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American Farm Bureau News
The Tulare County producer has installed an anaerobic digester system on his farm. The digester uses the methane from cow manure to power a generator, which then produces electricity.
"Originally I started this just to save on my electricity bill. Now it's looking like it might be important because of the energy crisis," Lourenco said.
Concrete runways near the feeding troughs accumulate a large portion of the cow manure. Water towers collect rain and the water used to wash the cows at milking. When those tanks are full, the water is released at the top of the runway. The rushing water sweeps the manure down to large manure lagoons that are covered with tarpaulins. Naturally occurring anaerobic activity in the lagoons generates methane. The gas bubbles to the top of the pond and is trapped under the tarp, looking like a giant air mattress. A vacuum pump draws the gas through a collection pipe to a generator. The generator produces electricity as it burns the gas. The leftover manure, mixed with the water, is used to fertilize farm fields.
Installation of the digester system on the Lourenco farm cost about $150,000. Cost-share funding from the state helped him with that bill.
"If I didn't have any help, pay back would probably take close to three and a half years, but with energy prices going up, payback will be faster," Lourenco said.
Some of the first farmers to install the systems even made money from the investment. They were able to generate more electricity than their operations needed and sold the excess to their power company. The power companies stopped paying for extra electricity when energy prices started to skyrocket due to shortages.
Lourenco estimated that electricity, which powers the milking machines and the refrigeration unit for the milk, consumes 2 percent to 3 percent of his bottom line. The monthly bill adds up to between $3,000 and $4,700. "If I can eliminate 2 to 3 percent of my costs, then that's 2 to 3 percent profit and every bit counts."
Currently there are only a handful of the digesters being used in California, but that could change. According to Lourenco, more dairies in the area are considering installation despite the hefty price tag. Many who thought it was a risky investment just a few years ago are giving the idea a chance due to the energy situation.
"With the cost of electricity what it is today, we've seen a lot more interest in this technology lately," said Dr. Ruinong Zhang, associate professor of biological and agricultural engineering at the University of California--Davis.
But Dr. Zhang says the technology may catch on around the country for reasons other than energy prices.
"This is not only an energy producing technology. It's also a waste treatment technology. It produces power and helps to solve some of the environmental problems associated with manure disposal," she explained.
"In a controlled biological degradation process (used by the digesters) there is much less odor," said Dr. Zhang. "It can really work for odor control."
While eliminating the bad smell from the animal waste, the process does not change the nutrient levels. So the manure is still a valuable fertilizer.
Those benefits have caught the attention of livestock farmers throughout the Midwest and on the East Coast, particularly swine producers.
Another environmental benefit is that the digesters lower greenhouse gas emissions by preventing methane release into the atmosphere.
"Livestock farmers throughout the nation could benefit from these systems," said Roy Sharp, a digester system consultant.
"Every livestock operation could have about 150 percent of its energy available from collectible manure. That means even a 200-cow dairy would be able to supply probably one and a half times its energy if the system is designed correctly. It's not just something for large operations. It will work on poultry, on swine, on dairy or feedlots if the waste can be collected correctly," he explained.
The technology can also help farmers proactively address the nation's energy woes.
"We obviously can't ignore major sources of new energy in this country," said
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