water must be measured to each field, and each set for optimum irrigation water management. A measurement at the diversion, lateral, or farm delivery point can be translated to each field if the water is not split and used on separate fields. Most water-measuring devices indicate the rate of flow and require a conversion to volume or depth applied. An irrigator needs to know how many acre-feet or acre-inches of water are being applied to a field of known area.
Estimated cost if Irrigation scheduling is used. Irrigation scheduling is deciding when and how much irrigation water to apply. The soil moisture deficit in the root zone must be measured (monitored) and irrigations scheduled in order to obtain good water management. Farmers use a number of irrigation scheduling methods that consider soil type, soil water storage capacity, crop growth stage, water availability and level of irrigator control. Scheduling generally involves monitoring plant available soil moisture, estimating current crop water use, and anticipating future crop water use during the scheduling period. Tools commonly used in scheduling include visual and or thermal measurement of crop condition, soil moisture sensing devices, rainfall monitoring, media Evapotranspiration (ET) reports, local crop ET networks, and commercial scheduling services.
Estimated cost if System Maintenance and/or an Upgrade is performed. A system must be maintained in order to be managed at its potential. Nozzles on sprinklers have to be replaced, drip emitters must be cleaned and replaced, fields need to be re-leveled, concrete ditches and structures for water control have to be replaced when they wear out or repaired when damaged. Replacement of old, worn-out, damaged, and obsolete systems is needed for efficient irrigation. The operator of a trickle or sprinkler system should use a pressure gage to periodically verify and regulate line pressure.
Estimates for pumping plant evaluation. Well tests should be run to establish overall pumping plant efficiency. A comparison between measured values and attainable field pumping plant efficiencies would indicate the need for adjustments, repair, or system improvements, which could result in lower annual pumping cost.
Want a more accurate estimation?
- If you need assistance running this tool, contact your local NRCS field staff.
Click to find your local NRCS office - For other sources of technical assistance and services you may want to contact the following:
- extension service
- irrigation or water districts
- Technical Service Providers
- pump or utility companies
- consultants
Definitions
Default
Value:
Flow
Meter:
An instrument used to measure the volume and/or rate of flow of water in a conduit or channel (Source: ASAE 526.2)
Irrigation
Scheduling:
The process of determining when to irrigate and how much water to apply, based upon measurements or estimates of soil moisture or water used by the plant (Source: ASAE 526.2)
Pressure
Ranges:
Pressure ranges
Operating pressure will vary for each individual system based on initial conditions but a general range follows. The range includes friction loss from the pump to the point of application.
| Low pressure | 0 – 25 psi | most surface and some drip/micro systems | | Medium pressure | 26 – 59 psi | some drip/micro and some sprinkler systems | | High pressure | 60 + - psi | some sprinkler systems |
Pumping
Plant Evaluation:
Pumping plant efficiency is the ratio of the amount of work done (output) by a pumping plant (pump and power unit) to the amount of energy required to do the work (input). Pumps and many engines and motors are designed to operate under a narrow range of conditions. They should be operated within this range for best efficiency. Pumps and power units are subject to wear, so close attention to maintenance is required to sustain desirable pumping efficiency.
An overall pumping plant evaluation can be conducted where "water or output horsepower" is calculated based on measured "total dynamic head" (pumping lift(ft) + discharge head (ft)), and flow rate. The fuel usage rate is measured while the pumping plant is in operation. The method used to measure fuel usage rate depends on the energy source. An overall pumping plant efficiency is determined and compared to the Nebraska Standard Pumping Plant Efficiency for the type of pumping plant evaluated. This comparison is usually expressed as a "Per Cent of Nebraska Standard Efficiency". Based on the results of the overall efficiency test, the producer can determine potential energy cost reductions that would be possible if the system was brought up to the standard. If the current system is at or above the standard efficiency, improvements may not be cost effective. A list of potential improvements is generally provided. Some of the potential problems may include
- Over loaded and under loaded engines and motors
- Natural gas pressure at carburetor too high, or too low
- Natural gas leaks
- Pumping plant valve problems
- Improper pipeline installations
- Electric motors improperly wired
- Damaged or improperly installed electric control panel
- Need for a change of spark plug, spark plug wires, cooling system service, or an engine overhaul
- Pump bearings or impellor needs replacing
- Irrigation system changes from a low pressure to a higher pressure system without changing or updating pump
Regular
Irrigation Application System Maintenance and Upgrades:
Any of a variety of repairs or maintenance activities that reduce water loss during the irrigation season, or increase the efficiency of the irrigation applications.
Seasonal
Gross Application:
System
Type:
Flood:
For the iPAT tool, this refers to any surface irrigation method that does not use furrows.
Based on:
Flood Irrigation, wild flooding: A surface irrigation system where water is applied to the soil surface without such flow controls as furrows, borders (including dikes) or corrugations.
(Source: ASAE 526.2)
Furrow:
Method of surface irrigation where the water is supplied to small ditches or furrows for guiding across the field.
(Source: ASAE 526.2)
MicroIrrigation:
The frequent application of small quantities of water as drops, tiny streams, or miniature spray through emitters or applicators placed along a water delivery line.
The microirrigation method encompasses a number of systems or concepts, such as bubbler, drip, trickle, line source, mist, or spray.
(Source: ASAE 526.2)
Sprinkler:
Method of irrigation in which the water is sprayed, or sprinkled, through the air to the ground surface.
(Source: ASAE 526.2)
|
|