Twofold Renewable in Tulare County

California’s Calgren Renewable Fuels uses renewable energy generated onsite to power its renewable fuel production process.
By Keith Loria | September 22, 2015

When the Calgren Ethanol Biodigester officially opened in Tulare County, California, early this year, it represented a major commitment by the state of California to employ sustainable energy production.
Located in the town of Pixley, the biodigester utilizes waste from dairy operation Four J Farms to power the production of tens of millions of gallons of ethanol, all consumed in the Central Valley. It is the first digester of its kind in the state, relying on agricultural waste to create renewable natural gas to power another renewable energy facility, essentially creating a zero-waste life-cycle.

The two-stage, mixed plug-flow Pixley Anaerobic Digester was designed by DVO Inc. of Chilton, Wisconsin, and built by Regenis of Ferndale, Washington, and is the first system in California to be 100 percent American made and constructed.

In the Beginning
The genesis of the project dates back to a conversation Daryl Maas of Farm Power had with Calgren’s president, Lyle Schlyer, nearly six years ago. “Daryl suggested we apply for a California Energy Commission grant to build a digester on-site and process dairy waste,” Schlyer says. “He owns and operates similar digesters in Washington and elsewhere. Since we are always looking for ways to lower the carbon intensity of our renewable fuel ethanol, we readily embraced the idea. Daryl stayed on and managed the project for us.”

Biogas generated at the plant’s site would drive Calgren toward a more sustainable business model and reduce cost, while enabling production of its own power. The company reached out to DVO because of its expertise in this area. “We were first approached in 2010,” says Melissa Van Ornum, vice president of marketing for DVO Anaerobic Digesters. ”The basic idea was there, but it took some time to get Calgren and the dairy to come together and put all the puzzle pieces together. We are the largest biodigester company in the country. We have a lot of experience; we’re currently in 18 states and have ventured internationally as well. We have a proven design, which always makes it easier when approaching investors.”

There were some unforeseen challenges after the idea was conceived, so the project took a little longer to come to fruition than Schlyer had anticipated. “Satisfying California’s Environmental Quality Act was by far the biggest challenge,” he says. “Unfortunately, CEQA can be easily highjacked and used for unintended purposes. In our case, it was used to oppose an environmentally sound project.”
Van Ornum notes that permitting in California is never easy. “The fact that Calgren already had the steam turbine in place—so we weren’t having to permit a new engine—was a huge help,” she says. “They had to get a new permit, but it was more like modifying an existing one. That made it a lot easier.”

Another challenge was the community wasn’t originally on board and needed some convincing to assuage their concerns. Van Ornum says that educating the community played a large part in getting the project up and running. “Many were concerned,” she says. “Few knew anything about digesters, and we needed to explain that it wouldn’t explode, there were no crazy odors, and all these other things that people worry about. It helped that we could explain what it was and it didn’t take long for people to come around.”

Mostly, it was the fear of the unknown, Schlyer adds. “Our opponents were concerned about odors and the idea of waste processing in their vicinity,” he says. “To help allay their concerns, we downsized and tightened up project parameters. We also agreed to relocate the digester from the north side of our facility to the south side.”

The key in getting the system permitted and approved in California, Schlyer notes, was perseverance by everyone involved, especially when it related to CEQA. Other important agencies were much more open to the idea and worked with Calgren to make the digester a reality. “The agencies with oversight of environmental emissions and the like were generally helpful,” he says. “Tulare County was exceedingly supportive, as was the Regional Water Quality Control Board and the California Energy Commission.”

The project was conceived in late 2009, and all CEQA issues were finally resolved in February of 2014. “We commenced construction immediately thereafter, and had the digester in operation by September 2014,” Schlyer says. “Initially, we hoped biogas would provide up to 20 percent of our fuel requirements, but we have had to pare back our expectations.”
The plant officially opened in February.

Building the Digester
Regenis served as the general contractor of the anaerobic digester, including design and layout of the facility. “Being the largest on-farm anaerobic digester contractor in the west, we have a vast knowledge of design and layout of digester facilities, which helps the owner achieve maximum operation in all facets of the facility,” says Mike Apol, Regenis’ regional manager for California and project manager for the Pixley Biogas Project.

The biggest challenge of the building process, according to Apol, was its short construction schedule. “The excavation started in March 2014, and the project was complete and producing biogas by September,” he says. “We were able to complete the project due to the team environment from all of the parties involved.”

How It Works
Constructed with the help of a $4.6 million grant from the California Energy Commission, in its simplest definition, the digester takes in cow manure from Four J Farms, and the generated methane is captured and burned as clean biogas to power the Calgren ethanol production process. The digester greatly reduces bacteria and pathogens so dairy farmers can reuse the liquids (water) safely on their crops, Schlyer says.

The pipeline that sends the raw manure to the digester also pipes back the digester liquid into the lagoon, which is used on crops, Van Ornum further explains. “In California, where drought is a problem, the farmer has liquid and they can play Mother Nature. It allows for more flexibility for the dairy farm as well.”

Benefits Abound
The Pixley Biogas anaerobic digester is the first anaerobic digester on a California farm permitted to use all feedstocks, including municipal green waste and food processing waste. According to Apol, one of the main reasons the finished project is so important to the industry is the environmental benefit in the reduction of methane being released into the atmosphere, which is 22 times more potent than any other green house gas. “A second reason was the opportunity to bring industry and agriculture together on the same project,” he says. “I believe this is the first time this has happened due to the close proximity of the ethanol plant and the dairy, which would both benefit from the byproducts of the anaerobic digester.”

Schlyer says that digesters lower the life-cycle carbon intensity of renewable fuels, something critical in California due to its Low Carbon Fuel Standard. Currently, other jurisdictions are considering similar policies. “We hope our current digester is but the first of many similar projects,” he says. “Liquid fuel is a mainstay of our transportation system. Using renewable biogas as process energy for the production of renewable fuel liquids sort of maximizes the whole concept.”

A New Trend?
While digesters are often talked about as solutions for sustainable energy, the number of operating facilities today in the U.S. doesn’t come close to mirroring the industry’s potential, especially in California. That could be changing in the years ahead, however. In January, the CEC issued rules that could increase the number of digester projects around the state.

Apol notes that Reginis’s mission is to reimagine reusable resources, and in California, the potential is nearly limitless. He believes that implementing digesters around the state would not only create hundreds of new construction and operation jobs in rural communities, but that organic waste is in such supply that it could power up to three million homes, or generate 2.5 billion gallons of clean, ultra-low carbon transportation fuels.

Around the industry, Western Plains Energy has an ethanol production facility in Gove County, Kansas, producing fuel-grade ethanol as well as distillers dry and wet grains. The feedstock used to produce ethanol includes corn and milo. Other examples include United Ethanol, which installed an anaerobic digester in an ethanol plant in Milton, Wisconsin, in 2010; and AG Processing Inc., which has an ethanol plant in Hastings, Nebraska. And the first three commercial-scale cellulosic ethanol plants that are in varying stages of commissioning in the U.S. have all added digesters on site and are utilizing them for process energy as well.

According to Schlyer, digesting waste at ethanol plants makes a lot of sense, especially if there are cattle nearby. “I would not be surprised to someday see waste digesters at a majority of ethanol plants,” he says.
Others in the industry aren’t so sure, perhaps suggesting that they aren't a good fit for all operations. “You must recognize that offsetting your natural gas with a biodigester is an enormous undertaking,” says one industry insider, who requested anonymity. “We’ve had several problems with ours—we had struggles. It’s a very difficult economic proposition, unless you have a strong feedstock source. Most of the time that needs to be free.”

Meanwhile, the Calgren digester has been operational for almost a year, producing somewhere around 350 cubic feet of biogas per minute. That number is expected to increase in the years ahead, providing a savvy sustainable energy solution for all in the area.  Things are running smoothly and it’s now working wonderfully, Shyler says, but as new concepts often require, it came with a little trial and error. There have been a few equipment issues and some learning curves for the workers, he adds, but overall, Calgren has been pleased with its operational performance.

Author: Keith Loria
Freelance writer, Biomass Magazine