Low-elevation sprinkler application (LESA) and low-elevation precision application (LEPA) irrigation technologies can be applied to center-pivot or wheel-line irrigation systems and compete with mid-elevation spray application (MESA) and subsurface drip irrigation (SDI). LESA applies water below the crop foliage using applicators positioned about a foot above the ground surface. Nozzle pressures can be regulated to as low as 6 to 10 psig. In contrast, MESA systems require water pressure of approximately 40 psig, which requires greater pumping energy and exacerbates any water leaks.
LESA is capable of using quad sprays, bubble emitters, drag socks, or hoses to release water directly on the ground. LESA systems tested in the Northwest use water pressure of about 6 psig and improve irrigation application efficiency to as high as 97 percent, by reducing water losses due to wind drift and evaporation from the top of foliage. The technology is especially effective during periods of high temperatures, high winds, and low humidity. Energy savings are dependent upon the baseline irrigation technology, which is generally MESA in the Northwest, although much less efficient high spray systems are still used. By increasing irrigation efficiency, less total water has to be pumped to meet the crop water requirements and pumping occurs at a lower pressure.
Results from the 2013 field tests in the Northwest documented a 15 to 20 percent reduction in water use accompanied by a 30 percent reduction in electrical energy consumption. Because center pivot equipment life is approximately 30 to 50 years, irrigation equipment manufacturers and distributors have developed retrofit kits that can be used to convert existing pivots into LESA units.
Current Stage: Approved for Implementation. See BPA Energy Efficiency Implementation Manual for measure and program details.