Come 2019, Longmont’s trash trucks will be powered by an entirely different kind of waste.
When wastewater — anything that gets flushed down a toilet or washed down a drain — comes into the Longmont Wastewater Treatment Plant, organic material is broken down by microorganisms in a process called anaerobic digestion.
The byproduct of anaerobic digestion is methane gas, 25 percent of which goes back into heating the anaerobic digestion process but the other 75 percent is simply set on fire.
“It’s the natural gas you get out of your home — methane. But there are a lot of contaminants in that gas so we are forced to flare it,” said John Gage, Longmont civil engineer. “If you were to burn it in an engine, it would cause all sorts of problems. So it’s a resource that, right now, is not being utilized.”
Longmont will install a biogas cleaning system that will turn the methane into compressed biogas that the city will use to fuel 11 of its 16 diesel trash trucks. The remaining five trucks will be replaced in 2021.
Longmont received a $1 million grant from the Colorado Department of Local Affairs to offset a portion of the costs required for the cleaning system and a $385,000 grant from the Colorado Regional Air Quality Council to offset costs of the more expensive trucks that run on biogas.
The city uses about 60,000 gallons of fossil fuels in the 11 trash trucks each year, according to a city news release. Diesel can run $3 or $4 a gallon, Gage said.
“It costs us to treat biogas the equivalent of $1 per gallon,” he said. “And we can maintain that for the foreseeable future.”
Longmont is the second city in Colorado to use methane from sewage treatment to fuel government vehicles. Grand Junction implemented its system in 2011.
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