The Digester Learning Curve: What's happened since these digesters fired up?

February 23, 2010 09:50 AM


California's John Fiscalini has formed his own company to help other dairy producers through the permitting process.

Dairy Today has covered numerous U.S. dairy digester and cap-and-trade projects in recent years. These producers tell what they've learned since we first featured them.

Wiser for the Experience
John Fiscalini, Modesto, Calif.

When we met California's John Fiscalini in "The Dark Side of Digesters” (March 2009), he had just fired up his $4 million digester after a frustrating three years of planning, permitting and construction. The launch, however, was short-lived.

Problems with utility phone lines forced Fiscalini to shut down his digester almost immediately. In June, though, it went back online and has been running ever since.

"The digester is running better and takes less time to manage than I anticipated,” Fiscalini says. "There's no need for a full-time employee. All that's needed is to walk in and look at dials and gauges four or five times a day.”

The complete-mix, two-tank digester and accompanying generator produce about 500 kW/hr., twice the power Fiscalini's dairy needs. The Modesto Irrigation District (MID) buys all of Fiscalini's electricity, selling him back enough to power his 1,500-cow dairy. MID pays him 1¢/kW over regular user rates. It's enough for Fiscalini to just make the bank payments for the project's financing. (Only 35% of the cost of the digester was covered by grants.)

The dairy's manure handling hasn't changed much, since Fiscalini still processes the solids through a double-slope separator and uses the dried manure for freestall bedding. But he's noticed a surprising benefit.

"The quality of the manure is substantially better,” he says. "Somatic cell counts have dropped from 200,000 to 100,000. I'm 80% sure [digester-processed solids] are the reason.”

The regional air- and water-quality boards are no easier to work with, Fiscalini says. Regulators still won't allow him to add off-site waste to the digester, a move that would produce more methane, generate more power and allow him to see a payoff in four years instead of 10, he says.

Fiscalini has received grants from the U.S. Department of Energy and the California Energy Commission to research his digester's air- and water-quality impact as well as its economic feasibility. "The grants will help us run the [generator's] engine more cleanly, make more money and keep the regulatory agencies happy rather than suspicious,” he says.

As the first dairy producer to install a digester under California's new regional environmental regulations, Fiscalini and his project manager, Nettie Drake, are among the very few who understand the state's digester permitting process. The two have formed a consulting partnership called Ag Power Development to help guide dairy producers through the digester-construction process.

"Overall, if you take away the experience with the air- and water-quality boards,” Fiscalini says, "we've got a cool piece of equipment that's doing good things.”

Malachy Coyne, Avon, N.Y.

Capitalizing on carbon credits was the driving force behind building a 7-million-gallon covered lagoon at Coyne Farms in western New York ("Taking Credit,” February 2008). The Environmental Credit Corporation (ECC) installed and paid for the lagoon at the dairy, where Malachy Coyne and his family milk 1,000 cows.

Since the lagoon covering was completed in July 2008, carbon credits have fallen sharply in value. In February, they traded below $1/metric ton, compared to earlier highs of $7/metric ton. Even so, Coyne isn't unhappy.

"No one's losing any sleep over the low value of carbon credits,” he says. "We and ECC are poised and ready for when and if they become valuable.”

Instead, the dairy is focusing on the covered lagoon's other benefits. "We've seen odor reduction and a lot less rainwater accumulation in the lagoon,” Coyne says.

Karl Czymmek of Cornell University's Pro-Dairy Program has followed the lagoon's progress. Using the Dairy Manure Storage Cost Calculator developed by his colleague Tim Shepherd, Czymmek estimates the Coynes save $7,000 to $8,000 a year (at 2¢/gal.) on hauling costs by "avoiding” 400,000 to 500,000 gal. of annual precipitation that would otherwise have landed on the surface of their manure storage.

"There are also up to 65 fewer tanker loads to haul and spread each year, which helps save time, especially in the spring,” Czymmek says.

The Coynes extract the liquids and solids from the lagoon to fertilize their 1,500 acres of cropland.

"The project is all in our favor as a farm,” Coyne says.

Success, Expansion and New Ideas
Lee Jensen, Elk Mound, Wis.

In 2005, Lee Jensen became one of the first U.S. dairy producers to accept this relatively risk-free offer from a digester manufacturer: The company would finance, build and operate an on-site, thermophilic complete-mix digester in return for the dairy's manure ("Partnering Up,” March 2007).

Since then, Jensen's Five Star Dairy has seen the digester's methane gas production meet or exceed project goals. Output today is enough to power 600 homes. Dairyland Power Cooperative not only owns the 775-kw generator but also buys the methane to fuel it.

In addition, Jensen has earned an average of about $25,000/year in carbon credit income. He's also added 200 cows and heifers to increase his herd size to 1,100.

Jensen and digester manufacturer Microgy, Inc., have ridden the learning curve of digester management. "We've learned we could probably get another 50% to 80% gas production out of the system,” Jensen says.

In January, Wisconsin's Department of Natural Resources gave the project permission to add additional substrate, or waste material, to the digester, which can "greatly enhance gas production,” Jensen says.

The Wisconsin producer is particularly excited about the digester's ability to score well in gauging biological oxygen demand (BOD), a test that indicates water quality after the process of decomposing organic waste.

"We've proven that the digester can dramatically burn up the BODs in raw manure and substrates,” he says. "It does a great job cleaning the manure and waste products and making them safer to land-apply.”

Moreover, the digester cuts air emissions and reduces odor. "Environmentally,” he says, "it's a no-brainer.”

Jensen is exploring ideas to use the waste heat from the digester and engine to warm water for dairy operations, thus reducing his liquid propane costs. "We're conducting an energy audit with a national engineering firm to get an idea of where we can get the biggest bang for our buck,” he says.

He's also considering installing a dryer that would use digester-generated methane as a heat source to dry manure or compost for better bedding or even to dry feed byproducts to feed his herd.

Jensen's wish list includes the possibility of Dairyland Power installing a second generator for the project. The expansion could generate and sell more power.

"The digester has so much potential,” Jensen says.

Hampered by permitting and financing difficulties, Carl Morris of Joseph Gallo Farms has spent four years trying to build a second digester on the large California dairy.
Harder the Second Time
Carl Morris, Joseph Gallo Farms, Atwater, Calif.

As one of California's pioneers in the dairy digester field ("Turning Waste into Kilowatts,” February 2005), Joseph Gallo Farms has had five years to perfect the manure-to-kilowatt technology. It's not, however, getting any easier.

With one digester operating since 2004, the five-dairy operation has been trying to get a second one built for more than four years. Growing difficulties with permitting and financing are making that tough and are also giving the original covered-lagoon digester "serious challenges,” says Carl Morris, general manager and chief operating officer.

"We really like digesters and feel the environmental and other benefits are tremendous,” Morris says. "But increasing standards from air- and water-quality regulators make it more difficult to build and operate them.” California's mounting environmental regulations could add $1 million to the cost of a midsized digester, he says.

The first digester, on the farm's 5,000-cow Cottonwood Dairy, provides power for the commercial cheese plant that Joseph Gallo Farms operates next door. When air-quality regulators tightened emission standards to 9 parts per million for nitrogen oxide compounds for a second generator, "we couldn't consistently meet the requirements, even with catalytic convertors on both engines,” Morris says. "We operated under a variance for over a year.”

Since then, the operation has "made a host of improvements to the system at a cost of well over $100,000,” Morris says. "The system seems to be running fine now.”

One plan for a second digester, located at the farm's 3,500-cow Santa Rita Dairy, is similar to the first system.

Morris has already successfully marketed carbon credits on the original digester. "They've been an important source of revenue,” he explains. "But that market is crazy. It's become speculative as people try and guess about cap-and-trade legislation.”

Morris has learned that careful planning is important with a digester. All the same, he adds, "Be ready for surprises, no matter how careful you are.”  


Bonus content:

Read previous digester stories:

"The Dark Side of Digesters” – John Fiscalini

"Taking Credit” – Malachy Coyne and Carl Morris

See the Dairy Manure Storage Cost Calculator developed by Cornell University's Tim Shepherd

"Turning Waste into Kilowatts” – Carl Morris, Joseph Gallo Farms

"Partnering Up” -- Lee Jensen

Read more follow-up stories:

"Cargill to convert waste to energy on Idaho dairy” – Bettencourt Dairy

"Methane for the Midsized” – Jerry Jennissen


Malachy Coyne stands atop the 7-million-gallon covered lagoon at
his New York dairy.

Happy with the Outcome

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