Is a biogas-to-RNG project right for your facility & community?

Northern Colorado Clean Cities recently interviewed CGRS and City of Longmont, Colorado, representatives about the ins and outs of constructing a system that converts biogas at a wastewater treatment plant to Renewable Natural Gas (RNG). The goal: provide useful information about the decision-making and construction processes, so other jurisdictions can determine if a similar project is right for their facilities and their communities. The following article is based on the content of those interviews.

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Cory Kahler
Operations Manager
Mobile: 720.537.9387

Renewable Natural Gas (RNG) projects aren’t for every wastewater treatment plant or community.

The City of Longmont checked all the necessary boxes as it constructed a Biogas Treatment and RNG Fueling Station at its Wastewater Treatment Plant (WWTP), which began operating earlier this year. The project captures the biogas from the WWTP, cleans and treats it, so it becomes RNG, then pipes it to a system that compresses it for fuel (Compressed Natural Gas or CNG) for its Waste Services fleet.

Cory Kahler, CGRS Water/Wastewater Operations manager and an expert in RNG/ CNG systems, said jurisdictions wondering if an RNG system is right for them should be “doing their research and figuring out what kind of (biogas) load they have and whether they’re going to be able to utilize all of that gas.”

He said what Longmont did doesn’t necessarily work for every community. If a WWTP produces biogas, they need to be able to use as much of it as they can if they capture and clean it for vehicle fuel.

If they can’t use all of it, he suggested they inject into the pipeline, so others can use it and the jurisdiction isn’t flaring off any of the quality methane its facility produces, Kahler noted. It costs more to build a system that injects RNG into the pipeline, because utilities such as Xcel have high expectations for that gas.

“It’s got to meet certain specifications,” he said. “It’s a lot more expensive to do it that way, but the ROI (return on investment) can be a much shorter duration if you’re capturing all of the methane that’s produced versus if you don’t have somewhere to put it.”

Longmont officials’ preplanning helped determine that Waste Services trucks could use all of that gas. They also set a long-term goal to fuel more vehicles, he added.

The timeframe for seeing the financial benefits is a year or longer, Kahler said. While Longmont no longer has to buy diesel fuel for 11 trucks, the total benefits have yet to reach full capacity. RNG systems are complex and it takes a while to work things out.

And while the market for these systems has slowed, they are catching on, thanks to municipalities like Longmont, Grand Junction, Boulder, and others that can show the impact they are having on their communities and their sustainability goals, he said.

Kahler said he’d like to see more organizations take advantage of the RNG opportunities available at WWTPs, landfills and dairies.

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