Blazing the Trail Ground in Co-Digestion and Renewable Natural Gas

Victor Valley authority embraces co-digestion to maximize production of biogas for conversion to renewable natural gas in a global-award-winning facility

Blazing the Trail Ground in Co-Digestion and Renewable Natural Gas

The view from atop one of the authority’s digesters, using Anaergia’s Omnivore technology.

Interested in Dewatering/Biosolids?

Get Dewatering/Biosolids articles, news and videos right in your inbox! Sign up now.

Dewatering/Biosolids + Get Alerts

It starts with biosolids and food waste fed to digesters at the Victor Valley Wastewater Reclamation Authority. It ends with hydrogen and electricity for a major Toyota port operation and hydrogen fuel for Toyota Mirai sedans.

In a landmark public-private partnership with Anaergia, the Victor Valley authority in Victorville, California, has taken a wide step beyond the combined heat and power facility commissioned in 2016. The SoCal Biomethane facility on the site of the authority’s regional clean-water plant converts biogas to pipeline-quality renewable natural gas for injection into the Southwest Gas network.

Most of that RNG is to be used by Toyota Motor North America’s Logistics Services Center at the Port of Long Beach. The plan is for the gas to be fed to fuel cells able to produce 2.3 MW of electricity, more than enough to power the facilities, plus 1.3 tons of hydrogen vehicle fuel per day.

For the co-digestion and biogas upgrading facility, the Victor Valley authority and Anaergia received the 2023 Global Water Award for Wastewater Project of the Year from Global Water Intelligence.

Sustainability history

Founded in 1978, the Victor Valley authority serves about 350,000 residents of five cities in a 279-square-mile area about 80 miles north of Los Angeles. Its regional biological nutrient removal clean-water plant in Victorville and two subregional membrane bioreactor plants have a combined capacity of 16 mgd. Biosolids are thickened, dried on solar beds and applied to farmland.

“We’ve always tried to optimize our processes and run everything as efficiently as we can,” says Kalin Westover, operations supervisor. As one example, for many years the authority ran its Turblex aeration blowers in a direct-drive configuration, using Waukesha engines fueled with biogas.

Brad Adams, director of operations and maintenance, recalls, “Our first venture with Anaergia was a smaller co-digestion project where we took in FOG and anaerobically digestible material from haulers and boosted biogas production to run two combined heat and power units, minimizing use of grid electricity and helping to save cost.” Those units, with a combined 1.6 MW capacity, use Caterpillar engines coupled to generators from 2G Energy.

“Based on the success of that project, we evaluated what we could do in addition,” says Adams. “We had about 1 million gallons of capacity available in three digesters original to the plant that had been inoperable. In talks with Anaergia we asked, ‘What if we built a larger receiving station and used the extra digester capacity to increase biogas production, and then sold that biogas on the open market?’”

That was in 2019, at the early stage of a California law requiring diversion of 75% of organic waste from landfills by 2025. “We wanted to jump in before there were a lot of other people doing the same thing,” says Adams. “That way we could get a bigger share of the potential revenues related to that law.”

Making biogas

The $27 million RNG project was financed by Anaergia under the public-private partnership; the Victor Valley authority did not have to invest money up front. After less than two years of construction, the SoCal Biomethane facility began injecting RNG into the Southwest Gas pipeline in December 2021.

The upgraded receiving station takes in mostly high-strength liquid waste from manufacturers. It includes off-specification syrup from a soft drink company, squeezings from materials recovery facilities, and other materials. “We’re open to anything that has organic value and can be digested,” Adams says.

The waste receiving infrastructure was funded in part by a $4 million grant from the California Department of Resources Recycling and Recovery (CalRecycle), which brings together the state’s recycling and waste management programs to move the state toward a circular economy.

The authority used the grant to help pay for engineer­ing and construction, community outreach and ed­ucation, grant administration, and the purchase of an organics polishing system, receiving station and feedstock storage tanks.

Anaergia took responsibility for procuring food waste from outside sources for co-digestion, drawing in part on relationships with haulers involved with the company’s other co-digestion projects in the region. Materials are lab-tested for organic content and digestibility before acceptance by the authority. Tipping fees of five cents per gallon paid by haulers cover receiving station operating costs.

Material discharged from trucks is run through a rock trap and shredder to remove large objects and then goes into storage tanks. Based on the organic load in storage at any one point, digester feed rates are established.

Victor Valley team members Brandon Talley and Andrei Davis run the receiving operation, making sure the material is properly screened and is put into the right storage tanks to ensure a consistent organic load to the digesters. Alex Nelson is the Anaergia lead in material receiving.

“We don’t want to have one storage tank that has weaker material and another with stronger material,” says Adams. “They balance which tank they need to send the material to.” Once that is done, wastewater treatment operators set the digester feed rates and monitor digester health. Facility staff members handle regular inspections and planned maintenance on all related equipment, including electrical components and instrumentation.

Authority staff members also handle all aspects of maintenance and service on the combined heat and power system. Those engine-generators now operate on pipeline natural gas: “The RNG we produce has much more value on the market than as fuel for the CHP engines,” says Adams.

Making the conversion

Anaergia operates the biogas upgrader that yields RNG, which must meet purity specifications set by Southwest Gas.

Michael Delaney is the lead operator of the gas treatment system, which removes hydrogen sulfide with iron media, strips ammonia with a scrubber system, removes volatile organic chemicals with a temperature-swing absorption system, and removes moisture using a chiller and a heat exchanger. Finally, the gas upgrader unit separates the methane from carbon dioxide before the RNG is compressed and injected into the pipeline.  

The fully automated treatment process is remotely monitored and is supported by service specialists from a similar facility in Rialto and from Anaergia’s main office in Carlsbad.

Because the RNG is made from renewable sources that otherwise would emit fugitive methane emissions from decomposition, it is considered carbon negative. When the RNG is then converted to hydrogen and electricity by fuel cells at the Toyota facility, both of those outputs will be considered zero-emissions and carbon negative.

 Anaergia estimates that converting the RNG to renewable electricity will avoid more than 9,000 tons of greenhouse gas emissions per year from generation of grid electricity. In addition, the hydrogen produced by Toyota is projected to avoid more than 4,000 tons of annual greenhouse gas emissions that would have been produced if the hydrogen had been created by the conventional process of steam reforming of fossil natural gas.

The fuel cells will also reduce the air pollution to nearby communities because their chemical reactions are essentially free of nitrogen oxides, sulfur oxides and particulate matter emissions.

As for project economics, the Victor Valley authority receives a lease payment from Anaergia for the land on which the biogas upgrader stands. The authority also shares in revenue from trucked-in waste tipping fees and sale of RNG.

Adams observes, “Through the revenue-sharing process we are paying back the capital expenses incurred by Anaergia to rehabilitate our assets on site. After seven years of operation, the capital costs will have been recovered in a way that is cost-neutral to the authority, and then we will receive our full share of the revenue.”

Reflecting on the project and the global recognition the project received, authority general manager Darron Poulsen observes, “The RNG project is a showcase of how public agencies, utilities and private business can come together to help resolve significant environmental challenges. I salute our staff for their hard work in making this project a success.” 


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.