Longmont Wastewater Treatment
Faced with high fuel prices and ever-increasing demands to cut costs and go green, communities around the country are looking for new ways to accomplish both. We recently visited one Colorado town who found their clean fleet solution in a not-so-clean place!
The city of Longmont calls itself ‘Colorado’s best kept secret.’ A community of 100,000 people located at the foot of the Rockies, 35 miles north of Denver. Steeped in small town charm with big city amenities, it takes just a few minutes of soaking in the spectacular mountain vistas and relaxed pace of life here to agree with that self-assessment.
Longmont’s waste services department collects refuse and recyclables from around 30 thousand homes a week, using a fleet of 22 collection trucks. Half of those are now powered by renewable natural gas, sourced and refined from, of all things, the city’s sewage system.
JOHN GAGE: "So, the process starts at our wastewater treatment plant. We have a one million gallon tank outfitted with mixing and heating equipment that converts some of that wastewater into a nutrient-rich fertilizer that is used beneficially locally in Colorado. But one of the side benefits of anaerobic digestion is that it creates a product called biogas. And biogas is comprised of about 60% methane and 40% CO2."
After removing the CO2 and common contaminants, they are left with a 90-95% methane concentration that is well-suited as a vehicle fuel.
With help from drive clean Colorado, local air quality groups, and grant agencies, Longmont has been able to purchase and convert 11 refuse trucks so far, with plans for the entire fleet to be upgraded to home-sourced natural gas within the next few years.
So, what was for decades being flared off as unwanted excess, is now completing the circle for a zero-waste clean fuel solution, now and for the future.
CHARLES KAMENIDES: "First off, going to CNG, we no longer use def or have to regen our trucks, which our drivers just love that.
But the other advantage of renewable natural gas over diesel is just the greenhouse gas output, and reducing our emissions as we’re driving through our community. We’re currently using 60 to 70 percent of all of the RNG that’s produced from our wastewater treatment plant. And we anticipate that as we continue to expand our RNG fleet, that we’ll have sufficient fuel to cover all of our needs."
The city built this dedicated facility to house the new trucks. Gas detectors and alarms throughout the building, as well as fans and vents that constantly refresh the air supply, allow the trucks to safely refuel with CNG indoors while being protected from harsh weather conditions year-round.
JOHN GAGE: "There are a lot of benefits to using renewable natural gas in vehicles. From the financial side, we received environmental credit through the EPA for utilizing renewable natural gas as vehicle fuel. Diesel fuel right now is anywhere between four to five dollars per gallon, and it only costs us a dollar and twenty cents to create a renewable natural gas diesel gallon equivalent."
Installing a system like this is not overly complicated, but does require a significant upfront investment in equipment to capture and scrub biogas into a useable vehicle fuel, along with the infrastructure to compress, store and dispense natural gas, and ongoing costs of replacing and converting vehicles.
That investment will pay off sooner rather than later, and projects like this are easily repeatable and worthy of consideration for many small cities. By all measures, Longmont’s renewable natural gas program is a resounding success. Though city residents have found one benefit of having clean trash haulers to be a mixed blessing.
CHARLES KAMENIDES: "Our residents scramble out, historically, when they hear the trash truck coming down the road. But with the new RNG, they’re super quiet, and they miss out on that opportunity to run out, so like everyone else, they have to take their trash out on time, before 7am."