First EQIP-Funded Digester in California

district conservationist Rick Aguayo (left) and Duane Turner admire the recycled/clean water mixing system that is used to irrigate adjacent alfalfa fields

Milking 2,000 Holsteins twice a day is not easy. Complying with air and water quality guidelines while trying to generate a profit is difficult too, but thanks to financial assistance from the NRCS Environmental Quality Incentives Program that’s exactly what Eddie Imsand is now able to do after installing an anaerobic digester on his El Mirage dairy in the High Desert of Southern California.  “We want to be proactive. We want to show our concern for the environment so the public and government officials can see that it can be done,” said Imsand.

With these goals in mind, Imsand set out to build an anaerobic digester like the one he first heard about in the late 1970’s while working his father’s dairy in San Bernardino. “It’s an excellent way to manage waste,” said Duane Turner, Imsand’s right hand man, “and it protects water quality and produces energy at the same time.” Instead of spreading raw manure over agricultural fields the manure is processed in an enclosed system. The end products are energy, pathogenic-free humus, and nutrients that are more readily available for plant use. Nearly all of Imsand’s energy needs for his 159 acre dairy are satisfied by processing the manure from his cows.

On average, 20,000 gallons of manure are collected each day and dumped into the dairy digester, which basically acts as an extension of the cow’s digestive system. The digester heats up the manure, releasing methane which fires a steam-driven turbine to generate electricity. The digester has produced nearly one million kilowatts of energy since coming online in July 2004. During this adjustment period, it has averaged 117 kilowatts a day, but is capable of generating 145 kilowatts. “Creating energy is a side benefit, it is the environmental benefits that really make this project a success,” said Rick Aguayo, district conservationist with NRCS.

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As the manure is processed, gray water is channeled into a clay-lined holding pond which prevents groundwater contamination. This water is then mixed with fresh water to irrigate Imsand’s alfalfa fields adjacent to the dairy. To ensure the appropriate mixture of nutrient rich water is applied, soils are monitored and adjustments to the mixture are made as necessary. The dried humus is also used to fertilize the fields, completing a holistic system of waste management. Enough energy is generated during winter months to supply 100 percent of demand for the dairy and 80 percent during summer months. Imsand hopes to add another turbine to increase his output and eventually have the ability to sell his energy to Southern California Edison.
Your contact is Rick Aguayo, NRCS district conservationist, at 760-843-6882, ext. 106.