Irrigation Pumping

Methods 5.0

upstream

on-farm

mechanical

Energy and emissions associated with pumping irrigation water from all sources to point of use.

Published

September 22, 2025

Introduction

Energy is required to lift and pressurize water for irrigation (Eisenhauer et al. 2021). For growers who apply irrigation water, the energy required to run irrigation pumps could be a significant contributor of on-farm energy use. The irrigation pump energy (\(PE\)) component is included in the energy and emission calculations for irrigated crops, as indicated by the grower. The estimated \(PE\) represents only the on-farm, mechanical portion of energy use; the methods below will also describe how indirect energy use (and emissions) are calculated.

Secondary water sources

A user may enter a second source of irrigation water that has a different depth and pressure requirements for pumping than the first source. If more than one water source is entered, the \(PE\) will need to be calculated separately for each source and then summed for total \(PE\).

Currently water source options may include:

Deep aquifer groundwater
Alluvial groundwater
Surface water
Combination

The selection here may affect a water conservation component within the Habitat Potential Index, but does not affect the \(PE\) calculation as that depends on other factors (e.g., depth, pressure, etc) described in the next section.

Methods

In the last version of the Fieldprint Platform, a user had the option of entering the actual energy consumed by a pump used for irrigating a crop. They could enter the total kWh or amount of fuel consumed. However, beginning in version 5.0 of the Fieldprint Platform, this option for direct input will be removed to simplify the user interface and because the information is unlikely to be handy to most users.

The method used for estimating energy consumption due to irrigation pumping is based on user inputs that engineering equations. The user enters data about the pumping system parameters, including:

pumping lift
- vertical distance from the pump base to the water level when not pumping (static water level).
  - For groundwater sources, add the depth of groundwater drawdown to the static water level depth.
- Enter the average total depth (feet) of the water source throughout the growing season. Approximation is acceptable.
pumping pressure
gross water pumped for crop irrigation
- “the total irrigation requirement including net crop requirement plus any losses incurred in distributing and applying water and in operating the system. It is generally expressed as volume of water per unit area (acre-inches per acre; or inches). (Source: ASAE 526.2)” (USDA-NRCS, n.d.)
- not the net amount of water that reaches the crop root zone

To estimate \(PE\), the ideal amount of energy used to pump the water is divided by the overall irrigation system efficiency (Hoffman, Howell, and Solomon 1990; Eisenhauer et al. 2021), which will be between 0 - 1, or 0 - 100%.

Irrigation system efficiency

Components of irrigation efficiency include:

Component	Efficiency (%)	Symbol
Application	ratio of the pumped water stored in the crop root zone to the gross water pumped; not used for Energy calculations	\(e_a\)
Pump¹	0.75	\(e_p\)
Drive²	0.95 for gear/belt driven 1 for direct motors (electric)	\(e_o\)
Power Unit, or Thermal	Table 3	\(e_e\) or \(e_q\)

¹ Modified for gross water pumped, \(D_g\), as the original \(D_n\) is divided by \(e_a\). Since \(e_a = \frac{D_n}{D_g}\) , the terms cancel out. Also, we chose \(e\) to represent efficiency, not \(E\), which is more commonly used for Energy. Considering thermal efficiency and power unit to be synonymous, and replaced with single \(e_q\) term.

² Eisenhauer et al. (2021)

The Fieldprint Calculator previously assumed an overall irrigation system efficiency (\(e_i\)) of 0.7125 based on section 19.3 from Hoffman et al. (1990, Pump x Drive = 0.75 x 0.95 = 0.7125). Peacock (1996) notes that 0.70 is a reasonable value for pumping efficiency, and can be used in estimating the amount of energy needed to lift the reported amount of water. However, the implementation in Fieldprint Platform 4.0 omitted accounting for thermal losses of energy at the power unit. In other words, the energy needed to lift the water is not equivalent to the energy needed to compensate for power unit losses and lift the water.

Hoffman, Howell, and Solomon (1990) mentioned a power unit energy efficiency (\(e_e\)) in Equation 19.1, which will be incorporated in version 5.0 of Fieldprint Platform as the power unit, or thermal, efficiency. This improvement will lead to a lower \(e_i\) for non-electric pumping systems, and therefore increased energy use and emissions for irrigation activities. Electric pumping systems may get similar energy use values.

Sources confirm that the efficiency of diesel and electric motors, for example, are roughly as follows:

Motor Type	Hoffman	Martin et al. (2011)	Arkansas (2024)	Harrison (2012)
Diesel	0.303	0.31	0.18-0.35	0.25-0.5
Electric	0.906	0.88	0.75-0.85	0.85-0.92

The last two columns reflect overall efficiency, not just power unit (thermal) efficiency.

Power Unit (Thermal) Efficiency

The power unit efficiency (\(e_q\)) accounts for thermal energy losses (i.e. heat, or \(q\) ). It comes from the difference between the representative, or theoretical, energy content of the energy source and the actual brake energy produced per unit of input (see Table 3).

As an example, consider the case in which diesel fuel was used as the pump’s energy source. Let’s assume the energy needed to pump water was 1 unit of energy. If 1 unit of diesel fuel contains 1 unit of energy, we might assume 1 unit of diesel was needed and used. However, this assumption ignores thermal efficiency. When that unit of diesel was burned, only ~30% of the energy was converted by the power unit into work; the rest was lost as heat. Therefore, the pump actually used ~3.3 units of diesel to provide 1 unit of energy.

Testing

After accounting for power unit efficiency, the revised \(PE\) formula (Equation 1) gave an energy estimate within 10% of the output given by the USDA-NRCS Irrigation Energy Estimator tool. The NRCS tool uses national averages and indicates the potential for variability (USDA-NRCS, n.d.).

Application Efficiency

The Fieldprint Platform asks for the gross volume of water applied, not the net volume (water pumped - water losses); energy use is dependent on the pump running. The net volume available to the crop depends on factors such as the efficiency at which the irrigation water was applied (\(e_a\)) to the cropland, which will be less than 100% (Washington State 2024). That information could be used to inform water use efficiency beyond the Energy Use metric.

Inputs

Input	Value	Units	Symbol
Effective irrigated area	User entry	ac (converted to ha)	\(A_i\)
Irrigation method	User selection: Center pivot Center pivot with polyacrylamide Level basin/blocked end Sprinkler Surface Graded border and surge graded furrow graded furrow with polyacrylamide wild flood Trickle/drip	-	-
Irrigation water source	User selection: Deep aquifer groundwater Alluvial groundwater Surface water Both surface water and deep aquifer groundwater	-	-
Gross depth (volume) of water pumped per acre for crop irrigation	User entry from water meter or via Fieldprint Platform Estimator tool³	acre-inch/acre (converted to mm)	\(D_g\)
Do you use energy⁴ to irrigate the field through pumping?	Yes/No	-	-
Pumping pressure	User entry (commonly 0-130)	psi	\(P\)
Pumping lift	User entry (commonly 0-1500)	feet	\(L\)
Energy source	User selection; Diesel, LPG, Natural gas, Electricity, Gasoline
Pumping units conversion factor	0.0979		\(CF_{pump}\)
Pressure conversion factor	0.703448	psi m_head^-1
Length conversion factor	0.3048	ft m_head^-1
Energy conversion factor	947.81712	BTU MJ^-1	\(CF_{mj}\)

³ Opens in pop-up window for user.

⁴ Some irrigation is achieved by gravity only.

Formula

Pumping energy is the energy to pump the total volume of water (\(E_{ideal}\)) divided by the irrigation system efficiency (\(e_i\)). The formula below is based⁵ on Hoffman, Howell, and Solomon (1990) (see Eq. 19-1 pp 722). The symbols are listed in the table above.

⁵ Modified for gross water pumped, \(D_g\), as the original \(D_n\) is divided by \(e_a\). Since \(e_a = \frac{D_n}{D_g}\), the terms cancel out. Also, we chose \(e\) to represent efficiency, not \(E\), which is more commonly used for Energy. Considering thermal efficiency and power unit to be synonymous, and replaced with single \(e_q\) term.

\[ PE = \frac{E_{ideal}}{e_i} = \frac{(P + L) \times D_g \times A \times CF_{pump} \times CF_{mj}}{e_p \times e_o \times e_q} \tag{1}\]

Steps

Throughout these steps, make sure all unit conversions are accounted for.

Calculate the total head (\(P + L\)).
Calculate the ideal energy (\(E_{ideal}\)) .
Calculate the overall irrigation efficiency (\(e_i\)) .
Divide ideal energy by \(e_i\).
1. If there is a secondary irrigation source, this calculation process will be repeated using new user input values.
Calculate total fuel or electricity used

\[ V_{diesel} = \frac{PE}{E_{diesel}} \]
Calculate all direct and indirect energy and emission components
- Up to this point, only direct energy use has been estimated. Knowing, for example, the amount of diesel used on-farm for pumping allows us to determine not only the direct emissions of component GHGs due to combustion, but also the upstream energy and emissions associated with the diesel (e.g. manufacturing).
  
  In this case, the amount of diesel is multiplied by a given component’s energy or emission factor per gallon (Table 4) . Lastly, standardize to kg CO₂e with Global Warming Potential factors (CO₂ = 1, CH₄ = 27, N₂0 = 273).
  
  For example: \(Upstream\ CO_2 = V_{diesel} * C_{upstream\ CO_2} * GWP_{CO_2}\), where \(C\) is a constant for upstream CO2 emissions (units = kg gal^-1) and \(GWP\) in this case would be 1.

Example

A grower is thinking about switching to an electric pump due to higher diesel prices. The Fieldprint Calculator puts her farm in the SPNO eGRID region based on field location. The grower pumped 10 acre-inches of water for her 100 acre wheat field. The 40 psi, diesel-powered pump drew from an average depth of 250 feet. How much energy and emissions are associated with this field? How would emissions change if she switched to electric?

Answer

To pump 10 arce-inch of water for irrigation on 100 acres, 3,355 gal of diesel were used, resulting in 539,833 MJ of total energy use and 38,866 kg CO₂e emitted.

By switching to an electric pump, total energy use was greater at 945,935 MJ or about 42.9 MWh , but with fewer total emissions of 20,538 kg CO₂e. The electric pump emissions could be 47.2% less than the diesel pump emissions.

Result tables

Table 1: Energy and emissions associated with the example diesel pumping system.

metric	system_boundary	source_category	CO2_fossil	CH4_fossil	N2O	MJ	units
Energy Use	Upstream	Energy use associated with production of fuels	0.000	0.0000	0.00000	53482.44	MJ
Energy Use	On-Farm Mechanical	Energy use associated with stationary machinery	0.000	0.0000	0.00000	486350.61	MJ
GHG Emissions	Upstream	GHG emissions associated with production of fuels	3270.534	232.8780	17.89084	0.00	kg_CO2e
GHG Emissions	On-Farm Mechanical	GHG emissions associated with stationary machinery	34237.954	126.9118	979.55387	0.00	kg_CO2e

Table 2: Energy and emissions associated with the example electric pumping system.

metric	system_boundary	source_category	CO2_fossil	CH4_fossil	CH4_biogenic	N2O	NF3	SF6	MJ	units
Energy Use	Upstream	Energy use associated with electricity generation and distribution	0.00	0.00	0.000000	0.00000	0.0000000	0.00000	945934.8	MJ
GHG Emissions	Upstream	GHG emissions associated with electricity generation and distribution	19907.39	545.63	1.191602	82.30514	0.0010829	1.02432	0.0	kg_CO2e

Tables

Thermal Efficiency

Table 3: Energy content and performance criteria of pumping plants from Table 19.1 Hoffman et al 1990.

pumping_energy_source	thermal_efficiency
Diesel (ag equipment)	0.303
LPG	0.247
Natural gas	0.226
Gasoline	0.236
Electricity (grid)	0.906

Energy and Emission Factors

Table 4: Sample of data in full table. Units for GHG gases are kg per unit of energy source. Units for energy (mj) are MJ per unit of energy source.

metric	system_boundary	source_category	source_detail	pumping_energy_source	subregion	CO2_fossil	CO2_biogenic	CH4_fossil	CH4_biogenic	N2O	SF6
GHG Emissions	Upstream	GHG emissions associated with electricity generation and distribution	Irrigation Operations \| Electricity (grid)	Electricity (grid)	AKGD	512.7149	NA	0.6143385	0.0035084	0.0061415	0.0000000
GHG Emissions	Upstream	GHG emissions associated with electricity generation and distribution	Irrigation Operations \| Electricity (grid)	Electricity (grid)	AKMS	247.1273	NA	0.1314090	0.0007640	0.0020166	0.0000000
GHG Emissions	Upstream	GHG emissions associated with electricity generation and distribution	Irrigation Operations \| Electricity (grid)	Electricity (grid)	AZNM	383.9731	NA	0.4666912	0.0024147	0.0036553	0.0000002
GHG Emissions	Upstream	GHG emissions associated with electricity generation and distribution	Irrigation Operations \| Electricity (grid)	Electricity (grid)	CAMX	254.3928	NA	0.3751704	0.0045993	0.0027512	0.0000002
GHG Emissions	Upstream	GHG emissions associated with electricity generation and distribution	Irrigation Operations \| Electricity (grid)	Electricity (grid)	ERCT	378.2250	NA	0.4781203	0.0024133	0.0036671	0.0000005
GHG Emissions	Upstream	GHG emissions associated with electricity generation and distribution	Irrigation Operations \| Electricity (grid)	Electricity (grid)	FRCC	399.0436	NA	0.5913092	0.0044074	0.0034492	0.0000000

References

Arkansas. 2024. “Pumping Plant Efficiency.” https://www.uaex.uada.edu/environment-nature/water/agriculture-irrigation/pumping-plant-efficiency.aspx.

Eisenhauer, Dean E, Derrel L Martin, Derek M Heeren, and Glenn J Hoffman. 2021. Irrigation Systems Management. American Society of Agricultural; Biological Engineers (ASABE).

Harrison, Kerry. 2012. “Irrigation Pumping Plants and Energy Use.” https://extension.uga.edu/publications/detail.html?number=B837&title=irrigation-pumping-plants-and-energy-use.

Hoffman, Glenn J, TA Howell, and Kenneth H Solomon. 1990. Management of Farm Irrigation Systems. Joseph, MI, USA: American Society of Agricultural Engineers.

Martin, Derrel L, Tom W Dorn, Steve R Melvin, Alan J Corr, and William Kranz. 2011. “Evaluating Energy Use for Pumping Irrigation Water.” In.

Peacock, Bill. 1996. “Energy and Cost Required to Lift or Pressurize Water.” University of California, Pub. IG6-96.

USDA-NRCS. n.d. USDA-NRCS Energy Consumption Awareness Tool: Irrigation. https://ipat.sc.egov.usda.gov/.

Washington State. 2024. “Program Guidance: Determining Irrigation Efficiency and Consumptive Use,” March. https://apps.ecology.wa.gov/publications/summarypages/2011076.html.